Pneumatic Grips - double actuator

Pneumatic specimen grips are recommended for strain rate control in accordance with standards DIN EN ISO 6892-1:2009 and ASTM E8–09

Pneumatic specimen grips are particularly useful when a variety of materials, especially those sensitive to clamping forces, must be gripped with minimum amount of changeover. The gripping force is generated by pneumatic cylinders acting directly on the jaws or via a lever system.
Pneumatic specimen grips are ideal if a high specimen throughput is required.

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Significant Advantages and Features of Pneumatic Grips

Advantages and features

The separation of tensile and gripping forces ensures a constant gripping force over the course of the entire test sequence. For specimens prone to shrinkage, the gripping force is uniformly maintained by constant pneumatic pressure.
The contact force on the specimen is reproducible.
Gripping-sensitive specimens can be held securely by adjusting the pneumatic pressure, avoiding jaw breaks.
The primary stress is the tensile load and it can be static or pulsating. Depending on the type of grips, compression and alternating load tests may be performed.
Depending on the design principle, the gripping area is freely accessible.
The larger grips can remain in place while small load cells, specimen grips, test fixtures and test devices are attached without having to dismantle the specimen grips—a great time saver.
There are a wide range of jaws with respect to material, surface, and area of the clamping surface.
Pneumatic grips offer a low-cost alternative to hydraulic grips.

Types

There are three types of ZwickRoell pneumatic grips:

Single-actuator
Single-actuator pneumatic grips can be used for the symmetrical and asymmetrical gripping of specimens (e.g., for shear strength tests). Some of the single-actuator pneumatic grips up to 1 kN have an integral control valve—no additional external pneumatic control unit required.
Double-actuator
Double-actuator pneumatic grips always close symmetrically with respect to the tensile axis. This eliminates the need for thickness adjustment: This is a big advantage, above all, for soft specimens and/or if specimen thickness changes.
For temperature chambers (single- and double-actuator)
These pneumatic grip are single- or double-actuator specimen grips that are specifically designed for use in temperature chambers.

Other ZwickRoell specimen grips

Pneumatic specimen grips, double-actuator

In this next section you will find information about double-actuator pneumatic specimen grips, their range of application and more about the technical data and the various models offered by ZwickRoell,

Specimen grips with control valve can be mounted in different ways

Fmax 20 N

Advantages and features

The symmetrically closing jaws save time required for adjusting to varying specimen thicknesses and ensure that the specimen is held exactly in the test axis.

The jaws can be changed quickly and easily for different applications - no tools required. The jaws are centered automatically.

Constant gripping force enables repeatable test results to be achieved.

Constant pneumatic pressure allows even specimens prone to shrinkage to be held securely.

Grips operated via toggle lever for fast, easy specimen changes.

Ergonomic, open design for fast, easy specimen insertion and clamping

Function description

The jaws are secured with a threaded locking-pin. and can be changed without the use of tools.

An additional pneumatic control unit is not required. Soft opening and closing of the jaws takes place via a toggle valve. This offers advantages in terms of zero-force control.

The pneumatic gripping pressure on the grips cannot be changed. This is only possible by means of an additional pressure control valve.

Technical data, Fmax 20 N

Item No.	080489
Type	8095
Test load F_max	0.02	kN
Gripping force at 6 bar, approx.	115	N
Gripping force at 8 bar, approx.	150	N
Operating pressure, max.	8	bar
Dimensions
Height	102	mm
Width	57	mm
Depth	60	mm
Opening width, max. with jaws	5	mm
Gripping of the specimen	The specimen must be gripped with the entire height of the jaw.
Weight per specimen grip, approx.	118	g
Connection, stud	Ø 8	mm
Ambient temperature	+10 ... +35	°C
Pneumatic connection (provided by the customer)	DN7 quick action coupling
Scope of delivery	2^[1]	pieces

Included in delivery: 2 toggle valves with flexible mounting position, with throttle check valve

Pneumatic specimen grips, double-actuator

Fmax 200 N and 1 kN

Advantages and features

The symmetrically closing jaws save time required for adjusting to varying specimen thicknesses and ensure that the specimen is held exactly in the test axis.

The jaws can be changed quickly and easily for different applications - no tools required. The jaws are centered automatically.

Constant gripping force enables repeatable test results to be achieved.

Constant pneumatic pressure allows even specimens prone to shrinkage to be held securely.

Ergonomic, open design for fast, easy specimen insertion and clamping

The specimen grip has a large opening width that makes the testing of thicker specimens also possible.

