Lecture 12: Manufacturing Processes and Process Selection PDF

Engineering Design and Material Selection Lecture 12 — Manufacturing Processes and Process Selection Prof. Dr. Kristina Shea Dr. Tino Stankovic Prof. Kristina Shea 1  Course Schedule Week/ Topic...

Engineering Design and Material Selection Lecture 12 — Manufacturing Processes and Process Selection Prof. Dr. Kristina Shea Dr. Tino Stankovic Prof. Kristina Shea 1  Course Schedule Week/ Topic Case study Quiz Lecturer Dates 1 Introduction and Sketching 2 Introducing Engineering Design Health Prof. Dr. Kristina Shea 3 Technical Drawing: Projections and Cuts 4 CAD: Introduction and Modeling Operations 5 CAD: Features and Parametric Modeling Future Mobility 6 CAD: Freeform Modeling Dr. Tino Stankovic 7 CAD: Assemblies and Standard Mechanical Parts X (45 min) 8 Technical Drawing: Dimensioning Health 9 Sustainability in Engineering Design 10 Materials and their Properties 11 Material Selection Sustainable Materials Prof. Dr. Kristina Shea 12 Manufacturing Processes and Process Selection 13 Review and Q+A X (75 min) Prof. Kristina Shea Engineering Design + Computing Laboratory 2  Answer the Question on Next Week’s Lecture: Q&A EduApp to vote for lectures that should be revisited Several answers possible Clicker-Question closes on Tuesday, December 10th, 17:00 Use the Course Channel on EduApp (“Questions About Lecture Content”) to post specific topics or questions Upvoting of existing suggestions possible Anonymous contributions possible Which Topic(s) would you like to have revisited? Do you have specific questions? (Reach out to us directly: [email protected] or [email protected]) Prof. Kristina Shea Engineering Design + Computing Laboratory 3  Learning Objectives ▪ Understand the close connection between manufacturing processes and material properties, feasible shapes and part function ▪ Learn a general classification of manufacturing chains and processes ▪ Understand the fundamentals of selected manufacturing processes ▪ Learn about Design for Manufacturing and Design for Additive Manufacturing ▪ Understand the role of the choice of manufacturing processes during the design process Prof. Kristina Shea Engineering Design + Computing Laboratory 4  History: Material shapes technology Ashby, 2011 Prof. Kristina Shea Engineering Design + Computing Laboratory 5  Manufacturing Processes in the Engineering Design Process Phase 1: Phase 2: Phase 4: Phase 5: Phase 3: Phase 0: Planning Concept System- Testing & Production Detail Design Development Level Design Refinement Ramp-Up Target Process General Considerations Refine Process Which part is processed What is feasible? What part of the process with which method? What is the approximate can be optimized? What are the production cost? process chains? The manufacturing process is iteratively defined in every stage of the engineering design process. The choice of the manufacturing process is related to many design aspects, such as the part shape, choice of material, production cost, quality needed and environmental factors. Prof. Kristina Shea Engineering Design + Computing Laboratory 6  The Manufacturing Method Influences the Design Process Dependencies: Shape ▪ The choice of manufacturing processes is often limited due to availability and cost. ▪ The material and shape needed to fulfill the design’s function restrict the possible manufacturing processes ▪ Even if different manufacturing processes can be Function used to create the same geometry with the same material, the resulting behavior can differ due to, e.g. imperfections, caused by the material Material Process treatment during manufacturing. Prof. Kristina Shea Engineering Design + Computing Laboratory 7  Oval Handle Fins Ergonomics: optimum shape for Oxo Goodgrips Ergonomics: allow for comfortable grip hand grip and comfort with thumb and index fingers Peeler Aesthetics: oval shape was a very popular shape at the time; does not Aesthetics: overall shape of the curve echoes the oval shape of the handle. Thin show dirt or oils parallel ribs make handle appear lighter Manufacturing: holding tolerance of fin Manufacturing: shape (and thickness challenges structural integrity of material Santoprene) is easy to Santoprene mold Cross section of handle Material - Santoprene: polymer Countersunk Hole Ergonomics: allows owner to guide that behaves like rubber product onto a holder post (elastomer) but is processed like a thermoplastic, for Aesthetics: the counter sunk hole is more subtle than a hole with example using molding