Spring technologies

KERN-LIEBERS technology: the best thing that can happen to a spring.

Wire springs

From innovative product development to reliable processes for high volume production with a high level of vertical integration.

Winding

  • Use of CNC-controlled coiling machines
  • With rotating windings pins for optimized application of the spring ends
  • Highly flexible
  • Reduced setup times
  • High precision
  • 100% inspection of the unstressed spring length and diameter if required

Coiling

  • Spring body coiled around a mandrel
  • CNC coiling machines
  • High precision
  • Laser and camera checks

Bending

  • CNC and stamping/bending machines
  • Highly flexible
  • Reduced setup times
  • High precision
  • Laser and camera checks if required
  • 3D bent parts

Hot tensioning / hot setting

  • Minimized relaxation of the spring in operation through higher tensions and temperatures during the process than in the actual application
  • Springs tensioned during hot tensioning in templates or with spacing in "press shoes". The springs are heat treated in furnaces while in this state
  • In the hot setting process, the springs are heated in a furnace in the free state and quenched with coolant under presses to the required length

Cold setting and 100% inspection

  • Use of automatic cold setting equipment
  • Measuring ranges: From 2 N, to 100 N, to 1000 N and to 2000 N
  • 100% inspection of spring lengths/forces, lengths/force deltas and spring rates
  • Load cells adjusted to the respective spring forces
  • Different machine designs for different quality requirements (tolerances)
  • Sorting of compression springs into separate classes
  • Grinding of the length to a wire diameter of 1.5 mm with fully automatic loading/unloading
  • Grinding of larger wire diameters in a process in which the upper disc is moved down while the loading plate rotates continuously
  • Customized grinding technologies (machine and grinding disc qualities) for the grinding of patented drawn, oil-tempered and stainless steel wires and special alloys

Wire springs are manufactured for the most part from spring tempered round wires and profiles. The winding or coiling of the spring introduces high internal bending stresses that have a negative impact on the spring properties in terms of service life and usable spring force. Most of these stresses can be removed with a heat treatment process adapted to the material, at the same producing an increase in the initial strength and an increase in the elastic yield strength in the material.

We set the properties of the springs to their optimum values with defined heat treatment regimes. We have a wide range of heat treatment systems in place, including convection, inert gas and vacuum furnaces.

For special materials, for use for example in high-temperature applications, we can offer systems with temperatures of up to 1,350° C. We can also offer springs with special individual or mixed goods hardening processes on customer request.

Surface compacting

  • Shot-peening with steel balls from 0.3 to 0.4 mm in diameter
  • Ceramic shot peening with glass beads from 150 microns to 250 microns in diameter
  • The process is used to introduce internal compressive stresses into the surface