1. Jason Maestas Tim Ngo Stephen Neidigk David Ortegel
Ch. 38: Computer-Aided Manufacturing
Ch. 40: Product Design and Process Selection in a Competitive Environment
Group 9 4/26/05
Jason Maestas
Tim Ngo
Stephen Neidigk
David Ortegel

2. Ch. 38 Computer-Aided Manufacturing
38.1 Introduction
38.2 Manufacturing Systems
38.3 Computer-Integrated Manufacturing
38.4 Computer-Aided Design and Engineering
38.5 Computer-Aided Manufacturing
38.6 Computer-Aided Process Planning
38.7 Computer Simulation of Manufacturing Processes and Systems
38.8 Group Technology

3. Introduction
Computer-aided design (CAD) assists the graphical descriptions of parts.
Computers are used in the direct control of manufacturing processes and computer-aided manufacturing.
Computers can also simulate manufacturing processes and systems.
Group technology approaches allow the rapid recovery of previous design and manufacturing experience and apply information to new situations in a straightforward manner.

4. Manufacturing Systems
Factors:
Supply and cost of raw materials
National and global market changes
Impact of constantly developing technologies
Machine-tool characteristics and performance
Human behavior and performance

5. Computer-Integrated Manufacturing
Computerized integration of all aspects of product design, process planning, production, and distribution, as well as the management and operation of the whole manufacturing organization
The effectiveness of CIM critically depends on the use of a large-scale integrated communications system involving computers, machines, and their controls.

6. Computer-Integrated Manufacturing
Figure A schematic illustration of a computer-integrated manufacturing system. Source: U. Rembold, et al., Computer-Integrated Manufacturing and Engineering. Addison-Wesley, 1993.

7. CIM Subsystems Functions Business planning and support Product design
Manufacturing process planning
Process automation and control
Production monitoring systems
Functions
Business planning
Business execution

8. Database Product data: Part shape, dimensions, and specifications
Data management attributes: Revision level, and part number
Production data: Manufacturing processes used
Operational data: Scheduling, lot sizes, and assembly requirements
Resources data: Capital, machines, equipment, tooling, personnel, and their capabilities

9. Benefits of CIM
Emphasis on product quality and uniformity, as implemented through better process control
Efficient use of materials, machinery, and personnel and major reduction of work-in-progress inventory, all of which improve productivity and lower product cost
Total control of the production, schedules, and management of the entire manufacturing operation
Responsiveness to shorter product life cycles, changing market demands, and global competition

10. Computer-Aided Design and Engineering
CAD involves the use of computers to create design drawings and product models through interactive computer graphics.
CAE allows several applications to share the information in the database. Applications include (a) finite-element analysis of stresses, strains, deflections, and temperature distribution in structures and load bearing members, (b) the generation, storage, and retrieval of data, and (c) the design of integrated circuits and various electronic devices.

11. Elements of CAD systems
Geometric modeling
Figure Various types of modeling for CAD

12. CAD Representations
Figure (a) Boundary representation of solids, showing the enclosing surfaces of the solid model and the generated solid model. (b) A solid model represented as compositions of solid primitives. (c) Three representations of the same part by CAD. Source: P. Ranky.

13. Octree representation
Figure The octree representation of a solid object. Any volume can be broken down into octants, which are then identified as solid, void, or partially filled. Shown is two-dimensional version, or quadtree, for representation of shapes in a plane.

14. 38.5 Computer-Aided Manufacturing
Computer-aided manufacturing (CAM):
The use of computers to assist in all phases of manufacturing.
CAD/CAM systems:
Features:
Information can be transferred from the design stage into the stage of planning for manufacture without the need to reenter the data on part geometry manually.
Database developed during CAD is stored and processed further by CAM into the necessary data and instructions for operating and controlling production machinery, material-handling equipment, and automated testing and inspection for product quality.
Has the capability to describe the tool path in machine operations to check for possible tool collisions with clamps, fixtures, or other interferences visually.

15. Benefits of CAD/CAM
- Reduces design effort, tryout, and prototype work and significantly reduces manufacturing costs and improves productivity.
Example: the two-engine Boeing 777 passenger airplane.
Designed by computer (paperless design) with 2000 workstations linked to eight computer.
Developed from CAD/CAM software , and no prototypes or mockups were built.
Cost for this development was $6 billion.

16. Applications of CAD/CAM systems:
Programming for numerical control and industrial robots.
Design of dies and molds for casting.
Dies for metalworking operations.
Design of tooling and fixtures and EDM electrodes.
Quality control and inspection.
Process planning and scheduling.
Plant layout.