consistent diameter Manufacturing: the hole reduces amount of Santoprene, reducing cost Prof. Kristina Shea Engineering Design + Computing Laboratory 8 Manufacturing Processes Involved in Ski Fabrication Cutting (Laser) Grinding 3D Printing Milling Laminating Bending Cutting (Mechanical) Source: https://www.jans.com/alpine-ski-anatomy (20.06.2022) Prof. Kristina Shea Engineering Design + Computing Laboratory 9  Manufacturing is a chain of processes Primary Production Manufacturing Nature Product Sourcing Preparation Feedstock Shaping Finishing Joining Creation Recycling Disassembling Reusing Repairing Prof. Kristina Shea Engineering Design + Computing Laboratory 11  Example of wood used in ski fabrication Primary Production Manufacturing Sourcing Preparation Feedstock Shaping Finishing Joining ▪ Harvesting ▪ Drying Creation ▪ Milling ▪ Painting ▪ Laminating ▪ Sawing ▪ Oiling Prof. Kristina Shea 12  Example of metal used in ski fabrication Primary Production Manufacturing Sourcing Preparation Feedstock Shaping Finishing Joining ▪ Mining Creation ▪ Bending ▪ Gluing ▪ Laminating Prof. Kristina Shea 13  Edge Bending Machine Master Thesis, Andrin Widmer, with Oxess, ETH Zurich, 2024 Prof. Kristina Shea Engineering Design + Computing Laboratory 14  Focus on Manufacturing Possible Manufacturing Steps Subtractive Additive Joining Deforming Material removal Adding material Joining multiple Plastic from a bulk to an already parts deformation of material to existing part until permanently or raw material or achieve a the desired temporarily to already existing desired shape. shape is created. make an shapes to create assembly or a new shapes. joined shape. Prof. Kristina Shea Engineering Design + Computing Laboratory 15  Machining Milling, drilling, turning and cutting processes are subtractive processes. The material is processed by cutting material with a blade. Milling Drilling Turning Cutting The processes mainly differ in the relative movement of the “workpiece” and tool as well as the geometry of the tool. Prof. Kristina Shea Engineering Design + Computing Laboratory 16  Machining Milling Drilling ▪ Workpiece moves in multiple axes ▪ Workpiece is fixed and the tool while the tool rotates to remove rotates to remove material material ▪ Creates holes on mostly flat ▪ Rectangular geometries are surfaces standardly possible to make ▪ Curved geometries are possible, but some difficult to achieve Turning Cutting / Sawing ▪ Workpiece is rotated and the ▪ Workpiece is fixed or moves while cutting tool is moved to remove the tool rotates to create the cut material ▪ Deep and thin cuts ▪ Creates cylindrical or conical parts and surfaces Note: The “workpiece is the bulk material that is being machined, or “worked”. Prof. Kristina Shea Engineering Design + Computing Laboratory 17 Machining Advantages Drawbacks Wide variety of shapes and Tools are either expensive and/or dimensions possible (from sub need a high skill level to operate. millimeter to several meters) Suitable for many engineering Very complex geometries are hard or materials. impossible to manufacture (e.g., fine lattice structures) Very high automation possible due to If the geometry becomes more industry standards. complex, complex programming and multiple machines are needed for one part. Industrial 5-axis CNC milling Excellent understanding of process High waste potential due to the machine, typical cost above parameters due to establishment in nature of subtractive manufacturing. $500k industry. Good surface finish, excellent accuracy Image Source: https://makeitfrommetal.com/how-much-does-a-cnc-machine-cost/ (28.06.2022) Prof. Kristina Shea Engineering Design + Computing Laboratory 18  Casting One of the most prominent casting methods is sand casting. Molten metal is poured into a negative made from sand. The mold is designed such that the air initially in the form can escape through smartly placed openings. Cores can be placed in the form to create more complex forms. Casting is the general term for creating a geometry by pouring liquid material into a solid form. Although it is mostly associated with metal casting, it is a much broader term and there are casting processes for almost any material that can be melted. Image Source: https://knordslearning.com/sand-casting-process/ (28.06.2022) Prof. Kristina Shea Engineering Design + Computing Laboratory 21  Casting and Molding Advantages Drawbacks Very fast process with low cost per Individual parts are very expensive part, suitable for mass production. due to the