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Topic Tag: biomaterials

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Hey, low-techies. This is a plate mold made with accessible metal-working tools and machinery (angle grinder and MIG welder). Most of our other biomaterial heat press molds have been made on the CNC or engine lathe so far. We wanted to make a mold using tools that are easier (and cheaper) to come across. The main material tests for iterations of this mold were done using wheat bran. In the first iteration of this mold, we used angled steel and sheet steel to create a square plate with 45 degrees opposite bevel walls. These walls offer the right depth and shape for a standard plate. They also help the material spread while the mold is under compression. The bottom negative half for this mold was made using four pieces of 3cm angled steel cut at 45-degree angles to make a frame (19.5x19.5cm). The frame was welded onto a sheet of 5mm steel. The top positive part was made by creating a smaller frame of 1cm angled steel, also cut at 45-degree angles. This frame was welded onto another sheet of steel. Supports were tacked in place inside the frame and then covered by a square sheet of steel to create an enclosed positive. I welded/ground the form to “refine” it a bit and to fill some gaps. After testing it a few times I found that there was too much space in the bottom part of the mold, which made the plate way too thick. I cut a 5mm sheet of steel to fit in the bottom of the mold and beveled the edges so that it sat flat on the bottom of the mold, along the angled edges of the frame. This helped in reducing the thickness of the wheat bran plate. The major pain points of this design, however, came from the lack of pressure building up along the top edge of the plate walls and in the corners. The mold refused to close entirely, and this lack of pressure produced crumbly, weak walls... not the crisp, sturdy, straight walls we were going for. After multiple attempts adjusting the amount of material, temperature, water content, and press time we got the mold to produce a functioning plate with (somewhat) intact walls. The wheat bran plate finally started coming out of the mold in one solid piece when I let it sit and “cook” inside the mold for 10-15 minutes after removing it from the heat press. How material was packed into the mold mattered ~ a lot ~. Unlike the cup or bowl molds which we have used a lot here at Beyond Plastic, the material doesn’t all collect into the deepest point of the negative half of the mold. Since the plate is such a shallow shape, I thought pressure around the top edges could be created simply by getting the mold to close and having sufficient material. On one hand, the flatness of this plate mold compared to deeper vessels allows us to pre-spread the material into all the hard-to-reach places before pressing. On the other hand, for this to work effectively, enough pressure needs to build at the top, and this mold design wasn’t allowing for this. After refining the material packing method multiple times we still couldn’t produce the right plate. Moving on, we decided to redesign the bottom half of the mold to create more pressure.
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