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MACOR® Machinable Glass Ceramic (MGC)

Special Properties of MACOR®

  • Machinable with HSS tools used for metals
  • Highly temperature-resistant
  • Non-porous
  • Dimensionally stable
  • Does not outgas
  • Odorless, opaque, white material
  • Excellent electrical insulator
  • The coefficient of thermal expansion is close to that of many metals and sealing glasses
  • Available as semifinished parts
  • Radiation-resistant
  • No post-firing required

Typical Applications

  • High-precision workpieces
  • Contact holders, sockets, bushings, and feedthroughs
  • Space and aviation applications
  • Equipment for field ion microscopes
  • Ultra-high vacuum and continuous vacuum applications
  • Medical devices
  • Laser cavity components
  • Insulators for electronic connectors
  • Semiconductors and electronics
  • Nuclear research
  • Welding nozzles
  • Bushing tubes
  • Mounting brackets
  • Laser alignment components

Related Ceramic Materials

  • SHAPAL™ Hi M-soft
    (Aluminum nitride ceramic)
  • Al2O3
    (Alumina high-performance ceramic)

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What is MACOR®?

MACOR® is a machinable glass ceramic (MGC) made by CORNING. It is a white, odorless, and opaque material comprising 55% MIKA and 45% borosilicate glass. The high-performance Small machined parts made of MACOR® from CORNING material has ideal properties for a wide range of industrial applications. MACOR® allows the design and precise manufacturing of complex-shaped parts with tight tolerances. It can be CNC-machined with conventional HSS tools commonly used for machining metal. No expensive special equipment, machinery, or diamond tools are required to process MACOR®.

 

Finished MACOR® part with complex details
Figure: A finished part with tight tolerances made of MACOR® MGC

 

MACOR® is a Material with Special Properties

MACOR® can be used at temperatures of up to 800 °C for long periods and withstands even up to 1000 °C without load. It has zero porosity and is non-wetting. MACOR® does not deform or outgas. It can be used in vacuum environments and does not require post-firing like other ceramics do. Moreover, it is an excellent insulator for high voltages at various frequencies, as it provides low conductivity. MACOR® MGC sets a standard in the industry for machinable ceramics. It is ideal for various applications in aerospace, medical, and semiconductor.

 

Very small MACOR® workpieces MACOR® allows the design of such tiny and intricate parts with high precision.

 

To get a quote for MACOR® glass ceramic material or a finished part with a custom shape and dimensions according to your drawing, please click the button below:

 

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Specifications, Properties,
and Raw Materials

 

Semifinished MACOR® materials

We stock MACOR® sheets, rods, and bars which allows short lead times. These are the starting points for complex-shaped parts. Please see below for all stock dimensions:

Rods
Rod diameter
(mm)		 Lengths
(mm)
3 | 4 | 5 | 6 | 8 | 12.5 70
19 | 25 | 30 | 38 | 50 75 | 150 | 300
Get a quote for a MACOR rod
Bars
Size
(mm x mm)		 Lengths
(mm)
12.5 × 12.5


75 | 150 | 300
19 × 19
25 × 25
30 × 30
50 × 50
Get a quote for a MACOR bar
Sheets
Size
(mm x mm)		 Thicknesses
(mm)
75 × 75
12.5 | 19 | 25 | 30 | 50
150 × 150
300 × 300
Get a quote for a MACOR sheet

The lead time for the materials above is typically one week or less. The larger dimensions may take a little longer.

 

MACOR® MGC Machining Guidelines

Density

  • 2.52 g/cm3

Coefficient of Thermal Expansion per °C

  • 74 × 10-7 (-200–25 °C)
  • 93 × 10-7 (25–300 °C)
  • 114 × 10-7 (25–600 °C)
  • 126 × 10-7 (25–800 °C)

Thermal Characteristics

  • Continuous operating temperature: 800 °C
  • Max. operating temperature: 1000 °C (no load)
  • Thermal Diffusivity: (25 °C): 7.3 × 10-7 m2/s
  • Thermal Conductivity: (25 °C): 1.46 W/m°C
  • Specific Heat (25 °C): 0.79 KJ / kg°C

Mechanical Characteristics

  • Porosity: 0%
  • Young's Modulus: (25 °C): 66.9 GPa
  • Poisson's Ratio: 0.29
  • Shear Modulus: (25 °C): 25.5 GPa
  • Knoop Hardness: (100 g): 250
  • Modulus of Rupture: (25 °C): 94 MPa
  • Compressive Strength: 345 MPa
  • Fracture Toughness: 1.53 MPa m0,5

Electrical Characteristics

  • Dielectric Constant: (25 °C): 6.03 (1 kHz)
  • Dielectric Loss Tangent: (25 °C): 4.7 x 10-3 (1 kHz)
  • Dielectric Strength: (25 °C): 40 kV / mm
    (at 0.254 mm thickness)
  • Volume Resistivity: >1016 Ω-cm

 

Composition of MACOR® Glass Ceramic

Substance approximate weight
percentage
Silicon oxide (SiO2) 46
Magnesium oxide (MgO) 17
Alumina (Al2O3) 16
Potassium oxide (K2O) 10
Boron oxide (B2O3) 7
Fluorine (F) 4

Chemical Properties

Medium pH Time
(h)		 Temp.
(°C)		 Weight loss
(mg/cm2)
5% HCL 0.1 24 h 95 °C Approx. 100
0.002 N HNO3 2.8 24 h 95 °C Approx. 0.6
0.1 N NaHCO3 8.4 24 h 95 °C Approx. 0.3
0.02 N Na2CO3 10.9 6 h 95 °C Approx. 0.1
5% NaOH 13.2 6 h 95 °C Approx. 10
H2O (water) 7.6 24 h 95 °C Approx. 0.01
Components made of MACOR® glass ceramic

Precise workpieces made of original MACOR® glass ceramic material.

 

All data and specifications given are average guide values and are not guaranteed. Moreover, please consider the “Notes on Specifications”.

© 1994 – 2025 Präzisions Glas & Optik GmbH

Last update: September 23, 2025