Met 402 mod_1 (1)

MODULE 1 COURSE OUTCOMES

Different mfg processes

Design for mfg

Selection of materials for mfg processes

Selection of mfg process

Production systems

Product quality

Economics of mfging on mfg processes

Introduction to Mfg

MFG : Converting raw material into finished product.

• Some products are a single components (nail, bolt, fork, coat hanger, etc.)

• Some products are assemblies of many components (ball point pens, automobiles, washing machines, etc.)

Manufacturing Processes: Casting

Schematic illustration of various casting processes

Manufacturing Processes: Forming

Schematic illustration of various bulk deformation processes

Manufacturing Processes: Forming

Schematic illustration of various sheet metal forming processes

Manufacturing Processes: Forming

Schematic illustration of various polymer processing methods

Manufacturing Processes: Machining

Schematic illustrations of various machining and finishing processes.

Manufacturing Processes: Joining

Schematic illustration of various joining processes

Design for manufacturability (also known as design for manufacturing)- is

the art of designing products in such a way that they are easy to

manufacture.

Each part or component of a product must be designed so that it not only

meets design requirements & specifications but can also be mfged

economically and with relative ease.

This approach improves productivity and allows a manufacturer to remain

competitive.

DFM integrates product design process with materials, manufacturing methods, process planning, assembly, testing, and quality assurance.

DFM

Design

70 - 80%

Manufacturing

20 - 30%

What Internal Organization has the most Influence over Price, Quality, & Cycle Time?

Design for Mfg Guidelines

1. Minimize Total Number of Parts2. Develop a Modular Design3. Minimize Part Variations4. Design Parts to be Multifunctional5. Design Parts for Multiuse6. Design Parts for Ease of Fabrication7. Avoid Separate Fasteners

Design for Mfg Guidelines (Cont.)

8. Minimize Assembly Direction (Top Down Direction Preferred)

9. Maximize Compliance in Assembly10. Minimize Handling in Assembly11. Minimize complexity of Design12. Maximize common Jigs and Fixtures13. Optimize Work Position14. Ease Access

Manufacturing a Product: General Considerations

• Material Selection

• Processing Methods

• Final Shape and Appearance

• Dimensional and Surface Finish

• Economics of Tooling

• Design Requirements

• Safety and Environmental Concerns

Material Selection

“Because without materials, there is no engineering.”

Selecting Materials for Products

The following are the factors in selection of materials for products :

1. Material Substitution2. Material Properties3. Cost and Availability4. Service Life and Recycling

Selection of materials for products requires much experience, but several databases and expert systems are now available

Material substitution Majority of the design and mfging activities are concerned with improving existing products

Reasons for substituting materials are:

1. Reduce the costs of materials and processing2. Improve mfging, assembly, and installation3. Improve the performance of the product4. Increase stiffness-to-weight and strength-to-weight

ratios5. Reduce the need for maintenance and repair6. Reduce vulnerability to the unreliability of the

supply of materials7. Improve compliance with legislation and

regulations

Substitution of Materials in the Automobile Industry

• Automobile industry is a major consumer of both metallic & nonmetallic materials

• Constant competition among suppliers, particularly in steel, aluminum, and plastics

• Efforts in investigating the advantages and limitations of principal materials

Material Substitution

Material SubstitutionSubstitution of Materials in the Aircraft and Aerospace Industries

• Advanced materials are used in the Lockheed C-5A transport aircraft

Material Substitution

Material Substitution in Common Products• Available products can be made by either set

of materials:1. Metal vs. wooden baseball bat2. Metal vs. reinforced-plastic or wood handle for

a hammer3. Plastic vs. metal intake manifold4. Cast-iron vs. aluminium lawn chair5. Plastic vs. sheet-metal light-switch plate

Material Substitution

Material Changes between C-5A and C-5B Military Cargo Aircraft

• Table shows the changes made in materials for components of the two aircraft listed and the reasons for the changes

Properties of Materials Mechanical Properties: strength, toughness, ductility, hardness, elasticity, fatigue, creep.