Technical data, Fmax 200 N and 1 kN

Type	8187	8287
Item No.	313852	313874
Operating principle/identification	Opening width adjustable via lever	Opening width adjustable via lever
Test load F_max	0.2/0.1^[1]	1/0.5^[1]	kN
Gripping force, max. at 6 bar	0.2/0.1	1/0.5	kN
Gripping force, max. at 10 bar	0.33/0.16	1.6/0.8	kN
Operating pressure	0.5 ... 10	1 ... 10	bar
Dimensions
Height	95	160	mm
Width	202	240	mm
Depth	42	65	mm
Depth with connection unit	133	156	mm
Gripping travel of pneumatically operated side	12/22	12/22	mm
Opening width, max. with jaws, thickness 5 mm	12/22	12/22	mm
Gripping of the specimen	The specimen must be gripped with at least 2/3 of the jaw height.
Connection, stud	Ø 8	Ø 20	mm
Ambient temperature	+10 ... +35	+10 ... +35	°C
Weight per specimen grip, approx.	1	2.8	kg
Scope of delivery	2	2	pieces

The gripping stroke is adjustable from 0 - 12 mm to 0 - 22 mm. This reduces the gripping force by 50 % to 100 N and 500 N.

Pneumatic specimen grips, double-actuator

Fmax 2.5 kN

Advantages and features

The symmetrically closing jaws save time required for adjusting to varying specimen thicknesses and ensure that the specimen is held exactly in the test axis.

The jaws can be changed quickly and easily for different applications - no tools required. The jaws are centered automatically.

Precise test results combined with high number of cycles achieved through centric insertion of specimen using easily adjustable centering stop.

Constant gripping force enables repeatable test results to be achieved.

Constant pneumatic pressure allows even specimens prone to shrinkage to be held securely.

Ergonomic, open design for fast, easy specimen insertion and clamping

The projecting jaws enable a clear view and access for optical and mechanical extensometers, even with short gauge lengths.

Function description

The closing force is initialized via a centrally positioned pneumatic actuator. It transfers the closing movement via a steering lever to the symmetrical closing jaws.

The jaws for the jaw mountings are permanently guided play free in the tensile direction via spring elements. The jaws are secured via a locating spring. You can replace the jaws without using tools.

Technical data, Fmax 2.5 kN

Item No.	038545
Type	8297
Test load F_max	2.5	kN
Gripping force, max. at 6 bar	6.5	kN
Gripping force, max. at 10 bar	10.5	kN
Operating pressure	1.5 ... 10	bar
Dimensions
Height	170	mm
Height with centering stop	182	mm
Width	210	mm
Depth	82	mm
Opening width, max. with jaws, thickness 5 mm	20	mm
Gripping of the specimen	The specimen must be gripped with at least 2/3 of the jaw height.
Weight per specimen grip, approx.	4.7	kg
Connection, stud	Ø 20	mm
Ambient temperature	+10 ... +35	°C
Scope of delivery	2	pieces

Pneumatic specimen grips, double-actuator

Fmax 10 kN, 20 kN

Advantages and features

The symmetrically closing jaws save time required for adjusting to varying specimen thicknesses and ensure that the specimen is held exactly in the test axis.

The jaws can be changed easily for different applications.

Precise test results combined with high number of cycles achieved through centric insertion of specimen using easily adjustable centering stop.

Constant gripping force enables repeatable test results to be achieved.

Constant pneumatic pressure allows even specimens prone to shrinkage to be held securely.

Save time by attaching small specimen grips and test fixtures to large specimen grips quickly and easily via T-slot systems. The precise alignment ensures reliable test results.

Function description

A patented switching device is integrated in the specimen grip. It switches between the following, depending on the load:
High closing speed with a low closing force, and a
Low closing speed with high closing force

This switching takes place automatically as soon as the jaws meet the specimen.

This patented principle of closing force application makes very high closing forces possible in instances where sizes are compact and opening widths are large.

Precise positioning of the specimen is simplified because of the adjustable stop screws with scale (included in the delivery scope) and markings on the jaws.

The specimen grip has a large opening width that makes the testing of thicker specimens also possible.

