Maintenance and service
ZwickRoell is the world’s leading supplier of static material test machines. In the field of dynamic testing, the company, with headquarters in Ulm, has been offering successful solutions for fatigue test systems for decades. ZwickRoell machines perform approximately 80,000,000 tests on materials and components of all kinds every year. There are over 18,200 standards for material testing alone. It's a huge challenge for the experts at ZwickRoell to find the optimal test solution for the customer’s requirements amid this real jungle of specifications. They work with passion and precision down to the smallest detail to find the optimal test solution for accurate, repeatable, comparable, transparent and reliable test results.
Test machines are the key to continuously improving the safety of a wide range of products and materials. ZwickRoell material test machines are used worldwide in research & development and quality assurance in more than 20 industries. These include, for example, the automotive and aerospace industries, medical technology and plastics and metal processing.
Dynamic testing plays a special role. It examines the mechanical properties of materials under dynamic loads. Unlike static material testing, where the material is subjected to a constant load, dynamic material testing applies varying forces, speeds or deformation rates to the material. Dynamic testing is particularly important to investigate the behaviour of materials under realistic conditions, as many applications, such as aerospace, automotive or mechanical components, are exposed to dynamic loads.
Hydraulics are central components of:
Servo-hydraulic test machines are used for static or dynamic testing of materials or components. In order to be able to evaluate the behaviour of materials or components over their service life, cyclic loads are generated.
With servo-hydraulic systems, even piston speeds of up to 20 m/s can be achieved, which are required for impact dynamic tests and crash investigations. Depending on the type of construction, the ZwickRoell machines achieve a force level of up to 2,500 kN. The load frames of the machines are designed for material and component testing under oscillating loads in a closed force flow. They stand on vibration-isolating levelling elements.
During assembly, the hydraulic units of ZwickRoell’s servo-hydraulic test machines are filled with mineral oil-based hydraulic fluid HLP ISO VG 22, 46 or synthetic fluid HLP ISO VG 46. Depending on the type and purpose of the machine and the forces to be determined, up to 600 litres of hydraulic oil are required.
The purpose of the annual inspection is not only to maintain the reliability and full functionality of a testing machine. It is also necessary because normative requirements such as DIN EN ISO 7500-1 outline the need for inspection prior to calibration. Calibration, in turn, ensures that the material testing machine produces highly accurate and reliable test results.
The reliable function of a servo hydraulic testing machine depends heavily on its hydraulic oil and its purity. If a hydraulic oil is contaminated with particles from wear and tear or from the environment, this has a negative effect on the control of a machine with its sensitive valves and thereby on the accuracy of the test results. In addition, particles can accelerate any wear processes in the system. If hydrostatic cylinders are installed in a servo-hydraulic testing machine, they are quite sensitive to dirt. Not all particles necessarily damage the system, but the lower the number of critical particles, the lower the likelihood of component damage.
An oil analysis is always scheduled as part of an annual inspection and subsequent calibration by ZwickRoell service technicians.
The OELCHECK all-inclusive Analysis Kits 4 are ideal for examining the hydraulic oils from the servohydraulic test machines. They are used to assess the general condition of the oil, determine signs of wear and the content of additives. In addition, any impurities and their types are examined closely. Automatic particle counters use their laser sensors to determine the size and number of particles, which are then sorted by purity class. Classified according to particle sizes >4 µm, >6 µm and >14 µm, the particle numbers are then listed in the laboratory report. The particle numbers are cumulative, which means that the stated particle figure for > 6 µm consists of all particles >6 µm plus particles >14 µm.
ZwickRoell recommends changing the hydraulic oil after two years or sooner if necessary. However, if an OELCHECK laboratory analysis has determined correspondingly good values, the replacement interval can ideally be slightly extended.
→ Regular inspections with subsequent calibration and the accompanying OELCHECK hydraulic oil analyses enable the functionality of the test systems to be maintained. They also guarantee precise test results and increase the service life of the machines.
The company is a world leader in the development of test machines for material and component testing. Customers of the ZwickRoell Group benefit from over 160 years of experience in material testing for various industries. In the 2024 financial year, the Group achieved sales of EUR 312 million. The ZwickRoell Group has production sites in Germany, Austria, the UK and China, as well as subsidiaries and branches in 56 other countries. ZwickRoell currently has more than 1,800 employees, of which 1,200 employees (including 100 trainees) work at the Ulm-Einsingen site.
related links
OELCHECKER Winter 2025, page 9-10