COMPUTER INTEGRATED MANUFACTURING SYSTEMS

Transcription

1 COMPUTER INTEGRATED MANUFACTURING SYSTEMS (For B.E. Mechanical Engineering Students) Dr. S. Ramachandran, M.E., Ph.D., Professor and Research Head, Faculty of Mechanical Engineering, Sathyabama University, Chennai M.L. Moorthy, M.E., Dr. A. John Rajan, M.E., Ph.D., Professor, School of Mechanical Engineering Department of Manufacturing, VIT University, Vellore AIR WALK PUBLICATIONS (Near All India Radio) 80, Karneeshwarar Koil Street, Mylapore, Chennai Ph.: ,

2 First Edition: July 2016 All Rights Reserved by the Publisher This book or part thereof should not be reproduced in any form without the written permission of the publisher. ISBN : Books will be door delivered after payment into AIR WALK PUBLICATIONS A/c No (IFSC: BKIDOOO8016) Bank of India, Santhome branch, Mylapore, Chennai 4 (or) S. Ramachandran, A/c No (IFSC:IDIB000S201), Indian Bank, Sathyabama University Branch, Chennai Typeset by: Akshayaa DTP, Chennai 89, Ph:

3 i CIM ME6703 COMPUTER INTEGRATED MANUFACTURING SYSTEMS CHAPTER 1: INTRODUCTION Brief introduction to CAD and CAM Manufacturing Planning, Manufacturing control Introduction to CAD/CAM Concurrent Engineering CIM concepts Computerised elements of CIM system Types of production Manufacturing models and Metrics Mathematical models of Production Performance Simple problems Manufacturing Control Simple Problems Basic Elements of an Automated system Levels of Automation Lean Production and Just-in-Time Production. CHAPTER 2: PRODUCTION PLANNING AND CONTROL AND COMPUTERISED PROCESS PLANNING Process planning Computer Aided Process Planning (CAPP) Logical steps in Computer Aided Process Planning Aggregate Production Planning and the Master Production Schedule Material Requirement planning Capacity Planning Control Systems Shop Floor Control Inventory Control Brief on Manufacturing Resource Planning-II (MRP-II) & Enterprise Resource Planning (ERP) Simple Problems. CHAPTER 3: CELLULAR MANUFACTURING (Group Technology (GT), Part Families Parts Classification and coding Simple Problems in Opitz Part coding system Production flow Analysis Cellular Manufacturing Composite part concept Machine cell design and layout Quantitative analysis in Cellular Manufacturing Rank OrderClustering Method Arranging Machines in a GT cell Hollier Method Simple Problems.)

4 Syllabus ii CHAPTER 4: FLEXIBLE MANUFACTURING SYSTEM (FMS) AND AUTOMATED GUIDED VEHICLE SYSTEM (AGVS) (Types of Flexibility F MS FMS Components F M S Application & Benefits FMS Planning and Control Quantitative analysis in FMS Simple Problems.Automated Guided Vehicle System (AGVS) AGVS Application Vehicle Guidance technology Vehicle Management & Safety.) CHAPTER 5: INDUSTRIAL ROBOTICS Robot Anatomy and Related Attributes Classification of Robots Robot Control systems End Effectors Sensors in Robotics Industrial Robot Applications Robot Part Programming Robot Accuracy and Repeatability Simple Problems. *********

5 i CIM CONTENTS CHAPTER 1: INTRODUCTION Introduction Computer aided design (CAD) The factors to be considered while selecting a CAD system Role of Computer in CAD Applications of CAD Uses of CAD Computer Aided Design and Drafting Packages Reasons for Implementing a CAD Benefits of CAD Applications of CAD Design Process in CAD System (or) Elements of a CAD Geometric Modelling Engineering Analysis Computer Aided Manufacturing (CAM) Manufacturing Planning Manufacturing Control CAD/CAM Interface CAD/CAM Vs CIM Concurrent Engineering Introduction of CIM 1.22

6 Contents ii Definition CASA/SME Model of CIM/CIM Wheel Nature and Role of the Elements of CIM System Reasons for Implementing CIM Objectives/Goal of CIM CIM I Vs CIM II Benefits of CIM Computer Integrated Manufacturing (CIM) as a Concept and a Technology Computerised Elements of a CIM-System Types of Production Manufacturing Models and Metrics Mathematical models of Production Performance Production Rate Production capacity Utilization Availability Manufacturing lead time Work in-process (WIP) Manufacturing Costs Fixed and Variable Costs Direct labour, Material and Overhead Manufacturing Control Basic Elements of an Automated System 1.53

7 iii CIM Power to accomplish the automated process Program of Instructions Control System Basic Terminology used in Control System Types of Control System Basic terms used in Closed Loop Control System Comparison between Open Loop and Closed Loop Control System Levels of Automation Lean Manufacturing Objectives of Lean Production Principles of Lean Manufacturing Benefits of Implementing Lean Operational Improvements The five steps of Lean Implementation Just in time Approach (JIT Approach) Key Elements in JIT Approach Kanban 1.80 CHAPTER 2: PRODUCTION PLANNING AND CONTROL AND COMPUTERISED PROCESS PLANNING Process Planning Computer Aided Process Planning (CAPP) 2.2