Technical data, Fmax 10 kN and 20 kN

Item No.	353412^[1]	320032^[1]
Type	8397	8497
Test load F_max	10	20	kN
Gripping force, max. at 6 bar	27	27	kN
Gripping force, max. at 10 bar	45	45	kN
Operating pressure	3 ... 10	3 ... 10	bar
Dimensions
Height	208	225	mm
Height with connection unit	230	247	mm
Width	242	242	mm
Depth	112	112	mm
Depth with connection unit/overhang	n/a	132
Gripping travel^[2]	10	10	mm
Opening width, max. with jaws, thickness 5 mm	20	25	mm
Gripping of the specimen	The specimen must be gripped with at least 2/3 of the jaw height.
Weight per specimen grip, approx.	14	14	kg
Connection, stud	Ø 20	Ø 36	mm
Ambient temperature	+10 ... +35	+10 ... +35	°C
Scope of delivery	2	2	pieces

Recommended and approved for strain rate control to the standards DIN EN ISO 6892-1:2009 and ASTM E8-09

See the diagram that depicts the correlation between the gripping stroke and the specimen thickness/opening width

Specimen grip with high gripping force

Fmax 20 kN

Advantages and features

The specimen grip has an extremely high closing force and is particularly suited for technical fabrics.
The symmetrically closing jaws save time required for adjusting to varying specimen thicknesses and ensure that the specimen is gripped exactly in the middle of the test axis.
Dove-tail jaw system enables easy, tool-free insert change. Easy side insertion into specimen grip and centering and fixing of jaws occur automatically.
Quick and uncomplicated insertion of the specimen: Exact location of the specimen with scale is quickly preset with adjustable centering stop.
Uniform test requirements through reproducible gripping force on the specimens
Constant gripping force securely holds even specimens that lose thickness during testing.
The jaws close flush with the specimen grips. Specimens with small clamping lengths can also be gripped.
Small load cells, specimen grips, tools and fixtures can be quickly accommodated via the optional mounting unit and without having to dismantle the specimen grips.

Function description

Precise positioning of the specimen is simplified because of the adjustable stop screws with scale (included in the delivery scope) and markings on the jaws.

The specimen grip has a large opening width that makes the testing of thicker specimens also possible. The opening width is set manually.

An extremely high gripping force is achieved through a special design principle.

Technical data, Fmax 20 kN

Item No.	320712^[1]
Type	8497
Test load F_max	20	kN
Gripping force, max. at 6 bar	50	kN
Gripping force, max. at 8 bar	68	kN
Operating pressure	2 ... 8	bar
Dimensions
Height	225	mm
Height with connection unit	247	mm
Width	242	mm
Depth	112	mm
Depth with connection unit/overhang	132	mm
Gripping travel	8	mm
Opening width, max. with jaws, thickness 5 mm	20	mm
Gripping of the specimen	The specimen must be gripped with at least 1/2 of the jaw height.
Connection, stud	Ø 36	mm
Ambient temperature	+10 ... +35	°C
Weight per specimen grip, approx.	14	kg
Scope of delivery	2	pieces

Recommended and approved for strain rate control to the standards DIN EN ISO 6892-1:2009 and ASTM E8-09

Pneumatic specimen grips, double-actuator

Fmax 50 kN, 100 kN

Advantages and Features

The symmetrically closing jaws save time required for adjusting to varying specimen thicknesses and ensure that the specimen is held exactly in the test axis.

The jaws can be changed easily for different applications.

Precise test results combined with high number of cycles achieved through centric insertion of specimen using easily adjustable centering stop.

Constant gripping force enables repeatable test results to be achieved.

Constant pneumatic pressure allows even specimens prone to shrinkage to be held securely.

Save time by attaching small specimen grips and test fixtures to large specimen grips quickly and easily via T-slot systems. The precise alignment ensures reliable test results.

Function description

A patented switching device is integrated in the specimen grip. It switches between the following, depending on the load:
High closing speed with a low closing force, and a
Low closing speed with high closing force

This switching takes place automatically as soon as the jaws meet the specimen.

This patented principle of closing force application makes very high closing forces possible in instances where sizes are compact and opening widths are large.

Precise positioning of the specimen is simplified because of the adjustable stop screws with scale (included in the delivery scope) and markings on the jaws.

The specimen grip has a large opening width that makes the testing of thicker specimens also possible. The opening width is set manually.

