Macor

MACOR

PROPRIETÀ

APPLICATIONS

Ultra-High Vacuum Environments

MACOR machinable Glass Ceramic is used as an insulator or coil support and for vacuum feed-throughs. In these applications, the conductive materials are supported by the MACOR MGC part and a compatible sealing glass is used to produce a vacuum-tight, hermetic seal.

Constant Vacuum Applications

MACOR MGC parts are found in spacers, headers and windows for microwave tube devices and as sample holders in field ion microscopes.

Aerospace Industry

Over 200 distintly shaped MACOR MGC parts can be found on America's reusable Space Shuttle Orbiter. Retaining rings of MACOR MGC are used at all hinge points, windows and doors.

Also, large pieces of MACOR glass ceramic are used in a NASA spaceborne gamma radiation detector. For this application, frame corners are joined by a combination of machined (butt-lap) mechanical joints and a sealing glass.

Nuclear-Related Experiments

Since MACOR MGC is not dimensionallt affected by irradiation, small cubes of the material are machined to a tolerance of one micron and used as a reference piece to measure dimensional change in other materials.

Welding Nozzles

Welding equipment manufacturers are using MACOR MGC as a nozzle on the tips of oxyacetylene torches. The material's nonwetting characteristic means molten particles won't adhere to and decrease the effectiveness of the nozzle.

Fixtures

MACOR MGC is used as an electrode support and burner block in several industrial high heat, electrical cutting operations due to its low thermal conductivity and excellent electrical properties.

Medical Equipment

Producers of medical components are intrigued by MACOR MGC's inertness, precise machinability and dimensional stability.

The point is this: when you need the performance of a technical ceramic (high use temperature, electrical resistivity, zero porosity) and your application demands the ready fabrication of a complicated shape (quickly, precisely, privately), look at MACOR MGC. Il will lower costs and substantially reduce the time between design and actual use.

COMPOSITION

MACOR Machinable Glass Ceramic is a white, odorless, porcelain-like (in appearance) material composed of aproximately 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 folloing compounds:


Approximate Weight %
Silicon - SiO2 46%
Magnesium - MgO 17%
Aluminium - Al2O3

16%

Potassium - K2O 10%
Boron - B2O3 7%
Fluorine - F 4%

Randomly oriented mica flakes in the microstructure of MACOR MGC are the key to its machinability.

Microstructure of MACOR MGC5000X magnification.

MACHINING

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 aluminium-oxide grinding wheels can be used.

Polishing

Start with loose 400-grift silicon carbide on a steel wheel. For the final polish, use cerium oxide or alumina on a polishing pad for glass or ceramics. A 0.5 µin.-AA finish can be achieved.

Sawing

Use a carbide grit blade at a band speed of 100 fpm. An alternative is 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-.200 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 cap in one direction only. (Turning the tap back and forth can cause chipping.) Continously flush with water or coolant to clear chips and dust from the tap.

 

 

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