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Wet grinding of glass ceramics

Milling and grinding with the same machine: The wet grinding option is an extra module for vhf's dental milling machines of the Impression S line. The highlight of this module is that it turns these CNC milling machines for a little surcharge optionally into grinding machines. Thus materials like glass ceramics which can only be ground with cooling liquid may be processed by the same machine which is normally used for milling.

Wet grinding of glass ceramicsSo there is no need for buying a new machine for wet grinding – just an external module and appropriate holders for the glass ceramics blocks for the Impression S models. The wet grinding module which regulates the liquid circulation is connected with two hoses for supply and drainage with the machine. From three nozzles that are already integrated into the spindle block, cooling liquid will be directly targeted to the tip of the tool. Thus an efficient cooling is ensured during the whole grinding process. An extension of the DentalCAM software with machining strategies especially for grinding is also part of the wet grinding option.

Patent pending technology

The external wet grinding module has a refined system for drying the air and filtering the liquid from grinding particles. The air is dried by a patent pending air guiding system. It separates the suction mixture of air and liquid into two circuits. Due to the intelligent labyrinth air guiding system, a large part of the humidity will be separated from the extracted air. So the wet grinding option can be operated with the same dry vacuum cleaner which is already used for milling. In the liquid circuit, the cooling liquid will be drawn by a membrane pump through a multi-level filter system where it will be cleaned from grinding particles before it will be pumped back to the machine. A contact-less ultrasonic sensor constantly monitors the liquid level.

Due to the rigid construction of the Impression S models and the highly precise spindle one will achieve optimal results by using the cooling lubricant vhf Tec Liquid and the appropriate vhf grinding tools. For instance, it is possible to grind a fully anatomic crown of the materials IPS e.max® or VITABLOCS® Mark II within approximately 25 minutes.

For wet grinding, vhf's range of tools includes a torus grinding tool with coarser grain size for roughing, as well as a fine-grained radius grinding tool for finishing the surface afterwards. Both tools distinguish themselves by a good abrasion and break resistance, and their endurance is very long. A diamond grit with especially good binding to the shank avoids microcracks and reduces the sensitivity for thermal impact. The tools are adapted to the vhf grinding strategies in the DentalCAM software.

A video which explains the functionality of the wet grinding option can be found at dental.vhf.de in the section Impression S models where also the complete technical data is listed. The wet grinding option – like also the vhf dental milling machines – is exclusively sold via OEM partners and authorised resellers.

External wet grinding module

External wet grinding module in a compact stainless steel housing. It serves for recycling the cooling liquid and for drying the exhausted air. The same dry vacuum cleaner which is also used for milling will be connected with this module.

Glass ceramics crown

Finished glass ceramics crown.