8 Contents iv 2.3. Process Planning Techniques Manual Approach Variant CAPP systems (Retrieval CAPP systems) Generative CAPP system Production Planning and Control Demand Forecasting Aggregate Production Planning Process Planning Estimating Master Production Scheduling Material Requirement Planning (MRP) Purchasing Machine loading and scheduling Dispatching Expediting Quality Control Shipping and Inventory Control Aggregate Production Planning Master Production Schedule (MPS) Sources of Input Data to MRP Capacity Planning Control Systems Shop Floor Control System (SFC) 2.20

9 v CIM Functions of Shop Floor Control Inventory Control Inventory Costs Inventory Control Techniques Economic Order Quantity (EOQ) ABC Analysis MRP VED Analysis Cost Control Manufacturing Resource Planning (MRP-II) Evolution of MRP-II Features of MRP-II MRP versus MRP-II ERP Definition of ERP Need for ERP Evolution of ERP Stages of ERP Evolution Benefits of ERP Risks of ERP 2.48 CHAPTER 3: CELLULAR MANUFACTURING Group Technology (GT) Objectives of Group Technology 3.3

10 Contents vi 3.2. Part Family Identification of a Part Family Part Classification and Coding Coding System Structure Selection of Coding System Part Coding Systems Simple Problems Production Flow Analysis (PFA) Cellular Manufacturing Composite Part Concept Machine cell design and layout Quantitative Analysis in Cellular Manufacturing Rank Order Clustering Hollier s method of Sequencing 3.37 CHAPTER 4: FLEXIBLE MANUFACTURING SYSTEM (FMS) AND AUTOMATED GUIDED VEHICLE SYSTEM (AGVS) Flexible Manufacturing System (FMS) Flexibility Different types of Flexibility in FMS Types of FMS FMS Components 4.9

11 vii CIM 4.6. FMS Application & Benefits FMS Planning and Control Quantitative Analysis of FMS Bottleneck model Extended Bottleneck method General Behavior of Bottleneck Station Sizing the FMS Automated Guided Vehicle System (AGVS) Components of AGV Advantages of using an AGV Applications of AGV Vehicle Guidance Technologies Steering Control Path Decision Vehicle Management and Safety System Management Traffic Control 4.52 CHAPTER 5: INDUSTRIAL ROBOTICS Introduction Laws of Robotics History of robots Robot terminology 5.3

12 Contents viii Components of Robot Robot Anatomy Basic Robot Motions Robotic wrist Work Envelope Classification of Robot Robot Control System Drive Systems End Effectors Sensors in Robotics Industrial Robot Applications Robot Part Programming User Program Robot Accuracy and Repeatability 5.57 *********

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14 CHAPTER 1 INTRODUCTION Brief introduction to CAD and CAM Manufacturing Planning, Manufacturing control Introduction to CAD/CAM Concurrent Engineering CIM concepts Computerised elements of CIM system Types of production Manufacturing models and Metrics Mathematical models of Production Performance Simple problems Manufacturing Control Simple Problems Basic Elements of an Automated system Levels of Automation Lean Production and Just-in-Time Production INTRODUCTION: CAD means Computer Aided Design and CAM means Computer Aided Manufacturing. CAD is defined as the use of computer systems to assist in the creation, modification, Analysis (or) optimization of a design. CAM can be defined as the use of computer systems to plan, manage & control the operations of a manufacturing plant through either direct (or) indirect computer interface with production resources. Computer system consists of the hardware and software to perform the specialized design functions required by the particular user firm.

15 1.2 Introduction 1.2. COMPUTER AIDED DESIGN (CAD): What is CAD? It is the technology used to integrate the design activities with the help of computer which includes transformation and modification of images of part geometry, printing the images on a printer or plotter and design data analysis. CAD can also be defined as the process in which computers are utilised in the creation of model, modification and analysis of a design to get the optimum model Why should we go for CAD? 1. For improved documentation, more standardization, better Engineering drawings, reduced drawing errors and clear perception of drawings. 2. The design quality is improved, moreover any problem encountered during design can be rectified and suitable alternatives are suggested. There is an inbuilt feature which checks for any calculation errors and leads to better quality and accuracy of design. 3. The productivity is increased, the synthesis time is greatly reduced as the design engineer has better visualisation of part geometry The factors to be considered while selecting a CAD system: (a) Reliability (b) Compatibility with other system (c) Cost Factors (d) Memory size and storage requirement (e) Type of peripherals requirement.

