Automated Manufacturing Systems Lecture Notes PDF

Lecture Notes on Automated Manufacturing Systems Department of Mechatronics Engineering Dr. Nikhil Vivek Shrivas  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Introduction: This course is offer...

Lecture Notes on Automated Manufacturing Systems Department of Mechatronics Engineering Dr. Nikhil Vivek Shrivas  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Introduction: This course is offered by Dept. of Mechatronics Engineering as a department program elective course, targeting students who wish to pursue the course focusing on the principles, concepts and technologies required/used to automate current manufacturing systems containing different equipment: robots, conveyor belts, automated guided vehicles, etc. The automotive industry is a known example of a sector applying these systems. Good automation practices, allied with the latest technology, are fundamental in improving production efficiency. This is a precondition for sustaining and/or increase industrial production. This course provides an overall exposure to the technology of Automated systems as widely seen in factories of all types both for discrete and continuous manufacturing. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Course Objectives: [MC4164.1] Identify the basics [MC4164. 2] Summarising [MC 4164.3] Examining of [MC4164.4] Understanding the [MC4164.5] Understanding the and different levels of different manufacturing rapid prototyping systems. fundamentals of cellular aspects of Product Life Cycle automation and strategies. aspects with respect to manufacturing and FMS. Management. additive manufacturing. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Criteria Description Maximum Marks Sessional Exam (Closed Book) 30 Assessment Plan: Internal Assessment (Summative) In class Quizzes and Assignments , Activity feedbacks (Accumulated and Averaged) 30 End Term Exam End Term Exam (Closed Book) 40 (Summative) Total 100 Attendance A minimum of 75% Attendance is required to be maintained by a student to be qualified for taking up the End Semester examination. The allowance of 25% (Formative) includes all types of leaves including medical leaves. Make up Assignments Students who misses a class will have to report to the teacher about the absence. A makeup assignment on the topic taught on the day of absence will (Formative) be given which has to be submitted within a week from the date of absence. No extensions will be given on this. The attendance for that particular day of absence will be marked blank, so that the student is not accounted for absence. These assignments are limited to a maximum of 5 throughout the entire semester. Homework/ Home There are situations where a student may have to work in home, especially Assignment/ Activity before a flipped classroom. Although these works are not graded with marks. Assignment However, a student is expected to participate and perform these assignments with full zeal since the activity/ flipped classroom participation by a student will (Formative) be assessed and marks will be awarded. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Syllabus Overview of Manufacturing and Automation: Production systems, Automation in production systems, Automation principles and strategies, Manufacturing operations, production facilities. Additive Manufacturing : Process Chain for Additive Manufacturing Processes, Rapid Prototyping Data Formats, Liquid Based Process, Rapid Freeze Prototyping, Solid Based Process, Powder Based Process, Rapid Tooling Application in design, engineering, analysis and planning, Applications. Subtractive Manufacturing: Computer numerically controlled machining, Numerical control in Non- Traditional Machining, Adoptive control Machining system. Basics of CNC programming (Simulation). Flexible Manufacturing System: Group Technology, Cellular Manufacturing, Quantitative Analysis of Cellular Manufacturing (Rank order Clustering), Flexible Manufacturing system (FMS), Quantitative analysis of FMS (Bottleneck model), Computer Aided Process Planning (CAPP). Product Life Cycle and Data Management (PLDM): Components of PLM, phases of PLM, PLM feasibility study, PLM visioning. PLM Strategies, Strategies for recovery at end of life, recycling. Product Data Management systems and importance, barriers to PDM implementation Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 References: C.K. Chua, K.F. Leong, C.S. Lim, Rapid Prototyping: Principles and Applications, (3e), 2010. Gibson, I, Rosen, D W., and Stucker, B., Additive Manufacturing Methodologies: Rapid Prototyping to Direct Digital Manufacturing, Springer, 2014. Groover Mikell P, Automation, Production Systems, and Computer Integrated manufacturing, (4e), Prentice Hall of India. New Delhi, 2016. Kalpakajain, Manufacturing Engineering and Technology, (4e), Addison Wesley, New York, 2014. Saaksvuori, Antti, Immonen, Anselmi, Product Lifecycle Management, (2e), Springer-Verlag Berlin Heidelberg, 2005. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Lecture Plan: Lec No Topics Session Outcome Mode of Delivery Corresponding CO Mode of Assessing the Outcome 1 Overview of Manufacturing and Automation: To acquaint and clear teachers Lecture 4164.1 NA Production systems, Automation in production expectations and understand student systems, expectations along with focus on introduction of automation 2 Automation principles and strategies, Explaining what is automation and its Lecture 4164.1 In Class Quiz ( Not Accounted) principles 3 Manufacturing operations, production facilities. Learning basic components of Lecture 4164.1 In Class Quiz automation End Term 5 Additive Manufacturing: Process Chain for Additive Define the term additive manufacturing. Lecture 4164.1 End Term Manufacturing Processes, Identify different levels 4164.2 6,7 Additive Manufacturing: ProcessChain for Additive Knowledge of types of AM processes Activity (Think Pair 4164.2 In Class Quiz ManufacturingProcesses, and able to summarise working of such Share) systems End Term 8 Rapid Prototyping Data Formats Expressing of different RP data formats Activity (Think Pair 4164.2 Class Quiz Share) Mid Term I End Term 9 Liquid Based Process Knowledge of liquid based process 10 Rapid Freeze Prototyping Able to interpret and understand Lecture 4164.3 Class Quiz identification technologies of RFP Mid Term 1 4164.3 End term Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 11 Solid Based Process, Lecture Plan: Identifying the types and basics of Lecture 4164.2 Home Assignment Solid based process of RP Class Quiz Mid Term 1 End Term 12 Powder Based Process, Able to compare the powder based Lecture Class Quiz process with other RP 4164.3 Mid Term 1 End Term 13 Rapid Tooling Application in design, engineering Recall applications of tools in design Activity (Think Pair Class Quiz Share) Mid Term I End Term 14 analysis and planning, Applications. Recall the basis of RP Lecture with PPT 4164.3 Class Quiz End Term 15,16 analysis and planning, Applications. Examining the RP AM. Lecture/ Activity 4164.3 Class Quiz (Think Pair Share) Mid Term II End Term 17 Subtractive Manufacturing: Recall production lines in context to automation thorough SM 18,19 Computer numerically controlled machining, Identify and examine non-traditional Lecture/ 4164.3 Class Quiz Numerical control in Non-Traditional Machining machining lines of production assembly Demonstration 4164.4 Mid Term II End Term 20,21 Adoptive control Machining system Recall adaptive control systems in Lecture/ 4164.3 Class Quiz context to automation Demonstration 4164.4 Mid Term II End Term Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Lecture Plan: 22,23 Basics of CNC programming (Simulation). Inferring the use of group Lecture/ 4164.4 Class Quiz technology in cellular Demonstration Mid Term II manufacturing End Term 24,25 Flexible Manufacturing System: Group Examining the applications of group Lecture/ 4164.4 Class Quiz Technology technology Demonstration End Term 26 Cellular Manufacturing, Quantitative Analysis Identify different basics of FMS Lecture/ 4164.4 Class Quiz of Cellular Manufacturing (Rank order Demonstration Clustering), End Term 27 Quantitative analysis of FMS (Bottleneck Describe the approaches of FMS Lecture 4164.4 Class Quiz model), Computer Aided Process Planning and its analysis (CAPP). End Term 28 Product Life Cycle and Data Management