Macor (Machinable Ceramic)
A glass-ceramic machinable with ordinary tools
Typical values for the temper in the title
Macor (by Corning) is a glass-ceramic whose crystal structure lets it be machined with ordinary tools (turning, milling, drilling) to tight tolerances, with no firing after machining. It is electrically and thermally insulating, non-porous and vacuum compatible.
Its strength is low compared with technical ceramics (about 94 MPa in bending in the database), but it allows a precise ceramic part to be made quickly. It is used for insulators in vacuum and scientific instruments, prototypes, aerospace and space parts, and fixtures for heating elements.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Modulus of elasticity E | 67 GPa | |
| Density ρ | 2.52 g/cm³ | |
| Flexural strength | 94 MPa (flexural) | database value |
| Machinability | standard carbide tools! | relative rating in the site database |
Structure and production
| Feature | Value | Meaning |
|---|---|---|
| Type | glass-ceramic | machinable |
| Porosity | zero | vacuum compatible |
| Insulation | electrical and thermal |
Typical values per producer data.
Grades and production routes
Macor is supplied as rods and plates ready for machining, without further treatment.
| Version | Properties | When to choose it |
|---|---|---|
| Rods and plates | machinable with ordinary tools | all uses |
Applications
- Insulators in vacuum and scientific instruments
- Ceramic prototypes
- Aerospace and space parts
- Fixtures for heating elements
- Precise spacers and insulators
Fabrication
Machining
With carbide tools (database: "standard carbide tools"), at low speed, with water cooling. The dust is harmful to breathe.
Strength
Low compared with sintered ceramics. Not for highly loaded parts.
Heat
Insulating and stable when hot, but not suited to strong thermal shock.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| Alumina (Al₂O₃ 99.5%) | 380 MPa | Not possible | alumina: much stronger and harder, needs grinding · material page |
| PI (Vespel) | 90 MPa | Not possible | polyimide: insulating, ductile, for lower heat · material page |
| PTFE | 25 MPa | Sintering only | PTFE: insulating, soft, for low heat · material page |
Common mistakes
Using Macor for a loaded part
Strength is low.
Machining dry and without extraction
The dust is harmful.
Assuming it is as strong as alumina
Its advantage is machinability, not strength.
Equivalents, standards and supply
| Standards | Producer specification (Corning) |
|---|---|
| Forms | block · rod · disk |
| Producers | Corning · Accuratus |
Learn more
Values are typical and for comparison only. In ceramics, strength is measured in bending and scatters widely (depending on flaws and finish), so design to producer data with suitable safety factors. Sources: ISO 513, ISO 13356, ASTM F603, producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026