Q&A: Cast Shot Blast Media Questions Answered by Transmet Engineers

We sat down with engineers from Transmet Corporation to discuss cast shot blast media and answer the questions that are frequently asked at trade shows, on the phone, and in the field.

Transmet manufactures Cast Zinc Shot and Cast Aluminum Shot at their plant in Columbus, Ohio. The high durability blast media is used in various manufacturing operations across the world.

Q&A: Cast Shot Blast Media

Q: When should we use Cast Zinc Shot and when should we use Cast Aluminum Shot?

A: We typically recommend Cast Zinc Shot first, because it has a higher density and typically works faster. When a part is prone to warping during shot blasting, Cast Aluminum Shot is a better choice.

Q: What gives Transmet Blast Media its teardrop shape?

A: The tails, as we like to call them, are a product of our unique casting process. The soft metal rounds up in about 50 cycles. Even with 100% new cast shot blast media you will not see any issue with the tails. As part of a working mix new shot is less that 1% part of any mix.

Q: What is the cycle life of Cast Aluminum Shot compared to the 14,000 cycle life of Cast Zinc Shot?

A: Cast Aluminum Shot has a cycle life of 8,000 hits. These numbers come from testing in the Ervin Test Machine.

Q: Can Transmet blast media (Cast Zinc Shot and Cast Aluminum Shot) be used in existing wheel blast and tumble blast machines, as nobody wants to change their machinery?

A: Yes, both Zinc Shot and Aluminum Shot work well in wheel blast (tumble and others) machines, as well as air blast systems.

Q: Can we use Cast Aluminum Shot for removing powder coat from aluminum parts?

A: Yes, Cast Aluminum Shot will work, but we have found that Cast Zinc Shot works faster.

Q: Our aluminum castings turn black after heat treatment. What type of Transmet blast media should be used and can it make the castings brighter and more appealing?

A: Both types of Transmet blast media will work, but Cast Zinc Shot will be faster. Cast Aluminum Shot on aluminum parts will leave a flatter, more matte surface finish. Cast Zinc Shot is going to leave a brighter, more shiny surface on aluminum parts.

Q: What product do you suggest to customers who are already using Stainless Steel Shot for blasting?

A: Cast Zinc Shot is typically a great replacement for Stainless Steel Shot blast media.

Q: Can Transmet Cast Aluminum Shot completely remove flash with a thickness of 0.50 mm, and if so, will it damage the casting?

A: Cast Aluminum Shot will have difficulty removing flash at that thickness. Cast Zinc Shot would be a better choice, most likely our larger RSZ-850-ZA4 (850-micron) Shot.

Q: Can Transmet Aluminum Flakes be used in Polyester molds and Vinylester molds? What are the technical benefits and cost benefits of using Transmet Aluminum Flakes?

A: The Aluminum Flake tends to float on top of the resin systems; mixing is required to get it into solution. Our 2N alloy Cast Aluminum Shot wets out very well in resin systems with no mixing necessary. Loadings up to 60% by volume can be used. Heat transfer rates can be improved by 5X. Cast Aluminum Shot is also cheaper than most resin systems, so displacing the resin with aluminum is a cost benefit.

Q: Your blast media is measured in Knoop hardness; what is the equivalent hardness in BRC and BHN?

A: We use the Knoop scale for our blast media hardness measurements. The Rockwell C scale does not measure in this range. Most of your aluminum casting customers should have some familiarity with Koop hardness. Brinell is another scale used in aluminum casting and it is similar in number to Knoop.

Q: Can we use Cast Zinc Shot or Cast Aluminum Shot for sheet metal blasting?

A: We have not been strong in this market.

Q: Does Cast Aluminum Shot work for paint removal from gas cylinders?

A: Yes, Cast Aluminum Shot works well in this application. Cast Zinc Shot will work even faster for removing paint from gas cylinders.

If you have questions of your own for Transmet Corporation, please Contact Us.