Custom Machinable Glass Ceramic Parts for OEM Equipment

What Are Machinable Glass Ceramic Parts?

Machinable glass ceramic parts are custom technical ceramic components produced from machinable glass ceramic blanks for insulation, vacuum, thermal and precision fixture applications.

Machinable glass ceramic parts are CNC-machined technical ceramic components used when engineers need complex shapes, electrical insulation, dimensional stability and clean ceramic performance without the long development cycle of fully sintered custom ceramics.
Unlike many dense ceramics that require diamond grinding after sintering, machinable glass ceramic can be shaped into holes, slots, pockets, grooves, spacers, standoffs and fixture plates with conventional machining methods. This makes it useful for prototype parts, low-volume assemblies, insulating supports and equipment components that require accurate geometry and ceramic-level insulation.
ADCERAX supplies drawing-based machinable glass ceramic parts for vacuum equipment, laser and optical modules, high-voltage assemblies, analytical instruments and thermal processing fixtures. Each part should be reviewed according to temperature, load, voltage, vacuum condition, edge design and assembly method before production.

Feature	Why It Matters
Machinable ceramic blank	Allows complex geometry without long mold development.
Electrical insulation	Suitable for high-voltage supports and isolation components.
Low thermal expansion behavior	Helps maintain geometry in temperature-changing equipment.
Vacuum-compatible ceramic surface	Useful for fixtures and insulating parts in vacuum systems.
Drawing-based machining	Supports custom plates, blocks, spacers, standoffs and holders.

Machinable Glass Ceramic Parts Benefits

Conventional machining of complex geometries
Machinable glass ceramic parts can be turned, milled, drilled and tapped with standard metalworking tools, allowing deep pockets, undercuts and multi-level fixtures that are difficult or costly in fully sintered ceramics.
Stable at high temperature with matched expansion
The material works continuously around 800 °C with peak excursions to about 1000 °C under no load, and its thermal expansion matches many metals and sealing glasses, which helps reduce stress at interfaces.
High-temperature electrical insulation
Machinable glass ceramic parts provide strong dielectric performance at elevated temperature and across a wide frequency range, making them suitable for high-voltage standoffs, coil supports and insulated mounts.
Low porosity and low outgassing for vacuum
When properly baked, machinable glass ceramic exhibits zero or near-zero open porosity and very low outgassing, which supports use in high and ultra-high vacuum chambers and pumping lines.
Dimensional stability without post-firing
Parts are machined in the final state so there is no shrinkage from post-sintering; this allows consistent tolerances on mating features and repeatable interchange of machinable glass ceramic parts in long-term production.

Machinable Glass Ceramic Parts Properties

Machinable Glass Ceramic Physical Properties
Property	Typical value	Notes
Purity	≥ 99.9 %	Some grades can reach 99.99 %
Density	2.5–2.6 g/cm³	Archimedes method
Open porosity	≤ 0.07 %	Effectively non-porous
Water absorption	0 %	No measurable uptake
Colour	White	Clean, uniform appearance
Hardness (Mohs)	4–5 (up to 6–7)	Depending on grade
Machinable Glass Ceramic Thermal Properties
Property	Typical value	Notes
Coefficient of thermal expansion (CTE)	72 × 10⁻⁷ /°C	Average from −50 to 200 °C
CTE 25–300 °C	90 × 10⁻⁷ /°C	For design over mid-range temperatures
CTE 25–600 °C	112 × 10⁻⁷ /°C
CTE 25–800 °C	123 × 10⁻⁷ /°C
Thermal conductivity	1.7 W/m·K	At 25 °C
Continuous use temperature	~800 °C	Long-term service
Short-term maximum temperature	~1000 °C	Depends on load and atmosphere
Machinable Glass Ceramic Mechanical Properties
Property	Typical value	Notes
Young’s modulus	≈ 65 GPa	Room temperature
Flexural strength	≥ 100 MPa	Three-point bending
Compressive strength	≥ 500 MPa	Room temperature
Impact resistance	≥ 2.56 kJ/m²	Indicative value for brittle fracture
Poisson’s ratio	≈ 0.29
Shear modulus	≈ 25 GPa	Derived from E and ν
Machinable Glass Ceramic Electrical Properties
Property	Typical value	Notes
Dielectric constant (1 kHz)	6–7	25 °C
Dielectric loss (tan δ, 1 kHz)	1–4 × 10⁻³	25 °C
Dielectric strength	> 40 kV/mm	Sample thickness 1 mm
Volume resistivity @ 25 °C	≈ 1.0 × 10¹⁶ Ω·cm	High insulation level
Volume resistivity @ 200 °C	≈ 1.5 × 10¹² Ω·cm
Volume resistivity @ 500 °C	≈ 1.1 × 10⁹ Ω·cm