setup cost (mold, initial setup, …) Low material waste Molds can limit the possible geometries Suitable for most meltable materials Design changes are expensive (low melting point desired) Complex geometries can be Mold for plastic injection produced molding for a customized part. Image Source: https://icomold.com/newsletters/custom-plastic-injection-molds-shipped-to-you-from-icomold/ (28.06.2022) Prof. Kristina Shea Engineering Design + Computing Laboratory 22  Additive Manufacturing Additive Manufacturing Powder Based Liquid Based Solid Based Material Particle Polymerization Fusion Adhesion Melting ▪ Sheet Lamination ▪ Selective Laser ▪ Binder ▪ Stereolithography Sintering Jetting ▪ Inkjet/PolyJet ▪ Fused Filament ▪ Selective Laser Printing Fabrication (FFF) Melting ▪ Direct Ink Writing ▪ Electron Beam Melting Prof. Kristina Shea Engineering Design + Computing Laboratory 24  Fused Filament Fabrication (FFF) Machine: uPrint SE Plus, Stratasys Material: ABSplus 430 (thermoplastic) Layer height 0.254mm Maximum build envelope (XYZ): 203 x 203 x 152 mm Prof. Kristina Shea Engineering Design + Computing Laboratory 25  Comparison of AM to Machining and Molding Build File (G-code) No custom programming! vs. CNC source://german.injectionmouldtooli ng.com No molds! vs. injection molding, stamping, casting, etc. Prof. Kristina Shea 26 Engineering Design + Computing Laboratory 26  E3D Toolchanger and Motion System General Specifications ▪ Configuration: Core XY ▪ Build Volume: 300mm x 200mm x 290mm ▪ Controller: Duet3D Duet 2 ▪ 4 Tool Positions: ▪ Bowden and direct extruders ▪ Additional axis possible such as a 5-axis tool ▪ Additive & Subtractive Manufacturing By Layer (ASMBL) possible ▪ Advantages: ▪ Multimaterial printing ▪ High accuracy and large material range ▪ Open source P. Kolb, Semester Thesis, ETH Zurich, 2023 Prof. Kristina Shea Engineering Design + Computing Laboratory 27  Additive Manufacturing ▪ Additive manufacturing is the general term for every Future layers process building up geometries by depositing material on an already existing geometry. Working plane ▪ Typically, the geometry is built up layer by layer, starting from a build plate. Complete layers ▪ By filling voids in the geometry using support material and printing further layers on it, almost any imaginable geometry can be produced. ▪ After printing, the support material is removed, and the printed part is ready for post processing. ▪ Depositing the layers can vary significantly. The process chosen is depends on the material and needed properties. Prof. Kristina Shea Engineering Design + Computing Laboratory 28  Isotropy / Anisotropy Isotropic material has properties which are independent of the material direction. Anisotropic material vary in their mechanical properties for each main direction (x,y,z). All properties must be given for all directions for a full description of the material. Typical fracture of wood is perpendicular to Strength is higher in the the growth direction and. vertical direction than in the two traverse directions. Additive manufactured parts are often weaker in the build direction due to the adhesion of the layers. Print orientation is very crucial to control. Prof. Kristina Shea Engineering Design + Computing Laboratory 29  Additive Manufacturing Applications AM Technologies AM for Prototyping AM for Manufacturing AM for Tooling Produce physical models Produce end-use, and prototypes Produce tools, molds or dies single and series parts FDM, Stratasys, Inc. source: http://www.voxeljet.de source: http://www.maschinenmarkt.vogel.de/themenkanae le/additive_fertigung/articles/443675/ Functional Parts 3DP, Z Corp, Inc. Prof. Kristina Shea 30  Additive Manufacturing Advantages Drawbacks Low material waste Material selection limited Low setup time, e.g. no molds Relatively new process, parameter needed influence less known for new materials Suitable for prototyping and some Limited for mass production mass production Part customization possible for every Production cost of individual part individual part relatively high Free-form geometries possible Low surface quality, post processing needed Multi-material AM possible with High anisotropy in some processes “Multi-Material Designs” some methods due to layering AM varying material properties to tune mechanical strength Prof. Kristina Shea Engineering Design + Computing Laboratory 31  Process Selection Strategies – General Approach Translation Screening Ranking Validation Reinterpret the design Derive attribute limits Order the viable