Design for Manufacture

The idea of Design for Manufacture (DFM) is to consider the technologies used to create the final product while designing the part. A part designed for 3D printing, injection molding, and machining are going to look different because the technologies each have unique limitations. Another key to DFM is accounting for the cost of features while designing. Each manufacturing technology has features that are more expensive to create. For example, in machining the tools used for creating a radius in the x-y plane are more expensive than the tools used for chamfering. Also, internal features in the z-direction should have a corner radius that matches a common endmill radius.

• 3d prints produce non-homogeneous parts - features that need strength should not be printed vertically
• voids create overhang problems - objects should be solid, allowing the slicer to fill the volume with infill at the desired percentage
• heated chambers achieve strengths closer to the bulk material strength - if strength needs to be optimized, heated chambers should be used
• deceleration increases print time - features in the x-y plane should be radiused so that the printer does not need to decelerate to a sharp corner
• bed adhesion is effected by differential shrinkage - the bed contact area should be kept as small as possible while still providing enough support to print a stable part
• auto generated supports are inefficient - where possible, support material should be designed in the CAD package

• tool selection has a high impact on cost - parts should be designed to use common tools where possible
• stock size has a high impact on cost - parts should be designed to be slightly smaller than a common stock size so that cleanup passes can be run without oversized stock
• machine time is effected by tool changes - parts should be designed to use as few different tools as possible, each new feature type often requires a new tool
• automation decreases cost - parts should be designed with the workholding and automation capabilities of the manufacturer in mind
• number of operations has a high impact on cost - parts should be designed to require the fewest operations possible, features in two planes make a 2 op part while features in 3 planes create a 3 op part

• silicone volume has a high impact on cost - shell molds should be used where possible
• internal features are difficult to reproduce - designing two parts to be joined is often better than a single complex part
• material choice has a high impact on mold life - the correct silicone needs to be selected based on the complexity of the part and casting media