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