AN OVERVIEW OF PERMANENT MOLD
Permanent mold casting is an aluminum casting process that employs reusable molds made out of steel or iron. We often recommend permanent mold casting as an alternative to sand casting and high pressure die casting. Permanent mold employs a reusable steel mold like high pressure die casting as opposed to a sand mold’s one-time use and can incorporate sand cores to create internal cavities and undercuts.
HOW DO YOU KNOW IF PERMANENT MOLD IS RIGHT FOR YOU?
Permanent mold is the right solution if you:
- Produce a quantity of 500-100,000 of the same part per year.
- Require a +/- 0.015” tolerance in dimensional accuracy, high surface finish and consistent mechanical properties.
- Fabricating a component using multiple parts and incurring inventory and production costs.
- Require volume of product cast but can’t justify the higher cost of high pressure die cast tooling.
This table is a guideline you can follow to determine which process is best suited for you and your needs. It outlines key details including turnaround time, per-piece cost, and more.
| Fabrication | Sand Casting | Permanent Mold Casting | High Pressure Die Casting | |
| Surface Finish | Poor | Good | Better | Best |
| Dimensional Tolerance/Stability | Poor (+/- 0.060″) | Good (+/- 0.030″) | Better (+/- 0.015″) | Best (+/- 0.005″) |
| Undercuts and Internal Passages via Sandcoring | No | Yes | Yes | No |
| Minimum Wall Thickness | N/A | Good | Better (min. 3/16″ typical) | Best |
| Annual Production Volumes | 1-1,000 | 100-5,000 | 500-100,000 | 20,000-1,000,000+ |
| Tooling Cost | Low | Low | Medium | High |
| Per-Piece Cost | High | High | Medium | Low |
| Tooling Turnaround Time | Good | Best | Good | Poor |
3 KEY BENEFITS OF PERMANENT MOLD CASTING
1) DIMENSIONAL ACCURACY
Next to high pressure die casting, permanent mold casting is the most reliable process that produces dimensionally and visually consistent parts.
2) PERMANENT MOLDS TOOLS
Permanent mold castings tools (molds) typically last 100,000 cycles before needing replacement. Additionally, in some cases you can avoid replacement by refurbishing molds and by removing or adding features (to the mold) when necessary.
3) PER-PIECE COST
If you’re using the fabrication or sand casting processes, the shift to permanent mold casting can result in reducing your per-piece cost. Depending on features of the part we’re able to introduce multiple cavities, creating the potential for a higher number of total finished parts per life of the tool.
Custom Castings is vertically integrated with in-house processes including sand cores, machining, heat treating, coating, and assembly. Custom Castings has decades of experience casting for customers in many industries including aerospace, medical, transportation, and construction, providing extensive knowledge and expertise.