manufacturing engineering technology general introduction 授課教師：楊宏智教授 1...

MANUFACTURING ENGINEERING TECHNOLOGY GENERAL INTRODUCTION

授課教師：楊宏智教授

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楊宏智（台大機械系教授）

MANUFACTURING ENGINEERING

TECHNOLOGY

機械製造

CHAPTER OUTLINE1. What Is Manufacturing?2. Product Design and Concurrent Engineering3. Design for Manufacture, Assembly, Disassembly, and Service4. Green Design and Manufacturing5. Selection of Materials6. Selection of Manufacturing Processes7. Computer-integrated Manufacturing8. Quality Assurance and Total Quality Management9. Lean Production and Agile Manufacturing10. Manufacturing Costs and Global Competition11. General Trends in Manufacturing

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WHAT IS MANUFACTURING?

Application of physical and chemical processes to alter the geometry, properties, and/or appearance of a starting material to make parts or products.

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MANUFACTURING - ECONOMIC

Transformation of materials into items of greater value by one or more processing and/or assembly operations.

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ECONOMIC IMPORTANCE

U.S. Economy

Sector: %GDP

Agriculture and natural resources 5

Construction and public utilities 5

Manufacturing 15

Service industries 75

100

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Products around us consist of numerous individual pieces that shall be built and assembled:

Clip – one part

Lawn mower – 300 parts

Grand piano – 12,000 parts

Automobile – 15,000 parts

Boeing 747-400 – 6 million parts

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WHAT IS MANUFACTURING? EXAMPLE 1.1

Paper Clips

Functional and Service Requirement

-Clamping forces (stiffness,strength- permanent deformation; material select: shape and size)

-Corrosion resistance

Style and Cost

-Metallic or plastic? What shape (round or else)? It’s dia? Surface finish?

Production Consideration

-How to shape (hand or machine)? Batch quantity

-Bending without cracking or breaking

-Easily cut without causing excessive wear on tooling

-Produce smooth edge on the wire (burs not desire)

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What Is Manufacturing?

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Example 1.2

Incandescent Light Bulbs

• Component of a common incandescent light bulb

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MANUFACTURING STEPS IN MAKING ANINCANDESCENT LIGHT BULB (PROD. RATE >1000/MIN)

Filament manufacturing: Tungsten powder (sintering) – Ingot (swaging) –Rods (drawing)- thin Wire (60W, 0.045 mm dia)

Wire dia. 1%less causes 25% life shortage (heated to 2200 to 3000 C)

Bulb vacuumed or filled w N2 or Argon gas (water drop causes 0.5m blackened); coil spacing accuracy (heat concentration); position accuracy – heat deflection disk, and lead-in wire (Fe+Ni w Cu coating)= glass thermal expansion coefficient

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PRODUCT DESIGN AND CONCURRENT ENGINEERING

The Design Process

• Design and manufacturing activities take place sequentially

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The Design Process

• It would be more desirable to:

1. Use a different material

2. Use the same material but in a different condition

3. Modify the design of a component

Concurrent Engineering

• Also called simultaneous engineering

• From the earliest stages of product design and engineering, all are simultaneous

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Concurrent Engineering

• Any iterations will require a smaller effort and less wasted time would occur

Market

Specification

Concept design

Detail design

ManufactureSell

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Life Cycle

• Life cycle of a new product consists of:

1. Product start-up

2. Rapid growth of the product in the marketplace

3. Product maturity

4. Decline

• Life-cycle engineering requires that the entire life of a product be considered

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Role of Computers in Product Design

• Product models are simplified through computer-aided design (CAD) and computer-aided engineering (CAE) techniques

• CAD systems are capable of rapid and complete analysis of designs

• This is the process known as paperless design

• Performance of structures can be analysed16


Role of Computers in Product Design (Con’t)

• Computer-aided manufacturing involves all phases of manufacturing

• Performing tasks such as:

1. Programming for numerical control machines

2. Designing tools, dies, moulds, fixtures, and work-holding devices

3. Maintaining quality control17


Prototypes

• A prototype is a physical model of an individual component or product

• Rapid prototyping use CAD/CAM and various specialized technologies

• Prototypes developed can review for possible modifications to the original design, materials, or production methods

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Virtual Prototyping

• It is a software-based method that uses advanced graphics and virtual-reality environments

• To allow designers to view and examine a part in detail

• Also known as simulation-based design

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DESIGN FOR MANUFACTURE, ASSEMBLY, DISASSEMBLY, AND SERVICE

• Design for manufacture (DFM) integrate the design process with production methods, materials, process planning, assembly, testing, and quality assurance

• Design for assembly (DFA), Design for manufacture and assembly (DFMA), and Design for disassembly (DFD) are all important for manufacturing

• Assembly requires a consideration of the ease, speed, and cost of individual components of a product

