Linear bearings in polishing milling machine for plastic shells defy dust exposure

• What was needed: drylin® linear units; spindle liner units SHT
• Requirements: fine dust clogged the machine components
• Industry: Machine tool construction
• Success for the customer: drylin® linear modules are resistant to dirt and work smoothly in the application, and the milling machine also works with the highest precision on all axes

This CNC polishing milling machine from ORTOTIKA s.r.o. is used to produce positive moulds for the subsequent manufacture of plastic shells used in the field of prosthetics. The patient's body parts are scanned using 3D scanning, after which a mould can be created using a computer. The positive polyurethane pattern is created for the subsequent milling process. A polar system is used to optimise the shapes. The biggest challenge for the system's components is the very fine dust, which is also deposited on the linear guides and can lead to increased wear if not cleaned regularly. The environmental conditions in the application rule out the use of conventional recirculating ball bearing guides, so the company had to look for another solution.

The manufacturer now uses drylin® SHTspindle linear modules for the X-axis (radius) and the vertical Z-axis in the polishing milling machine. The Y-axis (angular rotation) is secured by the rotation of the drive unit.
The drylin® linear units are resistant to dirt, which is why the use of these modules in the application offers a major advantage over other linear guides. The polar system also has the further advantage that all precision requirements are met on the X and Z axes. These are just within a few tenths of a millimetre (up to a maximum of 1 mm). The linear guides were installed on a separate frame within the milling machine for reasons of stability and to avoid vibrations.