Describe the aspects of PLCM in Lecture 4164.5 Class Quiz (PLDM): Components of PLM automation End Term 29 , phases of PLCM, PLCM feasibility study Recall the process with aspects of Lecture 4164.5 Class Quiz PLCM End Term 30,31 PLM visioning. PLM Strategies Examining the techniques of PLCM Lecture 4164.5 Class Quiz End term Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Lecture Plan: 32 PLM visioning. PLM Strategies Understanding of PLCM tools Lecture/ Activity 4164.5 Class Quiz (Think Pair Share) 33 Strategies for recovery at end of life, recycling. Recall the fundamentals of recycling Lecture 4164.5 Class Quiz Mid Term II End Term 34,35 Product Data Management systems and Examining the benefits of DMS w.r.t Lecture/ Activity 4164.5 Class Quiz importance PLCM (Think Pair Share) Mid Term II End Term 36 barriers to PDM implementation Hurdles in implementing PLCM Lecture/ Activity 4164.5 Class Quiz (Think Pair Share) Mid Term II End Term Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Lecture- 1 Introduction Sections: 1. Production Systems 2. Automation in Production Systems Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Production System Defined A collection of people, equipment, and procedures organized to accomplish the manufacturing operations of a company Two categories: Facilities – the factory and equipment in the facility and the way the facility is organized (plant layout) Manufacturing support systems – the set of procedures used by a company to manage production and to solve technical and logistics problems in ordering materials, moving work through the factory, and ensuring that products meet quality standards Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Production System Facilities Facilities include the factory, production machines and tooling, material handling equipment, inspection equipment, and computer systems that control the manufacturing operations Plant layout – the way the equipment is physically arranged in the factory Manufacturing systems – logical groupings of equipment and workers in the factory Production line Stand-alone workstation and worker Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Automation in Production Systems Two categories of automation in The two categories overlap the production system: because manufacturing support Automation of manufacturing systems are connected to the systems in the factory factory manufacturing systems Computerization of the Computer-Integrated manufacturing support Manufacturing (CIM) systems Computer Integrated Manufacturing Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Automation Principles and Strategies The USA Principle Ten Strategies for Automation and Process Improvement Automation Migration Strategy Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Input/output analysis Understand the Value chain analysis Charting techniques existing process and mathematical modeling U.S.A Simplify the Reduce unnecessary steps and moves process Principle Ten strategies for Automate the automation and production systems process Automation migration strategy Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Ten Strategies for Automation and Process Improvement 1. Specialization of operations 2. Combined operations 3. Simultaneous operations 4. Integration of operations 5. Increased flexibility 6. Improved material handling and storage 7. On-line inspection 8. Process control and optimization 9. Plant operations control 10. Computer-integrated manufacturing Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Automation Migration Strategy For Introduction of New Products 1 2 3 Phase 1 – Manual Phase 2 – Automated Phase 3 – Automated production production integrated production Single-station manned cells Single-station automated Multi-station system with working independently cells operating independently serial operations and Advantages: quick to set up, As demand grows and automated transfer of work low-cost tooling automation can be justified units between stations Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 What Is Additive Manufacturing? Additive Manufacturing (AM) refers to a process by which digital 3D design data is used to build up a component in layers by depositing material Additive manufacturing is the formalized term for what used to be called rapid prototyping and what is popularly called 3D Printing. The basic principle of this technology is that a model, initially generated using a three-dimensional Computer-Aided Design (3D CAD) system, can be fabricated directly without the need for process planning. Parts are made by adding material in layers; each layer is a thin cross-section of the part derived from the original CAD data. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Process Chain for Additive Manufacturing ( Generic AM process) Step 1: CAD CAD models that fully describe the external geometry are required for all AM parts. Any professional CAD solid modelling software can be used to create this, but the final product must be a 3D solid or surface model. To create such an image, reverse engineering equipment (for example, laser and optical scanning) can also be used. Step 2: Conversion to STL Upon completion of the digital model, the STL (Standard Tessellation Language) file format must be used to create the stereolithography. Nearly every CAD system supports this format, which is how AM machines communicate. The STL file serves as the basis for calculating the slices of the model. Step 3: Transfer to Machine In the third step, the STL file is transmitted to the AM machine. As a result of this step, it is possible to adjust the build so that it is positioned and sized correctly. A computer controls the AM machine. The AM machine is controlled by the computer, that computer only generates the required instruction in the form of G-codes and M-codes based on the given process parameters. It generates instructions automatically, if any correction is needed for the betterment of the part to be built it can be corrected. Step 4: Setup Before the building starts, the equipment must be set up. The settings can constitute power, speed, layer thickness, and other several parameters related to material and process constraints, etc. Step 5: Build The fifth step is the actual building of the CAD model, melting layer by layer. This process can be semi, or fully automated but some online monitoring is often conducted, so that the machine does not run out of material or that some software error occurs. Step 6: Part Removal Once the part is manufactured it must be removed from the process, which is normally done manually. This may require interaction with the machine, which may have safety interlocks to ensure, for example, that the operating temperatures are sufficiently low or that there are no actively moving parts. Step 7: Post-processing After the build, the part might need some post-processing before it is finished. Of course, depending on the material and AM process used, some parts might need machining, cleaning, polishing, removal of support structures, hot isostatic pressing (HIP), and heat treatments. Step 8: Application At this stage, the part can be ready for use. Nevertheless, it could also need some additional treatments, like painting, or assembling with other components before it is fully usable. For example, they may require priming and painting to give an acceptable surface texture and finish. Treatments may be laborious and lengthy if the finishing requirements are very demanding. They may also be required to be assembled with other mechanical or electronic components to form a final model or product. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Geometric Modeling Prototyping Prototyping ❶ First Phase: 2D Wireframe ❶ First Phase: Manual Prototyping Started in mid-1960s Traditional practice for A prototype is the first or original example of Few straight lines on display may be: manycenturies circuit path on a PCB Prototyping as a skilled crafts is: something that has been or will be copied or plan view of a mechanical component traditional and manual “Natural” drafting technique based on material of prototype developed; it is a model or preliminary version; “Natural” prototyping technique ➋ Second Phase: 3D Curve andSurface Modeling ➋ Second Phase: Soft or VirtualPrototyping e.g.: A prototype supersonic aircraft. Mid-1970s Mid-1970s Increasing complexity Increasing complexity Types of Prototypes Representing more information about precise Virtual prototype can be stressed, simulated 1. the implementation of the prototype; from shape, size and surface contour of parts and tested, with exact mechanical and other properties the entire product (orsystem) itself to its sub-assemblies and components, ⮊ Third Phase: Solid Modeling ⮊ Third Phase: Rapid Prototyping Early 1980s Mid-1980s Edges, surfaces and holes are knitted together Benefit of a hard prototype made in a very 2. the form of the prototype; from a virtual to form a cohesive whole short turnaround time is its main strong point prototype to a physicalprototype, and Computer can determine the inside of an (relies on CAD modeling) object from the outside. Perhaps, more Hard prototype can also be used for limited importantly, it can trace across the object and testing 3. the degree of the approximation of the readilyfind all intersecting surfaces and edges Prototype can also assist in the manufacturing prototype; from a very rough representation No longer ambiguous but exact of the products to an exact replication of the product. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Rapid Prototyping A family of unique fabrication processes developed to make engineering prototypes in minimum lead time based on a CAD model of the item 1. Input:-Input refers to the electronic information required to describe the physical object with 3D data. There are two possible starting points — a computer model or a physical model. The computer model created by a CAD system can be either a surface model or a solid model. On the other hand, 3D data from the physical model is not at all straightforward. It requires data acquisition through a method known as reverse engineering. In reverse engineering, a wide range of equipment can be used, such as CMM (coordinate measuring machine) or a laser digitizer, to capture data points of the physical model and “reconstruct”it in a CAD system. 2. Method:-While they are currently more than 20 vendors for RP systems, the method employed by each vendor can be generally classified into the following categories: photo-curing, cutting and glueing/joining, melting and solidifying/fusing and joining/binding. Photo-curing can be further divided into categories of single laser beam, double laser beams and masked lamp. 3. Material:-The initial state of material can come in either solid, liquid or powder state. In solid state, it can come in various forms such as pellets, wire or laminates. The current range materials include paper, nylon, wax,resins, metals and ceramics. 4. Applications:-Most of the RP parts are finished or touched up before they are used for their intended applications. Applications can be grouped into (1) Design (2) Engineering, Analysis, and Planning and (3) Tooling and Manufacturing. A wide range of industries can benefit from RP and these include, but are not limited to, aerospace, automotive, biomedical, consumer, electrical and electronics products. The Rapid Prototyping Wheel depicting the four major aspects of RP Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 ADVANTAGES OF RAPID PROTOTYPING Benefits to Product Designers Benefits to the Tooling and Manufacturing Engineer Benefits to Marketing Benefits to the Consumer Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 CLASSIFICATION OF RAPID PROTOTYPINGSYSTEMS 1. Liquid-Based Liquid-based RP systems have the initial form of its material in liquid state. Through a process commonly known as curing, the liquid is converted into the solid state. The following RP systems fall into this category: (1) 3D Systems’ Stereolithography Apparatus (SLA) (2) Cubital’s Solid Ground Curing (SGC) (3) Sony’s Solid Creation System (SCS) (4) CMET’s Solid Object Ultraviolet-Laser Printer (SOUP) (5) Autostrade’s E-Darts (6) Teijin Seiki’s Soliform System (7) Meiko’s Rapid Prototyping System for the Jewelry Industry (8) Denken’s SLP (9) Mitsui’s COLAMM (10) Fockele & Schwarze’s LMS (11) Light Sculpting (12) Aaroflex (13) Rapid Freeze (14) Two Laser Beams (15) Microfabrication Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 CLASSIFICATION OF RAPID PROTOTYPINGSYSTEMS Except for powder, solid-based RP systems are meant to encompass all forms of material in the 2. Solid-Based solid state. In this context, the solid form can include the shape in the form of a wire, a roll, laminates and pellets.The following RP systems fall into this definition: (1) Cubic Technologies’ Laminated Object Manufacturing (LOM) (2) Stratasys’ Fused Deposition Modeling (FDM) (3) Kira Corporation’s Paper Lamination Technology (PLT) (4) 3D Systems’ Multi-Jet Modeling System (MJM) (5) Solidscape’s ModelMaker and PatternMaster (6) Beijing Yinhua’s Slicing Solid Manufacturing (SSM), Melted Extrusion Modeling (MEM) and Multi-Functional RPM Systems(M-RPM) (7)CAM-LEM’s CL 100 Ennex Corporation’s Offset Fabbers Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 CLASSIFICATION OF RAPID PROTOTYPINGSYSTEMS 3. Powder-Based In a strict sense, powder is by-and-large in the solid state. However, it is intentionally created as a category outside the solid-based RP systems to mean powder in grain-like form. The following RP systems fall into this definition: (1) 3D Systems’s Selective Laser Sintering (SLS) (2) EOS’s EOSINT Systems (3) Z Corporation’s Three-Dimensional Printing (3DP) (4) Optomec’s Laser Engineered Net Shaping (LENS) (5) Soligen’s Direct Shell Production Casting (DSPC) (6) Fraunhofer’s Multiphase Jet Solidification (MJS) (7) Acram’s Electron Beam Melting (EBM) (8) Aeromet Corporation’s Lasform Technology (9) Precision Optical Manufacturing’s Direct Metal Deposition(DMDTM) (10) Generis’ RP Systems (GS) (11) Therics Inc.’s Theriform Technology (12) Extrude Hone’s PrometalTM 3D Printing Process Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 RAPID PROTOTYPING PROCESS CHAIN As such all RP systems generally have a similar sort of process chain. Such a generalized process chain is shown in Figure. There are a total of five steps in the chain and these are 3D UV Curing Oven, Ultra- sonic Cleaning, Chemical Material and Devices 3D 3D CAD Modeling Workstation 1. 3D MODELING 2. DATA CONVERSION AND Data Conversion & Transmission Diskette, email or LAN TRANSMISSION 3. CHECKING AND PREPARING 4. BUILDING Building Checking & Preparing RP Equipment C omputer of RP Equipment (SLA, SLS, FDM, etc) 5. POSTPROCESSING Process chain of Rapid Prototyping process Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Additive Processes Additive rapid-prototyping operations all build parts in layers, which are typically 0.1 to 0.5 mm thick and can be thicker for some systems. Additive operations require elaborate software. The first step is to obtain a CAD file description of the part. The computer then constructs slices of the three-dimensional part. Each slice is analyzed separately, and a set of instructions is compiled in order to provide the rapid-prototyping machine with detailed information regarding the manufacture of the part. Starting Materials in Material Addition RP 1. Liquid monomers that are cured layer by layer into solid polymers 2. Powders that are aggregated and bonded layer by layer 3. Solid sheets that are laminated to create the solid part Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 The common approach to prepare the control instructions (part program) in all of the current material addition RP techniques involves the following steps 1. Geometric modeling. This consists of modeling the component on a CAD system to define its enclosed volume. Solid modeling is the preferred technique because it provides a complete and unambiguous mathematical representation of the geometry. For rapid prototyping, the important issue is to distinguish the interior (mass) of the part from its exterior, and solid modeling provides for this distinction. 2.Tessellation of the geometric model. In this step, the CAD model is converted into a format that approximates its surfaces by triangles or polygons, with their vertices arranged to distinguish the object’s interior from its exterior. The common tessellation format used in rapid prototyping is STL, which has become the de facto standard input format for nearly all RP systems. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 3. Slicing of the model into layers In this step, the model in STL file format is sliced into closely spaced parallel horizontal layers. Conversion of a solid model into layers is illustrated. These layers are subsequently used by the RP system to construct the physical model. By convention, the layers are formed in the x-y plane orientation, and the layering procedure occurs in the z-axis direction. For each layer, a curing path is generated, called the STI file, which is the path that will be followed by the RP system to cure (or otherwise solidify) the layer. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Production of STL file from 3d cad model There are many different ways to 3D print an object. But nearly all of them utilize computer aided design (CAD) files. CAD files are digitalized representations of an object. They're used by engineers and manufacturers to turn ideas into computerized models that can be digitally tested, improved and most recently, 3D printed. In 3D printing or additive manufacturing CAD files must be translated into a "language," or file type, that 3D printing machines can understand. Standard Tessellation Language (STL) is one such file type and is the language most commonly used for stereolithography, as well as other additive manufacturing processes. Since additive manufacturing works by adding one layer of material on top of another, CAD models must be broken up into layers before being printed in three dimensions. STL files "cut up" CAD models, giving the 3D printing machine the information it needs to print each layer of an object. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 What is a STL File? A STL file is a format used by Stereolithography software to generate information needed to produce 3D models on Stereolithography machines. In fact, the extension "stl" is said to be derived from the word "Stereolithography." A slightly more specific definition of a stl file is a triangular representation of a 3D object. The surface of an object is broken into a logical series of triangles (see illustration at right). Each triangle is uniquely defined by its normal and three points representing its vertices. The stl file is a complete listing of the xyz coordinates of the vertices and normals for the triangles that describe the 3D object. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Often a stl file can be termed "bad" because of translation issues. In many CAD systems, the number of triangles that represent the model can be defined by the user. If too many triangles are created, the stl file size can become unmanageable. If too few triangles are created, curved areas are not properly defined and a cylinder begins to look like a hexagon (see example ). When creating a stl file, the goal is to achieve a balance between unmanageable file size and a well-defined model with smooth curved geometries. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 How to create a STL file? Most CAD software packages offer stl conversion add-ins. If we have access to conversion software, stl translation is relatively simple as long as you have a clean-surfaced 3D model and a high-end computer. Traditionally when converting to a stl file, the user is given several options for resolution (sometimes called chord height, triangle tolerance, etc.). Depending upon the size of the model, the geometry of small details, and the overall curvature of the part, the tolerance can typically be set to.001 inch for average models. Small parts or models with fine details may require a tighter tolerance. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Additive Process techniques include; ❑ Stereolitliograpliy, ❑ MultiJet/ PolyJet modeling, ❑ Fused deposition modeling, ❑ Ballistic-particle manufacturing, ❑ 3D printing, ❑ Selective laser sintering, ❑ Electron-beam and ❑ Laminated-object manufacturing. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Stereolithography This was the first material addition RP technology, dating from about 1988 and introduced by3DSystems, Inc. based on the work of inventor CharlesHull. (STL) is a process for fabricating a solid plastic part out of a photosensitive liquid polymer using a directed laser beam to solidify the polymer Part fabrication is accomplished as a series of layers, in which one layer is added onto the previous layer to gradually build the desired three dimensional geometry. The stereolithography apparatus consists of (1) a platform that can be moved vertically inside a vessel containing the photosensitive polymer (2) a laser whose beam can be controlled in the x-y direction. At the start of the process, the platform is positioned vertically near the surface of the liquid photopolymer, and a laser beam is directed through a curing path that comprises an area corresponding to the base (bottom layer) of the part. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 STL (STereoLithography) is a file format native to the stereolithography CAD software created by 3D Systems. STL is also known as Standard Tessellation Language. This file format is supported by many other software packages; it is widely used for rapid prototyping and computer-aided manufacturing. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 This and subsequent curing paths are defined by the STL file (step 3 in preparing the control instructions described in the preceding). The action of the laser is to harden (cure) the photosensitive polymer where the beam strikes the liquid, forming a solid layer of plastic that adheres to the platform. When the initial layer is completed, the platform is lowered by a distance equal to the layer thickness, and a second layer is formed on top of the first by the laser, and so on. Before each new layer is cured, a wiper blade is passed over the viscous liquid resin to ensure that its level is the same throughout the surface. Each layer consists of its own area shape, so that the succession of layers, one on top of the previous, creates the solid part shape. Each layer is 0.076 to 0.50 mm thick. Thinner layers provide better resolution and allow more intricate part shapes; but processing time is greater. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 After all of the layers have been formed, the photopolymer is about 95% cured. The piece is therefore ‘‘baked’’ in a fluorescent oven to completely solidify the polymer. Excess polymer is removed with alcohol, and light sanding is sometimes used to improve smoothness and appearance. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Photopolymers are typically acrylic , although use of epoxy for STL has also been reported. The starting materials are liquid monomers. Polymerization occurs upon exposure to ultraviolet light produced by helium-cadmium or argon ion lasers. Scan speeds of STL lasers typically range between 500 and 2500 mm/s. The time required to build the part by this layering process ranges from 1 hour for small parts of simple geometry up to several dozen hours for complex parts. Other factors that affect cycle time are scan speed and layer thickness. The part build time in stereolithography can be estimated by determining the time to complete each layer and then summing the times for all layers. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 A common rapid-prototyping process-one that actually was developed prior to fused-deposition modeling-is stereolit/aography (STL). This process is based on the principle of curing (hardening) a liquid photopolymer into a specific shape. A vat containing a mechanism whereby a platform can be lowered and raised is filled with a photocurable liquid- acrylate polymer. The liquid is a mixture of acrylic monomers, oligomers (polymer intermediates), and a photoinitiator (a compound that undergoes a reaction upon absorbing light). Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Multijet/Polyjet Modeling Multijet Modeling (MJM) or Polyjet process is similar to inkjet printing, where print heads deposit the photopolymer on the build tray. Ultraviolet bulbs, alongside the jets, immediately cure and harden each layer, thus eliminating the need for any postmodeling curing that is needed in stereolithography. The result is a smooth surface of thin layers as small as 16µm that can be handled immediately after the process is completed. Two different materials are used: One material is used for the actual model, while a second, gel-like resin is used for support Each material is simultaneously jetted and cured, layer by layer. When the model is completed, the support material is removed with an aqueous solution. