Module 5 Lecture 2 Fundamentals of Numerical Control Machines 2023 PDF

Ch 7: Computer Numerical Control (CNC) Sections 1. Fundamentals 2. Programming Assoc. Prof. Khalil Al-Hatab Fall 2023/2024 (#)  Module 4 - Lecture 1: Numerical Control (NC)-Fundamentals Sections: 1. Histor...

Ch 7: Computer Numerical Control (CNC) Sections 1. Fundamentals 2. Programming Assoc. Prof. Khalil Al-Hatab Fall 2023/2024 (#)  Module 4 - Lecture 1: Numerical Control (NC)-Fundamentals Sections: 1. Historical Note on NC 2. Fundamentals of NC Technology 3. Computer Numerical Control 4. CNC Components 5. DNC 6. Applications of NC 7. Advantages & Disadvantages of CNC 8. Analysis of NC Positioning Systems 9. Motion Control Systems ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Production Facilities in a Manufacturing System In a manufacturing system, the raw materials are transformed into finished products through a series of manufacturing processes, which are performed at production facilities. Figure 5.1 shows the transformation of a manufacturing system. A manufacturing system is represented by a number of major activities in an information flow and a material flow. An information flow describes all of the decision-making activities involved in a product lifecycle. A material flow describes the transportation from raw materials, pre- fabricates, parts, components, and integrated objects to finished products as a flow of entities. Production facilities are the hardware components that make physical touches to physical objects in the ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. materialNo flow. portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Humans and Machines in a Manufacturing System ▪ For the material flow on the left, human operations are productive for some intricate tasks but underperform compared with machines for simple and repetitive tasks; humans are dispensable for some tasks where the human flexibility and agility are critical. ▪ For the information flow on the right, humans are extremely efficient in making decisions where the manufacturing environment is very complex and involves many changes and uncertainties. Humans are not efficient where a mathematic model or a computer algorithm can reach optimum decisions. ▪ In the middle range, either humans or computers can deal with the scopes and ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. the Nocomplexities portion of this material mayof decision-making be reproduced, Therefore, in any form or by any means, there without permission arefromlimits in writing for For the publisher. thethe automation level exclusive use of adopters inbook of the both the Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. problems. material flow and the information flow.  Automated Decision-Making Supports ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Automation in Manufacturing Execution Systems (MESs) ❑ A manufacturing execution system (MES) is used to connect, monitor, and control complex manufacturing systems and data flows collected from the material flow. ❑ An MES ensures effective executions of manufacturing processes for high production outputs, faster deliveries, and competitive costs. ❑ A manufacturing system consists of different types of hardware resources; at the device level, every hardware device corresponds to its own automated solution. Therefore, an MES is a comprehensive solution to automate all hardware systems in a manufacturing plant. ❑ Computer programs in MES support all of the required decision-making activities; cooperation and coordination of different information processing units. ❑ Depending on the scale and business scope of a manufacturing system, system components in an MES are classified in terms of the level of ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. automation into mayelement-level, No portion of this material be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. machine-level, and system-level.  Automation in Manufacturing Execution Systems (MESs) One difference between the automations at different levels is the frequency of updating control commands: ▪ The real-time performance over 100 Hz is usually required for the controls at the element level, ▪ While the frequencies at the machine level and system level are normally 10 and 1 Hz, respectively. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book The rest of the chapter will concentrate on the Fundamentals of Numerical Control Machines. Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Numerical Control (NC) ❑ A numerically controlled (NC) machine is usually a machining system consisting of a machine tool, a number of motors to move the cutting tool along the path, and a controller that is responsible to generate and execute NC commands. ❑ Numerical control (NC) is a form of programmable automation in which the mechanical actions of a machine tool or other equipment are controlled by a program containing coded alphanumeric data as well as other instructions needed to operate the machine. ❑ Numerical Control (NC) is the grandfather of CNC. ▪ The alphanumeric data represent relative positions between a workhead (e.g., cutting tool or other processing apparatus) and a work part (the object being processed). When the current job is completed, a new program can be entered for the next job. ▪ Applications of NC divide into two categories: (1) Machine tool applications, such as drilling, milling, turning, and other metal working; and (2) Other applications, such as assembly, rapid prototyping, and inspection. The common