17. 38.6 Computer-Aided Process Planning (CAPP)
CAPP is concerned with selecting methods of production: tooling, fixtures, machinery, sequence of operations, and assembly.
When done manually by process planners, this task is highly labor-intensive and time-consuming and relies heavily on their experience.
In CAPP individual steps involved in making each part are coordinated with others and are performed efficiently and reliably.
CAPP is effective particularly in small-volume, high-variety parts production.

18. A document containing the sequence of processes and operations to be performed, the machines to be used, the standard time for each operation, and similar information.
Individual routing sheets are stored in computers affixed with a barcode or other id to the part for future reference.

19. Elements of CAPP systems
Variant system (Derivative System)
Searches are made in the database for existing plans based on its shape and manufacturing characteristics.
Contains information such as the types of tools and machines to use, sequence of operations to be performed, the speeds, the feeds, and time required for each sequence.
Minor modifications can be made to existing plans.
Generative system.
Generative system is capable of creating a new plan instead of having to use and modify an existing plan.
Contains detailed information of the part shape and dimensions; process capabilities; selection of manufacturing methods, machinery, and tools; and the sequence of operations.
It has advantages such as: flexibility and consistency for the process planning for new parts; and higher over planning quality which optimizes the planning and utilizes up-to-date manufacturing technology.

20. 38.7 Computer Simulation of Manufacturing Processes and Systems
Simulation takes two basic forms:
It is a model of an operation intended to determine the viability of a process or to optimize its performance.
It models multiple processes and their interactions to help process planners and plant designers layout machinery and facilities.

21. Group Technology (GT)
A concept that seeks to take advantage of the design and processing similarities among the parts to be produced.
Figure Grouping parts according to their geometric similarities and manufacturing attributes.

22. Advantages of group technology
Makes possible the standardization of part design and the minimization of design duplication, which saves time and effort.
New and less experienced engineer can benefit from previous designs and process plans made by the more experienced.
Manufacturing costs, statistics on materials, processes, number of parts produced, and other factors can be obtained easily.
Setup times are reduced, and parts are produced more efficiently and with better and more consistent product quality.
Improves productivity and reduces cost by 5% to 75%. Which saves lots of $$$.

23. Product Design and Process Selection in a Competitive Environment
Chapter 40:
Product Design and Process Selection in a Competitive Environment

24. 40.1 Introduction
Today the task of producing high-quality products has become a major challenge.
There are Extensive varieties in Materials and manufacturing processes.
Product Design, Product Quality and Life Expectancy, Life-Cycle Assessment and Engineering, Material Selection, Material Substitution, Manufacturing Process Capabilities, Process Selection, Manufacturing Cost

25. 40.1: Product Design
Advances in Materials and technologies are being made Continually for the manufacturing and Assembly of products.
Software packages such as Pro-E are readily available
These advance help with the development for products, by allowing designer to develop Fewer components, and reduce assembly time and manufacturing cost

26. Design Considerations
Have all alternative product designs been investigated thoroughly?
Can the design be simplified and the number of its components minimized without adversely affecting its intended functions and performance?
Can unnecessary features of the product or components be eliminated or combined with other features?
Are some of the components commercially available?
Have modular design and building-block concepts been considered for a family of similar products and for servicing and repair, upgrading, and installing options?
Can the design be made smaller and lighter?
Are there specified dimensional tolerances and surface finish unnecessarily tight?
Will the difficulty or excessively time consuming to assemble and disassemble for maintenance, servicing, or recycling of its components?
Is the use of fasteners minimized?

27. Product design and quantity of material
The cost of materials can significantly be a large portion of a products cost
Cost of material cannot be reduced below market levels but the quantity of materials can be reduced.

28. Design Problems Thin Cross-sections
Casting or molding of thin cross-section can present difficulties in die and mold filling and maintaining dimensional accuracy and surface finish
Forging requires high forces, due to friction and rapid cooling
Impact extrusion becomes difficult
Formability decreases and thickness decreases
Machining and grinding causes part distortion, poor dimension accuracy, and chatter
Welding thin sheets causes significant distortion

29. Design Problems Large Cross-sections:
In casting and injection molding, production rate decreases
Unless controlled, porosity can develop
Bendability decreases as thickness increases
In powder metallurgy, there are significant variations in density and properties throughout the part
Welding presents problems in depth and quality of weld joint
In die cast, thicker cross-section will have a lower strength per unit than this cross section because of the thicker grain sizes

30. 40.3: Product Quality and Life Expectancy
A well defined technical consideration in development and a human option
Characteristics:
Satisfies the need and expectations of the customer, including the cost.
Compatible with the customers working environment.
Products functions are resalable and safe over its life
Aesthetics
Instillation, maintenance, and future improvements easy to perform at low cost
Availability in quantities when desired

