Testing of Springs

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Among the most important classical design elements are springs, in which the elastic properties of materials are exploited for energy storage and conversion. Without springs—regardless of their design—no mechanical or electro-mechanical system would operate. The main functions of engineering springs are

  • Absorbing impacts and vibrations
  • Distributing and counterbalancing forces
  • Maintaining pretensioning
  • Maintaining a defined position or state
  • Measuring and regulating forces and moments

Zwick offers special solutions for the most varied spring systems.

Uniaxial Testing of Helical Compression Springs

Rapid technical advance has led to a significant increase in the demands placed on the accuracy and durability of springs. The corollary of this is greater demands on manufacturing accuracy due to ever-smaller dimensional, form, and positional tolerances, with similarly enhanced requirements for testing technology.

The PrecisionLine series easily meets the increasing demands placed on state-of-the-art precision spring testing machines, where the highest level of accuracy and repeatability is called for. It was developed for the testing of springs with very low tolerances, such as those used in many mechatronic assemblies and function units in the automotive industry. The series design takes all error influences into account.

Key features

  • Force is applied to the center axis of the test area; there are no guides in the flow of force 
  • The material measure (non-contact incremental measuring system) is aligned with the measurement path
  • Load cell deformation is compensated mechanically

The zwickiLine (single-column testing machine) with testControl electronics, together with the precision spring compression test kit, is ideally suited for use as a precision spring testing machine. The kit is extremely transverse force-resistant and protects against overload. The ground, demagnetized compression platens have a parallel alignment of 1 µm/10 mm and precision guides permit only precise vertical movement of the compression platens. Measuring errors caused by deformation or lateral forces of the springs are reduced to a minimum thanks to the extremely stiff load cell, which is resistant to transverse forces.

Springs3
Springs4

Multi-Channel Spring Testing

Multi-channel measuring platforms allow the force vector of compression coil springs (used as a valve spring or in MacPherson struts) to be determined. Standard testing systems are equipped with a six- or nine-component force measuring platform for this. This enables the specific determination of the spring intersection points and the resulting force from the force components when loading the spring under compressive force. These characteristic values are important to evaluate the following quality attributes: friction, wear, and service life.

Testing Pneumatic Springs

Testing Pneumatic Springs at Various Temperatures 

With this testing system, the visco-elastic properties of pneumatic springs and their fatigue properties are examined under various temperatures. A servo-hydraulic testing machine with hydrostatic cylinder bearing serves as the foundation. A special compression unit (mounted on a T-slotted plate) allows you to mount various pneumatic spring shapes and sizes. The fixture is also equipped with two measuring transducers for measuring the pneumatic spring diameter. The entire fixture can be inserted into a temperature chamber in a temperature range from -80 to +250 °C.
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Testing of Multi-Axial Springs

Multi-axial loading of pneumatic springs to EN 13597 

This testing system supports quality assurance and the development of pneumatic springs. It consists of a floor-standing testing machine with Fmax 250 kN. It is equipped with an additional horizontal, electromechanical drive with Fmax 50 kN and a force measuring platform with five load cells (3 vertical and 2 horizontal). The axial and horizontal stiffness characteristics of pneumatic springs are determined under vertical, horizontal or combined loading, and the following channels can be individually controlled:

  • Force and travel, vertical
  • Force and travel, horizontal
  • Air or liquid internal pressure

For easy insertion of the specimen, the system is equipped with a loading table that can be used to push the specimens into the testing machine.

Multi-Axial Testing of Struts

This testing system is equipped with three test axes to measure the damping characteristics of the hydraulic shock absorbers. The vertical force (wheel load) is applied by the testing machine axis. Horizontal forces and torsion moments that occur when maneuvering curves, approaching, and braking, etc. are generated through a horizontally affixed single testing actuator and a torsion drive. The test axes can be individually and independently controlled from one another. This way you can determine the characteristics (damping friction, viscosity) at different axial speeds with and without lateral forces and torque.
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