16 CIM Role of Computer in CAD: (a) (b) (c) (d) (e) Computer improves accuracy of design. Various dimension and other design attributes can be conveniently manipulated by computers. Another important role played by Computers is creation of part libraries for standard components. Similarly multiple components can be included in these part libraries. Moreover, the modification of a model is very simple which helps the designer to look in for further improvement. Calculation of various geometric properties such as area, volume and dimensioning can be accurately done Applications of CAD in simple words: (a) (b) (c) (d) (e) (f) (g) Finite element analysis. CNC programming. Building drawing using Architectural CAD. Piping system for Engineering Industries. CAPP (Computer Aided Process Planning). Kinematic analysis for systems. Dynamic analysis for systems Uses of CAD: (a) (b) (c) Creating several colour combinations for a product to improve its appeal. Exploded views of assemblies can be effectively done. Resizing and Rotation of the objects can also be done for viewing the objects from different angles (different perspectives).

17 1.4 Introduction (d) (e) (f) (g) (h) (i) Material requirement for manufacturing a part, cost involved and other details can be predicted. A complete comprehensive drawing can be made including the dimensions, tolerances and other functional specifications. Assembly drawings and assembly procedures can be done. Cross sectional details and other inner details can be effectively created. Interference checking between mating parts can be done. Eg: cone clutch. Here the female cone and male cone interference can be checked. Any drawing after completion can be stored in computer file, which can later be printed. Note: How CAD is integrated with CAE and other functions (Activities) is shown below Computer Aided Design and Drafting Packages: For drafting, Modelling and analysis. 1. Auto CAD 2. Pro-Engineer (PRO-E) 3. Ideas 4. Unigraphics

18 CIM Mechanical Desktop 6. ANSYS 7. Nastran 8. Pro-Mechanica 9. CATIA Reasons for Implementing a CAD: To create and modify appearance of objects. It improves the productivity of the designer. Improves communication. Improves the efficiency of Design. Create database for manufacturing Benefits of CAD: 1. Increased design and productivity. 2. Flexibility in design. 3. Improved design analysis. 4. Greater accuracy in design. 5. Easier creation and correction of engineering drawings. 6. Better visualization of drawings. 7. Faster new product design. 8. Shorter lead time.

19 1.6 Introduction Applications of CAD: Table 1.1 Area Applications Design Analysis Documentation Manufacturing Management Assembly layout, New-part design, Standard part library, Tolerance specifications, Clearance specifications Interference checking, Fit analysis Weight balance, Volume and area properties, Structural analysis, Tolerance checking, Kinematic analysis Drawing generation, Bill of materials, Image reading. Process planning, NC machine simulation, NC part program generation, NC part program verification, Inspection programming, Factory layout, Robot programming and verification. Review and release, Engineering changes, Project control, Project monitoring, Selection of standard parts and assembly, Design standards.

20 CIM DESIGN PROCESS IN CAD SYSTEM (OR) ELEMENTS OF A CAD: The various design related tasks which are performed by a modern computer aided design system can be grouped into four functional areas: 1. Geometric modelling 2. Engineering analysis 3. Design review and evaluation 4. Automated drafting Fig. 1.1: Application of computers to the design process These four areas correspond to the final four phases in Shigley s general design process, illustrated in Fig Geometric modeling corresponds to the synthesis phase in which the physical design project takes from on the ICG system. Engineering analysis corresponds to phase 4, dealing

21 1.8 Introduction with analysis and optimization. Design review and evaluation is the fifth step in the general design procedure. Automated drafting involves a procedure for converting the design image data residing in computer memory into a hard-copy document. It represents an important method for presentation (phase 6) of the design. The following four sections explore each of these four CAD functions Geometric modelling: In computer-aided design, geometric modelling is concerned with the computer-compatible mathematical description of the geometry of an object. The mathematical description allows the image of the object to be displayed and manipulated on a graphics terminal through signals from the CPU of the CAD system. The software that provides geometric modelling capabilities must be designed for efficient use both by the computer and the human designer. To use geometric modeling, the designer constructs the graphical image of the object on the CRT screen of the ICG system by inputing three types of commands to the computer. The first type of command generates basic geometric elements such as points, lines and circles. The second command type is used to accomplish scaling, rotation or other transformations of these elements. The third type of command causes the various elements to be joined into the desired shape of the object being created on the ICG system. During this geometric modelling process, the computer converts the commands into a mathematical model, stores it in the computer data files and displays it as an image on the CRT screen. The model can subsequently be called from the data files for review, analysis or alteration. There are several different methods of representing the object in geometric modelling. The basic form uses wire frames to represent the object. In this form, the object is displayed by interconnecting lines, as shown in Fig Wire-frame

22 CIM geometric modeling is classified into three types, depending on the capabilities of the ICG system. The three types are: Fig. 1.2: Example of wire-frame drawing of a part 1. 2D. Two-dimensional representation is used for a flat object D. This goes somewhat beyond the 2D capability by permitting a three-dimensional object to be represented as long as it has no side-wall details. 3. 3D. This allows for full three-dimensional modelling of a more complex geometry Engineering Analysis: In the formulation of nearly any Engineering design project, some types of analysis is required. The analysis may involve stress-strain calculations, heat transfer or use of differential equations to describe the dynamic behaviour of the system being designed. CAD/CAM systems often include engineering analysis software which can be called to operate on the current design model.

