May 30 2002
Topics Covered
Background
Sawing
Milling
Turning
Drilling
Tapping
Grinding
Polishing
Background
Macor is a machinable glass ceramic produced by Corning.
It can be machined using high speed steel and carbide tools, with the latter being preferred due to longer service life. It is also recommended that water soluble cutting oils designed for glass and ceramics are used when machining Macor. No heat treatment is required after machining.
Sawing
Macor can be cut using a carbide grit blades at a speed of 100 fpm. Silicon carbide and diamond cut-off wheels can also be used.
Milling
Recommended milling parameters are, cutting speed 20-35 sfm, chip load 0.002 ipt and depth of cut 0.150-0.200 in.
Turning
Recommended turning parameters are, cutting speed 30-50 sfm, feed rate 0.002-0.005 ipr and depth of cut 0.150-0.200 in.
Drilling
Recommended drilling parameters are:
Drill Size
(in) |
Spindle Speed
(rpm) |
Feed Rate
(ipr) |
| 0.25 |
300 |
0.005 |
| 0.50 |
250 |
0.007 |
| 0.75 |
200 |
0.010 |
| 1.00 |
100 |
0.012 |
| 2.00 |
50 |
0.015 |
A minimum of 0.05” of extra material should be allowed on the back side of the workpiece for breakout. Excess material can be machine off after drilling.
Tapping
Clearance holes should be drilled one size larger then those recommended for metals. It is also recommended to chamfer both ends of the hole to reduce the likelihood of chipping.
When tapping holes avoid turning the tap back and forth as this can promote chipping. The work area should also be continuously flushed with water or coolant to remove dust and chips from the tap.
Grinding
Grinding of Macor can be accomplished successfully using diamond, silicon carbide or alumina grinding wheels.
Polishing
Loose 400 grit silicon carbide on a steel wheel is the recommended starting material, while ceria (cerium oxide) or alumina and a suitable polishing pad for glass and ceramics can be used for finishing. This technique can be used to produce a 0.5 µin-AA finish.
Primary author: AZoM.com