Behavior Under Loading: tension, compression, bending, torsion, shear.

Physical Properties: density, specific heat, thermal expansion, thermal conductivity, melting point, electrical and magnetic properties.

Chemical Properties: oxidation, corrosion, degradation, toxicity, flammability.

Engineering Materials

Materials

Metals Plastics

Steel

Stainless steel

Die & tool steel

Cast iron

Ferrous Non-ferrous

Aluminum

Copper

Zinc

Titanium

Tungsten

Thermoplastics

Acrylic

Nylon

ABS

Polyethylene

Polycarbonate

PVC

Thermosets

Phenolic

Polymide

Epoxies

Polyester

Elastomers

Rubber

Polyurethane

Silicone

Engineering Materials

Materials

Metals PlasticsCeramics

Glass

Carbides

Nitrides

Graphite

Diamond

Glasses

Glass ceramics

Composites

Reinforced plastics

Metal-Matrix

Ceramic-Matrix

Laminates

The Choice ………

In many cases metals and non metals are viewed as competing materials

The selection is being based on how well each is capable of providing the required properties

When both perform adequately total cost often becomes the deciding factor

1. The cost of material2. Plus the cost of fabricating the desired component

Ferrous Metals: Applications

• Structural: building structures, concrete reinforcement

• Automotive: chassis, engine parts, drive train, body parts

• Marine: ship hulls, structure, engines

• Defense: tanks, weapons

• Consumer Products: appliances, recreational vehicles, toys, utensils and tools

Nonferrous Metals: Applications

• Architectural: aluminum windows and doors

• Automotive: aluminum engine blocks, copper wiring, mag wheels

• Marine: brass/bronze fittings, bearings, propellers

• Defense: brass shell casings

• Consumer Products: electrical wiring, utensils, jewelry, electronics

Plastics (Polymers)

• Compared to metals, plastics have lower density, strength, elastic modulus, and thermal and electrical conductivity, and a higher coefficient of thermal expansion

• The design of plastic parts should include considerations of their low strength and stiffness, and high thermal expansion and low resistance to temperature.

Plastics: Applications

• Architectural: electrical and thermal insulation, weather seals, carpets, wall coverings, paint

• Aerospace: electrical and thermal insulation, instrument panels, seals

• Automotive: body panels, instrument panels, upholstery, electrical and thermal insulation, seals, hoses, tires

• Consumer Products: toys, sporting goods, appliances, tools, utensils, clothing, shoes, packaging

Cost and Availability

Cost and availably of raw matl/processed matls are major concern in mfg.

If raw/ processed materials are not commercially available in the desired shape, dimensions, tolerance, & quantities substitutes or additional processing may be required; which will increase production cost.

Service Life and Recycling

Wear, fatigue ,creep and dimensional stability are important considerations.

Recycling or proper method of disposal of the components

The proper treatment and disposal of toxic wastes

Selecting Manufacturing Processes

Processing methods for materials can be listed as follows:

1. Casting2. Forming and shaping3. Machining4. Joining5. Micro manufacturing and nanomanufacturing6. Finishing

Selecting Manufacturing Process A wide range of mfg process are used to produce a variety of parts, shapes and sizes.

There is usually more than one method of mfg a part from a given material.

Part shape, size, and thickness, dimensional tolerances, and surface-finish requirements greatly influence the selection of a process

Quantity of parts and production rates determine the processes that are used and the economics of production.

Function

Material Shape

Process

Material selection and process cannot be separated from the shape and the function of the product, two way interaction.

Function dictates the choice of material and shape.

Process interacts with shape.

Process is influenced by material

Shape restricts the choice of material and process.

Various methods of making a simple part: (a) casting or powder metallurgy, (b) forging or upsetting, (c) extrusion, (d) machining, (e) joining two pieces.

Manufacturing a Sheet-metal Part by Different Methods

• Two methods of making a dish-shaped sheet metal part:

(a) press working (b) explosive forming

Shapes and some common methods of production.

