MIM molds use several types of moving components to create features that cannot be formed by a simple two-part mold opening. Each adds cost and complexity.
Definitions of each component:| Component | What It Does | Feature It Creates | Cost Impact | Typical Life |
|---|---|---|---|---|
| Core pin | A fixed or retractable pin that forms a hole | Holes, through-holes, blind holes | Low (simple pin in stationary side) | 100k-500k shots before wear |
| Core pull | A retractable pin that moves before ejection | Side holes, angled holes, threaded features | Moderate — adds hydraulic cylinder + control | 200k-1M shots |
| Slide | A moving mold section that forms an undercut, then retracts | Undercuts, external side features | High — adds slides, gibs, wear plates, cam system | 200k-500k shots |
| Lifter | An angled component that lifts under the part during ejection | Internal undercuts, snap-fit features | Moderate — simpler than full slide | 100k-300k shots |
| Collapsible core | A segmented core that collapses inward for ejection | Internal threads, internal undercuts | Very high — multiple moving segments | 50k-200k shots |
| Rule | Guideline | Rationale |
|---|---|---|
| Avoid slides where possible | Orient features parallel to mold opening | Each slide adds 20-30% to tooling cost |
| Limit undercut depth | < 3 mm for simple slides | Deeper undercuts require more complex slide mechanisms |
| Allow clearance for slide travel | Minimum 5 mm behind the undercut feature | The slide must retract fully before ejection |
| Consider post-sintering machining | For small numbers of side features | A drilled hole costs pennies; a slide adds thousands |
A core pin is a simple rod that forms a hole — low cost, long life. A slide or side action is a moving section of the mold that retracts before ejection to create an undercut — adds 20-50% to tooling cost. A core pull is retractable pin for side holes. As a DFM rule: design to use core pins wherever possible (features parallel to mold opening) and avoid slides (features perpendicular) to minimize tooling cost.