Tensile testing machine – tensile test according to standard / configurable

The basis of a tensile testing machine is the machine frame

This is produced in

• C-design for table testing machines for test forces up to 2,5 kN (e.g. QUASAR 2,5 kN)
• O-design for table machines for test forces 5 / 10 / 25 / 50 / 100 kN
• O-design for stationary machines for test forces 200 / 250 / 600 / 1000 / 1200 / 2000 kN

The travel traverse is moved by low-wear and low-maintenance ball screws. These are driven by a brushless (wear-free and maintenance-free) AC motor via a gear reduction. In a modern tensile testing machine, the motor receives its travel commands from a digital motor controller. This outputs a higher or lower number of step commands / current quantities for different speeds. This concept is the basis for all quasi-static tensile testing machines (group of universal testing machines).

Almost all manufacturers use specially designed electronics for control and measurement data acquisition. Since these are developed and built exclusively for static (and dynamic) material testing machines, the production batches are small, which sometimes leads to extremely high manufacturing costs. And this is where the tensile testing machines we offer differ significantly for the first time: GALDABINI uses industrial electronics for control and measurement data acquisition, such as those used in machine tools (milling machines, lathes, presses, etc.). The significantly higher production quantities of these electronics enable significantly lower production costs. This is reflected in the significantly lower prices of GALDABINI tensile testing machines. This system is also scalable (modular configuration): The basic electronics, which are fully equipped for standard applications, can be expanded with special modules as required - without great effort (bus system). Another advantage is that if (contrary to expectations) a module goes defective, the entire electronics (motherboard) does not "die" straight away, but the individual plug-in module is replaced. This exchange is straightforward and can be carried out by a factory electrician or even by the user themselves: open the housing, take a photo of the wiring, replace the module, reconnect the cable – it works!

In order to be able to use these modules as control and evaluation electronics for tensile testing machines, a virtual control is used within the embedded PLC (embedded WIN 10 PC). The firmware communicates with the electronic modules for force, crosshead travel, strain gauge, other measuring channels and the motor control. This software level receives the execution commands (test sequence) from the test software (LabTest). Test sequences are generated in the test software and transferred to the electronics in packets, because: Test software is never able to control the testing machine directly via the WINDOWS PC - the measuring chain (sensor, measuring amplifier, CPU, communication line to the PC, test software, interpretation there and reaction / command back to the motor controller -> motor) is by no means responsive enough for this (all manufacturers). The machine is always monitored and controlled directly by the responsive electronics. If an event occurs (e.g. a yield point detection ReH), the test software sends a new data packet to the electronics…

In a tensile testing machine, the force measurement and often the deformation measurement (crosshead travel measurement) form the basis of the evaluation. In addition, the elongation and damage limit (yield limits) are evaluated or the transverse elongation / width reduction (R+N value for sheet metal) is determined.

A GALDABINI tensile testing machine can – depending on the expandable equipment – ​​be used for e.g.:

• Standards ISO6892-1, ISO 527, ISO 37 etc.: Mechanical-technological tests for the qualification of material qualities:
  Tensile test metal ISO6892-1 (method A + B); tensile strength, yield strength ReH, proof strength Rp0,2, tensile strength Rm, uniform elongation Ag, elongation at break A, etc.
  Plastic: Yield stress σY, Yield strain ɛY, Tensile strength σM, Strain at tensile strength ɛM Stress at strain σX%
  Rubber DIN 53504, Rubber ISO 37 (all standards), R+N value determination ISO1275, Screws ISO 898, Reinforcing steel DIN 488, shear tests
• Testing of adhesive forces, shear-tensile test, peeling (peeling test), tear propagation tests, separation tests, peel tests, friction coefficient determination
• cyclic tests – mechanical test piece aging through repeated force application or defined extension
• Testing of parts or components in general (tensile test / compression test / bending test)
• Compression test – e.g. metal DIN 50106, press-in force, compression test on parts, assemblies, components, 
• 2-point bending test, 3-point bending tests Plastic ISO 178 / ASTM D 790 DIN EN 3327 Hard metal, metal DIN EN ISO 7438, ISO 14125, weld bending test, 4-point bending test, component bending test
• Settling behavior of samples, parts, components (no dynamic tests)
• spring test / Spring characteristic curve (spring length measurement L0, set length, spring constant C, force L1, force L2 …

The tensile testing machines offered are suitable for all tests that can typically be carried out with quasi-static machines according to the standard or freely programmed tests. This type of machine is referred to as static tensile testing machines / universal testing machines because the required test speeds are relatively low (approx. 0,01 – 1000 mm/minute). For example, the standard ISO 6892-1 As the strain rate for the critical area of ​​a test (in the elastic part), a strain rate of 0,00025 mm/mm/s is specified (tolerance +/- 20%). Since the reference length in metal tensile tests varies depending on the cross-section or the resulting L0, this base value is multiplied by the calculated (or fixed) initial measuring length L0. This results in a typical strain rate for e.g. a round metal tensile specimen with Ø 10 = L0 50mm = 0,0125mm/second or 0,75mm/minute in the area of ​​elastic strain and at the transition to plasticity.

For example, for plastics, a speed of 1 mm/minute is specified for determining the modulus of elasticity. The modulus is determined at 0,05 to 0,25% elongation. After that, the speeds in the tensile test for plastic elongation are increased significantly (steel depending on L0 approx. 20 - 50 mm/minute, rubber even up to 1000 mm/minute).