DESIGN FOR MANUFACTURING (DFM) DESIGN FOR ASSEMBLY (DFA)
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Transcript of DESIGN FOR MANUFACTURING (DFM) DESIGN FOR ASSEMBLY (DFA)
DESIGN FOR MANUFACTURING (DFM)
DESIGN FOR ASSEMBLY (DFA)
DECISIONS
Casting ? Stamping ?
… but, correct decisions require knowledge of manufacturing process
[Andreasen 1988]
DECISIONS AGAIN; HOW TO MANUFACTURE A FORK?
DESIGNERS’ KNOWLEDGE OF MANUFACTURING PROCESSES
[Boothroyd et al 1994]
Some of manufacturing processes for plastic products:
GRP - glass reinforced plastics
SMC - Sheet Molding
BMC - Bulk Molding
LFT - Long Fiber Thermoplastic Molding
GMT - Glass Mat Thermoplastic Molding
Thermoforming
HIP - Hot Isostatic Pressing
…. + vast number of other technologies
DESIGNERS’ KNOWLEDGE OF MANUFACTURING PROCESSES
SUPERPLASTIC FORMING
This method consists in hot
forming up to 1000° Celsius
superplastic alloys by using
an inert gas pressured up to
50 bars. Combined with
diffusion bonding, this
process allows honeycomb
structures made of several
sheets in a single operation.
Loading: The blank is loaded in the form die. The hot press heats the die and the blank to the material super-plastic temperature.
Forming: Once the temperature is reached, it is accurately controlled, while the gas pressure slowly inflate the blank.
Forming: The gas keeps inflating the part to fit the die. The material at the super-plastic temperature can allow up to 500% elongation
Release: At the end of the forming cycle, the part perfectly conforms with the die, even in its smallest details.
EXAMPLES OF SOME “EXOTIC” MANUFACTURING PROCESSES
http://www.cyrilbath.com/plasticforming_process.html
Thixomolding® is the
injection molding of
thixotropic metal alloys
(magnesium to date) in a
semi-solid or plastic-like state.
The process takes place in a
specially designed machine
resembling a plastic injection-
molding machine. Click here
http://www.thixotech.com/
to see the schematic of a
Thixomolding® machine.
EXAMPLES OF SOME “EXOTIC” MANUFACTURING PROCESSES
http://www.jsw.co.jp/en/mg_f/mg_tixo_f/mg_tixo_proce.htm
EXAMPLES OF SOME “EXOTIC” MANUFACTURING PROCESSES
Spinning
Shear molding
Flow molding
Process classification
EXAMPLES OF SOME “EXOTIC” MANUFACTURING PROCESSES
Note that “exotic” does not necessarily mean “new”, it may be just forgotten.
Metal spinning
DIRECT LABOR COSTS – UNITED STATES
Process Processing Cost ($/hr in 1998 dollars)
Injection Molding 30 + 0.06T (where T is the tonnage of the machine)
Die casting 30.00
Machining 50.00
Powder Metal 40.00
Sheet Metal 30.00
Manual Assembly 30.00
Electrical work (assembly, PCB) 30.00
Finishing (paint, labeling) 30.00
SHAPES AND COMMON METHODS OF PRODUCTION
[Boothroyd et al 1994]
MANUFACTURING PROCESSES WE REVIEW IN MME2259a
DESIGN FOR MANUFACTURING (DFM)
1. Machining - is the process of removing or separating pieces of material from a workpiece (i.e. material removal).
2. Forming - is the process of giving shape to a workpiece without adding material to, or removing material from, the workpiece (i.e. material deformation, casting, and injection molding).
3. Joining - is the process of fastening workpieces together, permanently or semi-permanently.
4. Finishing - is the process of modifying a workpiece surface for the purposes of protection and/or appearance (i.e. surface treatment).