Seek documentation for requirements in terms from the constraints and candidates by a criterion the top-ranked of function, applying these to isolate that maximizes or candidates, exploring constraints, a subset of viable minimizes some their established uses objectives, and free processes. measure of and behavior in relevant variables. performance. environments until a detailed picture is built up to make a final choice. Like Material Selection Strategies in Lecture 11 Adapted from: Ashby, 2011 Prof. Kristina Shea Engineering Design + Computing Laboratory 32  Process Selection Strategies – General Approach Function Constraints Translation ▪ Technical ▪ Quality ➜ Same as in Lecture 11: – Material – Tolerance Guides the choice of material, – Shape – Roughness shape, and now manufacturing – Mass ▪ Economic process. – Minimum section – Batch size Objectives Free Variables Design Requirements ▪ Minimize cost ▪ Choice of ▪ Environmental manufacturing impact process ▪ Operating conditions Prof. Kristina Shea Engineering Design + Computing Laboratory 33  Process Selection Strategies – General Approach ▪ Compatibility matrix: Process - Screening Materials Shape Function Material Process Adapted from: Ashby, 2011 Prof. Kristina Shea Engineering Design + Computing Laboratory 34  Process Selection Strategies – General Approach ▪ Compatibility matrix: Process - Shape Screening Shape Function Material Process Adapted from: Ashby, 2011 Prof. Kristina Shea Engineering Design + Computing Laboratory 35  Process Selection Strategies – General Approach ▪ Bar charts: Section thickness Screening Shape Function Material Process Section thickness mm Adapted from: Ashby, 2011 Prof. Kristina Shea Engineering Design + Computing Laboratory 36  Process Selection Strategies – General Approach ▪ Tolerance (T) & Surface Roughness (R) Screening T (mm) R (µm) Shape Function Actual shape Material Process ≠ Ideal shape Prof. Kristina Shea Engineering Design + Computing Laboratory 37  Process Selection Strategies – Case study “Sharpening a pencil” Requirements for the manufacturing process Function Sharpen a pencil Translation Material Wood Shape Circular (conical) Technical Mass 5g Minimum section 8 mm Constraint Tolerance < 1 mm Design Quality Surface < 50 μm Requirements Roughness Economic Batch size 1000 Objective Minimize cost Choice of sharpening Free variables process Prof. Kristina Shea Engineering Design + Computing Laboratory 38  Process Selection Strategies – Case study “Sharpening a pencil” ▪ Cost vs batch size 𝐶𝑓 Slope: -1 Ranking 𝐶 = + 𝐶𝑣 𝑛 𝐶 : Cost per part Plateau ➜ Minimizing cost 𝐶𝑓 : Fixed costs 𝐶𝑣 : Variable costs Invested capital (e.g. mold) 𝑛 : Unit produced Break-even points (batch size) Material, Energy, 𝐶𝑓 Tooling, Labor log 𝐶 = log + 𝐶𝑣 𝑛 For small 𝑛 → log 𝐶𝑓 − log 𝑛 For large 𝑛 → log 𝐶𝑣 Economic batch size (for electric sharpener) Adapted from: Ashby, 2011 Prof. Kristina Shea Engineering Design + Computing Laboratory 39  Process Selection Strategies – General Approach ▪ Economic batch size Ranking ➜ Minimizing cost Adapted from: Ashby, 2011 Prof. Kristina Shea Engineering Design + Computing Laboratory 40  Process Selection Strategies – General Approach ▪ Documentation Example: Turning Validation Look for: Design guidelines Technical notes ➜ Seek documentation before the final Typical uses process choice The economics The environment Data taken from Granta EduPack Prof. Kristina Shea Engineering Design + Computing Laboratory 41  Question: Which criteria should be considered when choosing a manufacturing process? ▪ A. Feasible materials that can be processed ▪ B. Accuracy ▪ C. Environmental impact ▪ D. Fixed costs, or “set-up” costs ▪ E. Batch size Prof. Kristina Shea Engineering Design + Computing Laboratory 42  Information Equipment Design for Manufacturing (DfM) Tooling A process of designing engineering parts to facilitate the manufacturing process and reduce manufacturing costs while also improving or maintaining product quality, time, and cost. Raw materials Finished Labor Manufacturing Goods Design for Manufacturing is a convergent process system throughout the whole design process and is considered in parallel to other requirements. Purchased Components Waste Services Supplies Energy Milling, Injection Molding, Additive Adapted from: Ulrich and Eppinger, Product Design and Development, 4th Edition, McGraw Hill, 2008. Manufacture,… Prof. Kristina Shea Engineering Design + Computing Laboratory 43  Design for Manufacturing: Design Guidelines - Machining Techniques in Reverse