Specimen Preparation for Metals

Good testing starts with a good specimen.

Nowadays test pieces from steel sheet and metal foils are produced economically and accurately using specimen blanking machines. Standards stipulate that test results must not be influenced by any material change caused by work hardening in the specimen edge zone.

Numerous structural examinations of steel sheet have shown that the work-hardened zone along the cutting line is generally a maximum of 10% of specimen thickness. This is achieved by a low cutting-speed and special blanking tool design and offers substantial economic advantages in the event of subsequent grinding. In this way high specimen quality is ensured.

Testing metals with Zwick

Specimen Blanking

Advantages and features

  • Fast and cost-effective production of tensile specimens
  • No technical personnel required; machine can be operated by anyone after brief instruction
  • Finishing with grinder produces very high quality specimens
  • Robust, easy-to-maintain machines
  • Blanking tools have a long service life and are capable of repeated re-grinding.

Range of application

Nowadays test pieces from steel sheet and metal foils are produced economically and accurately using specimen blanking machines. Standards such as ISO 6892 and ASTMA 370 stipulate that test results must not be influenced by any material change caused by work hardening in the specimen edge zone.

Numerous structural examinations of steel sheet have shown that the work-hardened zone along the cutting line is generally a maximum of 10% of specimen thickness. This is achieved by a low cutting speed and special blanking tool design and offers substantial economic advantages in the event of subsequent grinding. In this way high specimen quality is ensured.

Blanking Tools

  • Fast and cost-effective production of tensile specimens
  • No technical personnel required; machine can be operated by anyone after brief instruction
  • Finishing with grinder produces very high quality specimens
  • Robust, easy-to-maintain machines
  • Blanking tools have a long service life and are capable of repeated re-grinding.
Specimen preparation_specimen blanking machine

C-shaped specimen blanking machine (M-Cut 65)

The open design of the machine and the blanking tool (C-shape) allows removal of test pieces from sheets and foils also. If several blanking tools are in use, the side extension table (option) is recommended. This is in the form of a roller table and enables the blanking tools not currently required to be stored out of the way. Using the extension table, tool changes take about 20 seconds, offering significant time-savings in the event of frequent tool changes. The M-cut 65 specimen blanking machine (for 650kN compressive force) is suitable for material thicknesses from 0.04 to 6mm (depending on tensile strength and specimen shape).

Specimen preparation_specimen blanking machine

O-shaped specimen blanking machines (RZ 100/RZ 150)

The closed O-shape requires precut strips. These blanking machines are already equipped with a side extension table.

Technical overview of specimen blanking

Technical data, M-Cut 65

Type

M-Cut 65

Item no.

048979

Pressure, max.

650

kN

Design

C-shaped

Punching from

Soft elastic foam

Piston stroke

20

mm

Strokes per minute

5

Specimen length, max.

300

mm

Electrical connected load

4

kVA

Dimensions:

Width

760

mm

Depth

760

mm

Height

1615

mm

Weight, approx.

1500

kg

Paint finish

RAL 7032

Technical data, RZ 100/RZ 150

Type

M-Cut 65

Item no.

048979

Pressure, max.

650

kN

Design

C-shaped

Punching from

Soft elastic foam

Piston stroke

20

mm

Strokes per minute

5

Specimen length, max.

300

mm

Electrical connected load

4

kVA

Dimensions:

Width

760

mm

Depth

760

mm

Height

1615

mm

Weight, approx.

1500

kg

Paint finish

RAL 7032

Zwick 7140 Specimen Grinder

Specimen preparation_grinding machine

Advantages and features

  • Can be used for different specimen shapes
  • Fixed stops for dimensionally accurate specimen machining
  • Wet grinding technology eliminates need for extraction system
  • For removal of work-hardened zone
  • Machining in tensile direction
  • Specimen parallelity <0.03 mm
  • Maximum specimen thickness 20 mm

Range of Application

The Zwick 7140 specimen grinder allows work hardened areas of the specimen to be ground off quickly and economically.

No other method can produce such high-quality specimens with relatively little effort.

Grinding is carried out in the tensile direction so that machining marks have no effect on the test result.

Form tolerance within parallel specimen length Lc is better than 0.03 mm, in accordance with the requirements of ISO 6892-1 for sheet-metal specimens Types 1 to 3. Parallelity within parallel specimen length Lc is better than 0.02 mm with reference to the central axis of the specimen, in line with a recommendation by the IDDRG (International Deep Drawing Research Group).

A specimen-grinding machine consists of a main body, clamping fixture (selected according to the required specimen shape), drive-roller of the appropriate radium and abrasive belt, available in different grit sizes.

The grinder can be used to machine a wide range of specimen shapes.

The fixture is changed by simply operating a few knobs. Built-in mechanical travel limiters ensure that each specimen is finished accurate to size.

Multiple specimens can be held in the clamping fixture simultaneously (up to a total thickness of 20 mm), enabling cost-effective operation.

Technical data

Type

7140

Item No.

034688

Specimen thickness, max. (max. clamping width of grinder platen)

20

mm

Peripheral speed (grinding drive motor)

45

m/s

Electrical supply

230/50 (1 L/N/PE)

V/Hz

Paint finish

RAL 7032 gray

Table height (working height)

1030

mm

Width

768

mm

Depth

710

mm

Height

577

mm

Weight (without coolant), approx.

125

kg

1:47

Specimen-grinding machine with wet grinding technology

Specifically designed for specimen preparation of standard-compliant dumbbell specimens made of metal

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