There is much scope for error in conventionally drilled centre holes; misalignment, out-of-round, 60 degree angle too large or too small, lobed and certainly with a poor surface finish.
But the manufacture of precision shafts demands perfect centres in the shaft ends HENNINGER Centre and Cone grinders not only make poor centres precise but can move them as required to the optimum position – for example, onto the axis of a gear halfway along a shaft bent during hardening.
Some of the benefits;
- When a subsequent external grinder – cylindrical, gear, spline, thread and its dead centres are in good condition, runout less than 0.001 mm can be obtained on work whose centres have been HENNINGER centre ground.
- Subsequent grinding times are DRAMATICALLY reduced.
- Even case-depth can be assured on important surfaces.
- Subsequent roundness and concentricity checks have known bases.
- When centre condition is unknown, inspection charts and diagrams are purely speculative.
- Full and correct contact between work and dead centres prolongs the principle of planetary grinding life of expensive carbide centres.
There are three machine sizes in the HENNINGER ZS range each with varying bed length options to cover work from 5 to 225 mm clamping diameter and work length 20 to 2400 mm.
Standard ZS machines are manually controlled and intended for small batches of work. For higher production numbers machines are available with fully automatic work cycle.
(1) and (2) below show the ZS251 centre grinding unit designed for centre grinding large work pieces. The unit is conveniently mounted on a lathe or roundness of a workpiece with centres grinding machine bed.
(3) shows the double end ZS2000 for simultaneous centre grinding both ends of a workpiece – intended for high volume production.