Computer Integrated Manufacturing

Unit 1By:- Mayur N Patel

CAD

• “CAD can be defined as a use of computer systems to assist in the creation, modification, synthesis, and/or optimization of a design.”

CAM

• CAM can be defined as a use of computer system to plan, manage, and control the manufacturing operation through the direct or indirect computer interface with manufacturing machine.

CIM

• CIM is the complete integration and automation of all functions of factory. i.e. Design, manufacturing planning and control, manufacturing, and business functions.

Evolution of CIM

• It started developing as a technology since 1980.

• With globalization of economy, the manufacturing industries all over the world started competing with each other.

• Transformed the market from seller driven to customer driven.

• This led to the emergence of the CIM

Prime factor for development in CIM

• Development and advancement of CNC, FMS and automation technologies.

• Development of cost-effective and high speed computer system.

• Market challenges such as high labor cost, global competition, and buyer driven market.

• Customer demands such as product variety, better quality and low cost product.

SCOPE of CIM

• CIM applies computer and communication technology to completely integrate following four function.

1. Design2. Manufacturing3. Manufacturing planning and control4. Business function

• The two terms CAD/CAM and CIM are very closely related. However, coverage of CIM is broader than that of CAD/CAM.

• CIM includes all functions of factory operations which CAD/CAM covers in addition of it, also includes business functions of the factory.

• The ideal CIM system applies the computer and networking technology to all the operational and information processing functions In manufacturing from order receipt, through design and production, to shipment of product.

Benefits of CIM1. Products quality improvement. 2. Shorter time in launching new product in the market. 3. Flow time minimized. 4. Inventory level reduced. 5. Competitiveness increases. 6. Improved scheduling performance. 7. Shorter vendor lead time. 8. Improved customer service. 9. Increase in flexibility and responsiveness. 10. Total cost minimized. 11. Long term profitability increases. 12. Customers lead time minimized. 13. Manufacturing productivity increases. 14. Work in process inventory decreases.

Classification of Manufacturing Systems

• Factors that define and distinguish manufacturing systems:1. Types of operations performed2. Number of workstations3. System layout4. Automation and manning level 5. Part or product variety

Types of Operations Performed• Processing operations on work units versus assembly operations to

combine individual parts into assembled entities• Type(s) of materials processed• Size and weight of work units• Part or product complexity

– For assembled products, number of components per product– For individual parts, number of distinct operations to complete

processing• Part geometry

– For machined parts, rotational vs. non-rotational

Number of Workstations

• Convenient measure of the size of the system– Let n = number of workstations– Individual workstations can be identified by subscript i,

where i = 1, 2,...,n• Affects performance factors such as workload

capacity, production rate, and reliability– As n increases, this usually means greater workload

capacity and higher production rate– There must be a synergistic effect that derives from n

multiple stations working together vs. n single stations

System Layout

• Applies mainly to multi-station systems• Fixed routing vs. variable routing

– In systems with fixed routing, workstations are usually arranged linearly

– In systems with variable routing, a variety of layouts are possible

• System layout is an important factor in determining the most appropriate type of material handling system

Automation and Manning Levels

• Level of workstation automation – Manually operated– Semi-automated– Fully automated

• Manning level Mi = proportion of time worker is in attendance at station i– Mi = 1 means that one worker must be at the station

continuously– Mi 1 indicates manual operations

– Mi < 1 usually denotes some form of automation

Part or Product Variety: Flexibility

“The degree to which the system is capable of dealing with variations in the parts or products it produces”

• Three cases:1. Single-model case - all parts or products are identical (sufficient

demand/fixed automation)2. Batch-model case - different parts or products are produced by the

system, but they are produced in batches because changeovers are required (hard product variety)

3. Mixed-model case - different parts or products are produced by the system, but the system can handle the differences without the need for time-consuming changes in setup (soft product variety)

Three Cases of Product Variety in Manufacturing Systems

(a) Single-model case, (b) batch model case, and (c) mixed-model case