Wedge Grips for Tensile Testing

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- Overview

- Jaw Inserts

- High-Capacity Reinforcing Door

- Downsize Adapters

- Products

Overview:

Wedge grips are used for high strength tensile testing. These mechanical grips are designed to self-tighten as the tensile test progresses. Each wedge grip must also include 2 grip face inserts based on the geometry of the sample. Rounded samples use a "Vee" insert while flat samples use a standard serrated grip face. Some of the higher capacity grips involve locking a lateral door in order to maintain the integrity of the fixed wedge. Universal Grip supplies wedge grips with a unique, compact design. The lever is located on the side which keeps it away from the cross head and columns of the Universal Testing Machine. 

The opening for these grips is not very large, therefore thinner samples are typically used. Thicker samples can be used if the wedge is resized to properly accomodate them. Popular ASTMs that use wedge grips include ASTM D1002 for lap shear strength testing as well as ASTM E8 for metals tensile testing. Wedge grips are used to pull the sample apart and measure values such as Ultimate Strength and Elongation.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Jaw Inserts:

Wedge grip jaw inserts can be interchanged for samples with different geometries. The most common jaws are serrated and are used for testing flat samples like dogbones. Vee inserts are used for round or cylindrical samples such as pipes.  There are a few different options for the jaws including reversible jaws. The reversible jaws can be flipped around when the serrated file pattern starts to wear out. This essentially gives the jaws double the lifetime. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

wedge grip inserts
Wedge Grip Diagram
Wedge Grip Design

Reinforcing Door for High Capacity (100kN+)

Tensile testing at high capacity (over 100kN or 20,000 lbs.) requires a well-designed wedge grip. Universal Grip offers a high quality and long-lasting wedge grip with a reinforcing the door. Once the door is locked, it increases the structural integrity which prevents any sample slippages. The door is easily opened and closed with a key crank which is included. These grips are over-engineered in order to last for many years without fail. Invest in lab equipment that will last decades instead of years. 

 
 
 

Wedge Grips get Heavy! use a Downsize Adapter.

 

A downsize adapter can help when tensile testing at smaller scales. Special insert plates are used to convert the end of the wedge grip into a standard clevis pin style adapter. Platens can be added for compression testing too. Load Cells can also be attached in this manner for low capacity testing. 

 
small wedge grips
1K lbs. - Wedge Grips - 5 kN

The 1,000 lb. wedge grip is quite narrow and is designed to pinch the sample with an increasing amount of force. This solution is great for thin, non-flexable samples. 

Tensile Testing Wedge Grips
2K lbs. - Wedge Grips - 10 kN

This grip is great for lower strength plastics and is used commonly in plastics tensile tests such as ASTM D638. The handle is used to tighten the sliding grip jaws onto the sample before the test starts. 

Wedge Grips for Tensile Testing
4.5K lbs. - Wedge Grips - 20 kN

4,500 lb. grips start to become heavy. These grips weigh about 25 lbs. each. Check out the literature page for a 3D schematic of the working principle. 

50kN wedge grips
12K lbs. - Wedge Grips - 50kN

The 50kN tensile wedge grips use a 1 1/4" adapter with a 1/2" pin. These grips are commonly used for lap shear strength testing and other tests involving metal and reinforced plastics.

50kN Wedge Grips Closed Door with Crank
50kN Wedge Grips with Crank

The 50kN Wedge Grips use a crank to force the jaws onto the sample and create a pre-grip, prior to starting the tensile test. These grips are great hard plastics and soft metals like aluminum

big wedge grips
22.5K lbs. - Wedge Grips - 100kN

100kN wedge grips utilize a door which is closed and locked with a key. This particular picture shows a Nickel alloy grip which has better thermal stability for use in furnaces.

High Capacity Wedge Grips
100kN+ High Capacity 

100kN+ Wedge grips are available upon request. They use a similar door locking mechanism as the 22,500 lbs grips. 

150kN High Capacity Wedge Grips
150kN or 33K lbs. Wedge Grips

The 150kN wedge grip design is overengineered with hardened steel in order to hold up to high strength tensile testing over several decades. A special door mechanism is used to keep grip strain to a minimum. Test with confidence by using a high quality wedge grip. 

300kN High Strength Wedge Grip
300kN or 66K lbs. Wedge Grips

The 300kN wedge grip is designed with a small wedge angle of 11 degrees to allow for high capacity testing. This grip has a 60mm female coupling and uses a 40mm locking pin. Each grip weighs about 80kg. 

Hydraulic Wedge Grip
Hydraulic Wedge Grip 300kN+

Hydraulic Wedge Grips are necessary when testing above 300kN of force. Many tensile pulls on metal bars will require hydraulic wedge grips. UGC also supplies HPUs, however if the UTM already has a hydraulic unit, the grips may be able to piggyback off of the existing HPU.