Engineering and New Product Source: Otto, K. & Wood, K. (2001) Product Design: Development Prof. Kristina Shea Engineering Design + Computing Laboratory 44  Why do we need Design for Additive Manufacturing (DfAM) Methods? Restrictive DfAM Methods ▪ Catalog process restrictions ▪ Optimize the AM fabrication process ▪ Design complex geometries Opportunistic DfAM Methods ▪ Understand how and when to consider AM ▪ Transfer of AM knowledge ▪ Break out of conventional mindset and bias Prof. Kristina Shea Engineering Design + Computing Laboratory 45  Restrictive DfAM Restrictive DfAM aims to improve manufacturability and cost of AM parts under the constraints imposed by the process. Part Surface Quality Support Material Anisotropy Images: Materialise More detailed: Booth, J. W., Alperovich, J., Chawla, P., Ma, J., Reid, T. N., and Ramani, K. "The Design for DfAM Worksheet Additive Manufacturing Worksheet." https://doi.org/10.1115/1.4037251 Prof. Kristina Shea Engineering Design + Computing Laboratory 46  DfAM – Balloon Powered Car – Impact of Part Orientation Support Material: 11.4cm3 Support Material: 8.1cm3 Print time: 2:11h Part fit and tolerances Print time: 1:47h determined by iterative testing Support Material: 7.2cm3 Support Material: 5.6cm3 3D Printer: uPrint SE Plus, Stratasys Print time: 1:43h Print time: 0:48h Prof. Kristina Shea Engineering Design + Computing Laboratory 47  Gibson et al., 2015, "Design for Additive Manufacturing," Additive Manufacturing 25 Design Heuristics for AM (DHAM) in 8 Categories Technologies: 3D Printing, Rapid Prototyping, and Direct Digital Manufacturing Part Consolidation Example: Consolidate parts to Customize reduce assembly Convey Information Loncke, 2014, "Following Moore's Law," Mikroniek time Material Material Distribution Embed/Enclose Lightweight Reconfiguration Example: Optimize structure of water manifold to reduce vibrations https://edac.ethz.ch/Research/current-research-projects/Design-Heuristics-AM.html Prof. Kristina Shea Engineering Design + Computing Laboratory 48 Prof. Kristina Shea Engineering Design + Computing Laboratory 51 Prof. Kristina Shea Engineering Design + Computing Laboratory 52  25 DHAM Objects ▪ Physical representation of each heuristic ▪ User can experience and interact with heuristic ▪ Domain neutral ▪ Similar in same category ▪ Designs evolved over time Download the DHAM Objects from Thingiverse: https://www.thingiverse.com/edac_eth_zurich/coll ections/design-heuristics-for-additive- manufacturing Prof. Kristina Shea Engineering Design + Computing Laboratory 53  Manufacturing Processes – Wrap Up Manufacturing processes, often a chain of processes, can be classified according to their way of material forming. Common manufacturing processes in engineering design include machining, injection molding and additive manufacture. The manufacturing process has a high influence on the performance, cost, and environmental impact of parts. Design for Manufacturing (DfM) is a method to take the manufacturing process and constraints into account while designing. Design for Additive Manufacturing (DfAM) consists of both restrictive and opportunistic methods. Developing the manufacturing process is an iterative process running in parallel to engineering design. Prof. Kristina Shea Engineering Design + Computing Laboratory 54  References For Block 3 the following book may be consulted for further information and explanation. It is free to download within the ETH domain. M.F. Ashby, Materials Selection in Mechanical Design, Elsevier, Fourth Edition, 2011. https://www.sciencedirect.com/book/9781856176637/materials-selection-in-mechanical-design Supplementary reading for Lecture 12: Chapter 13 in Ashby (2011). Another good reference for Design for Manufacture is Chapter13 in: Ulrich, Karl T., Eppinger, Steve D., and Yang, Maria C., Product Design and Development. 7th ed., McGraw-Hill Education, 2020. Prof. Kristina Shea Engineering Design + Computing Laboratory 55  Exercise 12: Manufacturing Processes and Process Selection How can you fabricate these objects? Prof. Kristina Shea Engineering Design + Computing Laboratory 65  Examinable Material from Lecture 12 and Exercise 12 ▪ All lecture material ▪ All exercise material with a focus on the following manufacturing processes: ▪ Milling ▪ Turning ▪ Drilling ▪ Cutting and Sawing ▪ Injection Molding ▪ Additive Manufacture ▪ Additional manufacturing process used in the exercise will not be part of the final quiz. Prof. Kristina Shea Engineering Design + Computing Laboratory 66