23 1.10 Introduction Example: 1. Analysis of mass properties 2. Finite element analysis 3. Design, Review & evaluation: Checking the accuracy of the design can be accomplished conveniently on the graphics terminal. A procedure called layering is often helpful in design review. Eg: A good application of layering involves overlaying the geometric image of the final shape of the machined part on the top of the image in the rough casting. Another procedure for design review is interference checking. 4. Automated drafting: It involves the creation of hardcopy engineering drawings directly from the CAD database. CAD systems can increase productivity in the drafting function more over 5 times of manual drafting. Thise feature includes automatic drawing, hatched areas, scaling, zoom, etc COMPUTER AIDED MANUFACTURING (CAM): Computer Aided Manufacturing: The computer systems are used to plan, manage and control the operations of the production plant through the computer interface with the plant s production resources. This is known as Computer Aided Manufacturing. CAM is most closely associated with process planning and numerical control (NC) part programming.

24 CIM The functions of CAM are given below. 1. Computer Aided Process Planning (CAPP) 2. CNC Part Programming 3. Computer Aided Work Standards 4. Production Scheduling 5. Materials Requirements Planning (MRP) 6. Shop Floor Control The advantages of Computer Aided Manufacturing: The Computer application in manufacturing makes use of common database. The data is transferred from one function to another automatically to give a base for the concept of Computer Integrated Manufacturing (CIM). The other advantages of CAM are given below: 1. Increased Productivity. 2. Shorter lead time 3. Improved reliability. 4. Freedom in modifying design. 5. Flexibility in operations. 6. Reduced scrap and rework. 7. Reduced Maintenance. 8. Better Control of Management.

25 1.12 Introduction Fig. 1.3: The information processing cycle in a typical manufacturing firm The application of CAM can be classified into two categories: 1. Manufacturing planning 2. Manufacturing control Manufacturing planning: In this process computer is used indirectly to support the production function, but there is no direct connection between the computer and process. Important Applications are: 1. CAPP Computer Aided process planning 2. Computer Assisted NC part programming 3. Computerized machinability data systems 4. Computerized work standards 5. Cost Estimating

26 CIM Production and Inventory planning 7. Computer Aided line balancing Manufacturing control: Manufacturing control is concerned with managing and controlling the physical operations in the factory. The following areas to be controlled by manufacturing control, 1. Process monitoring 2. Quality control 3. Shop floor control 4. Inventory control 5. First in time production CAD/CAM Interface: CAD/CAM is concerned with the engineering functions in both design and manufacturing. CAD/CAM must be interfaced to achieve improvement in manufacturing, improved productivity and quality. The various data (like component geometry data) generated for designing and developing CAD drawings can be reused for manufacturing instruction. These data can be used for CNC production processes. Computer aided process planning (CAPP), Computer aided production planning and control (PPC) and shop floor control (SFC). The CNC production processes CAPP, PPC and SFC with the aid of computers are known as Computer Aided Manufacturing (CAM). So the current trends in manufacturing is to interface the CAD and CAM. The both CAD and CAM are sharing common database to eliminate the unwanted wall separating the design and manufacturing functions. Refer Fig. 1.4(a).

27 1.14 Introduction Fig. 1.4(a): CAD/CAM Interfaced Design and Manufacturing with CAD/CAM The CAD/CAM interface allows the manufacturing function to influence the design process and also to make the designers to know the effects of design features on the manufacturing function. Advantages of CAD/CAM Interface: 1. Productivity can be increased due to fast mathematical calculations, data storage and retrieval. 2. Quality can be improved since the designer can select best design among the various design alternatives easily by knowing their effects on manufacturing function. 3. Communication is improved. The design documents like drawings, part lists, bill of materials and specifications are sent to common data base which are utilized by manufacturing department.

28 CIM By using 3-D Computer models, rapid prototype is developed with less cost. It eliminates the expensive prototypes. 5. Customers taste can be responded and implemented on the design, result in manufacturing. The following diagram Fig. 1.4(b) haws the concept of CAD/CAM interface. Fig. 1.4(b): CAD/CAM Interface In CAD department, the part 3D model is developed in the computer terminal using CAD softwares like AutoCAD, PRO-Engineering, Ideas, Unigraphics etc. This is known an Geometrical modelling. This part is analysed using Finite Element analysis for the structure and its mechanical behaviour using FEM softwares like Ansys and Nastron. Kinematic studies are performed using softwares like ADAMS. Then the design is reviewed and evaluated for its effect on manufacturing function. Thereafter the engineering drawings are produced. The manufacturing department utilizes the geometric description from the common database. It prepares the process planning and developes CNC programs for machine tools. It instructs Robots to handle the rolls and workpieces. It schedules the plant operations with production planning and control system.

