Ultrasonics in Working Machinable Glass Ceramics
Ultrasonic-assisted techniques enhance surface finishes when cutting machinable glass ceramics. Read on for Multi-Lab’s guide for more information.
Machinable glass ceramics
Machinable glass ceramics find applications in difficult environments such as medicines and dentistry as well as aerospace and electronics because of their superior performance, compared with metals. These materials have a higher resistance to corrosion and high strength combined with a low thermal expansion – properties that are hard to achieve with metals.
A further advantage is that they can be machined using standard carbide cutting tools rather than expensive specialist implements. However, care must be taken to avoid indentation in cutting edges during machining, as this may cause brittle fracture and reduce the strength of the material. Ultrasonic techniques can reduce this indentation by up to 20 per cent.
Machinable glass ceramics are composite materials combining glass and crystal phases. The crystallization process is controlled to produce easily cleavable, plate-shaped crystals similar to mica. When this material is machined with a standard metal working tool, it does not break into pieces like an ordinary glass.
The cracks that are created at the cutting edge do not run into the interior of the working piece to cause a catastrophic breakage. Instead, the energy generated during cutting is absorbed in the working piece through the formation of many small cracks along the cutting edge.
The energy generated during cutting also comes in the form of high temperatures generated at the contact between the cutting edge of the work piece and the cutting tool. A good cutting performance can be ensured by introducing a cutting fluid at this time to ensure both cooling and lubrication.
But any improvement in cutting results is limited if the fluid is applied simply to cool the high temperatures around the tool. One solution is to use ultrasonic cutting techniques. This involves using a tool that oscillates at a frequency of around 20 hertz that is pushed into the materials. This ultrasonic cutting process can be six to 10 times faster than using standard carbide or diamond tools.
The accuracy of the cut and the final surface finish will be enhanced because a vacuum is created around the cutting edge during the machining process. The vacuum enhances the flow of the cutting fluid to the edge and accelerates the high temperature cooling between the tip of the tool and the edge of the work piece. This in turn enhances the quality and finish of the final cutting edge.
If you would like more information then please contact a Multi-Lab team member today or visit the website.