operating feature of NC in all of these applications is control of the work head movement relative to the work part. ❑ Computer Numerical Control (CNC): A form of electromechanical motion control used on machine tools, whereby a computer and computer program are used to perform machining operations. Historical Note on NC Historical Note on NC  NC System ❑ The NC machine in Figure above consists of a program input unit, a machine control unit (MCU), and the processing equipment. A program is a sequence of planned operations and is written as numerical codes by human operators. Early NC programs were punched into punch cards, which were also called tape readers. The codes were sent to the MUC line by line and control commands were converted into the instructions to move the processing equipment. NC programs were eventually executed by the processing equipment.  NC System ❑ The capabilities of NC machines can be expanded as direct numerical controls (DNCs) and machining centres. ❑ A DNC in next Figure is a collection of NC machine tools, where the control programs are stored and shared by the set of NC machines. The programs are provided to the networked machines by on-demand distribution of data to machines. With the network, one computer can be used to control a number of NC machine tools, which eliminates the need for substantial hardware for individual controllers of each NC machine tool. A machining centre is capable of performing multiple machining operations and processes in a single setup. As shown in next Figure, a machining centre usually has multiple axes and is equipped with an automatic mechanism to change tools. All of the motion axes are driven by servomotors that are equipped with positioning feedbacks for precise closed-loop controls of machine motions. CNC System  Basic Components of an NC System 1. Program of instructions ▪ Part program in machining 2. Machine control unit ▪ Controls the process 3. Processing equipment ▪ Performs the process ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Part Program ▪ The set of detailed step-by-step commands that direct the actions of the processing equipment. ▪ The individual commands refer to positions of a cutting tool relative to the worktable on which the work part is fixtured. ▪ Additional instructions are usually included, such as spindle speed, feed rate, cutting tool selection, and other functions. ▪ The program is coded on a suitable medium for submission to the machine control unit such as 1-in wide punched tape, magnetic tape, diskettes, and electronic transfer of part programs from a computer. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Part Program ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Part Program ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. NC programs were once stored as holes punched in a paper or plastic tape.  Tape Format ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Tape Format ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Tape Format ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Machine Control Unit (MCU) MCU consists of a data processing unit (DPU) and the control loop unit (CLU). The DPU decodes the information contained in the part-program, processes the information, and provides the instructions to the CLU. The CLU operates the drives attached to the machine by lead screws. The CLU provides the feedback about the actual position and velocity of the motion axes.  MACHINE CONTROL UNIT (MCU) ▪ A microcomputer and related control hardware that stores the program of instructions and executes it by converting each command into mechanical actions of the processing equipment, one command at a time. ▪ The related hardware of the MCU includes interface components, feedback control elements and one or more reading devices. ▪ Software residing in the MCU includes control system software, calculation algorithms, and translation software to convert the NC part program into a usable format for the MCU. ▪ Because the MCU is a computer, the term computer numerical control (CNC) is used to distinguish this type of NC from its technological ancestors that were based entirely on hardwired electronics. Today, virtually all new MCUs are based on computer technology.  Machine Control Unit (MCU) The drive units are actuated by voltage pulses. The number of pulses transmitted to each axis determines the required incremental motion and the frequency of these pulses represents axial velocities. BLU: basic length unit ➔ smallest programmable move of each axis. One BLU represents the resolution of the NC machine tool, i.e. one BLU corresponds to the positional resolution of the axis of motion. A BLU is also referred to as a bit (binary digital), i.e. one pulse → one BLU → one bit. Controller components: Controller: (Machine Control Unit, MCU) ➔ Electronic 1. Data Processing Unit (DPU) and computerized interface between operator and m/c 2. Control-Loops Unit (CLU) 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  Machine Control Unit (MCU) ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Processing Equipment ▪ The third basic component of an NC system is the processing equipment that performs the actual productive work (e.g., machining). ▪ It accomplishes the processing steps to transform the starting workpiece into a completed part. ▪ Its operation is directed by the MCU, which in turn is driven by instructions contained in the part program. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ▪ Since the introduction of NC in 1952, there have been dramatic advances in digital computer technology. ▪ The physical size and cost of a digital computer have been significantly reduced at the same time that its computational capabilities have been substantially increased. ▪ Today, NC means computer numerical control (CNC), which is defined as an NC system whose MCU consists of a dedicated microcomputer rather than a hardwired controller. ▪ The latest computer controllers for CNC features: high speed processors, large memories, solid-state memory, improved servos, and bus architectures ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control Components of a CNC system: ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ▪ Since 1990s, personal computers (PC) were adopted as the platform of CNC systems. Different from former CNC system platforms, PCs have standard hardware architecture, communication interfaces and uniform operating systems. ▪ Open architecture controllers (OPC) are organized in modular manner so that functions are interchangeable. By using open interfaces, users can integrate user-specific applications into the system. With OPC as key enabling technology, manufacturing systems become reconfigurable. Functions are configured only when needed. Therefore, manufacturing costs and system ramp- up time are reduced. ▪ Currently there are mainly three kinds of Open architecture controllers, namely PC embedded in NC, PC plus motion control card and PC with real-time operating systems (RTOS). 1. PC Embedded in NC Architecture: PC serves as human-machine interface (HMI), while real-time interpolation and motion control functions are undertaken by stand-alone NC kernel. 1. The part program that a programmer generates based on the shape of the part, cutting conditions, and tools are entered into CNC via the MMI ▪ Calculating the movement path by interpreting the part program. 2. The NCK subsequently ▪ Generating velocity profile generates the control and displacement for each commands for the drivers axis by interpolation. from the part program ▪ Smoothing the movement by through various stages: acceleration/deceleration (Acc/Dec) control. ▪ Generating position control command ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control 2. PC plus motion control card architecture: NC functions are still undertaken by NC kernel which is plugged in PC through standard interface such as PCI. ❑ In the above two kinds of CNC architectures, openness is limited since NC kernel is vendor specific. 2. PC with Real-Time Operating System “RTOS” Architecture: all the control functions are executed by PC and no other numerical control platforms are needed. PC communicates with servo drives through field-bus or Industrial Ethernet. A PC is needed to guarantee exact timing for real-time tasks. Because PC is responsible for real-time interpolation and position control algorithms. Since CNC functions are executed by PC software, this type of controller is called “soft-CNC”. Though soft-CNC has enough openness theoretically, it is still difficult to reconfigure CNC controllers and reuse the function modules. Core functions are based on the application program interfaces (API) of real- time operating systems. These functions must be carefully designed in order to not deteriorate real-time performance of the controller ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ❑ With more hardware/software resources as enabler, more functions are integrated in CNC controllers. Traditionally CNC controllers read G-code as input. G-code mainly contains information of tool path trajectory, feed command and input/output (IO) functions, which are not sufficient for multiple functions and cannot serve as bi- directional information flow between CNC controllers and high-level systems such as CAD/CAM. ❑ Therefore, STEP-NC (Standard for The Exchange of Product Data-Numerical Control) has been proposed as object-oriented machining task description program. Using object- oriented approach, STEP-NC programs contain information of machining features, machine tools, machining strategy, tool paths, etc. With the above high level information, CNC controllers have more decision making ability and intelligence, such as modifying machining strategy or machining tool paths. Meanwhile, modifications can be fed back to CAD/CAM systems. ❑ STEP-NC increases the interoperability of CNC controllers and fills the gap between CNC and CAD/CAM. Functions originally belong to CAD/CAM systems are integrated in CNC systems, such as manufacturing feature recognition and tool path generation. ❑ STEP-compliant CNC system is more than just a machine tool controller, but rather an integrated manufacturing data processing platform.  Computer Numerical Control ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Computer Numerical Control (CNC) – Additional Features 1. Storage of more than one part program. 2. Various forms of program input 3. Program editing at the machine tool 4. Fixed cycles and programming subroutines 5. Adaptive control 6. Interpolation 7. Positioning features for setup. 