Machinable Glass Ceramic vs Other Materials

Material	When It Fits Better	Main Limitation
Machinable Glass Ceramic	Suitable for complex shapes, fast prototype machining, electrical insulation and vacuum-compatible fixtures without post-sintering shrinkage.	Lower wear resistance and mechanical strength than fully sintered alumina or zirconia.
Alumina Ceramic	Suitable for higher hardness, wear resistance, electrical insulation and stable high-temperature structural parts.	Complex 3D machining can be more difficult and may require sintered blank planning.
Zirconia Ceramic	Suitable for higher toughness, wear resistance and precision mechanical components under load.	Not usually selected when low thermal expansion and easy machining are the main priorities.
Boron Nitride Ceramic	Suitable for high-temperature insulation, molten-metal contact and non-wetting applications.	Softer and less suitable for some load-bearing or abrasion-heavy parts.
Aluminum Nitride Ceramic	Suitable when thermal conductivity and electrical insulation are both required.	More specialized and should be selected only when heat dissipation is a core requirement.

Machinable Glass Ceramic Parts Specifications

Machinable Glass Ceramic Parts
Item No.	Diameter (mm)	Thickness (mm)
AT-KJG-TC9001	Customize

Machinable Glass Ceramic Parts Packaging

Each machinable glass ceramic part or matched set is separated in foam or soft-lined compartments to prevent edge chipping and surface contact during transport.

Application Scenarios for Machinable Glass Ceramic Parts

Machinable glass ceramic parts are often selected for equipment designs that require insulation, complex geometry, dimensional stability and clean ceramic surfaces in limited-volume production.

Application Scenario	Recommended Copy
Vacuum Equipment Insulation	Machinable glass ceramic parts are used as insulation blocks, spacers, standoffs and support plates in vacuum chambers and test equipment. They help isolate electrical paths while maintaining stable geometry around mounting points and feedthrough areas.
Laser and Optical Fixtures	The material is suitable for fixture plates, alignment supports and insulating holders in laser and optical modules. It allows machined holes, slots and pockets for precise positioning without using conductive metal parts.
High-Voltage Assemblies	Machinable glass ceramic components can be used as insulating spacers, washers, standoffs and support blocks in high-voltage systems. Proper edge radius, creepage distance and screw pressure should be reviewed before production.
Thermal Test Fixtures	These parts are used in thermal test systems, heating fixtures and temperature-sensitive assemblies where ceramic insulation and shape stability are required. The design should consider temperature range, thermal cycling and mechanical load.
Analytical Instruments	Machinable glass ceramic plates, holders and insulating supports are used in laboratory and analytical equipment. They are useful when the part needs clean ceramic behavior, small-batch customization and accurate machined features.
Prototype Ceramic Components	For early-stage equipment development, machinable glass ceramic allows engineers to test complex ceramic part designs before moving to higher-volume sintered ceramic solutions. It is suitable for low-volume custom parts and design verification.

Machinable Glass Ceramic Parts – Use Guide

Installation

1. Verify that mating metal parts are deburred and free from sharp burrs or raised edges to avoid point loading on machinable glass ceramic parts.
2. Use flat washers or load-spreading pads where bolts clamp directly onto ceramic surfaces.
3. Avoid overtightening fasteners; set torque levels appropriate for brittle materials and, where possible, test on sample parts before final assembly.
Use

1. Keep operating temperatures within the proven range for machinable glass ceramic parts, typically up to 800 °C for continuous use and peak temperatures near 1000 °C without mechanical load.
2. Limit rapid temperature changes; preheat assemblies gradually and avoid exposing only one side of a thick part to sudden heating or cooling.
3. In vacuum and controlled atmospheres, follow an agreed bake-out schedule so that outgassing is minimized before the ceramic is placed near sensitive detectors or optics.
Storage

1. Store machinable glass ceramic parts in padded trays or boxes with separators between parts to reduce the chance of chipping.
2. Keep parts in a dry, clean area away from abrasive dust or loose metal chips.
3. Maintain labels and drawing references with each batch so that orientation and critical faces remain traceable for installation.
Cleaning

Before vacuum or optical use, clean machinable glass ceramic parts with suitable solvents or detergents and deionized water, then dry completely; avoid leaving lint or particles on sealing or alignment surfaces.
For high-vacuum service, complete a controlled bake-out step after cleaning to remove residual moisture and surface volatiles.
Precautions and Typical Misuse Scenarios

1. Issue: Cracking after rapid thermal cycling
Symptom: A machinable glass ceramic part develops cracks or chips after repeated rapid heating and cooling.
Likely cause: Thermal gradients exceed the material’s shock resistance.
Mitigation: Reduce ramp rates, increase soak time for uniform temperature and redesign to reduce thick-to-thin transitions and sharp internal corners.

