The introduction of MACOR® material revolutionised the world of machinable ceramics. Historically, ceramics such as alumina and zirconia have been used to manufacture thermo-resistant components across multiple sectors. Whilst these traditional ceramics possess many desirable properties - and hold great value within manufacturing - they can be notoriously difficult to machine.
A distinct manufacturing material developed by Corning Inc, * MACOR® machinable ceramic combines the performance of a technical ceramic with the versatility of a high-performing polymer and the machinability of a soft metal. The distinctive glass-ceramic hybrid is composed of approximately 55% fluorophlogopite mica and 45% borosilicate glass, making it white in appearance, odourless, and non-porous.
The material’s unique combination of characteristics makes MACOR® a superior material for engineering and design, with the ability to be quickly formed into highly complex shapes and components. Today, MACOR® ceramic is a material of choice for machinable ceramics across the globe.
Shop MACOR® machinable ceramic
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MACOR® is used within cutting-edge R&D across multiple sectors
What are the properties of MACOR® material?
MACOR® machinable ceramic is an excellent electrical insulator at high voltages, various frequencies, and elevated temperatures. It’s also a fantastic thermal insulator with a coefficient of thermal expansion that readily matches most metals and sealing glasses.
Thermoresistant by nature, MACOR® material has a continuous use temperature of 800°C and a maximum use temperature of 1000°C. Unlike ductile materials, MACOR® doesn’t creep or deform, and it’s possible to eliminate outgassing in ultra-high vacuum environments if properly baked out before use. MACOR® is non wettable and can be easily joined or sealed - both to itself and to other materials.
For a detailed breakdown of the thermal, mechanical, electrical, and chemical properties of MACOR® machinable ceramic material, please see the tables below:
Thermal properties of MACOR®
|
Coefficient of Expansion |
-100 °C to 25 °C 25 °C to 300 °C 25 °C to 600 °C 25 °C to 800 °C |
81 x 10-7 / °C 90 x 10-7 / °C 112 x 10-7 / °C 123 x 10-7 / °C |
|
Specific Heat, 25 °C |
0.76 kJ / kg °C | |
| Thermal Conductivity, 25 °C | 1.46 W / m °C | |
| Thermal Diffusivity 25 °C | 7.3 x 10-7 m²/s | |
| Continuous Operating Temperature | 800 °C | |
| Maximum No Load Temperature |
1000 °C |
Mechanical properties of MACOR®
| Density | 2.5 g / cm³ |
| Porosity | 0% |
| Young's Modulus, 25 °C (Modulus of Elasticity) |
66.9 GPa |
| Poisson's Ration | 0.29 |
| Shear Modulus, 25 °C | 25.5 GPa |
| Hardness, Knoop 100 g | 250 kg / mm² |
| Modulus of Rupture, 25 °C (Flexural Strength) |
94 MPa (Minimum specified average value) |
| Compressive Strength (After polishing) |
345 MPa Up to 900 MPa |
Electrical properties of MACOR®
| Dielectric Constant, 25 °C | 1 KHz 8.5 GHz |
6.01 5.64 |
| Loss Tangent, 25 °C | 1 KHz 8.5 GHz |
4.0 x 10-3 2.5 x 10-3 |
| Dielectric Strength (AC) avg. (at 0.3mm thickness and 25 °C) |
45 kV / mm | |
| Dielectric Strength (DC) avg. (at 0.3mm thickness and 25 °C) |
129 kV / mm | |
| DC Volume Resistivity, 25 °C | 10-17 ohm • cm |
Chemical properties of MACOR®
| Solution | pH | Time | Temp | Weight Loss (mg / cm²) Gravimetric |
| 5% HCI (Hydrochloric Acid) |
0.1 | 24 hours | 95 °C | ~ 100 |
| 0.002 N HNO3 (Nitric Acid) |
2.8 | 24 hours | 95 °C | ~ 0.6 |
| 0.1 N NaHCO3 (Sodium Bicarbonate) |
8.4 | 24 hours | 95 °C | ~ 0.3 |
| 0.02 N Na2CO3 (Sodium Carbonate) |
10.9 | 6 hours | 95 °C | ~ 0.1 |
| 5% NaOH (Sodium Hydroxide) |
13.2 | 6 hours | 95 °C | ~ 10 |
| Resistance to Water Over Time H2O |
7.6 | 1 day * 3 days * 7 days * 3 days ** 6 days ** |
95 °C 95 °C 95 °C 95 °C 95 °C |
0.01 0.07 9.4 0.06 0.11 |
* Water not freshened daily ** Water freshened daily
MACOR® is used on the hinge points, windows and doors of NASA's Reusable Space Shuttle Orbiter
How is MACOR® material used within machining?