8. Acceleration and deceleration computations 9. Communications interface 10. Diagnostics ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  CNC Components ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Machine Control Unit(MCU) ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Machine Control Unit ▪ CNC Controllers Manufactures ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Machine Control Unit ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. MONITOR/KEYBOARD /CONTROL PANEL for the 8025 CNC 1 Function keys (SOFT-KEYS) 2 Alphanumeric keyboard for editing programs 3 ENTER. Allows information to be entered in the CNC memory, etc 4 RECALL To call a program to access blocks within a program, etc. 5 OP MODE. Allows a list of operating modes to be displayed on the screen. It is a previous step to accessing any of them. 6 DELETE. It allows deletion of a complete program or a block of the programme. Deletion of the graphic representation, etc. 7 RESET. To revert the CNC to the initial conditions and recognise new machine parameter values, decoded M functions, etc. 8 CL. To delete characters one by one during the editing process, etc. 9 INS. Key which allows characters to be inserted during the edition of a program block 10 Arrow keys for moving cursor. 11 Page up and page down keys 12 SP: reserves a space between characters of a comment. CAPS: Allows characters to be edited in capitals. SHIFT: Allows characters to be edited which are found on keys with double meaning 13 JOG keys for manual displacement of the axes. 14 RAPID FEED button. 15 Switch (M.F.O.), which allows a % variation of the programmed feed and to choose the different ways of working in the JOG MODE (continuous, incremental, electronic handwheel). 16 Spindle operating keys. 17 START. Cycle START key. 18 STOP. Cycle STOP key.  OPERATING MODES The CNC has 10 different operating modes: 0 AUTOMATIC : Execution of programs in a continuous cycle. 1 SINGLE BLOCK: Execution of part programs block by block. 2 PLAY-BACK : Creation of a program in memory while the machine is being operated manually. 3 TEACH-IN : - Creation and execution of a block without entering it into memory. - Creation, execution and entering of a block into memory; thus a program is created while being executed block by block. 4 DRY RUN : To check programs before actual execution of the first part. 5 JOG/HOME SEARCH: - Manual movement of the machine. - Machine-reference. - Presetting of any value and zero-setting the axes. - Entering and executing of F,S,M. - Setting initial conditions of the tool magazine. - Handwheel operation. 6 EDITING: Creation, modification and checking of blocks, programs and subroutines. 7 INPUT-OUTPUT: Transferring programs or machine-parameters from/to peripherals. 8 TOOL OFFSETS/ G53-G59: Input, modification and checking of the dimensions (radius and length) of up to 100 tools and of zero offsets (G53-G59). 9 SPECIAL MODES: General testing of the CNC. Verification of inputs and outputs. Setting of decoded M functions. Setting of machine-parameters. Input of values for leadscrew error compensation. Operate with the PLC.  Machine Control Unit ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Machine Control Unit ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. SW: soft-wired  Machine Control Unit ▪ The machine control unit (MCU) is the heart of a CNC system. It is used to perform the following functions: To read & decode the coded instructions. To implement interpolations (linear, circular, and helical) to generate axis motion commands. To feed the axis motion commands to the amplifier circuits for driving the axis mechanisms. To receive the feedback signals of position and speed for each drive axis. To implement auxiliary control functions such as coolant or spindle on/off and tool change. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  MCU: Types of CNC Software ▪ The CNC machines operates by means of software, there are three types of software programs used in CNC systems: (1) Operating system software: it is principal function is to interpret the NC part programs and generate the corresponding control signals to drive the machine tool axes. It consists of the following: (1) an editor, (2) a control program, and (3) an executive program. The operating system software also includes any diagnostic routines. (2) Machine interface software: is used to operate the communication link between the CPU and the machine tool to accomplish the CNC auxiliary functions. The I/O signals associated with the auxiliary functions are sometimes implemented by means of a programmable logic controller interfaced to the MCU, so the machine interface software is often written in the form of ladder logic diagrams (3) Application software: consists of the NC part programs that are written for machining (or other) applications in the user’s plant.  Configuration of CNC Machine Control Unit The MCU is the hardware that distinguishes CNC from conventional NC. The MCU consists of the following components and subsystems: (1) central processing unit, (2) memory, (3) I/O interface, (4) controls for machine tool axes and spindle speed, and (5) sequence controls for other machine tool functions. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  1. CENTRAL PROCESSING UNIT (CPU) ▪ The central processing unit (CPU) is the brain of the MCU. It manages the other components in the MCU based on software contained in main memory. The CPU can be divided into three sections: (1) control section, (2) arithmetic-logic unit, and (3) immediate access memory. ▪ The control section retrieves commands and data from memory and generates signals to activate other components in the MCU. In short, it sequences, coordinates, and regulates the activities of the MCU computer. ▪ The arithmetic-logic unit (ALU) consists of the circuitry to perform various calculations (addition, subtraction, multiplication), counting, and logical functions required by software residing in memory. ▪ The immediate access memory provides a temporary storage for data being processed by the CPU. It is connected to main memory by means of the system data bus.  2. Memory ▪ As with most other computer systems, CNC memory can be divided into two categories: (1) main memory and (2) secondary memory. ▪ Main memory consists of ROM (read-only memory) and secondary memory consists of RAM (random access memory) devices. ▪ Operating system software and machine interface programs are generally stored in ROM. These programs are usually installed by the manufacturer of the MCU. ▪ NC part programs are stored in RAM devices. Current programs in RAM can be erased and replaced by new programs as jobs are changed. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  2. Memory ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  3. Input / Output Interface ▪ The I/O interface. provides communication between the various components of the CNC system, other computer systems, and the machine operator ▪ The I/O interface transmits and receives data and signals to and from external devices. The operator control panel is the basic interface by which the machine operator communicates to the CNC system. ▪ This is used to enter commands related to part program editing, MCU operating mode (MDI MODE) (e.g., program control vs. manual control), speeds and feeds, cutting fluid pump on/off, and similar functions. Either an alphanumeric keypad or keyboard is usually included in the operator control panel. ▪ The I/O interface also includes a display to communicate data and information from the MCU to the machine operator. The display is used to indicate current status of the program as it is being executed and to warn the operator of any malfunctions in the system.  Input Media ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Input Media ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  4. Controls for Machine Tool Axes and Spindle Speed ▪ These are hardware components that control the position and velocity (feed rate) of each machine axis as well as the rotational speed of the machine tool spindle. ▪ Positioning systems can be classified as open loop or closed loop, and different hardware components are required in each case. A more detailed discussion of these hardware elements is presented in next Sections, together with an analysis of how they operate to achieve position and feed rate control. Some of the hardware components are resident in the MCU. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  5. Sequence Controls for Other Machine Tool Functions ▪ In addition to control of table position, feed rate, and spindle speed, several additional functions are accomplished under part program control. ▪ These auxiliary functions generally involve on/off (binary) actuations, interlocks, and discrete numerical data. The functions include cutting fluid control, fixture clamping, emergency warnings, and interlock communications for robot loading and unloading of the machine tool. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Examples of CNC Machines ▪ CNC controls are used to control various types of machine tools. ▪ Regardless of which type of machine tool is controlled, it always has a slide table and a spindle to control of position and speed. ▪ The machine table is controlled in the X and Y axes, while the spindle runs along the Z axis. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Examples of CNC Machines ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Examples of CNC Machines ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Direct Numerical Control (DNC) ▪ Direct numerical control (DNC) – control of multiple machine tools by a single (mainframe) computer through direct connection and in real time. ▪ The program was transmitted to the MCU directly from the computer, one block of instructions at a time. ▪ 1960s technology ▪ Two way communication ▪ Distributed numerical control (DNC) – network consisting of central computer connected to machine tool MCUs, which are CNC ▪ Present technology ▪ Two way communication of data between the shop floor and the central computer, which was one of the important features included in the old DNC. DNC DNC  General Configuration of a Direct Numerical Control System Connection to MCU is behind the tape reader (BTR). In distributed NC, entire programs are downloaded to each MCU, which is CNC rather than conventional NC. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Distributed Numerical Control Configurations ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Distributed Numerical Control Configurations 1. Switching Network Configurations: Complete part programs are sent to the machine tools, not one block at a time. The distributed NC approach permits easier and less costly installation of the overall system, because the individual CNC machines can be put into service and distributed NC can be added later Switching network ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Distributed Numerical Control Configurations 2. Local Area Network (LAN) Configurations: Local area network (LAN) ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Table 7.3 Flow of Data and Information Between Central Computer and Machine Tools in DNC Data and Information Downloaded from Data and Information Uploaded from the the Central Computer to the Machine Machine Tools to the Central Computer Tools 1. NC part programs 1. Piece counts 2. List of tools needed for job 2. Actual machining cycle times 3. Machine tool setup instructions 3. Tool life statistics 4. Machine operator instructions 4. Machine uptime and downtime statistics 5. Machining