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Macor (Machinable Glass Ceramic) - Machining Tips

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

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