Wedge grips apply a self-loading clamping mechanism that allows holding samples at high forces. They are often used to test metal and composite specimens and other materials exhibiting high breaking strengths. Wedge grips are the recommended grip type in tests such as ASTM E8 Metals Tensile Testing, ASTM E517 Sheet Metal Plastic Strain Ratio Testing, and ASTM D3039 Polymer Matrix Composite Tensile Testing.
Difference Between Grip Body/Jaw Movement
A question we frequently get is the difference between standard or moving-jaw wedge grips and moving-body wedge grips. This post covers the principles of operation of these two types of wedge grips.
1. Moving-Jaw Face Wedge Grips
Moving-jaw face wedge grips close down on the specimen by the movement of the jaws or the inserts. The grip body remains stationary as the wedges move, creating a compressive preload on the specimen. As tensile force is applied during testing, the wedge-shaped design of the jaws causes the clamping force to increase.
ADMET moving-jaw face wedge grip options include:
- GW-T: Self-tightening wedge grips with a lever arm for quick loading and release of samples,
- GW-XT: Wedge grips featuring a crank to open and close the front gear,
- GW-T-T: Pneumatic wedge grips.
Options for wide specimens and for low or high temperature testing are also available.
2. Moving-Body Wedge Grips
Moving-body wedge grips are self-clamping grips where the grip body moves and jaws stay stationary in the vertical direction. Jaws incorporated in this design only move horizontally. We recommend selecting moving-body style wedge grips to avoid compressive loading on the samples. In addition, taking the vertical distance between the top and bottom grips in account, operators can define the exact grip separation and enter to the software for automated result calculations.
There are a variety of tensile grip options available. For further information, read our informative blog post on tensile grip selection below.
ADMET grips and fixtures can be used with MTS, Instron, and other testing systems. The list below includes different types of wedge grips categorized by the force capacity. Click below for grip datasheets. Other options are available upon request. Please contact us to discuss your needs.