Key factors for successful machining are proper machining speeds and coolant.
MACOR® Machinable Glass Ceramic can be machined with high speed steel tools, but carbide tools are recommended for longer wear.
Achieve the best results by using a water soluble coolant, such as Cimstar 40 – Pink, especially formulated for cutting and grinding glass or ceramics.
No post firing is required after machining.
Grinding
Diamond, silicon-carbide or aluminum-oxide grinding wheels can be used.
Polishing
Start with loose 400-grit silicon carbide on a steel wheel. For the final polish, use cerium oxide or alumina on a polishing pad for glass or ceramics. A 0.5µin.-AA finish can be achieved.
Sawing
Use a carbide grit blade at a band speed of 100 fpm. An alternative is a silicon carbide or diamond cut-off wheel.
Turning
| Cutting speed | 30-50 sfm |
| Feed rate | .002-.005 ipr |
| Depth of cut | .150-.250 in. |
Milling
| Cutting speed | 20-35 sfm |
| Chip Load | .002 ipt |
| Depth of cut | .150-.250 in. |
Drilling
| Drill size | Spindle Speed | Feed Rate |
| 1/4 in. | 300 rpm | .005 ipr |
| 1/2 | 250 | .007 |
| 3/4 | 200 | .010 |
| 1 | 100 | .012 |
| 2 | 50 | .015 |
Allow at least .050″ of extra material on the back side for breakout. This excess can be removed after drilling.
Tapping
Make clearance holes one size larger than those recommended for metals. Chamfer both ends of the hole to reduce chipping. Run the tap in one direction only. (Turning the tap back and forth can cause chipping.) Continuously flush with water or coolant to clear chips and dust from the tap.
Composition
MACOR® Machinable Glass Ceramic is a white, odorless, porcelain-like (in appearance) material composed of approximately 55% fluorophlogopite mica and 45% borosilicate glass. It has no known toxic effects; however, the dust created in machining can be an irritant. This irritation can be avoided by good housekeeping and appropriate machining techniques. The material contains the following compounds:
| Approximate Weight % | |
| Silicon – SiO2 | 46% |
| Magnesium- MgO | 17% |
| Aluminum – SiO2 | 16% |
| Potassium – K2O | 10% |
| Boron – B2O3 | 7% |
| Flourine – F | 4% |
Macor Image Magnified
Randomly oriented mica flakes in the microstructure of MACOR® MGC are the key to its machinability.