Why a special finish hard turning machine is a must

In principle, hard turning is possible on any precision turning machine. However, to develop the full potential of finish hard turning in terms of workpiece quality and process reliability, a lathe specifically designed for finish hard turning is necessary such as Hembrug Mikroturn lathes. When compared to other precision lathes, the unique hydrostatic slide and spindle design of the Hembrug exceeds all others. This results in:

– Longer tool life thru a highly damped platform
– Consistent piece to piece repetitive part accuracies
– Higher productivity due to inherent platform stability requiring fewer adjustments
– Workpieces with accuracies in the sub-micron range

The highest possible workpiece quality
The relative cutting forces, the force required to pull the material away from the workpiece, are higher in hardened steel than in soft steel machining. A higher cutting force results in a significantly higher push back pressure on the guideways. Conventional precision turning machines are not designed to handle these higher forces (premature wear of the guideways). This leads to a drop-off in size tolerance capability, form inaccuracies, higher surface finishes and increased tool wear.

The “push back forces” or thrust forces are very high in finish hard turning. Only a machine specifically developed for finish hard turning can absorb these forces.

What conditions do the Hembrug Mikroturn finish hard turning lathes meet?

1) High static and dynamic stiffness
The Hembrug Mikroturn machines have a very high static and dynamic stiffness to absorb the high process forces that are released when machining hardened steel. This stiffness is absolutely necessary to dampen as much as possible vibrations at the cutting tool. This high dynamic rigidity (= damping) is also essential for high surface finish accuracy and extended tool life.

2) High thermal stability
Thermal stability is required to minimize size variations due to temperature change which is caused by heat producing sources such as motors, electrical components or hydraulic circuit. The superior thermal stability of Mikroturn lathes results in minimal piece to piece size change which is especially beneficial in higher volume production.

Piece to piece size change with a Mikroturn® hard turning lathe is up to three times better. 75 brass workpieces machined over a period of 160 min. without machine correction or operator intervention.

 

 

 

 

 

 

 

 

 

 

 

3) High repetitive accuracies
Accuracy here refers to; runout of the main spindle (< 0.1 micron), axis repeatability (± 0.2 micron), slide positioning accuracy (< 1 micron), resolution of the scale feedback system and servo control. The straightness or tracking of the slides also factors in to the finish quality of the workpiece.

It may not be visible on the outside, but the Hembrug Mikroturn finish hard turning lathes combine all of the above features and offer the highest machining accuracy possible. Discover the machines here

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