How Are Concrete Molds Made with Vacuum Formed ABS Plastic?

January 15, 2020 11:02 pm Published by Leave your thoughts

If you’ve ever made a concrete stepping stone or other decorative object, you probably used a mold. Molds make it possible to form concrete into beautiful shapes and designs, but you might not have ever given any thought as to how those molds are made until it comes time to make your own. Whether you’re a hobbyist or commercial enterprise, using custom vacuum formed plastic molds can open up a world of possibilities. If you have plastic vacuum forming ideas in Utah, we can help make them into a reality—call D&D Plastics to get started on your custom molds.

The following is a brief overview of the mold-making process.

What is plastic vacuum forming?

If you’re not familiar with the different types of plastic fabrication, you might not know what vacuum forming is. This process involves taking a sheet of plastic, heating it, stretching it over a mold form and then using vacuum suction to force the plastic to contour around the mold. This has a variety of uses, from vehicle parts to, of course, concrete molds.

How concrete molds are made with vacuum forming

The first step in the mold-making process is to create a shape for the mold. Many molds are made from metal-filled epoxy or solid metal, which is reusable and can withstand the high heat that vacuum forming requires.

After a rubber mold is made and the form is cast, the back is sanded flat. Then small holes are drilled into the casting, spaced out approximately three inches. Any holes deemed too large are filled in with Bondo, and then it’s time to begin the vacuum forming process.

For concrete molds, ABS or polystyrene are preferable. The plastic sheet is trimmed to fit the vacuum molding machine’s capacity, then the plastic is heated so that it can soften and conform to the cast object.

Depending on whether you use ABS or polystyrene, your heating temperatures and times may differ, but it can take as little as 160 seconds (or two minutes and 40 seconds). The plastic is removed from the vacuum-forming machine and allowed to cool.

At that point, the only thing left to do is finish it—using a band saw, the excess plastic is trimmed away, leaving a border (usually about an inch) around the edge. The sharp edges are sanded down, and voila: you have a reusable plastic mold suitable for forming concrete.

Make your plastic vacuum forming ideas a reality in Utah

D&D Plastics designs and develops plastic products, utilizing over 35 years of experience in design and plastic fabrication. We can take your concept and develop a custom design and plan, then create your product to your exact specifications. No matter what the size and scope of your project may be, the experts at D&D Plastics can help you in whatever capacity you need. Call us today to get started on your custom plastic concrete molds, or any other product you need. We look forward to working with you soon!

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