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New research on penetration vs. thickness in washes

This past April, Lawton Standard industrial engineer Nick Knotts had the opportunity to present some of his research at the annual AFS Metalcasting Congress in Milwaukee.

Nick had studied mold washes, particularly the effective penetration and mill thickness of refractory coatings.

Industrial Engineer Nick Knotts on his research findings

Nick Knotts’ research on mill thickness and penetration

Knotts presented his findings during a technical session event at AFS.

“We talked about the effective penetration and mill thickness of refractory coatings on the performance of the liquid refractory coatings in the context of reducing the quantity of burn-in sand,” said Knotts.

He continued “We did an experiment at Temperform specifically, where we made two test molds that were four on what we typically call a Gertzman-style test casting and there were four test cores on each impression.”

Knotts said they ran a zircon and an alumina-based wash at four different selected thicknesses and tested those, checked the mill thickness and the penetration of them. They used a test sample, which they destroyed, to evaluate the cavities once the liquid metal was poured into them. The research used ASTM and HD stainless steel at 2800 degrees Fahrenheit.

Different names mostly meaning the same thing

Different facilities call similar processes by different names, especially when it comes to refractory coatings and washes.

You may hear terms like mold wash, liquid coating, coating, refractory coating. Knotts says these terms are all generally interchangeable to a certain extent.

The results of the research and testing

“What we discovered is that penetration is more important than mill thickness build-up, or what they may call “thickness of the proud layer,” depending on the terminology you like to use,” said Knotts.

The  research yielded that penetration is much more important than thickness. “You want penetration into the sand with the refractory in order to gain the best qualities from your mold wash and reduce the quantity of burn-in sand as much as you can,” said Knotts.

Key takeaways from the refractory wash research

Knotts said there are some key takeaways for every foundry that was at his presentation, or those who are reading this.

“It’s important for them to know that penetration is a key part of their mold wash performance in their system,” said Knotts. He continued “Some manufacturers still recommend a high amount of thickness and my research seems to indicate that that’s less important. It might still be a good thing, but it’s not nearly as important as building up a layer into the sand and penetrating with the mold wash to at least 2 to 3 sand grains.”

What is the benefit for Lawton Standard?

Knotts says the big thing for Lawton Standard and its family of companies is that we can alter our wash densities across the platform.

He says this research shows we can reduce our grinding times by altering those wash densities.

More in-depth research on washes at Lawton Standard ahead

Knotts said he may have a project proposal currently on the table to take a more in-depth look at washes. “We want to look into some of the finer aspects of wash outside of how it effects burn-in sand and more on how it effects volatiles in the casting system,” said Knotts.

He couldn’t speak to the specific avenue that research is going to take as it isn’t finalized yet. “We’re actually looking at testing alcohol and water-based washes, that’s what I’m proposing right now,” said Knotts. “Whether or not that’s how it actually happens, I don’t know. But that’s the path I’m headed down now.”

Contact Temperform for your high-quality steel casting needs

Industrial engineer Nick Knotts works out of Lawton Standard’s Temperform location in Novi, Michigan.

Temperform produces high-quality steel and stainless steel castings from 2 pounds up to 5,500 pounds.

For a quote or for more information, give us a call at 1-800-227-8464.