Where we had it a few days ago here in the grinding blog from high-speed grinding, a few more remarks from the point of view of development & design on this technically exciting topic: There is a small but not insignificant technical contradiction in grinding, which is called "high speed, low stiffness of the grinding spindle and vice versa". What does this mean?

Large grinding wheels, large spindle bearings
Very simple: where geometry and accessibility of the workpiece allow, we use the largest possible grinding wheels in our Multigrind® grinding machines so that many abrasive grains remain cold longer, i.e. grind longer without becoming blunt. Our own high-precision, directly driven spindles then have to turn more slowly, but require a higher torque for a high grinding pressure. This means that large, stable bearings are required, and for physical reasons they cannot turn so quickly because they would heat up too much.

Small grinding wheels, light spindle bearings
The situation is different for applications where, for example, small notches or grooves have to be made in a cutting edge. This requires a small tool, i.e. a small grinding wheel. And in order for this small grinding wheel to achieve a high peripheral speed, it needs high speeds; and of course light spindle bearings.

Two spindles live, ah! in my grinding machine

Today we solve this contradiction (see above) with Haas grinding machines by installing, optionally, two spindles in one machine. For example, an HSK 80 with 30 kW (8,000 rpm) for 300 mm diameter wheels and an HSK 25 (70,000 to 120,000 rpm) for small wheels.

In order to be able to offer our users even more flexibility, we will be offering a strong all-round spindle (on well Swabian Midrange spindle) in the fairly foreseeable future. This will be designed as an HSK 50 single spindle solution (up to 35,000 rpm) for very small wheels up to grinding wheels with a diameter of 250 mm.

If you want to talk shop with me about grinding spindles, visit us at the AMB in Stuttgart from September 18th to 22nd. You will find us in Hall 7, Stand B 71. If you cannot come to Stuttgart, please write to me or visit us in Trossingen.

See you next time!