cycle time for part program 5. Product quality data 6. Data about when program was last used 6. Machine utilization 7. Production schedule information Two way communication ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Applications of NC ▪ Machine tool applications: ▪ Milling, drilling, turning, boring, grinding ▪ Machining centers, turning centers, mill-turn centers ▪ Punch presses, Presses for sheet metal bending, Welding machines, Tube bending and wire bending machines, Wire EDM, thermal cutting machines, etc. ▪ Each of the machining operations is carried out at a certain combination of speed, feed, and depth of cut, collectively called the cutting conditions ▪ Other NC applications: ▪ Rapid prototyping and additive manufacturing: Fused Deposition Modeling, 3-D Printing, Selective Laser Sintering, Stereo Lithography, etc. ▪ Component insertion machines in electronics ▪ Drafting machines (x-y plotters) ▪ Wood routers and granite cutters ▪ Coordinate measuring machines ▪ Tape laying machines for polymer composites ▪ Filament winding machines for polymer composites  Common NC Machining Operations Turning ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Common NC Machining Operations Milling Drilling The cutting speed is the velocity of the milling cutter relative to the work surface, m/min (ft/min). This is usually programmed into the machine as a spindle rotation speed, rev/min. In milling, the feed usually means the size of the chip formed by each tooth in the milling cutter, often referred to as the chip load per tooth. This must normally be programmed into the NC machine as the feed rate (the travel rate of the machine tool table). ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. Depth ofof this No portion cut is may material thebe reproduced, distance in anythe form ortool penetrates by any means, below without permission thetheoriginal in writing from publisher. For thesurface exclusive use of the ofwork, of adopters the book mm Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover. (in)  CNC Horizontal Milling Machine ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  NC Application Characteristics (Machining) Where NC is most appropriate: 1. Batch production 2. Repeat orders 3. Complex part geometries 4. Much metal needs to be removed from the starting workpart 5. Many separate machining operations on the part 6. The part is expensive ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Advantages of NC 1. Nonproductive time is reduced: This is achieved through fewer setups, less setup time, reduced workpiece handling time, and automatic tool changes. 2. Greater accuracy and repeatability: Parts are made closer to nominal dimensions, and there is less dimensional variation among parts in the batch. 3. Lower scrap rates: Because greater accuracy and repeatability are achieved, and because human errors are reduced, more parts are produced within tolerance. 4. Inspection requirements are reduced 5. More complex part geometries are possible 6. Engineering changes are easier to make 7. Simpler fixtures: Because accurate positioning of the tool is accomplished 8. Shorter lead times: Jobs can be set up more quickly and fewer setups are required per part, results in shorter elapsed time. 9. Reduce parts inventory and less floor space 10. Operator skill-level requirements are reduced  Disadvantages of NC ▪ Higher investment cost ▪ CNC machines are more expensive ▪ Higher maintenance effort ▪ CNC machines are more technologically sophisticated ▪ Part programming issues ▪ Need for skilled programmers ▪ Time investment for each new part ▪ Repeat orders are easy because part program is already available ▪ Higher utilization is required ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Drive System ▪ A drive system consists of amplifier circuits, drive motors, and ball lead-screws. ▪ The MCU feeds the control signals (position and speed) of each axis to the amplifier circuits. ▪ The control signals are augmented to actuate drive motors which in turn rotate the ball lead-screws to position the machine table. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Servomechanisms ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Servomechanisms ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  NC Positioning System ▪ Typical motor and leadscrew arrangement in an NC positioning system for one linear axis ▪ For x-y capability, the apparatus would be piggybacked on top of a second perpendicular axis.  Analysis of Positioning NC Systems ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Open-Loop Motion Control System Step Angle, Angle of Motor Shaft Rotation, Angle of Screw Rotation Gear Ratio, Linear Movement of Worktable, x-axis position relative to the starting position is: ▪ Number of Pulses required to achieve a specified x- position increment in a point-to-point system is: The table travel speed in the Rotational Speed of Screw vt = table travel speed, direction of screw axis is: mm/min (in/min) ; fr = table feed rate, mm/min (in/min); ▪ Required pulse train frequency to drive the table at a specified linear travel rate can be obtained by  Open-Loop Motion Control System ▪ Example: NC Open-Loop Positioning The worktable of a positioning system is driven by a ball screw whose pitch = 6.0 mm. The screw is connected to the output shaft of a stepper motor through a gearbox whose ratio is 5:1 (five turns of the motor to one turn of the screw). The stepper motor has 48 step angles. The table must move a distance of 250 mm from its present position at a linear velocity = 500 mm/min. Determine (a) How many pulses are required to move the table the specified distance and (b) The required motor speed and pulse rate to achieve the desired table velocity. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Closed-Loop Motion Control System ▪ A closed-loop system uses feedback measurements to confirm that the final position of the worktable is the location specified in the program. ▪ Closed-loop systems are normally specified for machines that perform continuous path operations such as milling or turning, in which there are significant forces resisting the forward motion of the cutting tool.  Precision in NC Positioning Three measures of precision: 1. Control resolution - refers to the control system’s ability to divide the total range of the axis movement into closely spaced points that can be distinguished by the MCU. Control resolution is defined as the distance separating two adjacent addressable points in the axis movement. Addressable points are locations along the axis to which the worktable can be specifically directed to go. 2. Accuracy - is defined under worst case conditions in which the desired target point lies in the middle between two adjacent addressable points. Accuracy is the maximum possible error that can occur between the desired target point and the actual position taken by the system 3. Repeatability - defined as 3 of the mechanical error distribution associated with the axis. Repeatability refers to the ability of the positioning system to return to a given addressable point that has been previously programmed. This capability can be measured in terms of the location errors encountered when the system attempts to position itself at the addressable point  Definitions of Control Resolution, Accuracy, and Repeatability open loop positioning system ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Types of Motion Control Systems ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Motion Control Systems ❑ Point-to-Point systems ▪ Also called position systems ▪ Move the worktable to a programmed location without regard for the path taken to get to that location and performs an operation at that location (e.g., drilling, punching a hole, robotics). ▪ The program consists of a series of point locations at which operations are performed.  Motion Control Systems ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Motion Control Systems ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Motion Control Systems ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Motion Control Systems ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Motion Control Systems ❑ Continuous path systems ▪ Also called contouring systems in machining ▪ Capable of continuous simultaneous control of two or more axes. This provides control of the tool path relative to the work part. ▪ System performs an operation during movement (e.g., milling and turning) ▪ Thus enabling the system to generate angular surfaces, two- dimensional curves, or 3D contours in the work part. Motion Control Systems Motion Control Systems Motion Control Systems  Interpolation Methods ▪ A fundamental problem in generating shapes using NC equipment is that they are continuous, whereas NC is digital. 1. Linear interpolation: Straight line between two points in space 2. Circular interpolation: Circular arc defined by starting point, end point, center or radius, and direction 3. Helical interpolation: Circular plus linear motion 4. Parabolic and cubic interpolation: Free form curves using higher order equations ▪ The interpolation module in the MCU performs the calculations and directs the tool along the path. In CNC systems, the interpolator is generally accomplished by software.  Linear Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Linear Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Linear Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Linear Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation Approximation of a curved path in NC by a series of straight line segments, where tolerance is defined on only the inside of the nominal curve ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation Approximation of a curved path in NC by a series of straight line segments, where tolerance is defined on only the outside of the nominal curve ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation Interpolation routines have been developed that calculate the intermediate points to be followed by the cutter to generate a particular mathematically defined or approximated Path. Approximation of a curved path in NC by a series of straight line segments, where tolerance is defined on both the inside and outside of the nominal curve ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Circular Interpolation ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  CNC Machine Rating 1. Accuracy, 2. Repeatability, 3. Spindle and axis motor horsepower, 4. Number of controlled axes, 5. Dimension of workspace, and 6. Features of the machine and controller. ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.  Special Requirements For Utilizing CNC ©2008 Pearson Education, Inc., Upper Saddle River, NJ. All rights reserved. This material is protected under all copyright laws as they currently exist. No portion of this material may be reproduced, in any form or by any means, without permission in writing from the publisher. For the exclusive use of adopters of the book Automation, Production Systems, and Computer-Integrated Manufacturing, Third Edition, by Mikell P. Groover.