29 1.16 Introduction CAD/CAM Vs CIM: CAD/CAM includes design, manufacturing planning & control. CIM means engineering functions of CAD/CAM & firm s business that are related to manufacturing. Fig. 1.5: The scope of CAM/CAD and CIM 1.5. CONCURRENT ENGINEERING: In olden days, in the conventional manufacturing process, the details about how to achieve quality of product, cost of product and variety of products are not given back to the designer at sufficiently early stage. Hence, the whole process takes too long. But, the current trends in manufacturing engineering break the firewall between the designer and manufacturing personnel to achieve high quality product throughout the product development phase. The current trends in manufacturing technology requires high quality with acceptable levels of defects (or) zero defects. So the achievement of high quality is the responsibility of everyone in an organization. The quality will be lost if there is a demarcation between design and manufacturing department. To get high quality, the design should be modified to meet the manufacturing requirements at an early stage.

30 CIM Hence the design and the manufacturing system should be developed simultaneously. This is known as simultaneous engineering or concurrent engineering. In concurrent engineering, the design is developed by the experts from various fields like materials, manufacturing processes, assembly, inspection, maintenance and marketing. The life cycle of a product consists of design phase, the manufacturing phase and the end-of-life phase. In conventional product cycle, the design and manufacturing are separated and occur sequentially as shown in Fig. 1.6 (a) & (b). Fig. 1.6(a): Phases of Product Life Cycle Fig. 1.6(b): Sequential Engineering The process planning bridges the gap between the two phases. The sequence of operations involved in the manufacturing of a new product are 1. Design 2. Process planning 3. Manufacturing 4. Assembly. In the conventional manufacturing, these stages proceed sequentially, as shown in Fig. 1.6(c). So the lead time for a new product is more.

31 1.18 Introduction Fig. 1.6(c): Various Stages Involved in the Manufacturing of a Product But in concurrent engineering, these operations are done in parallel and are overlapped, as shown in Fig. 1.6(d). Fig. 1.6(d): Various Stages involved in the Manufacturing of a Product in concurrent Engineering Environment Here the lead time for a new product is less. So, in concurrent engineering approach, the whole life cycle of a product is considered concurrently. Concurrent engineering carry out the design and manufacturing functions at the same time while designing the product. It makes the design engineer and manufacturing engineer to interchange the parameters to obtain optimum design of product and process. The concurrent engineering defines complete life cycle of product from prototype to manufacture, repair, eventual disposal and recycling. It combines the design and process planning into one common activity. It improves the inability of early design decisions. It reduces the life cycle cost of the product tremendously.

32 CIM The concept of concurrent engineering is shown in Fig. 1.6(e). Fig. 1.6(e): The concept of concurrent engineering In this, the design coordinator coordinates the suggestions from all the experts of various departments around him. The design coordinator moves the new design to all the experts. The experts discuss it and suggest design changes. The design is then passed back to the design coordinator. He accepts the suggestions, modifies the design and sends it to the experts again for evaluation. On each integration, there will be fewer and fewer changes and finally optimum design is arrived. Design for Manufacture and Assembly DFMA: DFM means design of product for ease of manufacture DFA means design of product for ease of assembly. Design for manufacture and assembly means that design the product for ease of manufacture and for ease of assembly. i.e. Design a component so that it can be easily manufactured and easily assembled.

33 1.20 Introduction It is the integration of product design, assembly and process planning into one common activity. It is one of the techniques for applying concurrent Engineering. The following are important points to be noted during design for manufacturing and assembly. 1. Number of parts to be designed should be minimum. 2. Variation of part should be minimised. 3. The parts designed should be used for so many functions. 4. Design a part so that it can be easily fabricated. 5. Avoid separate fasteners. 6. Design the part so that it can be easily assembled. 7. Evaluate assembly methods. 8. Avoid flexible components which are difficult to handle. 9. Trade with known and experienced vendors and suppliers. 10. Minimise subassemblies. 11. New technology should not be used unless it is necessary. 12. Emphasize standardization. 13. Use the simple and possible operations. 14. Minimize set up procedures and interventions. The DFMA reduces the time spent on the design process. The following flow Fig. 1.6(f) shows the steps taken for concurrent engineering using DFMA during design.

34 CIM Fig. 1.6(f): Concurrent engineering using DFMA technique In this, the DFA analysis is conducted at first to simplify the product structure. By this, early cost estimates for the products are obtained for both original design and new design and decide which one is economical. During this process, the best materials and best processes are selected for the various parts of the product. Suggestions for more economic materials and processes are taken into account at this stage. Once the best materials and processes are finalised, a thorough analysis about design for manufacturing (DFM) can be carried out. By this DFM, the detailed design of parts are evaluated. Then protype can be developed and tested. Finally the product will be manufactured. The goals of concurrent engineering are given below. 1. Avoid expensive components which are unnecessarily expensive to produce. (e.g) surface furnish smoother than necessary should be avoided.