The most intricate of shapes, both external and internal, may be cast. As a result, many other operations, such as

machining, forging, and welding, can be minimized or eliminated.

Because of their physical properties, some metals can only be cast to shape since they cannot be hot-worked into bars,

rods, plates, or other shapes.

Objects may be cast in a single piece.

Metal casting is a process highly adaptable to the requirements of mass production.

ADVANTAGES OF CASTING PROCESS

Large numbers of a given casting may be produced very rapidly.

For example, in the automotive industry hundreds of thousands of cast engine blocks and transmission cases are produced each year.

Extremely large, heavy metal objects may be cast when they would be difficult or economically impossible to produce otherwise.

Large pump housing, valves, and hydroelectric plant parts weighing up to 200 tons illustrate this advantage of the casting process.

Some engineering properties are obtained more favorably in cast metals. Examples are :: More uniform properties from a directional standpoint; i.e., cast metals exhibit the same properties regardless of which direction is selected for the test piece relative to the original

casting.

Strength and lightness in certain light metal alloys, which can be produced only as castings.

Good bearing qualities are obtained in casting metals.

Disadvantages of Casting:

Though casting is cheapest for MASS Production, it becomes non economical in case of JOB production.

Sand casting leaves rough surface which needs machining in most of cases. It adds up the cost in production.

Again in sand casting, poor dimensional accuracy is achieved.

Cast products are superior for compressive loads but they are very poor in tensile or shock loads.(They are brittle).

Advantages of Forging

·        The forgings are consistent in shape and do not have any voids, porosity, inclusions, or defects.

·       Parts that are produced by this method have high strength to weight ratio and therefore used in the design of the aircraft frames.

·         It offers low cost for moderate to long runs.

• High speed of production.

DISADVANTAGES High tool cost.

High tool maintenance.

Limitation in size and shape.

Production Methods

• Job Production – One-off production - each item might have particular specifications

• Mass Production – suitable for mass market products that are identical

• Batch Production – each stage of the production process has an operation completed on it before moving on to the next stage – allows modifications to be made to products that otherwise are the same

Manufacturing Costs and Cost Reduction

• The total cost of a product consists of material costs, tooling costs, fixed costs, variable costs, direct-labor costs, and indirect-labor costs

• Depending on the particular company and the type of products made, different methods of cost accounting may be used

• Costs are also attributed directly to product liability

Manufacturing Costs and Cost ReductionMaterials Costs• Costs depend on the type of material, processing

history, size, shape, and surface characteristicsTooling Costs• Costs are involved in making the tools, dies,

molds, patterns, and special jigs and fixtures required for manufacturing a product

• Greatly influenced by the production process selected

Manufacturing Costs and Cost Reduction

Fixed Costs• These costs include electric power,

fuel, taxes on real estate, rent, insurance, and capital

Capital Costs• Represent machinery, tooling,

equipment, and investment in buildings and land

Manufacturing Costs and Cost Reduction

Direct-labor Costs• Costs for labor that is directly involved in

manufacturing products• Time required for producing a part depends on its

size, shape, dimensional accuracy and surface finish• Labor costs in manufacturing and assembly vary

greatly from country to country• Manufacturers consider moving production to

countries with a lower labor rate known as outsourcing

Manufacturing Costs and Cost Reduction

Indirect-labor Costs• Consist of costs for supervision, maintenance,

quality control, repair, engineering, research, and sales and cost of office staff

Manufacturing Costs and Production Quantity• Large production require the use of mass-production

special machinery (dedicated machinery)• Small-batch production involves general-purpose

machines

Manufacturing Costs and Cost ReductionCost Reduction• Cost reduction use relative costs as a parameter• Some products require complex and expensive

production steps to process• Design phase has the largest influence on the

quality and success of a product in the marketplace

• Cost–benefit analysis requires reliable input data, technical and human factors

• Cost of a product is taking into consideration the product’s marketability and customer satisfaction.

• Major impact on manufacturing includes:1. Global competition2. Market conditions fluctuated widely3. Customers demand4. Product complexity

Manufacturing Costs & Global Competitiveness