An alumina ceramic pin is a precision locating part made from sintered alumina (Al₂O₃). Its job in a fixture is narrower than a metal pin's and more specific: hold the workpiece in position, and keep the locating point out of the electrical path. That combination is why it shows up in resistance and projection welding, in automation locating stations, and in any fixture where a steel pin would conduct current, pick up spatter, or soften under heat.
Alumina Ceramic Pin Specifications
Type 1: Alumina Ceramic Pin with Thread
| Alumina Ceramic Pin with Thread | |||||||
| Item No. | D （mm） | d (mm） | L1（mm） | L2 (mm） | L（mm） | M | Purity（%） |
| AT-CP-L001 | 6 | 4 | 7 | 3 | 9 | M2 | 96-99 |
| AT-CP-L002 | 7.5 | 5.5 | 25 | 16 | 29 | M2.5 | 96-99 |
| AT-CP-L003 | 8.6 | 6 | 65 | 40 | 70 | M3 | 96-99 |
| AT-CP-L004 | 9 | 7.5 | 50 | 35 | 55 | M3 | 96-99 |
| AT-CP-L005 | 10.5 | 9 | 43 | 27 | 47 | M5 | 96-99 |
| AT-CP-L006 | 11.8 | 8 | 67 | 42 | 72 | M4 | 96-99 |
| AT-CP-L007 | 12.5 | 8 | 52 | 33 | 56 | M8 | 96-99 |
| AT-CP-L008 | 15 | 10 | 46 | 24 | 50 | M8 | 96-99 |
| AT-CP-L009 | 16.4 | 11.5 | 80 | 40 | 84 | M10 | 96-99 |
| AT-CP-L010 | 18 | 14 | 53 | 35 | 57 | M12 | 96-99 |
| AT-CP-L011 | 21 | 15.5 | 45 | 35 | 48.5 | M14 | 96-99 |
| AT-CP-L012 | 23 | 16 | 32 | 22 | 36 | M14 | 96-99 |
Type 2: Alumina Ceramic Pin without Thread
| Alumina Ceramic Pin without Thread | |||||
| Item No. | D（mm） | d （mm） | L1 （mm） | L （mm） | Purity（%） |
| AT-CP-D001 | 8 | 6 | 9 | 11 | 96-99 |
| AT-CP-D002 | 10 | 6 | 5 | 8 | 96-99 |
| AT-CP-D003 | 11 | 5 | 13 | 16 | 96-99 |
| AT-CP-D004 | 11.8 | 6.3 | 15 | 18 | 96-99 |
| AT-CP-D005 | 12.6 | 8 | 16.5 | 20 | 96-99 |
| AT-CP-D006 | 13.5 | 10 | 20 | 24 | 96-99 |
| AT-CP-D007 | 15 | 10 | 14.5 | 17 | 96-99 |
| AT-CP-D008 | 16.4 | 11 | 21 | 23 | 96-99 |
| AT-CP-D009 | 18.5 | 14 | 40 | 45 | 96-99 |
| AT-CP-D010 | 20 | 15 | 43 | 47 | 96-99 |
| AT-CP-D011 | 24.2 | 16.2 | 52 | 56 | 96-99 |
| AT-CP-D012 | 25 | 20 | 16 | 20 | 96-99 |
| AT-CP-D013 | 30 | 18 | 40 | 46 | 96-99 |
Al2O3 Ceramic Pin Properties
Mechanical and physical properties
| Property | 999 | 997 | 995 | 990 | 960 | 950 |
|---|---|---|---|---|---|---|
| Al₂O₃ content (wt%) | 99.90 | 99.70 | 99.50 | 99.00 | 96 | 95 |
| IEC category | C799 | C799 | C799 | C795 | C795 | C795 |
| Color | Ivory | Ivory | Ivory | Ivory | White | Ivory / white |
| Bulk density (g/cm³) | 3.94 | 3.94 | 3.90–3.92 | 3.80–3.91 | 3.70 | 3.75 |
| Water absorption (%) | ≤0.01 | ≤0.05 | ≤0.10 | ≤0.10 | ≈0 | ≤0.20 |
| Flexural strength (MPa) | 315–340 | 330 | 320–350 | 300–320 | 300 | 280 |
| Compressive strength (MPa) | 2558–2900 | 2500 | 2400 | 2400 | 2000 | 2000 |
| Elastic modulus (GPa) | 359–375 | 370 | 365 | 355 | 275 | 340 |
| Fracture toughness KIC (MPa·m¹ᐟ²) | 3.8–4.2 | 3.6 | 3.5 | 3.3 | 3.5 | 3.0 |
| Mohs hardness | 9 | 9 | 9 | 9 | HV1 1600 | 9 |
Thermal and electrical properties
| Property | 999 | 997 | 995 | 990 | 960 | 950 |
|---|---|---|---|---|---|---|
| Thermal conductivity (W/m·K) | 35–42 | 35–40 | 30–38 | 24 | 25 | 18–25 |
| CTE (×10⁻⁶/K) | 7.6 | 7.6 | 7.6 | 7.2 | 8.2 | 7.6 |
| Grade selection limit (°C) | 1750 | 1700 | 1650 | 1600 | 1600 (max in air) | 1400 |
| Dielectric strength (kV/mm) | 10 | 10 | 10 | 10 | 8.3 AC | 10 |
| Relative permittivity (εr) | 9.8 | 9.8 | 9.7 | 9.6 | 9.0 | 9.4 |
| Dissipation factor (tan δ) | <0.0001 | <0.0001 | <0.0001 | 0.0006 | 0.0002 | 0.0004 |
| Volume resistivity (Ω·cm) | >10¹⁴ | >10¹⁴ | >10¹⁴ | >10¹⁴ | 10¹⁴ | >10¹² |
How to Choose the Right Alumina Pin for Your Fixture
Define the load, mounting method and fit before choosing a size or material grade.
1. Define the Working Load
Identify what the pin does and where the force acts:
- Locating or guiding: Check side loads on the stem.
- Welding fixtures: Check axial loads, electrode contact and electrical requirements.
- Repeated movement: Note impact, sliding contact and operating cycles.
Provide: the pin’s function, load direction and contact points.
2. Choose the Mounting Method
The mounting arrangement determines the shoulder position and supported length.
- Threaded mounting: Define the thread, seating face and engagement length.
- Bushing mounting: Define the bore, fit and supported length.
- Shoulder seating: Define the clamping arrangement and shoulder contact area.
Provide: a mounting drawing showing the shoulder, support and exposed stem.
3. Set the Fit with the Mating Part
Specify the fit against the actual workpiece hole, bushing or sleeve.
- Choose the required clearance, transition or interference fit.
- Include mating-part dimensions, tolerances and material.
- Account for temperature changes during operation.
Provide: the mating bore details, fit requirement and operating temperature.
4. Confirm the Alumina Grade
Select the grade against the defined mechanical, thermal and electrical requirements.
- Review wear resistance at the contact surface.
- Confirm temperature and insulation requirements.
- Evaluate 95–96% alumina where suitable; specify higher purity when the application requires it.
Higher purity does not eliminate alumina’s brittleness. Geometry and support still need review.
Final Geometry Check
A pin 8 mm in diameter and 80 mm long, with most of its length unsupported, needs particular attention under side load. Review the exposed length and support before changing the material grade.
Alumina Ceramic Pin Packaging
- Each alumina ceramic pin is first wrapped or separated in protective blister cells or foam slots to prevent ceramic-to-ceramic contact during transport.