35 1.22 Introduction 2. Reduce the material costs (or) make the optimum choice of materials and the optimum choice of processes INTRODUCTION OF CIM: The term CIM comprises three words Computer, Integrated and Manufacturing with all three words are equally significant. CIM is the application of computers in manufacturing, in an integrated way. The middle term integrated in CIM is very appropriate. It brings the home point that integration of the all resources capital, human, technology and equipment which are vital to success in manufacturing. Although computers and computer communication have been with us since 1950 s, CIM is relatively new. It began to draw attention only in the 1980 s. CIM is an umbrella term under which all functions of manufacturing and associated attributes such as CAD/CAM, Flexible Manufacturing System and Computer Aided Process Planning etc. CIM surrounds the entire range of product development and manufacturing activities with all the functions being carried out with the help of software packages. For example: The product data is created during design. This data has to be transferred from the modelling software to manufacturing software without any loss of data. CIM uses a common database to integrate design, manufacturing and associated business functions that combine the automated segments of a factory.

36 CIM What is Computer Integrated Manufacturing: Basically Computer Integrated Manufacturing (CIM) is the manufacturing approach of using computers to control entire production process. CIM is an operating philosophy aiming at greater efficiency across the whole cycle of product, design and manufacturing and Marketing, thereby improving quality, productivity & competitiveness Definition: There are many definition for CIM according to different aspects. Some of them are given below. 1. CIM is the concept of a totally automated in which all manufacturing process integrated and controlled by a CAD/CAM system. Kochan and Cowan 2. CIM is the application of Computer technology used in order to provide the right information to the right place at the right time, which enables the achievement of its product, process and business goals. Digital Equipment Corporation 3. CIM is the integration of the total manufacturing enterprise through the use of integrated systems and data communication coupled with new management philosophies that improve organization and personal efficiency. CASA/SME 4. CIM is nothing but a data Management and networking problem. Jack Conway 5. All the engineering function of CAD/CAM and business functions of the firm is called CIM. Mikill P Groover

37 1.24 Introduction 1.7. CASA/SME MODEL OF CIM / CIM WHEEL: CIM is the integration of total manufacturing enterprise by using integrated system and DATA communication with new managerial philosophies that improves organizational and personnel efficiency. At the beginning of 80 s CIM wheel was developed. Main idea was the holistic view of the enterprise, on the basis of the CIM. In center core of the CIM wheel stands the integrated architecture (Integrated System Architecture) with a common database (common DATA), the information administration and communication (information resources management & communication). On the second / middle level of the enterprise, functions such as factory automation, product and processes and manufacturing planning and conrol over the components of the integrated architecture links with one another. Fig. 1.7

38 CIM The third level is outer rim was considered administrative level. It concerns manufacturing management and personnel management, marketing, strategic planning and financial system. The advancement of the CIM wheel is the manufacturing enterprise wheel NATURE AND ROLE OF THE ELEMENTS OF CIM SYSTEM: Nine major elements of a CIM system are in Fig. 1.8 they are, Fig. 1.8: Major elements of CIM systems Marketing Product Design Planning Purchase Manufacturing Engineering Factory Automation Hardware

39 1.26 Introduction Warehousing Logistics and Supply Chain Management Finance Information Management. (i) Marketing: The need for a product is identified by the marketing division. The specifications of the product, the projection of manufacturing quantities and the strategy for marketing the product are also decided by the marketing department. Marketing also works out the manufacturing costs to assess the economic viability of the product. (ii) Product Design: The design department of the company establishes the initial database for production of a proposed product. In a CIM system this is accomplished through activities such as geometric modeling and computer aided design while considering the product requirements and concepts generated by the creativity of the design engineer. Configuration management is an important activity in many designs. Complex designs are usually carried out by several teams working simultaneously, located often in different parts of the world. The design process is constrained by the costs that will be incurred in actual production and by the capabilities of the available production equipment and processes. The design process creates the database required to manufacture the part. (iii) Planning: The planning department takes the database established by the design department and enriches it with production data and information to produce a plan for the production of the product. Planning involves several subsystems dealing with materials, facility, process, tools, manpower, capacity, scheduling, outsourcing, assembly, inspection,

40 CIM logistics etc. In a CIM system, this planning process should be constrained by the production costs and by the production equipment and process capability, in order to generate an optimized plan. (iv) Purchase: The purchase departments is responsible for placing the purchase orders and follow up, ensure quality in the production process of the vendor, receive the items, arrange for inspection and supply the items to the stores or arrange timely delivery depending on the production schedule for eventual supply to manufacture and assembly. (v) Manufacturing Engineering: Manufacturing Engineering is the activity of carrying out the production of the product, involving further enrichment of the database with performance data and information about the production equipment and processes. In CIM, this requires activities like CNC programming, simulation and computer aided scheduling of the production activity. This should include online dynamic scheduling and control based on the real time performance of the equipment and processes to assure continuous production activity. Often, the need to meet fluctuating market demand requires the manufacturing system flexible and agile. (vi) Factory Automation Hardware: Factory automation equipment further enriches the database with equipment and process data, resident either in the operator or the equipment to carry out the production process. In CIM system this consists of computer controlled process machinery such as CNC machine tools, flexible manufacturing systems (FMS). Computer controlled robots, material handling systems, computer controlled assembly systems, flexibly automated inspection systems and so on.

