Insulator alumina beads are small, high-alumina ceramic components used to electrically isolate and mechanically guide metal leads (thermocouple wires, heater/resistance wires) in hot zones of furnaces, kilns, vacuum chambers, and lab equipment. They are supplied as single beads, short tube-type segments, or flexible fish-spine strands with controlled hole geometry to keep conductors separated, prevent shorting or arcing, and simplify routing through baffles and feed-throughs.
Insulator Alumina Beads Benefits
- Consistent hole geometry: Controlled ID/spacing reduces mis-threading and improves assembly yield.
- High-temperature stability: Al₂O₃ matrix resists softening and creep in prolonged hot-zone exposure.
- Clean edges and deburring: Smooth bore and chamfer options protect wire insulation and metal sheaths.
- Low open porosity options: Minimizes contamination traps; supports vacuum/inert environments.
- Multiple formats: Single bead, short segment, and fish-spine strands fit straight or flex routing.
Insulation Alumina Ceramic Beads Properties
| Property | Unit | 99.7% Al₂O₃ | 99.5% Al₂O₃ | 99% Al₂O₃ | 96% Al₂O₃ |
| Color | Ivory White | Ivory White | Ivory White | Ivory White | |
| Density | g/cm³ | 3.94 | 3.9 | 3.83 | 3.6-3.75 |
| Water Absorption | % | 0 | 0 | 0 | 0 |
| Hardness | Mohs Hardness | 9.1 | 9 | 9 | 8.8 |
| Flexural Strength (20°C) | Mpa | 330 | 320 | 300 | 260 |
| Compressive Strength (20°C) | Mpa | 2300 | 2300 | 2210 | 1910 |
| Maximum Operating Temperature | °C | 1730 | 1700 | 1680 | 1450 |
| Thermal Expansion Coefficient(25°C to 800°C) | 10⁻⁶/°C | 7.6 | 7.6 | 7.6 | 7.6 |
| Thermal Conductivity (25°C) | W/(m·K) | 29 | 27 | 24 | 22 |
| Dielectric Strength (5mm thickness) | AC-kv/mm | 22 | 21 | 19 | 15 |
| Dielectric Loss at 25°C@1MHz | --- | < 0.0001 | < 0.0001 | 0.0003 | 0.0004 |
| Dielectric Constant at 25°C@1MHz | --- | 9.8 | 9.7 | 9.5 | 9.2 |
| Volume Resistivity (20°C) | Ω·cm³ | >10¹⁴ | >10¹⁴ | >10¹⁴ | >10¹⁴ |
| Volume Resistivity (300°C) | Ω·cm³ | 2*10¹² | 2*10¹² | 4*10¹¹ | 2*10¹¹ |
Insulator Alumina Beads Specifications
Type 1: Single hole pass wire insulator alumina beads

| Item | Bottom outer diameter(mm) | Boss outer diameter (mm) | Height(mm) | Hole Dia (mm) |
| AT-YM-JY1001 | Ø20 | Ø14 | 11 | Ø8 |
| AT-YM-JY1002 | Ø22 | Ø15 | 13 | Ø9 |
| AT-YM-JY1003 | Ø9 | Ø6 | 6 | Ø3.5 |
| AT-YM-JY1004 | Ø9 | Ø5 | 12 | Ø3 |
| AT-YM-JY1005 | Ø15 | Ø10 | 12 | Ø7 |
| AT-YM-JY1006 | Ø17 | Ø11 | 13 | Ø7.5 |
| AT-YM-JY1007 | Ø18 | Ø12 | 13 | Ø7 |
| AT-YM-JY1008 | Ø18 | Ø12 | 11 | Ø6.5 |
| AT-YM-JY1009 | Ø8 | Ø6 | 5 | Ø2.5 |
Type 2: two holes pass wire insulator alumina beads

| Item | Bottom outer diameter(mm) | Boss outer diameter (mm) | Height(mm) | Hole Dia (mm) |
| AT-YM-JY2001 | Ø6 | Ø5 | 5.5 | Ø1 |
| AT-YM-JY2002 | Ø8 | Ø7 | 7 | Ø2 |
| AT-YM-JY2003 | Ø8 | Ø7 | 7 | Ø2.5 |
| AT-YM-JY2004 | Ø10 | Ø8 | 7 | Ø2.5 |
| AT-YM-JY2005 | Ø11 | Ø9 | 9 | Ø3 |
| AT-YM-JY2006 | Ø12 | Ø10 | 8 | Ø2.5 |
| AT-YM-JY2007 | Ø13 | Ø12 | 7 | Ø3.5 |
| AT-YM-JY2008 | Ø14 | Ø10 | 10 | Ø3.5 |
| AT-YM-JY2009 | Ø14 | Ø11 | 9 | Ø3 |
| AT-YM-JY2010 | Ø15 | Ø12.5 | 7 | Ø4 |
| AT-YM-JY2011 | Ø15 | Ø12 | 10 | Ø3.5 |
| AT-YM-JY2012 | Ø16 | Ø14 | 11 | Ø4 |
| AT-YM-JY2013 | Ø16 | Ø12 | 10 | Ø7.5 |
| AT-YM-JY2014 | Ø16 | Ø10 | 10 | Ø3 |
| AT-YM-JY2015 | Ø16 | Ø12 | 10 | Ø3.5 |
| AT-YM-JY2016 | Ø17 | Ø15 | 12 | Ø4 |
| AT-YM-JY2017 | Ø18 | Ø14 | 11 | Ø4 |
| AT-YM-JY2018 | Ø20 | Ø14 | 12 | Ø4.5 |
Type 3: Alumina Fish Spine Beads

| Item | Outer Dia (mm) | Inner Dia (mm) | Height (mm) |
| AT-YM-YJ1001 | 4 | 1.5 | 4 |
| AT-YM-YJ1002 | 4 | 2 | 4 |
| AT-YM-YJ1003 | 5 | 2.5 | 5 |
| AT-YM-YJ1004 | 6 | 2 | 6 |
| AT-YM-YJ1005 | 6 | 2.7 | 6.5 |
| AT-YM-YJ1006 | 7 | 3.5 | 7 |
| AT-YM-YJ1007 | 8 | 4 | 8 |
| AT-YM-YJ1008 | 9 | 4.5 | 8.5 |
| AT-YM-YJ1009 | 9.5 | 5.2 | 8 |
| AT-YM-YJ1010 | 10.5 | 5.5 | 9 |
| AT-YM-YJ1011 | 13 | 7.5 | 9 |
Alumina Insulator Beads Packaging
- China insulator alumina beads are are packed in poly-bagged or carton with inner cushioning







