Rubber Plaster Mold Casting vs Investment Casting

Comparisons and advantages when looking at Rubber Plaster Mold Casting vs Investment Casting.

Rubber Plaster Mold vs Investment casting

What is Rubber Mold Plaster Casting?

Also know as RPM Castings, Rubber Plaster Mold casting is the process in which rubber is used to produce a plaster tool, then the plaster is used as a “die.” This genius and intuitive process can get the same results achievable with investment casting at a much lower cost.

Only non-ferrous metals such as aluminum and zinc can be used with RPM castings, but each other those metals have great benefits in the casting process. Learn more about our Foundry capabilities or learn more alloys from our casting alloys chart. 

This method of metal casting is the most popular casting alternative because of its low tooling costs and fast turn times.

Rubber plaster mold casting is best for Low-volume productions- from 5- 1,000 units per month.

Rubber Plaster Mold vs Investment casting

Alternatives to Investment Casting

When companies are looking for short-run, low-volume, or prototype parts, it makes more fiscal sense to select a casting process that has lower up-front costs.

When comparing rubber plaster mold casting vs investment casting there are several factors to consider:

What is the Lead time for Rubber Mold Castings?

Short lead times. Can be done in a matter of days. Want to know the lead time for your parts?  Get a free quote, it takes 2-5 minutes to complete 

What is the Tooling Cost for Rubber Mold Castings?

Justifying the cost of tooling is a major reason to select investment casting alternatives. Selecting your tooling option needs to meet the needs of how long that product is going to be in production and the volume of the manufacturing.

If a medical device is a short-run production or low-volume manufacturing, justifying die casts or investment cast costs are not the best choices and die-cast or investment cast alternatives like Rubber plaster mold casting or Sand castings are perfect options that can produce similar results.

Production Cost difference

It is substantially less to use rubber plaster mold casting vs investment casting.

Geometric shapes – Design freedom. RPM can be used to create more difficult shapes and can show detail as fine as a fingerprint.  Thin walls as .030” or .7mm wall thickness.

Surface Finish Capabilities for Rubber Plaster Mold Castings– 63 RMS surface finish and down to .080”. Very similar to Die Cast surface.

Companies that benefit from Rubber plaster mold castings are aerospace, medical, and defense.

Rubber Plaster Mold vs Investment casting

Plaster Mold Casting Steps

Rubber plaster mold casting vs investment casting proccess

Comparing these casting processes can help companies understand the cost and time differences between these processes.

In short, a Rubber mold is created using a Computer-Aided Design technique.

  1. Create master patterns (negatives, positives, and core boxes)
  2. Add the master patterns to cope and drag and seal in wooden boxes
  3. Pour in plaster mixture and let solidify to create plaster molds.
  4. Pin molds together and pour in molten non-ferrous metal such as aluminum or zinc.
  5. Shake or break out parts from plaster molds.

For more indepth learning read Rubber plaster mold casting process from Precise Cast or check out The Parts Guru to see videos on this and other casting options.


Advantages of Rubber Plaster Mold Casting vs Investment casting.

Cost is the biggest advantage of using this casting method. As discussed in this article. The lower tooling costs and lower upfront cost than die casting.

Using Rubber plaster mold castings can help prevent financial setbacks and won’t drain cash from your company.

Die-cast surface finish. We can obtain a 63 RMS surface finish very similar to a die-cast surface.

Something to consider when selecting your manufacturing partner is the financial stability of the company and how long the company has been in business.




Selecting a Metal Casting Partner

Something to consider when selecting your manufacturing partner is how long the company has been in business. At Precise Cast, we have worked for top industries  Fortune 500 companies, for over twenty years.  Our most recent work has been with Tesla, Ball Aerospace, John Deer Tractor, plus many more companies.

We built our foundry around our customer’s most demanding needs. Our central location near Denver, Colorado, gives us easy reach to all North America Markets.

Talk to our engineering experts by chat, email, or get a metal casting quote now. 



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Author : Marzeyeh Hagaman

Author : Marzeyeh Hagaman

Digital Marketing Manager

Marzeyeh is the Digital Marketing Manager at Precise Cast Prototypes and Engineering. She enjoys exciting people about manufacturing and metal castings.