1. MACHINING PROCESS - SAWING
TYPE DESCRIPTION EXAMPLES
1. MACHINING PROCESS - SHEARING
TYPE DESCRIPTION EXAMPLES
1. MACHINING PROCESS - MILLING
TYPE DESCRIPTION EXAMPLES
1. MACHINING PROCESS - TURNING
TYPE DESCRIPTION EXAMPLES
1. MACHINING PROCESS - DRILLING
TYPE DESCRIPTION EXAMPLES
[Lindbeck 1995]1. MACHINING PROCESS - SHAPING
TYPE DESCRIPTION EXAMPLES
1. MACHINING PROCESS ABRADING
TYPE DESCRIPTION EXAMPLES
1. MACHINING PROCESS ELECTRO - CHEMICAL
TYPE DESCRIPTION EXAMPLES
2. FORMING PROCESS - DRAWING
TYPE DESCRIPTION EXAMPLES
2. FORMING PROCESS - WIRE DRAWING
TYPE DESCRIPTION EXAMPLES
2. FORMING PROCESS CHART - BENDING
TYPE DESCRIPTION EXAMPLES
WORK PIECE
2. FORMING PROCESS CHART FORGING
TYPE DESCRIPTION EXAMPLES
Hot or cold
2. FORMING PROCESS - CASTING
TYPE DESCRIPTION EXAMPLES
2. FORMING PROCESS - ROLLING
TYPE DESCRIPTION EXAMPLES
2. FORMING PROCESS - EXTRUDING
TYPE DESCRIPTION EXAMPLES
3. JOINING AND FASTENING - MECHANICAL
TYPE DESCRIPTION EXAMPLES
3. JOINING AND FASTENING - ADHESIVE
TYPE DESCRIPTION EXAMPLES
3. JOINING AND FASTENING - COHESIVE
TYPE DESCRIPTION EXAMPLES
4. FINISHING PROCESS - MECHANICAL
TYPE DESCRIPTION EXAMPLES
4. FINISHING PROCESS - COLORING
TYPE DESCRIPTION EXAMPLES
4. FINISHING PROCESS COATING
TYPE DESCRIPTION EXAMPLES
Manufacturing Aluminum Cans
[Lindbeck 1995]
[Boothroyd et al 1994]
DESIGN GUIDELINES FOR MACHINING
Allow for run-out for tool
DESIGN GUIDELINES FOR MACHINING
Avoid completely spherical surfaces
DESIGN GUIDELINES FOR MACHINING
Use rectilinear shapes
Minimize machined areas
Use co-planar surfaces
Break-up large surfaces
DESIGN GUIDELINES FOR MACHINING
Thread run-outPoor design (no thread run-out)
DON’T DO
[Boothroyd et al 1994]
DESIGN GUIDELINES FOR MACHINING
Provide boss to avoid drilling into an inclined surface
DON’T DO
DESIGN GUIDELINES FOR MACHINING
Do not design very difficult (or impossible) to machine hollows or overhangs
DON’T DO
DESIGN GUIDELINES FOR MACHINING
Design for reasonable internal pockets radii
DON’T DO
R = 0impossible
DESIGN GUIDELINES FOR MACHINING
Use standard dimensions
Φ = 10.57mm Φ = 10 mm
DON’T DO
DESIGN GUIDELINES FOR MACHINING
Avoid long narrow holes
DON’T
DESIGN GUIDELINES FOR MACHINING
Avoid thin wall, they break when machining
DON’T DO
DESIGN GUIDELINES FOR MACHINING
Place holes away from edges
DON’T DO
DESIGN GUIDELINES FOR MACHINING
Provide access for tools
DON’T DO
DESIGN GUIDELINES FOR MACHINING
Avoid deep pockets that require long tools and cause tool vibration
DON’T
DESIGN GUIDELINES FOR MACHINING
Design parts that are easy to fixture (hold)
DON’T
Difficult to hold
DO
Easy to hold
DESIGN GUIDELINES FOR MACHINING
Avoid long thin sections that cause vibration when machined
DON’T
DESIGN GUIDELINES FOR MACHINING
Remember that holes can’t change directions
DON’T DO
DESIGN GUIDELINES FOR MACHINING
DON’T DO
Avoid external rounds which are difficult to machine, use chamfers instead