The Testing Times

The ASTM D429-03 69.1 (Method G) is for testing the adhesion properties of rubber. The rubber is pre-formed onto 3 metal plugs. this gives a double rubber sandwich that can then be tested. This attachment holds the metal components of the sandwich and allows a double shear test to be performed.

Imagine trying to hold a piece of fibre insulation (the stuff in your roof that stops the heat escaping) in a clamp and then pulling it apart using a tensile test, how on earth do you do it? It’s fibrous, comes in different thicknesses, breaks of easily into chunks… Well the answer is Nails, and lots of them. This is the most effective way to distribute the load across and through this particular sample, this means that the test specimen isn’t overly damaged when you grip it. If the sample is ‘waisted’ properly (like an hour glass), it will break in the weakest spot, not by the grip. This is a technique used time and again with all kinds of samples. You want to see how the material will break under load, not how the grip breaks it, and then the load pull it apart. As there are a lot of nails it’s quite hard to push them through the top surface of the specimen (Imagine trying to nail 20 nails at once into something soft. It might be soft but there is a lot of friction to overcome). To ...

Used on some of our smaller systems, the S0981 Tinius Olsen ASTM C736-00 Adhesion Test For Latex Sealants, quite a recent one, this grip design is used to test the strength of sealants and adhesives used in the production of windows. It's quite a complex process to prepare the samples, using a c shaped 'mold' the sealant is injected between a glass and aluminium plate. These are held together using (good ol ') G-clamps. It is then allowed to cure for a specific time... as it's nice to prepare a few of these samples to test, we provided a few kits (C section, and the aluminium and glass plates). It was odd, as you had to remember that the test specimen was a liquid that needed to cure, in a mold. I was something that I had to keep reminding myself. This test allows you to find the Adhesion strength of the Sealant between the desired structural material types. In this case glass and aluminium.