Engineering

The requirements for compression, tension and torsion springs in applications such as automotive fuel injection systems or complex electrical switches sometimes makes it necessary to measure the properties of the springs with 100% inspection. We have special machines available to do this, sometimes integrated into the work process. Separate spring setting and testing machines can take care of a wide range of testing procedures as required:

• Acquisition of force-displacement characteristics
• High-precision length measurement and force measurement system
• Integrated geometry measurement using a camera system
• Fully automatic test sequence
• Reliable selection
• High testing performance

High-performance dynamic fatigue test systems are available for testing the service life of wire springs and the fatigue strength of spring wires.

• High-speed test machines for testing service life
• Simultaneous testing of multiple springs
• Variable test frequency
• Different amplitudes (lift height)

Testing of the surface, shape, hardness and microstructure

• Traditional and computer-aided contour and hardness tests
• Testing of microstructure and texture
• High and very high resolutions and accuracies down to the nanometer range

In-process surface tests, including for example

• 3D surface test methods
• Interferometry
• Tactile measuring systems
• Thermography
• Ultrasound sensors
• Image processing

Strip often have to fulfill a complex requirement profile. In addition to the minimum requirements with respect to service life, some of which are statutory, the spring behavior must also be tested to ensure that it complies with standards and the application for which it is intended. To do this, we develop dedicated testing systems in consultation with our customers, which are often designed to determine the number of load cycles until failure of the spring or to demonstrate that a guaranteed minimum number of cycles can be met. These practical tests are supported by the latest statistical methods (e.g the Weibull method).

In serial testing, we ensure high levels of quality through continuous sampling
and control.

KERN-LIEBERS has a consistent approach towards quality, from product development through to final inspection and shipping. Modern methods of quality planning, such as FEM, APQP, FMEA and so on, are used extensively to support the planning process. Test planning is integrated into the planning process during the product development phase. The in-process tests for products are derived from the control plan. Our machine and test equipment engineers can meet complex testing requirements. At the end of the manufacturing process, our high quality levels are documented in the final inspection to ensure their traceability.

We design our production workplaces in accordance with ergonomic principles, and ensure that the most important product features are tested during the production process.

Our first-class supplier ratings testify to the success of our quality assurance strategy.

• Certificates

In modern precision mechanical systems, the avoidance of external particles is of great importance. In these systems, the smallest movements could potentially be blocked, lead to failure of the system. Given that these systems are closed and designed for lifetime use, subsequent cleaning is no longer possible.
The residual particle analysis serves two purposes: to detect and eliminate potential causes of external particles and to provide evidence to the customer that the shipped components are clean.

There are a wide range of testing requirements, both national and international. We adapt to customer-specific test variants. We can carry out some tests in our own laboratory. Where this is not possible, we work with external specialists.

The test results are documented and assessed in accordance with specified criteria.

At KERN-LIEBERS, FMEA plays an important role. A early and systematic feasibility analysis is carried out during the tendering phase. The use of FMEA is designed to identify and avoid potential sources of error at an early stage. By linking the product and process FMEA, we can exclude virtually all potential problems with functions in subsequent high volume production.

Fast-response quality control loops in production, technical planning and quality management at all locations allow us to successfully implement a global zero-defect strategy.

Our in-house special purpose machine engineering department specializes in the development of product-specific visual-tactile testing machines. Our hardware and software specialists adapt geometry and surface control by high-resolution vision systems with specific lighting systems to each particular application.

Our in-line process monitoring or 100% final inspection has a cycle time-neutral repeat measurement accuracy of a few microns, and surface defects can also be detected.

We use laser-based measurement processes for sampling, for in-line process control or for 100% final inspection.

Examples:

• Laser interferometry
• Laser triangulation
• Light-section processes

3D measurement processes, tests in goods receipt and issue, production line

• Visual, tactile and laser-based 2D and 3D measurement processes,
  measuring range up to 800 mm
• Tests in air-conditioned measuring rooms or in special measuring cells
• In-process tests integrated into the production line (operator, automatic testing), some fully automatic measuring cells integrated into production
• Adapted measurement solutions for specific applications

You can find our quality certificates here