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USA - Weston foundry melds ancient technique with modern casting method

Using a casting technique at least 5,000 years old, Don Marion and his sons at MCM Precision Casting, have been pushing the envelope in cast alloy technology since 1991.

While other foundries have been closing their doors, the Weston-based small business has been carefully honing three different casting methods with proprietary advances to increase efficiency and create castings that were previously considered impossible.

"Several years ago we did a rapid prototype that was the toggle for a zipper. It wasn't really a job, but to see if we could do it. We're always being told that something can't be done," said Doug Marion, plant operations manager. "We can do as small as a pencil eraser, but the casting may be 350 pounds."

Using the ancient method of lost-wax casting, also called investment casting, MCM creates a mold that starts with creating exact copies of the desired piece, in wax. It could be a single larger and heavier piece, like the high tech alloy part of a motorcycle frame that won them international acclaim, or it could be a couple thousand zipper pulls. Regardless, the pieces will need "gates" that will become the tunnels which both let the melted wax escape the mold and later allow gravity to fill each mold with molten metal.

The mold is created out of extremely fine sand, layered over the wax piece and turned into the ceramic mold into which the metal is poured.

The sand is mixed with citric acid into a slurry. It looks like cake batter in a giant mixer that might be seen in a pastry shop, but this isn't for pastries. Everything in the MCM foundry carries the seriousness associated with heat measured in four figures.

Temperatures at this "bakery" can get beyond 2,800 degrees Fahrenheit.

Molten metal glows like the sun. The ceramic molds glow to a translucence to the point where the metal inside is visible. The smallest bit of moisture causes explosions of sparks and liquid metal droplets that will burn through a human like a hot knife through butter.

Then things start to cool. With cooling comes shrinkage. Everything is dynamic in a foundry.

"You have to worry about tearing metal during shrinkage at high temperature. It's all mathematical calculations. Every wax pattern is an expendable pattern," said Doug.

MCM works with over 120 different alloys: high and low carbon steel, brass, bronze, aluminum. Alloy simply indicates a mixed metal, instead of a pure element, like iron, or copper.

Each ingredient is physically added to the heated mix, not unlike making soup on a stove.

"We know about what it (the alloy) is, and then we take it to the spectrograph to find out what we need to add to certify it," said Don. He has 52 years in the casting business. He can identify metal ingot types by sight.

With his years of experience, he will have the big guys, and they are all big strong men, pour a few more solid metal ingots, from a 50 gallon drum, into the melt.

The metal is poured from a cupola, with looks like a large spouted bowl, held between two men with five foot long handles. The men are dressed in silver heat-resistant suits, because everything is very, very, very hot.

After the casting is finished, the gates are cut off. Multiple pieces are separated and the new metal part is cleaned up, sometimes with just a water jet and grinder, sometimes with sanders and polishers.

Gone are the old days of filthy foundries in the United States. Almost everything in the casting process is recycled at MCM. Cleaning is done with high pressure water. Even the melted out wax is reclaimed. Every one of the 20 employees in this family business knows that they compete on a global scale and efficiency is the name of the game.

"We've seen ups and downs. It's the nature of the beast," said Don.

He points out that in addition to the investment casting, they can also do sand casting and ceramic casting.

"We have 3-D printers and can do a casting in a couple of hours. That's a big deal in our industry, rapid prototyping. There's many forms of it and there are a lot of materials out there," Doug said.

Doug points out that the difference between MCM and other foundries is they work in more types of materials and do more types of castings. They are also fast.

So next time you see a Tomahawk missile, the cap on the tusk of an elephant or pull up your zipper, you could be looking at some of the precision work of MCM Precision Casting.

MCM Precision Casting, Inc. is located at 13133 Beech St. in Weston. Contact them at 419-669-3226 or look them up on the web at www.mcmprecision.com.

Source: sent-trib.com

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