Guides / Applications

Why Instrument Builders Keep Ending Up in Ceramic

July 16, 2026

Mass spectrometers, electron microscopes, chromatography systems, semiconductor metrology and laboratory automation all end up with ceramic parts for the same reason: the part has to insulate, stay dimensionally stable, resist whatever it touches and not contaminate the measurement.

Few materials do all four. That is why instrument work is one of the steadiest sources of ceramic RFQs.

What the parts usually are

• Insulator standoffs, spacers and washers carrying voltage across a gap
• Sample holders and stages that must not react with the sample
• Feedthrough bodies where a conductor crosses a vacuum wall
• Guides, bearings and slides where a non magnetic, non lubricated surface is needed
• Ion optics mounts and apertures where position stability matters more than strength
• Heater and thermocouple supports in ovens and sources

The four requirements that drive grade choice

1. Dielectric performance. High purity alumina is the usual answer. Purity and density both raise breakdown strength, and porosity lowers it. Macor is excellent dielectrically but weak mechanically. See which alumina purity do you actually need.

2. Vacuum compatibility. Dense oxide ceramics outgas very little. Two practical points: porous or machinable grades behave differently, and bakeout temperature needs stating, because a part that is fine at 150 degrees C may not be at 300.

3. Chemical inertness and cleanliness. The part must not add anything to the measurement. That means asking about surface finish, cleaning method and whether grinding coolant or lapping slurry can be trapped in pores or corners.

4. Dimensional stability. Low thermal expansion helps, but stiffness matters more for optics and aperture positioning. Alumina and silicon carbide are both stiff. Zirconia is not, which surprises people who chose it for toughness.

Where instrument projects get caught out

Lead time against a build date. A sintered part that needs its own blank does not arrive in three weeks. Prototype in a machinable ceramic, then move to the sintered grade once geometry is settled. See when Macor is the right choice.

Threads. Instrument assemblies love M2 and M3 threads. Ceramic does not. Redesign to clearance holes with metal fasteners, a clamp, or a brazed insert. See holes, slots and threads in ceramic.

Thin unsupported features. Apertures, fins and knife edges look fine in CAD and chip in handling. Give them a flat or a radius.

Cleanliness after machining. A part that is dimensionally perfect and carries lapping residue in a corner will fail its first vacuum test. Specify the cleaning method, not just the finish.

Quantity of one. Many instrument parts are singles. That makes grinding from stock the right route almost every time, and it makes pressing tooling almost never the right answer.

What to put on the RFQ

1. Grade, or the environment including vacuum level and bakeout temperature
2. Voltage and creepage requirements for insulators
3. Which faces are functional, and their flatness and finish
4. Cleaning and packing requirements, including whether the part enters a cleanroom
5. Quantity now, and whether this is a prototype or a production instrument
6. The build date, because it usually decides the route

The general checklist is in the ceramic RFQ checklist, and the drawing limits are in the design guide.

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Frequently asked questions

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