SELECTING THE RIGHT GRIPS AND JAW FACES

Screw Action Grips

Screw action grips provide a very simple and efficient method for holding flat and round test specimens in applications where you must easily insert the specimen and quickly apply a clamping force. Jaw faces can be adjusted to accommodate different specimen thicknesses. This ensures that the line of tensile force remains concentric with the grip body. Grips can be equipped with a selection of interchangeable grip jaw faces in various sizes and choice of surfaces including smooth ground, rubber-coated and serrated. Line contact and specialcoated faces are also available

• Type of loading: Tensile, static and tension-tension cyclic tests (not suitable for high-cycle fatigue tests)

• Specimen material: Thin sheets, films, foils, threads, plastic tapes, fine wires, fabric and soft materials

• Specimen shapes: Round and flat specimens with or without shoulder tab ends

Manual Wedge Action Grips

The manual wedge-action grip is designed for easy specimen loading, alignment and positioning. After initial face-to-specimen contact, gripping force will increase as the testing load increases. Virtually no pre-load is seen during specimen clamping due to the Instron® design of moving grip bodies. This makes them particularly suitable for testing high-strength materials, such as metals and composites, ensuring that specimen slippage is eliminated. A strong clamping force can be applied to materials that are difficult to hold through a high mechanical advantage achieved by the tightening mechanism. The grip faces are springloaded against a shoe, which is in a fixed position in respect to the test frame holding mechanism. Only a light initial gripping force needs to be applied to the specimen. Where very good alignment is required, Precision Mechanical Wedge grips offer exceptional stiffness and superior alignment for critical tests on composites and aerospace materials.

• Type of loading: Tensile, static and tension cyclic tests (not suitable for high-cycle fatigue tests)

• Specimen material: Wires, plastics, metals, composites

• Specimen types: Flat, round

Mechanical Lever Action Wedge Grips

T-grip holders are available with two types of actuation: lever/spring or screw type. All capacities of T-grips are offered with lever/spring actuation, which uses a lever to raise and lower the jaws in the grip pocket and a spring to provide the initial clamping force on the specimen. When loading a specimen, the operator locks open the bottom jaw, opens the upper jaw and places the top half of the specimen inside. Once the specimen is clamped securely within the upper jaw, the operator positions the bottom half of the specimen into the lower grip jaws and unlocks the jaws. This provides clamping force and secures the specimen so that the test may be conducted.

• Type of loading: Static tension

• Specimen material: Wires, plastics, metals

• Specimen types: Flat or round specimens