CNC 635 external grinding center The CNC 635 external grinding center is available in two size versions. One version is designed for workpieces with a grinding length of up to 500 mm and the other for workpieces with grinding lengths up to 1000 mm. The machine is suitable for straight plunge cut and angular plunge cut grinding as well as for rough and thread grinding. It can be equipped with one, two or even three grinding supports, so that it is usually no longer necessary to reclamp on other cylindrical surface grinders.