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Build sizes are fairly large, with an envelope of up to 500 X400X200 mm. These processes have capabilities similar to those of stereolithography and use similar resins. The main advantages are the capabilities of avoiding part cleanup and lengthy postprocess curing operations, and the much thinner layers produced, thus allowing for better resolution. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Selective Laser Sintering Selective laser sintering (SLS) is a process based on the sintering of nonmetallic or (less commonly) metallic powders selectively into an individual object. The bottom of the processing chamber is equipped with two cylinders: I. A powder-feed cylinder, which is raised incrementally to supply powder to the part-build cylinder through a roller mechanism. 2. A part-build cylinder, which is lowered incrementally as the part is being formed. First, a thin layer of powder is deposited in the part-build cylinder. Then a laser beam guided by a process-control computer using instructions generated by the three- dimensional CAD program of the desired part is focused on that layer, tracing and sintering a particular cross section into a solid mass. The powder in other areas remains loose, yet it supports the sintered portion. Another layer of powder is then deposited; this cycle is repeated again and again until the entire three-dimensional part has been produced. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 The loose particles are shaken off, and the part is recovered. The part does not require further curing-unless it is a ceramic, which has to be fired to develop strength. A variety of materials can be used in this process, including polymers (such as ABS, PVC, nylon, polyester, polystyrene, and epoxy), wax, metals, and ceramics with appropriate binders. It is most common to use polymers because of the smaller, less expensive, and less complicated lasers required for sintering. With ceramics and metals, it is common to sinter only a polymer binder that has been blended with the ceramic or metal powders. The resultant part can be carefully sintered in a furnace and infiltrated with another metal if desired. Thickness 0.075 to 0.50mm Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Fused deposition modeling Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing System s | M C 4164 | 3 Credits | 3 0 0 3 In the fused-deposition-modeling process a gantry robot controlled extruder head moves in two principal directions over a table, which can be raised and lowered as needed. A thermoplastic filament is extruded through the small orifice of a heated die. The initial layer is placed on a foam foundation by extruding the filament at a constant rate while the extruder head follows a predetermined path. When the first layer is completed, the table is lowered so that subsequent layers can be superimposed. Some parts are difficult to manufacture directly, because once the part has been constructed up to height a, the next slice would require the filament to be placed in a location where no material exists beneath to support it. The solution is to extrude a support material separately from the modeling material. The use of such support structures allows all of the layers to be supported by the material directly beneath them. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 The support material is produced with a less dense filament spacing on a layer, so it is weaker than the model material and can be broken off easily after the part is completed. The layers in an FDM model are determined by the extrusion-die diameter, which typically ranges from 0.050 to 0.12 mm. This thickness represents the best achievable tolerance in the vertical direction. In the x-y plane, dimensional accuracy can be as fine as 0.025 mm-as long as a filament can be extruded into the feature. A variety of polymers are available for different applications. Flat wire metal deposition uses a metal Wire instead of a polymer filament, but also needs a laser to heat and bond the deposited Wire to build parts. Close examination of an FDM-produced part will indicate that a stepped surface exists on oblique exterior planes. If this surface roughness is objectionable, a heated tool can be used to smooth the surface, the surface can be hand sanded, or a coating can be applied (often in the form of a polishing Wax ). The overall tolerances are then compromise d unless care is taken in these finishing operations. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Electron-beam Melting A process similar to selective laser sintering and electron-beam welding electron-beam melting uses the energy source associated with an electron beam to melt titanium or cobalt-chrome powder to make metal prototypes. The workpiece is produced in a vacuum; the part build size is limited to around 200 x200 x180 mm. Electron-beam melting (EBM) is up to 95% efficient from an energy standpoint (compared with 10-20% efficiency for selective laser Sintering) The titanium powder is actually melted and fully dense parts can be produced. A volume build rate of up to 60 cm3/hr can be obtained, with individual layer thicknesses of 0.05 0-0.200 mm. Hot isostatic pressing also can be performed on parts to improve their fatigue strength. Although applied mainly to titanium and cobalt-chrome to date, the process is being developed for stainless steels, aluminum, and copper alloys. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 In the three-dimensional-printing (3DP) process, a print head deposits an inorganic binder material onto a layer of polymer, ceramic, or metallic powder. This RP technology was developed at Massachusetts Institute of Technology. Three-dimensional printing (3DP) builds the part in the usual layer-by-layer fashion using an ink-jet printer to eject an adhesive bonding material onto successive layers of powders. The binder is deposited in areas corresponding to the cross sections of the solid part, as determined by slicing the CAD geometric model into layers. The binder holds the powders together to form the solid part, while the unbonded powders remain loose to be removed later. While the loose powders are in place during the build process, they provide support for overhanging and fragile features of the part. When the build process is completed, the part is heat treated to strengthen the bonding, followed by removal of the loose powders. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 To further strengthen the part, a sintering step can be applied to bond the individual powders. The part is built on a platform whose level is controlled by a piston. Process will be as follows (1) A layer of powder is spread on the existing part-in-process. (2) An ink-jet printing head moves across the surface, ejecting droplets of binder on those regions that are to become the solid part. (3) When the printing of the current layer is completed, the piston lowers the platform for the next layer. Starting materials in 3DP are powders of ceramic, metal, or cermet, and binders that are polymeric or colloidal silica or silicon carbide. Typical layer thickness ranges from 0.10 to 0.18 mm. The ink-jet printing head moves across the layer at a speed of about 1.5 m/s, with ejection of liquid binder determined during the sweep by raster scanning. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 The sweep time, together with the spreading of the powders, permits a cycle time per layer of about 2 seconds Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Laminated-Object Manufacturing Laminated-object manufacturing produces a solid physical model by stacking layers of sheet stock that are each cut to an outline corresponding to the cross-sectional shape of a CAD model that has been sliced into layers. The layers are bonded one on top of the previous one before cutting. After cutting, the excess material in the layer remains in place to support the part during building. Starting material in LOM can be virtually any material in sheet stock form, such as paper, plastic, cellulose, metals, or fiber-reinforced materials. Stock thickness is 0.05 to 0.50 mm.In LOM, the sheet material is usually supplied with adhesive backing as rolls that are spooled between two reels. Otherwise, the LOM process must include an adhesive coating step for each layer. The data preparation phase in LOM consists of slicing the geometric model using the STL file for the given part. The slicing function is accomplished by LOMSliceTM, the special software used in laminated-object manufacturing. Slicing the STL model in LOM is performed after each layer has been physically completed and the vertical height of the part has been measured. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 (1) LOMSliceTM computes the cross-sectional perimeter of the STL model based on the measured height of the physical part at the current layer of completion. (2)A laser beam is used to cut along the perimeter, as well as to crosshatch the exterior portions of the sheet for subsequent removal. The laser is typically a 25 or 50 W CO2 laser. The cutting trajectory is controlled by means of an x-y positioning system. The cutting depth is controlled so that only the top layer is cut. (3)The platform holding the stack is lowered, and the sheet stock is advanced between supply roll and take-up spool for the next layer. The platform is then raised to a height consistent with the stock thickness and a heated roller moves across the new layer to bond it to the previous layer. The height of the physical stack is measured in preparation for the next slicing computation by LOMSliceTM. When all of the layers are completed, the new part is separated from the excess external material using a hammer, putty knife, and wood carving tools. LOM part sizes can be relatively large among RP processes, with work volumes up to 800 mm 500 mm by 550 mm (32 in 20 in 22 in). More common work volumes are 380 mm 250 mm 350 mm Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing System s | M C 4164 | 3 Credits | 3 0 0 3 Solid-ground Curing or solid based curing This process is unique in that entire slices of a part are manufactured at one time. As a result, a large throughput is achieved, compared with that from other rapidprototyping processes. However, solid-ground curing (SGC) is among the most expensive processes; hence, its adoption has been much less common than that of other types of rapid prototyping, and new machines are not available. Basic all , the method consists of the following steps: I. Once a slice is created by the computer software, a mask of the slice is printed on a glass sheet by an electrostatic printing process similar to that used in laser printers. A mask is required because the area of the slice where the solid material is desired remains transparent. 2.While the mask is being prepared, a thin layer of photoreactive polymer is deposited on the work surface and is spread evenly. 3. The photo mask is placed over the work surface, and an ultraviolet floodlight is projected through the mask. Wherever the mask is clear, the light shines through to cure the polymer and causes the desired slice to be hardened. 4. The unaffected resin (still liquid) is vacuumed off the surface. 5.Water-soluble liquid wax is spread across the work area, filling the cavities previously occupied by the unexposed liquid polymer. Since the workpiece is on a chilling plate and the workspace remains cool, the wax hardens quickly. 6. The layer is then milled to achieve the correct thickness and flatness. 7. This process is repeated-layer by layer-until the part is completed. Solid-ground curing has the advantage of a high production rate, because entire slices are produced at once and two glass screens are used concurrently. That is, while one mask is being used to expose the polymer, the next mask already is being prepared, and it is ready as soon as the milling operation is completed. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Rapid Tooling Rapid-prototyping techniques have made possible much faster product development times, and they are having a major effect on other manufacturing processes. When appropriate materials are used, rapid-prototyping machinery can produce blanks for investment casting or similar processes, so that metallic parts can now be obtained quickly and inexpensively, even for lot sizes as small as one part. Such technologies also can be applied to producing molds for operations (such as injection molding, sand and shell mold casting, and even forging), thereby significantly reducing the lead time between design and manufacture. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Several methods have been devised for the rapid production of tooling (RT) by means of rapid-prototyping processes. The advantages to rapid tooling include the following: 1. The high cost of labor and short supply of skilled patternmakers can be overcome. 2. There is a major reduction in lead time. 3. Hollow designs can be adopted easily so that lightweight castings can be produced more easily. 4.The integral use of CAD technologies allows the use of modular dies with base- mold tooling (match plates) and specially fabricated inserts. This modular technique can further reduce tooling costs. 5.Chill- and cooling-channel placement in molds can be optimized more easily, leading to reduced cycle times. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 6. Shrinkage due to solidification or thermal contraction can be compensated for automatically through software to produce tooling of the proper size and, in turn, to produce the desired parts. The main shortcoming of rapid tooling is the potentially reduced tool or pattern life (compared to those obtained from machined tool and die materials, such as tool steels or tungsten carbides). The simplest method of applying rapid-prototyping operations to other manufacturing processes is in the direct production of patterns or molds. Example : Investment casting The individual patterns are made in a rapid-prototyping operation (in this case, stereolithography) and then used as patterns in assembling a tree for investment casting. As drawn in CAD programs, the parts are usually software modified to account for shrinkage, and it is then that the modified part is produced in the rapidprototyping machinery. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Example: 3DP 3DP can easily produce a ceramic-mold casting shell or a sand mold in which an aluminum- oxide or aluminum-silica powder is fused with a silica binder. The molds have to be post processed in two steps: curing at around 150°C and then firing at 1000°-1500°C. Example: Injection Molding Injection molding in which the mold or, more typically, a mold insert is manufactured by rapid prototyping. The advantage of rapid tooling is the capability to produce a mold or a mold insert that can be used to manufacture components without the time lag (typically several months) traditionally required for the procurement of tooling. Furthermore, the design is simplified, because the designer need only analyze a CAD file of the desired part; software then produces the tool geometry and automatically compensates for shrinkage. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Other rapid-tooling approaches Room-temperature vulcanizing (RTV) molding/urethane casting can be performed by preparing a pattern of a part by any rapid-prototyping operation. The pattern is coated with a parting agent and may or may not be modified to define mold parting lines. Liquid RTV rubber is poured over the pattern, and cures (usually within a few hours) to produce mold halves. The mold is then used with liquid urethanes in injection molding or reaction-injection molding operations Epoxy or aluminum-filled epoxy molds also can be produced, but mold design then requires special care. With RTV rubber, the mold flexibility allows it to be peeled off the cured part. With epoxy molds, the high stiffness precludes this method of part removal, and mold design is more complicated. Thus, drafts are needed, and undercuts and other design features that can be produced by RTV molding must be avoided. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Acetal clear epoxy solid (ACES) injection molding, also known as direct AIM, refers to the use of rapid prototyping (usually stereolithography) to directly produce molds suitable for injection molding. The molds are shells with an open end to allow filling with a material such as epoxy, aluminum-filled epoxy, or a low-melting-point metal. Depending on the polymer used in injection molding, mold life may be as few as 10 parts, although a few hundred parts per mold are possible. Sprayed-metal tooling. In this process a pattern is created through rapid prototyping. A metal spray operation then coats the pattern surface with a zinc-aluminum alloy. The metal coating is placed in a flask and potted with an epoxy or an aluminum-filled epoxy material. In some applications, cooling lines can be incorporated into the mold before the epoxy is applied. The pattern is removed; two such mold halves are then suitable for use in injection-molding operations. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Keltool process. In the Keltool process, an RTV mold is produced based on a rapid-prototyped pattern, as described earlier. The mold is then filled with a mixture of powdered A6 tool steel tungsten carbide, and polymer binder, and is allowed to cure. The so-called green tool (green, as in ceramics and powdermetallurgy) is fired to burn off the polymer and fuse the steel and the tungsten-carbide powders. The tool is then infiltrated with copper in a furnace to produce the final mold. The mold can subsequently be machined or polished to attain a superior surface finish and good dimensional tolerances. Keltool molds are limited in size to around 150 >< 150 >< 150 mm, so, typically, a mold insert suitable for high-volume molding operations is produced. Depending on the material and processing conditions, mold life can range from 100,000 to 10 million parts. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 STL FORMAT Representation methods used to describe CAD geometry vary from one system to another. A standard interface is needed to convey geometric descriptions from various CAD packages to rapid prototyping systems. The STL (STereoLithography) file, as the de facto standard, has been used in many, if not all, rapid prototyping systems. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 STL FORMAT… The STL file, conceived by the 3D Systems, USA, is created from the CAD database via an interface on the CAD system. This file consists of an unordered list of triangular facets representing the outside skin of an object. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 TWO FORMATS OF STL FILE ASCII format Binary format The size of the ASCII STL file is larger than that of the binary format but is human readable. In a STL file, triangular facets are described by a set of X, Y and Z coordinates for each of the three vertices and a unit normal vector with X, Y and Z to indicate which side of facet is an object. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 SAMPLE STL FILE Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 ADVANTAGES OF STL FILE It provides a simple method of representing 3D CAD data. It is already a de facto standard and has been used by most CAD systems and rapid prototyping systems. Finally, it can provide small and accurate files for data transfer for certain shapes. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 DISADVANTAGES OF STL FILE The STL file is many times larger than the original CAD data file for a given accuracy parameter. The STL file carries much redundancy information such as duplicate vertices and edges shown in Figure. Second, the geometry flaws exist in the STL file because many commercial tessellation algorithms used by CAD vendor today are not robust. This gives rise to the need for a “repair software” which slows the production cycle time. ▪ Finally, the subsequent slicing of large STL files can take many hours. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 STL FILE PROBLEMS (1) Gaps (cracks, holes, punctures) that is, missing facets. (2) Degenerate facets (where all its edges are collinear). (3) Overlapping facets. (4) Non-manifold topology conditions Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 MISSING FACETS Tessellation of surfaces with large curvature can result in errors at the intersections between such surfaces, leaving gaps or holes along edges of the part model. A surface intersection anomaly which results in a gap is shown in Figure. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 DEGENRATE FACES Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 OVERLAPPING FACETS Overlapping facets may be generated due to numerical round-off errors occurring during tessellation. The vertices are represented in 3D space as floating point numbers instead of integers. Thus the numerical roundoff can cause facets to overlap if tolerances are set too liberally. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 NON-MANIFOLD CONDITIONS There are three types of non-manifold conditions, namely: (1) A non-manifold edge. (2) A non-manifold point. (3) A non-manifold face. These may be generated because tessellation of the fine features are susceptible to round-off errors. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 NON-MANIFOLD EDGE. Here, the non-manifold edge is actually shared by four different facets. A valid model would be one whose facets have only an adjacent facet each, that is, one edge is shared by two facets only. Hence the non-manifold edges must be resolved such that each facet has only one neighboring facet Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Non-manifold point & Non-manifold face Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 CONSEQUENCES OF BUILDING A VALID AND INVALID TESSELLATED MODEL A Valid Model : A tessellated model is said to be valid if there are no missing facets, degenerate facets, overlapping facets or any other abnormalities. When a valid tessellated model (see Figure (a)) is used as an input, it will first be sliced into 2D layers, as shown in Figure (b). Each layer would then be converted into unidirectional (or 1D) scan lines for the laser or other RP techniques to commence building the model as shown in Figure (c). Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 An Invalid Model Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 STL FILE REPAIR The STL file repair can be implemented using a generic solution and dedicated solutions for special cases. Generic Solution: The basic approach of the algorithm to solve the “missing facets” problem would be to detect and identify the boundaries of all the gaps in the model. Once the boundaries of the gap are identified, suitable facets would then be generated to repair and “patch up” these gaps. The size of the generated facets would be restricted by the gap’s boundaries while the orientation of its normal would be controlled by comparing it with the rest of the shell. This is to ensure that the generated facets’ orientation are correct and consistent throughout the gap closure process. The orientation of the shell's facets can be obtained from the STL file which lists its vertices in an ordered manner following Mobius’ rule. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 STL FILE REPAIR… The algorithm exploits this feature so that the repair carried out on the invalid model, using suitably created facets, would have the correct orientation. Thus, this generic algorithm can be said to have the ability to make an inference from the information contained in the STL file so that the following two conditions can be ensured: The orientation of the generated facet is correct and compatible with the rest of the model. Any contoured surface of the model would be followed closely by the generated facets due to the smaller facet generated. This is in contrast to manual repair whereby, in order to save time, fewer facets generated to close the gaps are desired, resulting in large generated facets that do not follow closely to the contoured surfaces. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 STL FILE REPAIR … Finally, the basis for the working of the algorithm is due to the fact that in a valid tessellated model, there must only be two facets sharing every edge. If this condition is not fulfilled, then this indicates that there are some missing facets. With the detection and subsequent repair of these missing facets, the problems associated with the invalid model can then be eliminated. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Other Translators Initial Graphics Exchange Specification (IGES) File Hewlett-Packard Graphics Language (HP/GL) File Computerized Tomography (CT) Data Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 IGES File IGES (Initial Graphics Exchange Specification) is a standard used to exchange graphics information between commercial CAD systems. The IGES file can precisely represent CAD models. It includes not only the geometry information (Parameter Data Section) but also topological information (Directory Entry Section). In the IGES, surface modeling, constructive solid geometry (CSG) and boundary representation (B-rep) are introduced. Especially, the ways of representing the regularized operations for union, intersection, and difference have also been defined. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Advantages of IGES File Wide adoption and comprehensive coverage. Since IGES was set up as American National Standard, virtually every commercial CAD/CAM system has adopted IGES implementations. Furthermore, it provides the entities of points, lines, arcs, splines, NURBS surfaces and solid elements. Therefore, it can precisely represent CAD model. Advantages of using IGES over current approximate methods include precise geometry representations, few data conversions, smaller data files and simpler control strategies. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 DISADVANTAGES (1)Because IGES is the standard format to exchange data between CAD systems, it also includes much redundant information that is not needed for rapid prototyping systems. (2)The algorithms for slicing an IGES file are more complex than the algorithms slicing a STL file. (3)The support structures needed in RP systems such as the SLA cannot be created according to the IGES format. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 HP/GL File HP/GL (Hewlett-Packard Graphics Language) is a standard data format for graphic plotters. Data types are all two-dimensional, including lines, circles, splines, texts, etc. The approach, as seen from a designer’s point of view, would be to automate a slicing routine which generates a section slice, invoke the plotter routine to produce a plotter output file and then loop back to repeat the process. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 ADVANTGE OF HP/GL The advantages of the HP/GL format are that a lot of commercial CAD systems have the interface to output the HP/GL format and it is a 2D geometry data format which does not need to be sliced. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 DISADVANTGES OF HP/GL First, because HP/GL is a 2D data format, the files would not be appended, potentially leaving hundreds of small files needing to be given logical names and then transferred. Second, all the support structures required must be generated in the CAD system and sliced in the same way. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 CT Data CT (Computerized Tomography) scan data is a particular approach for medical imaging. This is not standardized data. Formats are proprietary and somewhat unique from one CT scan machine to another. The scan generates data as a grid of three- dimensional points, where each point has a varying shade of gray indicating the density of the body tissue found at that particular point. Data from CT scans have been used to build skull, femur, knee, and other bone models on Stereolithography systems. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 CT Data The CT data consist essentially of raster images of the physical objects being imaged. It is used to produce models of human temporal bones. There are three approaches to making models out of CT scan information: (1) Via CAD Systems (2) STL-interfacing and (3) Direct Interfacing. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 ADVANTAGES OF CT Data The main advantage of using CT data as an interface of rapid prototyping is that it is possible to produce structures of the human body by the rapid prototyping systems. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 DISADVANTAGE OF CT Data Disadvantages of CT data include firstly, the increased difficulty in dealing with image data as compared with STL data and secondly, the need for a special interpreter to process CT data. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 NEWLY PROPOSED FORMATS SLC (StereoLithography Contour) file format CLI (Common Layer Interface) format RPI (Rapid Prototyping Interface) format LEAF or Layer Exchange ASCII Format Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 CNC Machines Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Computer Numeric Control A system in which actions are controlled by the direct insertion of numerical data at some point. The system must automatically interpret at least some portion of this data. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Computer Numerical Control (CNC) Machine Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Advantages and Disadvantages of CNC Advantages: High Repeatability and Precision e.g. Aircraft parts. Volume of production is very high. Complex contours/surfaces can be easily machined. Flexibility in job change, automatic tool settings, less scrap. More safe, higher productivity, better quality. Less paper work, faster prototype production, reduction in lead times. Disadvantages: Costly setup, skilled operators. Computer programming knowledge required. Maintenance is difficult. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Open Loop Systems Open loop systems have no access to the real time data about the performance of the system and therefore no immediate corrective action can be taken in case of system disturbance. Block Diagram of an Open Loop System. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 CNC terminology BLU: basic length unit ➔ smallest programmable move of each axis. Controller: (Machine Control Unit, MCU) ➔ Electronic and computerized interface between operator and m/c Controller components: 1. Data Processing Unit (DPU) 2. Control-Loops Unit (CLU) Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Controller components Data Processing Unit: Input device [RS-232 port/ Tape Reader/ Punched Tape Reader] Data Reading Circuits and Parity Checking Circuits Decoders to distribute data to the axes controllers. Control Loops Unit: Interpolator to supply machine-motion commands between data points Position control loop hardware for each axis of motion Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Types of CNC machines Based on Motion Type: Point-to-Point or Continuous path Based on Control Loops: Open loop or Closed loop Based on Power Supply: Electric or Hydraulic or Pneumatic Based on Positioning System Incremental or Absolute Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Open loop system Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Close Loop Systems In a close loop system, feed back devices closely monitor the output and any disturbance will be corrected in the first instance. Therefore high system accuracy is achievable. Block Diagram of a Close Loop System Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Close loop system Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Sy stems| M C 4164 | 3 Credits | 3 0 0 3 Open loop control of a Point-to-Point NC drilling machine NOTE: this machine uses stepper motor control Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Motion Control Systems 1. Point-To-Point Control in CNC Drilling of Three Holes in Flat Plate System moves to a location and performs an operation at that location (e.g., drilling) Also applicable in robotics Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 2. Continuous Path Control in CNC Profile Milling of Part Outline Also called contouring systems in machining System performs an operation during movement (e.g., milling and turning) Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Elements of a CNC System ❖ Input Device ❖ Central Processing Unit/ Machine Control Unit ❖ Machine Tool ❖ Driving System ❖ Feedback Devices ❖ Display Unit Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Input Devices Floppy Disk Drive USB Flash Drive Serial Communication Ethernet communication Conversational Programming Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0 0 3 Central Processing Unit/ Machine Control Unit The CPU is the heart of a CNC system. It accepts the information stored in the memory as part program. This data is decoded and transformed into specific position control and velocity signals. It also oversees the movement of the control axis or spindle and whenever this does not match with the programmed values, a corrective action as taken. Dr. Nikhil Vivek Shrivas, Assistant Professor, Manipal University Jai pur  Automated Manufacturing Systems | M C 4164 | 3 Credits | 3 0