MIM

What Is MIM?
   Process Overview
When to Use MIM
   General Guidelines
   Technology Comparisons
   Materials Range
   Materials List
Design Guidelines
   Designing for Manufacturability
   Uniform Wall Thickness
   Thickness Transition
   Coring Holes
   Draft
   Ribs and Webs
   Fillets and Radii
   Threads
   Holes and Slots
   Undercuts
   Gating
   Parting Lines
   Decorative Features
   Sintering Support
Secondary Operations

Undercuts

External undercuts as shown in Figure 9 can be readily formed on a parting line using a split mold; where additional mold members are required to produce them, tool costs are increased and production rates decrease. Some internal undercuts can be produced using slides while some others may be molded through the use of collapsible cores. The added costs and potential flashing problems that may ensue in these cases dictate avoidance of internal undercuts in most MIM designs.

Internally connected holes are possible, as shown in Figure 8b. To prevent potential sealing-off problems and issues with flashing, careful consideration must be given to the design. If possible, one hole should be D-shaped in order to provide a flat on the core pin for a robust tool seal-off, as well as to eliminate inordinate wear of the feathered edges that would otherwise be required on the contoured face of the mating member.