41 1.28 Introduction (vii) Warehousing: Warehousing is the function involving storage and retrieval of raw materials, components, finished goods as well as shipment of items. In today s complex outsourcing scenario and the need for just-in-time supply of components and subsystems, logistics and supply chain management assume great importance. (viii) Finance: Finance deals with the resources pertaining to money. Planning of investment, working capital, and cash flow control, realization of receipts, accounting and allocation of funds are the major tasks of the finance departments. (ix) Information Management: Information Management is perhaps one of the crucial tasks in CIM. This involves master production scheduling, database management, communication, manufacturing systems integration and management information systems REASONS FOR IMPLEMENTING CIM: 1. To solve following issues (a) (b) (c) (d) Strategic issue (Lack of information, technologies) Organization issue (Absence of total management system) Behavioural issue (Safety, Lack human involvement of CIM) Technological issues (Incompatible Computer System, short lead life, Frequent job changes) 2. To coordinate and organise data (i.e.) CIM used for various datas (i) Functional data (ii) Product data

42 CIM (iii) Operational data (iv) Performance data etc. 3. To meet competitive pressures Any organization to survive successfully, needs to face the following competitive pressures (i) Increased quality. (ii) Reduced production, material & labour cost. (iii) Reduce inventory. 4. To facilitate Simultaneous Engineering Concurrent (or) simultaneous engineering is a technology of restructuring the product development. Simultaneous Engineering can be easily implement with the CIM OBJECTIVES/GOAL OF CIM: The main objective are: (i) (ii) (iii) (iv) (v) (vi) More productivity and efficiency of the product. More reability. Cost of production, maintenance decreases To reduce number of hazardous job. To eliminate human error. To increase quality of product CIM I Vs CIM II: CIM I It refers to Computer Interfaced Manufacturing CIM II It refers to Computer Integrated Manufacturing. The concept has moved from interfacing to Integrating because of the advent of developments in Computer and Communication Technologies.

43 1.30 Introduction The first three generations of computer s uses vacuum tubes, transistor and Integrated Circuits (IC) etc. The fourth generation of computers in CIM I used LSI/VLSI (Large scale Integration/very large scale integration) with interfacing the data. The fifth generation of computers in CIM II used parallel processing with networking environment. Nowadays the term CIM I and CIM II are not used; Instead the term CIM is used. Difference between CIM I & CIM II: CIM I Vs CIM II 1. Computer Interfaced Manufacturing 2. Interfacing Existing System Fourth generation Computers Computer Integrated Manufacturing. Integration of total manufacturing enterprises Fifth generation Computers BENEFITS OF CIM: The following is the list of a few benefits that can be achieved by using CIM. 1. CIM improves the operational control by means of reduction in the number of uncontrollable variables, reducing dependents on human communication. 2. CIM improves the short run responsiveness. 3. CIM improves long run accommodations by means of changing product volumes.

44 CIM CIM reduces the inventory through reducing lot sizes, improving inventory turnover for the particular company. 5. Better quality in manufacturing products. 6. More accuracy in financial projections and improved cash flow. 7. It helps quicker design & development. 8. Faster access to current and past product information. 9. CIM increases machine utilizations by means of eliminating (or) reducing machine setup, utilizing automated features COMPUTER INTEGRATED MANUFACTURING (CIM) AS A CONCEPT AND A TECHNOLOGY: A number of definitions have been developed for computer integrated manufacturing (CIM). However a CIM system is commonly thought of as an integrated system that compares all the activities in the production system from the planning and design of a product through the manufacturing system, including control. CIM is an attempt to combine existing computer technologies in order to manage and control the entire business. As with traditional manufacturing approaches, the purpose of CIM is to transform product designs and materials in to salable goods at a minimum cost in the shortest possible time. CIM begins with the design of a product (CAD) and ends with the manufacture of the product (CAM). With CIM, the customary split between the design and the manufacturing functions is (supposed to be) eliminated. CIM differs from the traditional job shop manufacturing system in the role of the computer plays on the manufacturing process. Computer integer manufacturing system are basically a network of computer system tied together by a single

45 1.32 Introduction integrated database. Using the information in the database, a CIM system can direct manufacturing, distribution and financial functions into one coherent system COMPUTERISED ELEMENTS OF A CIM-SYSTEM: CIM Includes: Design parts/products Planning & control Automation Testing The concept of CIM is to integrate information from Marketing, accounting, planning, control and so on as shown in Fig Fig. 1.9: Computerized elements of a CIM system The main purpose of CIM is to be enable the company to transform ideas into a high quality of products in the minimum time, cost and CIM goes beyond the scope of FMS (or) CAD/CAM system.

