Turning is among the oldest and most important machining processes – and remains the backbone of any precision manufacturing of rotationally symmetrical components.

During turning, the workpiece rotates about its own axis while a stationary cutting tool is fed in a defined manner. At the point of contact, the cutting edge removes material in the form of chips, thereby producing the desired contour. The machining process can be precisely controlled via the depth of cut, feed rate and rotational speed.

What turning is used for

All workpieces with a rotationally symmetric basic shape are turned – from shafts, axles and bolts to bushes and sleeves, as well as complex precision components with internal contours, threads and undercuts. Modern turn-mill centres combine turning and milling in a single setup, enabling even demanding geometries to be manufactured in one pass.

Precision through modern CNC technology

The machinery ranges from CNC sliding head lathes for delicate microscopic parts to fixed head and chuck turning centres for larger diameters. Driven tools, multiple turrets and automatic loading and unloading enable a high degree of manufacturing integration while maintaining consistent quality – even across larger production runs.

• Rotationally symmetrical components with tight diameter and length tolerances
• internal and external threads, undercut reliefs, grooves and complex contours
• Complete machining in the turn-mill centre – fewer clampings, greater accuracy
• Hard turning as an economical alternative to grinding for hardened materials

Milling is the process of choice when it comes to prismatic components and complex three-dimensional geometries that cannot be produced by rotation.

Unlike turning, here the tool rotates while the workpiece is fed in a defined manner. The multi-edged cutter removes the material step by step. Using the number of axes and path control, almost any contours, pockets, grooves and free-form surfaces can be produced.

5-axis machining for complex parts

On 4- and 5-axis machining centres, the component is machined in several planes simultaneously. This reduces repositioning, shortens process chains and increases accuracy because datum surfaces are maintained in a single set-up. This is a decisive factor for quality and cost-effectiveness, especially for components with a high vertical range of manufacture.

What matters in milling

Tool geometry, cutting data and a stable clamping situation determine surface finish and dimensional accuracy. In the case of thin-walled parts, vibrations and heat input must be controlled in order to maintain form and position tolerances.

• Prismatic components, housings, brackets and complex free-form surfaces
• Pockets, grooves, hole patterns and threads in a single setup
• 5-axis simultaneous machining for complex geometries
• Tight geometrical tolerances even for delicate contours

Where the tightest tolerances and finest surfaces are required, there is no getting around grinding – it produces fits and qualities that other methods cannot achieve.

During grinding, a rotating grinding wheel with a multitude of geometrically undefined cutting edges removes minuscule amounts of material. This achieves micrometer-level dimensional accuracy and surfaces with very low surface roughness – frequently as finishing work following turning or milling, especially in the case of hardened materials.

The most important grinding processes

• External cylindrical grinding for cylindrical clearance fits with the tightest diameter tolerances
• Centreless grinding for the cost-effective machining of large quantities of rotationally symmetrical parts
• Surface grinding for flat surfaces with high parallelism and surface quality
• inner loops for precise drilling and internal contours

Loops as a quality feature

Particularly with implant components and highly stressed precision parts, the surface quality determines function and service life. By combining grinding with subsequent finishing processes such as honing and lapping, surfaces can be achieved that meet the highest requirements.