Design & Manufacturing of Materials 4.ppt

The Design Core
Market Assessment
Specification
Concept Design
Detail Design
Manufacture
Sell
DETAIL
DESIGN
A vast subject. We will concentrate on:
Materials Selection
Process Selection
Cost Breakdown
Systematic Process Selection
Subset of Processes
Supporting Information: handbooks, suppliers data sheets, databases, WWW
(Search “family history” of candidates)
All Processes
Screening: apply attribute limits (eliminate processes that cannot do the job)
Ranking: order by relative cost (find processes that can do the job economically)
Prime Candidates
Local Conditions
(does the choice match local needs, expertise etc.?)
Final Process Choice
Categories ponent Shape
SLENDERNESS
Ratio of section thickness to the square root of section area:
Similar to aspect ratio in 2-d
COMPLEXITY
Relates to the number of specified dimensions of ponent and the precision required:
But life is plicated, . spheres have plexity, but are difficult to pared with cylinders of plexity. We should also consider other attributes such as symmetry.
Process for a Vacuum Cleaner Fan
Constraint
Value
Materials -Nylon
-Al alloys
Complexity
Minimum section
Surface area
Volume
Weight
Mean precision
Roughness
Process
Tm = 550 - 573 K, H = 150 - 270 MPa
ρ= 1080 kg/m3
Tm = 860 - 933 K, H = 150 - 1500 MPa
ρ= 2700 kg/m3
2 - 3
- 6 mm
- m2
-5 - -4 m3
- kg
 mm
<1 shape preferred
Fans for vacuum cleaners are designed to be cheap, quiet and efficient. Nylon and Al alloys have been identified as candidate materials.
Net shape processing is preferred for low cost.
Complexity is classified as 3-D solid.
Process for a Vacuum Cleaner Fan
SLENDERNESS
Process choice is often limited by the capacity to make long, thin sections (slenderness S of ponent), where
The fan can be shaped in a large number of ways including die-casting for Al alloys and injection moulding for polymers.
The hot working processes for metals
cannot be chosen.
Define a s