The mechanical engineering company Imes-icore uses the zero-point clamping system from clamping device expert Andreas Maier from Fellbach (AMF) for its Coritec 350i dental processing machines. Since then, workpiece changes and the fully automatic milling of implant abutments, crowns and caps for dental restorations have been running smoothly.

As speed and precision are important in the manufacture of modern dental prosthetics, according to Sebastian Ullrich, Head of Mechanical Design at Imes-icore, the latest generation of the Coritec 350i was to be equipped with a zero-point clamping system. With the zero point, various adapter systems, for example for prefabricated abutments (support screws/root caps) or block materials such as glass ceramics or lithium, can be used quickly even without a loader. In the version with a loader, the twelve blanks can be automatically inserted from the blank magazine and clamped in the correct position for fully automatic processing in three-shift operation. The blanks are clamped in the blank holders, discs with diameters of 98 and 98.5 millimetres, from which 35 units for the dental prosthesis can be produced.

The AMF K5 pneumatic zero-point clamping modules with hardened cover and piston and a clamping repeatability of less than 0.005 millimetres are used in the Coritec 350i machines. With a diameter of 45 millimetres and an installation depth of 19.8 millimetres, the modules are very compact and have a holding force of 13 kilonewtons. Five bar of compressed air is sufficient to open the Coritec machines. Imes-icore has developed its own interface with pressurization for the K5 module on its machines.

So-called blank holders are clamped in the zero-point clamping modules, in which the actual workpieces - the blanks - are then clamped. These blanks are made of the main materials used in the dental industry, zirconium oxide, PMMA, wax or composites as standard, but also non-precious metals such as chrome-cobalt or titanium. Up to 35 individual implant abutments, crowns, bridges or full dentures are then milled from these in a single clamping operation using five-axis simultaneous machining.

The blank holders, in turn, are clamped directly. The appropriate clamping nipple is integrated into the base of the blank holder for this purpose. Elevations and recesses as well as a fixing hole are fitted around the nipple, which find their counterpart in an adjusting pin as well as matching elevations and recesses on the machine side around the zero-point clamping module, thus ensuring that the clamping cannot be mixed up and is held in place without twisting. If the zero point clamping module is opened pneumatically, the blank holder can be inserted. The nipple is then retracted and locked with up to 1.5 kilonewtons before the holding force begins its work. as