Precision machining - Competencies

We take it very seriously for you

Whether machining, grinding, deburring, pre-setting or steel cutting: KERN LIEBERS offers you a diverse portfolio of machining technologies for your springs, stamped parts and stamped-bent parts.

Machining

We offer a wide range of different machining processes to meet demanding part requirements - with high precision down to the micrometer range.

KERN LIEBERS uses hard machining for turning, milling, drilling and reaming in order to avoid grinding or honing operations.

Turning processes are used for the finishing of precision-cut blanks. The advantage of turning is the high concentricity of the dimensions produced during turning in a single clamping operation. For example, fineblanked punched blanks are partially (re)machined on the outer diameter and/or the inner diameter.

Our systems are automated with flexible robot loading and allow impact-free loading and unloading of the sensitive precision parts. For example, IT 7 fits (18 µm in the diameter range up to 25 mm) are possible in large series. Even materials that are difficult to machine or non-ferrous metals can be processed.

Turned parts for the medical and watchmaking industries

The focus here is on small parts between 2.5 mm and 10 mm with high precision
Material: Stainless steels, non-ferrous metals, special alloys on customer request
Applications Measurement and control technology, automotive industry, medical technology, precision mechanics, watch industry

KERN LIEBERS uses state-of-the-art multi-spindle machining centers for finish machining in order to meet customer requirements that cannot be fulfilled using punching or fineblanking technology. Up to four workpieces can be machined simultaneously. 5-axis machining enables a high degree of freedom.

From prototype production on CNC machining centers to fully automated production on robot-automated rotary transfer machining centers, we have the right machine for every quantity and every degree of complexity.

The special feature of KERN LIEBERS is its enormous machining spectrum. For this reason, we always start by checking whether holes can be drilled using more economical forming processes.

If we reach the limits of forming processes, we use multi-spindle drilling processes, for example. Up to 50 tools working in parallel are sometimes used on special cam-controlled linear indexers or our self-built systems, which enable economical and high-precision machining, including deburring. Coordinated machining sequences enable the production of burr-free bore blanks.

Loops

For high-precision applications of complex external geometries, the smallest tolerances can be optimally implemented using a wide variety of grinding processes.

Helical compression springs are ground at the ends to prevent misalignment and distribute the load evenly. This increases the stability and durability of the springs. We offer you ...

Continuous grinding of spring ends from a minimum wire diameter of 0.3 mm to a maximum of 1.5 mm with fully automatic loading/unloading.
Infeed grinding for larger wire diameters (up to 13 mm). The upper grinding wheel is moved downwards while the loading plate rotates continuously.
Adapted grinding technologies (machine and grinding wheel qualities) for grinding patented drawn, oil tempered and stainless wires and special alloys.

KERN LIEBERS specializes in the precision grinding of pump, injector and other precision parts. Typical tolerances that can be reliably maintained for thickness, parallelism and flatness are < 2 µm, with roughness values of < Rz 0.6 and a center roughness value of ra < 0.1.

Components with a diameter of 4 mm - 80 mm can be machined on different production systems. The part thickness here is 5 mm - 0.2 mm. Stainless steels, non-ferrous metals and special alloys are machined on customer request.

Deburring

From slight edge rounding to complete freedom from burrs - we implement your desired requirements using a wide range of deburring technologies.

We use electrochemical or chemical deburring processes to improve the surface topography and for deburring/rounding. This makes it possible to deburr even hard-to-reach areas, such as small bores or bore intersections. The material is dissolved during processing.

The process can be used very well when high demands are placed on the cleanliness of the parts (determination of residual dirt). The parts have a high gloss burr so that even visually sophisticated applications can be realized.

Glass bead blasting is used to remove burrs and impurities and to create a uniform, smooth surface. We offer glass bead blasting with glass beads 15 µm - 150 µm or 150 µm - 250 µm in diameter.

KERN LIEBERS has a fully equipped vibratory finishing department to meet the different requirements of our diverse products. Depending on the requirements and component geometry, the parts can be processed in rotary vibrators or centrifugal systems. However, it is not only deburring or rounding processes that are carried out here. This process is also used for optical requirements. The bend-free and damage-free machining of long and thin workpieces poses a particular challenge.

The continuous further development of processes is a matter of course for KERN LIEBERS and a prerequisite for securing our technological lead. In particular, the deburring and rounding of non-ferrous and non-ferrous metals places high demands on this process. But here, too, we have extensive expertise and many years of know-how to meet the highest customer requirements.

Belt grinding and/or brushing are common methods for removing burrs. Belt grinding removes the root of the burr (only on larger components) and subsequent brushing rounds off the edges. Small holes (less than 1 mm in diameter) are difficult to deburr as the bristles hardly penetrate the holes.

For small parts with small bore diameters, KERN LIEBERS uses its own part-specific brushing systems with special brushes. These systems can also be used for non-magnetic parts. However, we can also draw on our expertise for large quantities and edge rounding in the µm range, which must be produced with process reliability. Fully automated special solutions are usually used here.

We use a range of tried-and-tested processes for the edge processing of springs. For stainless spring band steels in particular, machining edge processing, known as "chasing" (rounding), has established itself. The blasted longitudinal edge minimizes friction in the installation space and achieves a long service life.

For the machining of carbon steels, the spring edge is machined using a combination of forming and deep rolling. This proprietary technology delivers the best results in terms of the service life of the spring.

Preset

Technical helical compression springs are cold set to increase their fatigue strength and stability. During cold setting, the spring is loaded beyond its elastic limit, which leads to plastic deformation. This minimizes subsequent setting losses and gives the spring a higher load capacity.

What we offer:

Use of automatic cold setting devices
Measuring ranges: up to 10 N, up to 100 N, up to 1000 N and up to 5000 N
100% testing of spring lengths/forces; length/force deltas and spring rates
Load cells matched to the respective spring forces
Different machine concepts for different quality requirements (tolerances)
Sorting of compression springs into separate individual classes

Steel cutting

We cut the raw material to the customer-specific nib width as required and just in time on our modern belt slitting lines, which work according to the roller shear principle.