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

Holes and Slots

Besides being used to reduce part mass and provide uniform wall thicknesses, holes and slots can provide useful functional features in MIM components, and can generally be produced without adding to the piece price. However, adding these features does increase the complexity of the mold, as shown in Figure 8a, which necessarily adds to its cost. Holes that are perpendicular to the parting line are the easiest (and least costly) to mold in. Holes that are located parallel to the parting line, while readily achievable, require mechanical slides or hydraulic cylinders, which increases the up-front tooling costs.

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.