Technical data, Fmax 50 kN and 100 kN

Item No.	320250^[1]	320710^[1]
Type	8497	8597
Test load F_max	50	100	kN
Gripping force, max. at 6 bar	60	110	kN
Gripping force, max. at 10 bar	100	170	kN
Operating pressure	2 ... 10	1.5 ... 10	bar
Dimensions
Height	306	341	mm
Width	390	390	mm
Depth	156	156	mm
Depth with overhang	186	190	mm
Gripping travel^[2]	21	15	mm
Opening width, max. with jaws	See jaw table	See jaw table
Gripping of the specimen	The specimen must be gripped with at least 1/2 of the jaw height.
Weight per specimen grip, approx.	53	53	kg
Connection, stud	Ø 36	Ø 60	mm
Ambient temperature	+10 ... +35	+10 ... +35	°C
Scope of delivery	2	2	pieces

Recommended and approved for strain rate control to the standards DIN EN ISO 6892-1:2009 and ASTM E8-09

See the diagram that depicts the correlation between the gripping travel and the specimen thickness/opening width

Wedge grips with pneumatic actuation

Fmax 10 kN

Wedge grips pneumatic grips body over wedge

Specimen material
Plastics, reinforced plastics, fiber composites, wood and similar materials
Specimen shape
Flat specimens (strip and dumbbell specimens)
Type of loading
Tensile

This pneumatic specimen grip is ideas for use in temperature chambers

Advantages and features

Whether you are testing sensitive specimens or specimens with short clamping lengths, these symmetrically designed grips guarantee optimum clamping.
When determining the exact nominal strain the grip-to-grip separation does not depend on specimen diameter. This minimizes set-up time.
Reduced weight plus a compact design simplify handling, ensure short heating and cooling times in the temperature chamber. and enable long travel.
Absolutely secure gripping right from the start of the test for specimens prone to light slippage.

Comparable, reproducible test results. Thanks to their parallel gripping operation the pneumatic specimen grips transmit the test speed directly to the specimen.
The modular design of these grips allows easy changeover between operation with and without extensions for maximum possible travel. A possible conversion to the pneumatic version offers reliability in the future.

Function description

With specimen grips from the body over wedge series the position of the jaws remains constant in the test direction as the specimen is gripped. This means that the grip-to-grip separation does not depend on the specimen thickness.

The pneumatic specimen grips emphasis is on fast, reproducible and, most importantly, parallel gripping. Full gripping force is available right from the start, so that the static jaws transmit the test speed directly to the specimen.

Simple extensions are used in combination with temperature chambers The pneumatic actuator is positioned outside the chamber.

Technical data, Fmax 10 kN

Type	8304
Item No.	1004956^[1] ^[2]
Test load F_max	10	kN
Operating principle/identification	Double-sided closing (wedge action)
Gripping force at 6 bar	18.46	kN
Gripping force at 10 bar	28.75	kN
Operating pressure, min.	1 ... 10	bar
Dimensions
Height	131 (280)	mm
Width	185	mm
Depth	185	mm
Opening width, max. with jaws	6.5	mm
Gripping area
Height	55	mm
Width	35	mm
Clamping length	Min. 20	mm
Weight per specimen grip, approx.	13,7	kg
Connection, stud	Ø 20	mm
Ambient temperature	0 ... +50	°C
Ambient temperature with extension piece	-70 ... +250	°C
Scope of delivery	2	pieces

Recommended and approved for strain rate control to the standards DIN EN ISO 6892-1:2009 and ASTM E8-09

In connection with an extension piece for temperature chambers the specimen grips can be used at temperatures from -70 ... 250°C (pneumatic actuator is located outside the temperature chamber).

Mounting in a temperature chamber

1. Base unit

2. Mechanical actuation

3. Pneumatic actuation

4. Grip inserts

5. Temperature chamber

6. Extension piece for use in temperature chamber

7. Flexure tools

Pneumatic grips for temperature chambers

Grips can be used in an ambient temperature range from –70 to +250 °C.

Range of application

Specimen material:
plastics, paper, textiles, elastomers, wood, insulating materials
Specimen shape:
round and flat specimens, asymmetrical specimens
Type of loading:
tensile, compression, alternating load

Advantages and features

Innovative quick-change system for jaw inserts.
Dove-tail jaw system enables easy, tool-free insert change. Easy side insertion into specimen grip and centering and fixing of jaws occur automatically.
Quick and uncomplicated insertion of the specimen: Exact location of the specimen with scale is quickly preset with adjustable centering stop.
Uniform test requirements through reproducible gripping force on the specimens
Constant gripping force securely holds even specimens that lose thickness during testing.
The jaws close flush with the specimen grips. Specimen with small clamping lengths can also be gripped.
Precise positioning of the specimen is simplified because of the adjustable stop screws with scale and markings of the jaws (centering stop optionally available).
Specimen stops enables the specimen to always be placed centrally in the specimen grip
The low overall height of the specimen grips facilitates optimal use of the test area.