31. Return on quality (ROQ):
Basis components:
Quality must be view as an investment
There needs to be a limit on how much should be spent on quality improvements
Expenditure specifically should be made toward quality improvement
Incremental improvement in quality VS. Additional cost involved must be reviewed

32. Life Expectancy of Products:
Life expectancy of products can vary, depending on the materials used and processes employed, and the quality of the product

33. 40.4 Life-Cycle Assessment and Engineering; Sustainable Manufacturing
Life cycle include:
Extraction of Natural resources
Processing of the raw materials
Manufacturing of products
Transportation and distribution to the consumer
Use, maintenance, and reusability of product
Disposal of the product or recovery and recycling of its components

34. Life Cycle Assessment (LCA):
A systematic set of procedures for compiling and examining the inputs and outputs of material and environmental impacts of producing a product.
Life Cycle Engineering:
Deals with greater depth with design, optimization and technical considerations for each component of a product that will effect the environment.

35. Sustainable Manufacturing:
There are limited natural resources
The necessity to conserve material and energy
Increase life cycle of products
Eliminate damage to environment
Ensure collective well being for future generations

36. 40.5 Material Selection for Products
Mechanical and physical properties:
Strength, toughness, ductility, stiffness, hardness, and resistance to fatigue, creep, and impact, Density, melting point, specific heat, thermal and electrical conductivity, Oxidation and corrosion
Material selection has become easier and faster because their availability and the extensive databases.

37. Considerations:
Do selected material have the appropriate manufacturing characteristics?
Can some material be replaced by others less expensive materials?
Do the selected materials have properties that unnecessarily exceed minimum requirements?
Are the raw material available in standard shapes, dimensions, tolerances, and surface characteristics?
Is the material supply reliable?
Does the material present any environmentally damaging effects?

38. Shapes of Commercially available materials:
Available forms, such as castings, extrusions, forgings, bars plates, sheets, foil, rods, wires and metal powders
Preformed materials cut cost on product manufacturing
Dimensional tolerances, surface quality, and straightness need to be taken accounted for

40. Reliability of material supply
A constant flow of material is very important for production
Geopolitical factor can effect supply
Strikes, material shortages

41. Cost of Materials and processing
Unit cost of raw material depends on the material itself, shape, size, and condition.
Cost is determined by cost per unit weight or cost per unit volume.
Fluctuations in cost by factors such as supply and demand or geopolitics

42. Chapter 40.6-40.9 Material Substitution
Manufacturing Process Capabilities
Process Selection
Manufacturing Cost and Cost Reduction

43. Materials Substitution
Many reasons for materials substitution
Reduce Costs
Improve manufacturing, assembly, and installation
Improve performance
Reduce maintenance

44. Materials Substitution
An example of Materials Substitution would be in the automotive industry

45. Manufacturing Process Capabilities
Each manufacturing process has advantages and limitations
Sand casting not very dimensionally accurate
Choosing the right method to make the part

46. Manufacturing Process Capabilities
Dimensional tolerances and surface finish
The closer the dimensional tolerances and the better the surface finish the more expensive and time consuming to manufacture

47. Manufacturing Process Capabilities
Lead time
Time required to begin production
Robustness of manufacturing process and machinery
Defined as a process or a system
Choosing the right manufacturing method taking all variables into account
Variable as large as materials and as minute as temperature

48. Process Selection
Many things must be taken into consideration when selection a process
Things to think about- geometric features of part production rate, are there tools to make the part
Goal is to make manufacturing as easy and inexpensive as possible
Figure Various methods of making a simple part: (a) casting or powder metallurgy, (b) forging or upsetting, (c) extrusion, (d) machining, (e) joining two pieces.

49. Manufacturing Costs and Cost Reduction
For a product to be successful its cost must be competitive with that of similar products

50. Manufacturing Costs and Cost Reduction
Total costs include
Materials costs
Tooling costs-costs involved in making the tools, dies, molds required to manufacture
Capital costs- investment in building, land, machinery, and tooling

51. Manufacturing Costs and Cost Reduction
Fixed costs- power, fuel, taxes on real-estate
Indirect labor costs- servicing the total manufacturing operation, supervision, repair, quality control, research and sales

52. Manufacturing Costs and Cost Reduction
Typical approximate breakdown of costs in manufacturing today
Design 5%
Material 50%
Direct Labor 15%
Overhead 30%

53. Bibliography http://www.gdrc.org/uem/lca/lca-define.html