MACOR® Properties

MACOR® machinable glass ceramic has a continuous use temperature of 800oC and a peak temperature of 1000oC. Its 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. When properly baked out, it won't outgas in vacuum environments.

MACOR® 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.

MACOR® contains the following compounds:

Material Approximate Weight
Silicon - SiO2  46%
Magnesium - MgO  17%
Aluminum - Al2O3  16%
Potassium - K2O  10%
Boron - B2O3  7%
Fluorine - F  4%


    Aluminum Silicate  
Property Units M-120F MACOR®
Color   Tan to Pink White
Density G/CC 2.3 2.52
Porosity % Water Absorption 3 0
Flexural Str. KPSI 9 13
Compressive Str. KPSI 40 50
Hardness Knoop 500 250
Thermal Cond. W/M°K
1.3 1.46
Coefficient of Linear Thermal Expansion 25° to 300°C
25° to 1500°C
3.3 9.3
Maximum Use Temp. °C 1150 1000
Vacuum Atmosphere °C -  
Dielectric Str. Volts/Mil
V/MMX 103
100 1000
Volume Resistivity ohm-cm 25° >1014 >1016
Dielectric Constant 1 MHZ 25°C
1 KHZ 25°C
Loss Factor 1 MHZ 25°C
1 KHZ 25°C
.053 .0047


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

Sealing, Joining and Metallising

MACOR® MGC can also be joined or sealed - both to itself and to other materials - in a number of ways; metallised 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 metallised using metal inks, or thin film metallised by sputtering.

Online ordering and quotation system

Ordering your standard size MACOR® products is now a whole lot quicker and easier. New and current customers can use our shop and apply for a customer account today and make the order process even faster.
