Design For Manufacturing
From concept to final product can be a large and daunting task, but we have found that communication is key. To streamline the process in designing your product with manufacturing in mind here are a few guidelines:
Transferring or Sending Files
The method of transferring files can either lead to a lot of confusion or it can be really smooth. By using a zipping utility and the naming convention of XXXXX_rev-$.zip (where XXXXX is the part number and $ is the current Rev of the part inside.) it is plainly clear what part number and rev. is being sent. All subsequent zip files with a new rev part should have the rev incremented appropriately.
-Always model to the nominal dimension, and if at all possible use symmetrical bilateral tolerances. Do not put unilateral tolerances on a part. i.e. - If you want a bore to be 0.500" +.004, -.000 then model and tolerance it 0.502" +-.002. If you use unilateral tolerances then programming from the solid model and holding tolerances becomes much more difficult.
- Use correct # of significant digits
Internal corner fillet radii such as in corners of pockets should be larger than a standard fractional inch size by 1.04*( standard size radius)
Example standard size fractional rad .25 should be 1.04*.250=.260
fillets at the bottom of walls that will be produced using a radius on the end of a tool such as a ball end mill or bull nose end mill should remain nominal inch sizes.
When calling out threaded holes keep in mind 1.5 x dia give you 95% thread strength and calling out a thread exceeding that by much can make tapping holes more difficult especially if they are blind holes. It is also very helpful to have some allowance for some untapped hole below the full thread. Usually .5 X dia is a safe guideline when possible.
Geometric Dimensions & Tolerances
Where critical fits between components exist applying geometric dimensions tolerances can often allow a more achievable and cost effective way to ensure your parts and assemblies work properly than just overly reducing tolerances with standard dimensions.