46 CIM Network and integrated systems are tied up with CIM technologies. The integration of data in CIM allows CAD system to link with Numerical Control, Computer Aided Manufacturing (CAM), Part programs, Manufacturing Control and Manufacturing planning. CIM can also be linked with the automatic material handling systems to facilitate material handling. Fully completed integrated system in CIM are not only automated but also integrated with each other and also integrated with manufacturing planning, control and scheduling TYPES OF PRODUCTION: Depending upon the quantities produced in a factory, the production system can be classified into three types (i) (ii) (iii) Job shop production (low production) Batch production (medium production) Mass production (high production) Fig. 1.10: Production quantity

47 1.34 Introduction Fig shows the relation between production quantity Vs product variety for different production system. (i) Job shop Production: Job shop production is a type of manufacturing process in which small batches of a variety of custom products are made. In the job shop process flow most of the products produced, require a unique setup and sequence of process steps. Here the volume of production ranges from 1 to 100 units/year. This type of production system comes under low volume production. Examples: A machine tool shop, a machining centre, a commercial printing shop and other manufactures that make custom products in small lot sizes. The following are the important characteristics of job shop type production system: Machines and methods employed should be general purpose as product changes are quite frequent. Planning and control system should be flexible enough to deal with the frequent changes in product requirements. Man power should be skilled enough to deal with changing work conditions. Schedules are actually non existent in this system as no definite data is available on the product In process inventory will usually be high as accurate plans and schedules do not exist. Product cost is normally high because of high material and labor costs.

48 CIM Grouping of machines is done on functional basis (i.e. as lathe section, milling section etc.) This system is very flexible as management has to manufacture varying product types. Material handling systems are also flexible to meet changing product requirements. (ii) Batch production: Batch production is defined by American Production and Inventory Control Society (APICS) as a form of manufacturing in which the job passes through the functional departments in lots or batches and each lot may have a different routing. Here the volume of production ranges from ,000 units/year. This production system justified by medium volume production. Examples: Electrical goods, newspaper, books etc. The following are the important characteristics of batch type production system: As final product is somewhat standard and manufactured in batches, economy of scale can be availed to some extent. Machines are grouped on functional basis similar to the job shop manufacturing. Semi automatic, special purpose automatic machines are generally used to take advantage of the similarity among the products. Labor should be skilled enough to work upon different product batches. In process inventory is usually high owing to the type of layout and material handling policies adopted.

49 1.36 Introduction Semi automatic material handling systems are most appropriate in conjunction with the semi automatic machines. Normally production planning and control is difficult due to the odd size and non repetitive nature of order. (iii) Mass Production: Mass production refers to the process of creating large number of similar products efficiently. This production system is justified by very large volume of production (i.e. 10,000 to millions of units per year). Manufacturing of cars and guns are the few examples of mass production. The following are the important characteristics of mass production system: As same product is manufactured for sufficiently long time, machines can be laid down in order of processing sequence. Product type layout is most appropriate for mass production system. Standard methods and machines are used during part manufacture. Most of the equipments are semi automatic or automatic in nature. Material handling is also automatic (such as conveyors). Semi skilled workers are normally employed as most of the facilities are automatic. As product flows along a pre defined line, planning and control of the system is much easier. Cost of production is low owing to the high rate of production.

50 CIM In process inventories are low as production scheduling is simple and can be implemented with ease MANUFACTURING MODELS AND METRICS: Many successful manufacturing companies use a variety of metrics to help their operations. Generally quantative metrics provide a company with the means. (i) (ii) (iii) To track performance in successive periods. Tryout new technologies and new systems to determine their merits, identify problems with performance. To compare alternative methods and to make good decisions. The two basic categories of manufacturing metrics are (i) (ii) Production performance measures. Manufacturing costs. Metrics that specify production performance include proportion uptime (or) equipment (a reliability measure), production rate, plant capacity and manufacturing lead time. Manufacturing costs in a company includes material and labour cost, the costs of producing its products and the cost of operating a given piece of equipment MATHEMATICAL MODELS OF PRODUCTION PERFORMANCE: Many features of manufacturing are quantitative Mathematical models of production performance includes production rate, production capacity, utilization & availability and manufacturing lead time.

51 1.38 Introduction Production Rate: Production rate for an individual processing is the number of goods that can be produced during a given period of time (i.e. work units completed/hr (or) piece/hr). Production rate is determined for the three types of production systems. (i) batch production (ii) Job shop production, (iii) mass production. For studying the above production process, we must know some basic terminology. Cycle Time: The period of time spent to complete one cycle of an operation (or) to complete a job from start to finish is called cycle time. It is given by where T c = T 0 + T h + T th... (1.1) T c T h T 0 T th cycle time (min/piece) handling time (min/piece) time of the actual processing (min/piece) tool handling time (min/piece) 1. Batch and Job shop production: In batch production, the time to process one batch consisting of N work units is the sum at the setup time and processing time. It is given by T b = T su + N T c... (1.2) T b batch processing time (min) T su setup time to prepare for the batch (min) N batch quantity (piece)