FMT-714 Vice grip with jaws

Screw grips are used for tensile tests of different materials. The prepared specimens are clamped between the upper and lower holder and pulled at a constant speed until the yield point is reached and the material breaks.

In the case of flat material, a specimen that is tapered in the middle is usually punched out. This is to prevent the material from being torn out at the crushing edge of the grips. The opposing jaws are individually adjustable. This allows asymmetrical specimens to be clamped, e.g. when testing the strength of connections between two components.

When using bolt clamping heads, the change in length can be recorded indirectly on the crosshead, as the closing angle is offset by 90° relative to the force axis. In contrast to wedge grips, however, the clamping force does not increase during the tensile test. Due to their low weight, the FMT-714 series bolt tensioners are suitable for tensile testing machines equipped with a 50 N load cell.

In the case of heavy bolt tensioners, the weight force would trigger such a strong preload on the load cell that it would be operated outside its specification. The maximum opening widths depend on the choice of clamping surface and are 6 to 8 mm. By selecting the correct clamping jaws, which have a clamping surface of 250mm², different material samples can be held securely.