Spring testing machines – testing of springs

Springs are among the most important classical structural elements and are used for energy storage and energy conversion. Here the elastic properties of the materials are used. 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

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 zwickiLine (single-column testing machine) with testControl II 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.

• Provide the highest level of accuracy and repeatability for testing springs with very small tolerances 
• Force is applied to the center axis of the test area
• Deformation of the load cell and the load frame is compensated during the test in testXpert III via a correction curve.

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 the spring testing machine. 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.

Spring testing machine for pneumatic springs - testing at different temperatures

With a spring testing machine, 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 mobile temperature chamber in a temperature range from -80 to +250 °C. 

This spring testing machine 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 spring testing machine is equipped with a loading table that can be used to push the specimens into the spring testing machine.