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GREEN DESIGN AND MANUFACTURING

• Manufacturing operations produce waste like:

1. Chips from machining and trimmed materials

2. Slag from foundries and welding

3. Additives in sand used in sand-casting

4. Hazardous waste and toxic materials

5. Lubricants and coolants

6. Liquids from heat treating

7. Solvents from cleaning operations

8. Smoke and pollutants from furnaces21


• Environmentally conscious design and manufacturing considers all possible adverse environmental impacts of materials, processes, operations and products

• Design for recycling (DFR) - two basic activities

1) Biological cycle

- Organic materials degrade and lead to new soil that sustain life

2) Industrial cycle

- Product that can be recycled and reused continuously22


Cradle-to-cradle Production emphasizes:

1. Sustainable and efficient manufacturing activities

2. Waste-free production

3. Using recyclable and nonhazardous materials

4. Reducing energy consumption

5. Using renewable energy

6. Maintaining ecosystems

7. Using available materials and energy sources

8. Exploring the reuse and recycling of materials23


Guidelines for Green Design and Manufacturing

1. Reduce waste of materials

2. Reduce hazardous materials products and processes

3. Investigate environmental-friendly manufacturing technologies

4. Improvements in methods of recycling and reusing

5. Minimize energy use

6. Encourage recycling24

SELECTION OF MATERIALS

• General types of materials used:

1. Ferrous metals

2. Nonferrous metals

3. Plastics (polymers)

4. Ceramics, glasses

5. Composite materials

6. Nanomaterials

7. Shape-memory alloys, amorphous alloys, semiconductors and superconductors

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Properties of Materials

1. Mechanical properties

2. Physical properties

3. Chemical properties

4. Manufacturing properties

5. Appearance

General Manufacturing Characteristics of Various MaterialsAlloy Castability Weldability MachinabilityAluminium E F E-GCopper G-F F G-FGray cast iron E D GWhite cast iron G VP VPNickel F F FSteels F E FZinc E D E

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Availability

• If materials are not available in the desired quantities, shapes, dimensions, and surface texture, substitute materials can be considered

• Reliability of supply is important in order to meet production schedules

• A country’s self-reliance on resources is a political goal

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Service Life

• A shortened service life of a product is due to:

1. Improper selection of materials

2. Improper selection of production methods

3. Insufficient control of processing variables

4. Defective parts or manufacturing-induced defects

5. Poor maintenance

6. Improper use of the product28


Material Substitution in Products

• We would want to consider the following substitutions:

1. Metal vs. wooden handle for a hammer

2. Aluminium vs. cast-iron lawn chair

3. Aluminium vs. copper wire

4. Plastic vs. steel car bumper

5. Plastic vs. metal toy

6. Alloy steel vs. titanium submarine hull29


Example 1.2

Baseball Bats

• Cross sections of baseball bats made of aluminium and composite material

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Example 1.3

U.S. Pennies

• Materials used undergone changes throughout history due to periodic material shortages and the cost of appropriate raw materials 1793-1837 100% copper

1837-1857 95% copper, 5% tin and zinc

1857-1863 88% copper, 12% nickel

1864-1962 95% copper, 5% tin and zinc

1943(WW II year) Steel, plated with zinc

1962-1982 95% copper, 5% zinc

1982-present 97.5% zinc, plated with copper31

SELECTION OF MANUFACTURING PROCESSES

• Some examples of manufacturing methods are:

1. Casting

2. Forming and shaping

3. Machining

4. Joining

5. Finishing

6. Microfabrication and nanofabrication32


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Process Selection

• Selection of process depends on geometric features of the parts and workpiece material and properties

• Some mechanical tools are being replaced by laser cutting

• Size of manufactured productsare getting smaller such as microscopic gears

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Net-shape and Near-net-shape Manufacturing

• Part is made in only one operation to the final desired dimensions, tolerances and surface finish

• Difference between the two is the degree of how close the product is to its final dimensional characteristics

• Examples of net-shape manufacturing are precision casting, forging, forming sheet metal, powder metallurgy, injection molding of metal powders and injection molding of plastics

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Ultraprecision Manufacturing

• Advantages are dimensional accuracies and mirror-like surfaces on metals

Types of Production

• Job shops: less than 100

• Small-batch production: 10 to 100

• Batch production: 100 and 5000

• Mass production: over 100,00038


Example 1.4

Saltshaker and Pepper Mill

• The two metal pieces for the pepper mill are made by powder-metallurgy techniques

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COMPUTER-INTEGRATED MANUFACTURING

• Computer-integrated manufacturing (CIM) integrates computer graphics, computer-aided modelling, and computer-aided design and manufacturing activities

