SELECTING THE RIGHT GRIPS AND JAW FACES

Pneumatic Wedge Action Grips

The grips are operated with a control knob mounted on the grip or with an Instron® standard pneumatic control kit. Powered by pneumatic control, the faces are moved by a pneumatic piston, which eliminates a costly hydraulic pump and its control. When under load, the wedge action provides additional clamping pressure to minimize specimen slippage. A unique carrier/ face mounting system allows for easy face insert changes. The carrier is placed on the grips and held on by springs from the grip body and against the driving piston. The faces sit on the carrier held by a couple of thumb screws (or by a magnet). The lubrication of the jaw face carrier is through a standard grease fitting. This eliminates the need to remove either the faces or the carriers for greasing. Each face set can accommodate a wide range of specimen types offering flexibility with a minimum number of face changes.

• Type of loading: tension (not suitable for through-zero/reverse stress or fatigue testing)

• Specimen material: wires, rigid plastics and metals

• Specimen shapes: flat, round

Pneumatic Side Action Grips

Pneumatic action grips clamp the specimen through a dual lever arm, actuated by air cylinders built into the grip body. The gripping force can be increased with air pressure to accommodate materials that are often difficult to hold. This constant gripping force is maintained on the specimen and provides the ultimate in “follow-up” action to compensate for any decay in the gripping force. The grips are closed or opened by a pneumatic footswitch for hands-free operation. An automatic air kit is also available for both hands-free and automated testing via software or system default settings. 3400 and 6800 fram controllers use smart close air kits.

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

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

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

Hydraulic Side Action Grips

Hydraulic grips are used where high tensile forces are required during testing. The grips are suitable for testing a wide range of metallic and high strength non-metallic materials. They are ideally suited for testing flat, hexagonal and round sections. The grips are designed so that the specimen can be entered from the front for fast accurate loading. Quick clamping and release of the test specimen is made possible through the use of a hydraulic power pack controller unit. The dual sided grips close symmetrically about the tensile axis.

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

• Specimen material: Wires, reinforcing bar, metals and alloys

• Specimen shape: Round, hexagonal and flat specimens