Features of the double-actuator specimen grip

The symmetrically closing jaws save time required for adjusting to varying specimen thicknesses and ensure that the specimen is gripped exactly in the middle of the test axis.
Small load cells, specimen grips, tools and fixtures can be quickly accommodated via the optional mounting unit and without having to dismantle the specimen grips.

Function description

These pneumatic grips are single or double-actuator grips specifically designed for use in temperature chambers.

The single-actuator grips can be used for both symmetrical and asymmetrical clamping. The opposing jaw features stepless adjustment.

Double-actuator specimen grips always close symmetrically to the tensile axis, eliminating the need for thickness adjustment.

The pneumatic grip has a special connector unit for use in temperature chambers with an integrated compressed air supply. A receptacle for condensation water serves as a drainage system to remove condensation from the test area.

The opposing jaw can be adjusted steplessly or set-by-step.

The height of the connector unit depends on the testing system in use, on the temperature chamber, and on the stroke ratios, which depend on the specimen, in the temperature chamber. Therefore they are determined according to the order.

Specimen grip for use in the temperature chamber⁽⁵⁾

Type 8097, Fmax 200 N, single-actuator

Type 8097, Fmax 200 N, single-actuator
Type 8297, Fmax 2.5 kN, single-actuator

Type 8297, Fmax 2.5 kN, single-actuator
Type 8287, Fmax 1 kN, single-actuator and double-actuator

The maximum opening width can be adjusted by adjusting an internal lever. A greater opening width results, however, in a lesser gripping force and thus a lesser Fmax.

Type 8287, Fmax 1 kN, single-actuator and double-actuator

The maximum opening width can be adjusted by adjusting an internal lever. A greater opening width results, however, in a lesser gripping force and thus a lesser Fmax.
Type 8304, Fmax 10 kN, double-actuator

Type 8304, Fmax 10 kN, double-actuator
Type 8397, Fmax 10 kN, double-actuator

These specimen grips can be installed in temperature chambers under 45° or 90°.

Type 8397, Fmax 10 kN, double-actuator

These specimen grips can be installed in temperature chambers under 45° or 90°.

Technical overview of pneumatic grips for temperature chambers

Fmax 1 kN, double-actuator

Item No.	313950
Type	8287
Test load F_max	1/0.5	kN
Gripping force, max. at 6 bar
At opening width 12 mm, approx.	1	kN
At opening width 22 mm, approx.	0.5	kN
Gripping force, max. at 10 bar and 12 mm gripping travel, approx.^[1]	1.1	kN
Gripping force, max. at 10 bar and 22 mm gripping travel, approx.^[1]	0.65	kN
Operating pressure	6 ...10	bar
Opening width, max. with jaws, thickness 5 mm	12/22	mm
Gripping of the specimen	The specimen must be gripped with at least 2/3 of the jaw height.
Dimensions
Height	181	mm
Width	240	mm
Depth	109	mm
Depth with pneumatic hoses	128	mm
Weight per specimen grip, approx.	2.8	kg
Connection, stud	Ø 20	mm
Ambient temperature	-70 ... +250	°C
Scope of delivery	2	pieces

The gripping travel is adjustable from 0 - 12 mm to 0 - 22 mm. Thus, the closing force is reduced by 50%.

Fmax 10 kN and 20 kN, double-actuator

Item No.	320005	320254
Type	8397	8497
Operating principle/identification	For temperature chamber	For temperature chamber
Test load F_max	10	20	kN
Gripping force, max. at 6 bar	25	35	kN
Operating pressure	1.5 ... 6	1.5 ... 6	bar
Dimensions
Height	213	213	mm
Width	242	242	mm
Depth	112	112	mm
Gripping travel	10	10	mm
Opening width, max. with jaws, thickness 5 mm	25	25	mm
Gripping of the specimen	The specimen must be gripped with at least 2/3 of the jaw height.
Weight per specimen grip, approx.	14	14	kg
Connection, stud	Ø 20	Ø 36	mm
Ambient temperature	-70 ... +250	-70 ... +250	°C
Scope of delivery	2	2	pieces

Pneumatic Control Unit for Specimen Grips

The gripping force of the pneumatic specimen grips can be steplessly set via a pneumatic control unit, which ensures the safe gripping of a wide range of different materials. The opening and closing of the specimen grips can be controlled by foot switches or the remote control of the materials testing machine for greater operating comfort.