All Glossary

Displacer

Displacers are used to minimize the amount of plaster or rubber needed to make a block or case mold for ceramics.

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Details

The advent of 3D printing for making molds in ceramics has enabled the design of more complex and geometrically precise pieces than ever before. And it enables creating molds having extremely thin walls. For example, we typically print block molds for the creation of rubber case molds, having walls as thin as 1.2mm. This would have been unthinkable before. 3D design also permits incorporating displacers of rubber or plaster that enable making much lighter and less expensive molds. Adding 3D printed side rails adds further savings (by enabling rubber side walls that are much thinner than would otherwise be practical).

More information coming as we incorporate this concept into molds going forward.

Related Information

3D printed displacer reduces the rubber needed

This is PMC-746 mold rubber being poured into a 3D printed mold (which has been made more rigid with glued on cardboards). The displacer is weighed down with rocks as the rubber is poured in. It reduces both the cost and the weight of the rubber mold. This is one of our early ventures into this method, going forward we will design-in the displacers from the start (this one could have displaced considerably more).

Ball pitcher mold ready to pour rubber. But how much rubber?

PMC-746 rubber is expensive - this is large and it will use a lot. The displacer (left) will reduce the pitcher walls to 1in thick (rather than a large solid piece of rubber). Following is how I calculated how much rubber is needed. First, I used Fusion 360 to generate a solid model of the upper part of a pitcher (this mold will forms that). I sent it to the slicer and it displays the volume in mm3 (as shown in the screenshot inset). To calculate the total volume of rubber needed I did this: Outer Box volume (250mm x 205mm x 107mm = 5484cm³) - Inner Box volume (231mm x 180mm x 96mm = 3991cm³) + Pitcher volume / 2 (1817cm³/2 = 908cm³) - Displacer volume (292cm³) = 2109cm³ + 10% error = ~2300cm³ PMC-746 has a specific gravity of 1.0 and the mix requires 2 parts yellow resin to 1 part blue hardener. Thus: 33.3% of 2300 = 765g blue 66.6% of 2300 = 1531g yellow.

By Tony Hansen Follow me on

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