Vise Grips

Vise Grips are the most basic type of grip used by a Universal Testing Machine(UTM) for tensile testing. There are two main types, Low-Profile and U-Style. The Low-Profile version is lower cost but has a limitation on the width of the grip face inserts. The U-style is more standard and can accommodate larger jaw inserts. Two versions of the screw action also exist. The single action style has one fixed jaw and one moveable jaw that is tightened with a screw mechanism. Dual action uses two moveable grip faces. There are a few different types of grip face inserts available including diamondized, plain smooth metal, rubber, serrated, and wavy. Quick change inserts and pneumatic versions of almost every grip size are also available.

The vise grips from Universal Grip have a special mechanism that allows them to strengthen the gripping force during a tensile test. The grip faces will slightly pivot as the tensile force increases. This changes the lateral grip force on the sample to be slightly angled. More force is subsequently placed on the back of the sample specimen. The diagram below demonstrates what is happening.

The Quick Jaw Carrier

The quick jaw carrier is a mechanism which allows the operator to easily switch out different jaw inserts. Instead of manually screwing in each jaw on the vise grip, the quick change jaws easily slide and lock into place. This function saves a lot of time, especially if the UTM technician is switching between several ASTM test procedures which require differently sized jaw inserts. The quick jaws are highly recommended for users in the textile industry who switch between ASTM D751, D5035, D5034, and other similar tensile and tear tests on fabrics.