2. Issue: Edge chipping during assembly
Symptom: Small chips appear on edges or hole entrances when machined parts are installed.
Likely cause: Hard contact with metal tooling or over-tightened fasteners.
Mitigation: Use alignment pins or soft jaw tooling during installation and apply torque in steps while monitoring for movement or sound changes.

3. Issue: Unexpected tracking or arcing at high voltage
Symptom: Localized discharge paths across the surface of machinable glass ceramic parts under high voltage.
Likely cause: Surface contamination films, inadequate creepage distance or unintended sharp points.
Mitigation: Improve cleaning, round sharp edges in high-field regions and increase spacing or add shields along the path between conductors.

Machinable Glass Ceramic Parts FAQ

Q: What is the maximum operating temperature of machinable glass ceramic parts?
A: Machinable glass ceramic parts based on Macor-type materials typically operate continuously around 800 °C, with short-term peak temperatures up to about 1000 °C when not under mechanical load.
Q: Can machinable glass ceramic parts be used in high or ultra-high vacuum systems?
A: Yes, machinable glass ceramic parts are widely used as supports and insulators in vacuum equipment because the material has zero or near-zero open porosity and, when baked properly, shows very low outgassing.
Q: How do machinable glass ceramic parts compare with fully sintered alumina components?
A: Machinable glass ceramic parts are easier to machine into complex 3D shapes and do not require post-sinter shrinkage allowances, but fully sintered alumina generally offers higher hardness and better wear resistance; the choice depends on whether geometry flexibility or wear resistance is more important.
Q: What part sizes are practical for machinable glass ceramic machining?
A: Standard slab and rod sizes cover a range from small blanks for compact parts up to larger plates and blocks that can be machined into sizeable fixtures; practical limits depend on available stock dimensions and the stiffness required in the final machinable glass ceramic part.
Q: What information should be included on drawings for machinable glass ceramic parts?
A: Drawings for machinable glass ceramic parts should define all critical dimensions and tolerances, reference faces, hole details, thread specifications, surface finish on sealing or optical areas, and any special notes on temperature, atmosphere or electrical isolation requirements.
Q: Can machinable glass ceramic parts be threaded?
A: Yes, simple internal or external threads can often be machined when the design provides enough wall thickness and avoids sharp stress concentration. Thread size, engagement length and loading condition should be reviewed before production.
Q: Are machinable glass ceramic parts suitable for load-bearing structures?
A: They can be used for fixtures, supports and spacers, but they should not be treated like metal parts. Load direction, screw pressure, vibration and edge design should be reviewed before use.
Q: How can edge chipping be reduced during assembly?
A: Use chamfers or small radii on exposed edges, avoid hard metal impact, apply torque gradually and use load-spreading washers where possible.
Q: When should alumina be selected instead of machinable glass ceramic?
A: Alumina is usually better when the part needs higher hardness, stronger wear resistance or long-term mechanical durability under abrasive contact.
Q: What files are useful for a custom machining review?
A: 2D drawings, 3D models, marked sketches, reference samples and notes about temperature, vacuum, voltage, load and critical inspection dimensions are useful for review.

Information Needed for a Machinable Glass Ceramic Parts Quotation

To quote machinable glass ceramic parts accurately, please provide the drawing or sample, target temperature, atmosphere or vacuum level, voltage or insulation requirement, critical dimensions, surface finish areas, quantity and any assembly constraints. ADCERAX will review material suitability, machining risk, edge details and inspection points before quotation.

RFQ Information	Why It Matters
Drawing or sample	Confirms geometry, tolerance and machining feasibility.
Temperature range	Helps check whether the material is suitable for continuous or peak use.
Vacuum or atmosphere	Supports cleaning, bake-out and low-outgassing discussion.
Voltage or insulation requirement	Helps review creepage distance, edge radius and spacing.
Critical dimensions	Identifies which features need tighter inspection.
Assembly method	Helps reduce edge chipping, cracking and over-tightening risk.
Quantity and delivery need	Supports quotation planning and production scheduling.

Catalogue No.	AT-KJG-TC9001
Density	2.52 g/cm³
CTE (25–300°C)	9.0 ×10⁻⁶ /K
Max Operating Temperature (Under Load)	800°C
Thermal Conductivity (25°C)	1.46 W/m·K

Custom Machinable Glass Ceramic Parts – CNC-Machined Complex Shapes and Cavities