Alumina Ceramic Insulators for Electrical & Electronic Applications
Kosremic manufactures alumina electrical insulators in ring, tube, bushing and spacer forms — high dielectric strength, stable volume resistivity, and custom geometries machined to your drawing. Purity grades from 95% to 99%, OEM per drawing.
Alumina Insulator Specifications by Purity Grade
Electrical performance drives insulator selection. Compare dielectric strength, volume resistivity, dielectric constant and dissipation factor across purity grades — final values are confirmed by the batch datasheet.
| Property | 95% Alumina | 96% Alumina | 99% Alumina |
|---|
Where a test method applies, results are reported as tested per applicable ASTM methods.
What the Electrical Specifications Mean for Your Design
| Feature | Technical Value |
|---|---|
| Dielectric strength (kV/mm) | Sets the voltage your insulation gap can hold — the first filter for high voltage assemblies. |
| Volume resistivity (Ω·cm) | Keeps leakage current low in continuous electrical service. |
| Dielectric constant / dissipation factor (1 MHz) | Determines signal loss and heating in high frequency and RF applications. |
| Max service temperature (°C) | One material covers both electrical insulation and elevated-temperature duty. |
| Custom machining per drawing | Threads, grooves and flanges machined to your assembly — the insulator arrives ready to install. |
Insulator Forms We Manufacture
Alumina Insulator Rings
The most common insulator geometry — concentric rings for conductor isolation, electrode spacing and sealing-adjacent insulation. This page covers insulation-duty rings in full; for rings whose primary job is sealing or wear, see our alumina ceramic seal rings.
Alumina Insulator Tubes
Single-bore and multi-bore tubes for conductor pass-through and sensor insulation. For tube-first specifications and full size ranges, see ceramic tubes.
Alumina Insulator Bushings
Stepped and flanged bushings that insulate and locate a conductor through a housing wall. For bushing-first specifications, see ceramic bushings.
Alumina Insulator Spacers & Standoffs
Precision spacers and standoffs that hold conductors at a fixed distance with stable dielectric performance. Custom heights, threads and hole patterns per drawing.
95% vs 99% Alumina for Electrical Insulation
Both grades insulate well. The choice turns on how much dielectric margin, temperature headroom and surface finish your assembly needs.
| Dimension | 95% Alumina | 99% Alumina |
|---|---|---|
| Surface finish after grinding | Standard | Finer |
| Typical duty | General electrical insulation | High voltage / high frequency |
| Cost positioning | Practical | Higher |
Metallized Alumina Insulator
For brazed or soldered assemblies (feedthroughs, RF packages), alumina insulators can be supplied with Mo-Mn metallization. Tell us your joining process and we will confirm the metallization specification.
Where Alumina Insulators Work
Electrical Insulation Components
Alumina electrical insulators isolate conductors in switchgear components, connectors, heaters and instrument assemblies — anywhere a compact, rigid, heat-resistant insulator is required.
High Voltage Assemblies
High voltage alumina insulators provide the dielectric margin for power supplies, vacuum equipment and HV feedthrough housings. Grade selection follows your voltage, frequency and temperature window.
Feedthrough Insulators
Alumina insulator feedthrough components carry conductors through vacuum or pressure boundaries, typically brazed to metal via a metallized layer.
Thermocouple Insulators
Thermocouple alumina insulators (single-bore and multi-bore tubes) separate and protect thermocouple wires at measurement temperatures. A dedicated thermocouple protection tube page is planned.
Spark Plug Insulator Cores
Alumina is the classic material for spark plug insulator cores. We manufacture the ceramic insulator core per drawing.
Datasheets & Drawings
Datasheet — grade-specific electrical and mechanical property tables. Status: Available on request.
Drawing submission — send your 2D/3D drawing for manufacturability review and quotation.
Product Datasheet
Grade-specific electrical and mechanical property tables.
Status: Available on request
Submit Your Drawing
2D/3D drawing review with manufacturability feedback.
Frequently Asked Questions
What is an alumina insulator?
How do I read dielectric strength and volume resistivity when selecting a grade?
What forms do alumina insulators come in?
Should I choose 95% or 99% alumina?
What is your lead time, and can you customize?
Related Products
Ceramic TubesSingle-bore and multi-bore ceramic tubes for furnace and sensor applications.
Ceramic BushingsStepped and flanged ceramic bushings per drawing.
Alumina CeramicMaterial overview: grades, properties and available product forms.
Get Your Alumina Insulator Quotation
Send your drawing or your voltage, temperature and form requirements — our product managers will recommend a purity grade and return a manufacturable option with a fast quotation. Custom alumina insulators are our daily work.