MACOR® can be machined easily - without the need for costly specialist tools. High-speed steel tools can machine MACOR®, however carbide tools are suggested for longer wear. No post-firing is needed after machining MACOR®, but a coolant (preferably a water-soluble coolant formulated for cutting and grinding glass or ceramics) should be used. The material can be ground, polished, turned, milled, sawed, drilled, and tapped.
Grinding MACOR®
Diamond, silicon carbide, or aluminium oxide grinding wheels can be used.
Polishing MACOR®
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 12.7 μmm-AA (0.5 μin-AA) finish can be achieved.
Turning MACOR®
| Cutting Speed | 9.14 - 15.52 SMM (Surface Metres / Minute) 30 - 50 SFM (Surface Feet / Minute) |
| Feed Rate | 0.0508 - 0.127 MM/PR (Millimetres per revolution) 0.002 - 0.005 IPR (Inches per revolution) |
| Depth of Cut | 0.381mm - 6.35mm 0.0150 " - 0.250 " |
Milling MACOR®
| Cutting Speed | 6.09 - 10.67 SM / M (Surface metres / minute) | 20 - 50 SF / M (Surface Feet / Minute) |
| Chip Load | 0.0508 mm / PR (Millimetres per revolution) | 0.002 IPR (Inches per revolution) |
| Depth of Cut | 0.381 mm - 5.08 mm | 0.0150 " - 0.2 " |
Sawing MACOR®
Use a carbide grit blade at a band speed of 100 fpm. An alternative is a silicon carbide or diamond cut-off wheel.
Drilling MACOR®
| Drill Size (⌀) | Spindle Speed | Feed Rate | ||
| 6.35 mm | ¼ " | 300 RPM | 0.127 mm / PR | 0.005 IPR |
| 12.7 mm | ½ " | 250 RPM | 0.178 mm / PR | 0.007 IPR |
| 19.05 mm | ¾ " | 200 RPM | 0.254 mm / PR | 0.010 IPR |
| 25.4 mm | 1 " | 100 RPM | 0.305 mm / PR | 0.012 IPR |
| 50.8 mm | 2" | 50 RPM | 0.381 mm / PR | 0.015 IPR |
Allow at least 1.27 mm (0.050") of extra material on the back side for breakout. This excess can be removed after drilling.
Tapping MACOR®
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.
What are the applications of MACOR® material?
The versatility of MACOR® makes it ideal for various machinable ceramic applications, including:
- Welding nozzles
- Spacers, headers, and windows
- High voltage insulators
- Research & development within numerous sectors of science, industry, engineering and technology
- Electrode support
- Retaining rings on hinges, windows, and doors for NASA's Space Shuttle
- Thermal breaks in high temperature processing equipment
MACOR® machinable ceramic, available at Goodfellow
Looking to buy MACOR®? We boast one of the most comprehensive offerings on the market.
- 44 MACOR® products in-stock and ready for despatch within 48 hours
- 3 forms to choose from (MACOR® bars, rods, and sheets)
- Custom MACOR® components are available with tolerances as small as +/- 0.02 mm
- No minimum order size
- Free global delivery
Looking for other machinable ceramics?
Our specialist product range includes over 150,000 advanced scientific materials to support your developments. From BNP-2 to Shapal™, our huge range of machinable ceramics is sure to meet your needs.
How Goodfellow's customers have used MACOR®
- Christensen, P.A., Ali, A.H.B.M., Mashhadani, Z.T.A.W. et al. A Direct Fourier Transform Infrared Spectroscopic Comparison of the Plasma- and Thermally-Driven Reaction of CO2 at Macor. Plasma Chem Plasma Process 38, 293–310 (2018).
DOI: https://doi.org/10.1007/s11090-018-9874-6
- A.H.M Ali et al 2021. Non-Thermal Plasma Conversion of N2, CO2 And CH4. IOP Conf. Ser.: Mater. Sci. Eng. 1051 012072
DOI: https://iopscience.iop.org/article/10.1088/1757-899X/1051/1/012072/meta
MACOR® is a registered trademark of Corning incorporated.
