Table of Contents
Design for Manufacturability
It is very important to consider how a part will be machined when designing it, even if you will be sending it out to be manufactured by somebody else. The design of a part has a direct influence on what machine tools and tooling is used to manufacture it. Poorly designed parts can be expensive to produce or sometimes impossible.
Mill
- Design the part to be machined in the fewest number of clampings possible
- Radii should usually be greater than 1/8". A 1/8" end mill is a common small end mill size
- Features requiring an end mill longer than 4 times it's diameter are usually difficult to machine
- Fillet internal corners
- A boring bar can be used on the student shop manual mills to bore large diameter holes
- External radii are usually difficult to machine accurately on a manual mill but you can alway use a file to add cosmetic fillets
- Steel is more difficult to machine than aluminum
- Tight tolerances will likely increase cost and manufacturing time
Lathe
- A wide variety of threads can be machined onto external diameters fairly easily. Even in the student shop
- Deep bores can be difficult to make because of tool deflection
Water Jet / Laser Cutter
- Very quick and inexpensive way to make parts with simple 2D geometry
- Holes with important diameters should be undersized and drilled to size on the drill press
- For tapped holes can be tapped after cutting
- There is usually some draft on the cut edges
- The surface finish of the cut edges is usually quite rough with water jet parts but can be easily cleaned up with files
- Water jet pats usually need to be submerged during cutting
- Flexure mechanism can easily be cut on a water jet
3D Printing
- The most practical application for 3D printing is to prototype injection moulded parts
- MS doesn't do any injection moulding but 3D printing can still be of use to us where a plastics might be used on a real car or where complex geometry is required but strength is not important
- Try not to design with geometry that can only be manufactured using 3D printing (bad practice)
- FDM 3D prints have orthotropic tensile strength
- You can use heat set inserts or helicoils to put tapped holes into plastic parts
Welding
- Welds should be easily accessible: welding out of position is difficult and welding in tight corner is sometimes impossible.
- Aluminum is far more difficult to weld than steel
- Welding can distort the geometry of your part
Solidworks
Sketch Geometry
Variables
Global Variables
In Context Mates
Fits
Press Fits
A good rule of thumb for a press fit diametral interference is 1/1000th of the diameter you are trying to fit. So if you have 10mm shaft,