• Capable of making possible

1. Responsiveness to rapid changes

2. Better use of materials, machinery, and personnel

3. Reduction in inventory

4. Better control of production and management

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COMPUTER-INTEGRATED MANUFACTURING• Various elements in CIM include:

1. Computer numerical control (CNC)

2. Adaptive control (AC)

3. Industrial robots

4. Automated materials handling

5. Automated assembly systems

6. Computer-aided process planning (CAPP)

7. Group technology (GT)

8. Just-in-time production (JIT)

9. Cellular manufacturing (CM)

10. Flexible manufacturing systems (FMS)

11. Expert systems (ES)

12. Artificial intelligence (AI)

13. Artificial neural networks (ANN)

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圖

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Example 1.5

Mold for Making Sunglasses Frames

• Machining a mold cavity for making sunglasses

• Computer model of the sunglasses as designed and viewed on the monitor

• Machining of the die cavity using a computer numerical-control milling machine

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QUALITY ASSURANCE AND TOTAL QUALITY MANAGEMENT

• Product quality influences customer satisfaction

• Quality must be built into the product from its initial design

• Quality assurance and total quality management (TQM) are the responsibility of everyone involved in the design and manufacture of products and their components

• Product integrity define the degree to which a product

1. Functions reliably

2. Suits its intended purposes

3. Can be maintained with relative ease44

QUALITY ASSURANCE AND TOTAL QUALITY MANAGEMENTAverage Life Expectancy of Various Products

Type of product Life expectancy(years)U.S. dollar bill 1.5Personal computer 2Car battery 4Hair dryer 5Automobile 8Dishwasher 10Kitchen disposal unit 10Vacuum cleaner 10Water heater(gas) 12Clothes dryer(gas) 13Clothes washer 13Air-conditionimg unit(central) 15Manufacturing cell 15Refrigerator 17Furnace(gas) 18Machinery 30Nuclear reactor 40

Relative Cost of Repair at Various Stages of Product Development Sale

Stage Relative cost of repairWhen part is being made 1Subassembly of the product 10Assembly of the product 100Product at the dealership 1000Product at the customer 10000

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• At six sigma, defective parts are reduced to only 3.4 per million parts made.

• Level reached only through manufacturing process capabilities to reduce variability in product quality

Quality Standards

• Global manufacturing and competitiveness lead to international quality control methods

• Thus the establishment of ISO 9000 and QS 9000 standards

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Human-factors Engineering

• Human-factors approach results in ergonomics design

• Defined as the study of a workplace and the design of machinery and equipment

Product Liability

• Involved with product design, manufacture and marketing

• Product’s malfunction or failure can cause bodily injury or even death

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LEAN PRODUCTION AND AGILE MANUFACTURING

• Lean production involves a thorough assessment of each activity of a company

• Lean production focuses on:

1. Efficiency and effectiveness of each and every manufacturing operation,

2. Efficiency of the machinery and equipment used

3. Activities of the personnel involved in each operation

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LEAN PRODUCTION AND AGILE MANUFACTURING

Agile Manufacturing

• Agile manufacturing is ensuring agility and flexibility

• Methodologies of both lean and agile production require that a manufacturer benchmarks its operations

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MANUFACTURING COSTS AND GLOBAL COMPETITION

• Manufacturing cost is about 40% of its selling price

• Total cost of manufacturing a product consists of:

1. Materials

2. Tooling

3. Fixed Costs

4. Capital

5. Labour50

GENERAL TRENDS IN MANUFACTURING

Global manufacturing trends

1. Product variety and complexity continue to increase

2. Product life cycles are becoming shorter

3. Markets have become multinational

4. Market conditions fluctuate widely

5. Customers are demanding

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Materials

6. Material composition, purity, and defects

7. Selection of materials for improved recyclability

8. Developments in nano-technology for materials

9. Testing methods and equipment

10. Increasing control over the thermal treatment

11. Higher strength-to-weight and stiffness-to-weight ratios52


Manufacturing operations

12. Predictive models of the effects of material processing parameters

13. Ultraprecision manufacturing

14. Computer simulation and modelling

15. Rapid-prototyping technologies

16. Optimization of manufacturing processes

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GENERAL TRENDS IN MANUFACTURINGManufacturing systems

17. Computer software and hardware

18. Control systems and automated inspection

19. Lean production and information technology

Goals in manufacturing

20. View manufacturing activities not as individual

21. Meet all design requirements, product specifications

22. Build quality into the product

23. Economical and environmentally friendly (green) manufacturing methods

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Goals in manufacturing

24. Evaluate advances in materials, production methods, and computer integration

25. Adopt flexible production methods

26. Achieving higher levels of productivity

27. Continuous improvement of a company’s products

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• http://www.youtube.com/watch?v=XSojNSwAb7I

參考影片

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manufacturing engineering technology general introduction 授課教師：楊宏智教授 1...

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