Macor®
Machinable Glass Ceramic

• is MACHINABLE with ordinary metal working tools.
• allows FAST TURNAROUND, no post firing required.
• holds TIGHT TOLERANCES, up to .0005".
• withstands HIGH TEMPERATURE, up to 1000°C (no load).
• is CLEAN, no outgasing and zero porosity.

With Macor® Machinable Glass Ceramic (MGC), fabrication is fast - because it can be machined into complicated shapes and precision parts with ordinary metal working tools, quickly and inexpensively, and it requires no post firing after machining. That means no frustrating delays, no expensive hardware, no post fabrication shrinkage, and no costly diamond tools to meet specifications.

Properties

Macor® Machinable Glass Ceramic has a continuous use temperature of 800°C and a peak temperature of 1000° C. It's coefficient of thermal expansion readily matches most metals and sealing glasses. It is non-wetting; exhibits zero porosity, and unlike ductile materials, won't deform. It is an excellent insulator at high voltages, various frequencies and high temperatures. And, when properly baked out, it won't outgas in vacuum environments.

Machining

Machining tolerances are surprisingly tight, up to .0005". It can be machined to a surface finish of less than 20?in. and polished to a smoothness of 0.5?in -AA. Configurations are limited only by available equipment and the experience of the machinist

Sealing, Joining and Metalizing

Macor® MGC can also be joined or sealed - both to itself and to other materials - in a number of ways: metalized parts can be soldered together and brazing has proven an effective method of joining the material to various metals; epoxy produces a strong joint, and sealing glass creates a vacuum tight seal Even a straightforward mechanical joint is possible. It can be thick film metalized using metal inks, or thin film metalized by sputtering.

Applications

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 lndustry
Over 200 distinctly 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 dimensionally affected by irradiation, small cubes of the material are machined to a tolerance of one micron and are 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. It will lower costs and substantially reduce the time between design and actual use.

Properties

l. Thermal

II. Mechanical

III. Electrical

IV. Chemical

Resistance to water over time

* Water not freshened daily
**Water freshened daily

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.

SAWING
Use a carbide grit blade at a band speed of 700 fpm. An after-native is a silicon carbide or diamond cut-off wheel.

TURNING

MILLING

DRILLING

Allow at least .050" of extra material on the backside 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.

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. 0.5 ?in. -AA finish can be achieved.

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 - Si02 46%
Magnesium- MgO 17%
Aluminum - Al203 16%
Potassium - K20 10%
Boron - B203 7%
Fluorine -F 4%