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.
Pneumatic grips

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.

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,
Pneumatic grips

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 Fmax

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

  1. Included in delivery: 2 toggle valves with flexible mounting position, with throttle check valve
Pneumatic grips

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 Fmax

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

  1. 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 grips

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 Fmax

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 grips_multiXtens

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 Fmax

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

  1. Recommended and approved for strain rate control to the standards DIN EN ISO 6892-1:2009 and ASTM E8-09
  1. See the diagram that depicts the correlation between the gripping stroke and the specimen thickness/opening width
Pneumatic grips

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 Fmax

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

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

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 Fmax

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

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

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

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

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.

Technical overview of pneumatic grips for temperature chambers

Fmax 1 kN, double-actuator

Item No.

313950

Type

8287

Test load Fmax

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

  1. 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 Fmax

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

Pneumatic control unit
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. 

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