Embossing, which rubber block?

Anyone know what hardness rubber block I should use for embossing thin aluminum sheet? Maybe a 6" square part.

Dan Gelbart does it in this video, but just says "hard rubber". But what durometer?

Building Prototypes Dan Gelbart part 7 of 18 Presswork - YouTube

I have used Neoprene from a shoe repair store for some work like that.

You may want to look into urethane, one of the metal shaping forums had some info on it......All MetalShaping - Powered by vBulletin

Here's some Google info;

urethane for sheet metal stamping press machine - Google Search

Kevin

If someone came up to me and said "hard rubber" without any more context I would provide 90 Durometer Shore A.

Coincidentally, 90A is about the "standard" hardness for most thermoset urethane products. Chloroprene (Neoprene) is available in that hardness but you'd need to ask about it, 70A is the standard for that compound.

Urethane and Chloroprene also both have great shock-absorbing properties, urethane being the best and CR second best.

One more thing to note is that you will want a material that has a LOW "Compression Set" material property. When squeezed, rubber will tend to act like an incompressible fluid with a fairly outrageous viscosity. Then, it will come back to almost the shape you started with, but stay a little squeezed. The compression set is the percentage of the recovery that the rubber fails to achieve when released back to its free state.

“Thin aluminum” isn’t super specific as to what you are doing, but usually 40A-60A durometer Neoprene for a forming operation. If its just shallow embossing you can use harder, if you need a lot of reach for instance to bend an edge along the perimeter of the part a softer durometer will flow more.

I recommend buying a sheet 1/2 the required thickness and stacking two together so you get more faces. It tears up over time so with two sheets you get 4 faces of rubber.

The harder durometer (70A if I remember correctly) we use without a box for a quick forming operation. The softer the rubber and the thicker it is, the more necessary it is to have a captive box for the sheet.

McMaster-Carr


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Guerin process, and Verson rubber pad pressing should kick up some numbers.
Here as well
Rubber pad forming - Wikipedia

Potter Press (potter USA.com) uses 95 durometer urethane in his embossing die pads. He has some sizes and containers in stock for jewelry work.

Here’s a chart with some useful info.......

Urethane Durometers | Acrotech Inc.

Kevin

Good info, thank you