Dos and Don'ts for Designers
Jensen, Cecil, Helsel, Jay and Short, Dennis. “The Nineteen Chapter.” Engineering Drawing & Design. Mc Graw Hill, 2008. 686-701. Print.
Designers want reliably functioning parts that are dependably procurable at the lowest installed cost. They can best meet their needs by consulting with vendors and understanding custom-metal part manufacturing and pricing. Here is the checklist to use in the design of the part or assembly:
Don'ts
Don't specify tolerances tighter than essential for mechanism functioning.
Don't specify every dimension as mandatory; mark non-critical ones as reference only.
Don't specify material that is a higher quality than necessary ( too expensive) for the service.
Don't specify material that is available only through special purchase unless there is no alternative. If in doubt, ask you vendor.
Do's
Do leave adequate space for assembly - bolt clearance, finger grips, and so on.
Do consider manufacturing economics.
Do consider utilizing stock items when you need only a small quantity or parts. Your savings in design time, procurement costs, and deliver time may be appreciable.
Do realize that for small quantities or one part, the cost of raw material is not important; material availability and minimum-quantity is purchase restrictions are important.
Do realize that for large-quantity purchases, precise specification of raw material can be extremely important.
Don realize that the total cost of a custom part is not the purchase cost but the installed cost
Do consider, in your product reliability the relation between part cost part reliability the the cost of replacement of a broken part including lost production time.
Do consider the environment impact of the design.