Basic rules and tips to get started designing a product for high volume 3D Printing.
Molding Design Does not Apply
This is a problem that plagues the industry. Designers conditioned to use molding do not adjust for the new process. 3D Printing is not injection molding. It is a different process. Just as you use difference rules when using wood rather than plastic, so to should you use different rules when considering 3D Printing or Injection Molding. If cost is the driving factor lead how 3D Printing compares to Injection Molding on Pricing.
An Injection Molded Design. Requires cavities and Thin walls to be produced. A 3D Printed design is lightweight and Filled with a honeycomb for optimal material use, strength and appearance
Round, Smooth, Fat
Here is the fundamental rule for designing a product for optimum production with FDM 3D Printing. If nothing else remember this when designing for FDM 3D Printing. Work to minimize Surface Area and do not worry about Volume This leads to several key design traits that should be paid special attention to.
Abandon Ribs and Hollowing. These features add surface area and better structures can be created by the 3D Printing process itself with much less material. So fill every cavity and merge features into walls.
Fillet and Round every edge. Sharp corners not only increase print time but can make a part more difficult to print. It is better to round ever edge as far as possible.
Always design with a Single Flat/Datum Edge.
FDM 3D Printing works by laying down one layer after another using a nozzle depositing melted plastic that hardens. This process must begin on the bed of the printer. Often glass. So every 3D Printed part should be designed to allow for this single flat side to be present. Do note that this side will likely have a difference texture from the rest of your part.
Every Part in the Photo is 3D Printed. Notice that each piece has a single flush/flat face.
Design for Additive Manufacturing (DFAM) is a an entire discipline that could fill textbooks. But here are the remaining design tips that you might need in one single chart. Though let us highlight a couple.
No feature smaller than 1mm. This applies to walls and surfaces. It can be embellished a bit, but this the optimum for low cost production and good quality parts.
No overhang Steeper than 30 degrees from horizontal. Again this is not universal and some parts will need a gentler overhang than that )i.e. 45 degrees). But this is certainly the max in most cases.