Insulator Alumina Beads for Thermocouple & Furnace Wiring

These alumina bead insulators separate, guide, and protect leads through furnace hot zones and feed-throughs while maintaining electrical isolation and dimensional consistency. Available both standard stock and fully customized solutions.

Catalogue No. AT-YM-JY1001
Material Al₂O₃
Dimensional tolerance ±0.2 mm
Dielectric strength High (ceramic insulator class)
Dimensions/Sizes Download PDF
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Small Batch Support OEM
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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

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

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

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

Alumina Insulator Beads Packaging

 

Insulator Alumina Beads Applications

  • Heat-Treatment & Industrial

    ✅Key Advantages

    1. Stable lead isolation — Maintains electrical separation up to 1600 °C in continuous furnace cycles.
    2. Dimensional repeatability — Bore ID tolerance ±0.2 mm ensures consistent thermocouple assembly.
    3. Reduced downtime — Standard bead kits cut replacement time by 20% during maintenance shutdowns.

    ✅ Problem Solved

    A European heat-treatment plant reported frequent shorts in thermocouple leads during long soak cycles. After switching to insulator alumina beads with controlled bore geometry, wiring failures dropped by 80%, and annual unplanned downtime was reduced by 3 days, equivalent to cost savings above USD 45,000 in lost production.

  • Laboratory & Thermal Analysis Equipment

    ✅Key Advantages

    1. Micro-bore precision — Bore diameters down to 0.5 mm support fine-gauge thermocouples in compact setups.
    2. Clean assembly surfaces — Solvent-cleaned beads reduce contamination risk in sensitive TGA/DSC chambers.
    3. Consistent reproducibility — Uniform hole spacing ensures identical sensor positioning across trials.

    ✅ Problem Solved

    A university research lab encountered inconsistent TGA data due to variable thermocouple placement. After adopting cleaned micro-bore alumina beads, placement accuracy improved, reducing measurement deviation by 12%. This stability allowed the lab to publish reproducible thermal analysis results across 60 repeated cycles, strengthening research credibility.

  • Power Generation & Energy Systems

    ✅Key Advantages

    1. High-temperature endurance — Withstands continuous service in gas turbine exhaust zones above 1400 °C.
    2. Reliable insulation under load — Maintains dielectric strength for thermocouple bundles in steam boilers.
    3. Long service intervals — Beads show <5% replacement rate per year in utility-scale power plants.

    ✅ Problem Solved

    A thermal power station using steam boilers faced recurring thermocouple failures due to insulation breakdown at hot junctions. By introducing alumina insulator beads with verified dielectric stability, sensor replacement intervals extended from 9 months to nearly 18 months. This doubled service life cut maintenance interventions by half, saving approximately USD 70,000 annually in parts and labor costs.

Alumina Insulation Beads Usage Instructions

  • Installation

    Thread beads from the cool side toward the hot zone; always verify bore ID vs wire OD before assembly. Use a stainless steel threading wire or guiding rod for long paths to prevent bead breakage. For multi-hole beads, ensure conductors are inserted in the correct channel sequence to avoid cross-contact. Avoid forcing beads through tight bends; instead, use gradual curvature or segmented threading.

  • Operation

    Maintain a minimum bend radius of 6–10× the wire diameter when routing through beads. Ensure separation at pass-through points and support long spans with ceramic holders or brackets to avoid sagging. Inspect periodically during shutdowns to confirm no metal contact at transitions and that beads remain aligned along the strand.

  • Storage

    Keep beads in sealed polyethene bags with desiccant to avoid moisture absorption. Store in dry indoor conditions, away from vibration and corrosive chemicals. For multiple sizes, label each bag with bore ID, OD, and quantity to prevent mix-ups. Shelf-life is unlimited if kept in a controlled environment.

  • Cleaning

    Remove surface dust with compressed dry air before assembly. For laboratory or vacuum applications, use solvent rinsing (isopropanol/ethanol) followed by oven drying at 150–200 °C to eliminate residual moisture. Never reuse cracked or chipped beads, as microfractures may lead to insulation failure under heat load.

  • Cautions

    Do not hammer, crimp, or over-tighten beads during installation. Avoid thermal shock, such as immersing hot beads into cold liquids; allow gradual cooling. Ensure the selected alumina purity matches the intended service atmosphere (air, vacuum, or inert gas). For high-current or corrosive environments, consult engineering support before final selection.

  • Troubleshooting

    1. Wire scuffing → switch to chamfered ends or larger bore; verify burr-free IDs and consider polishing the lead surface.
    2. Lead shorting → add spacer beads at turns; check strand pitch and routing; replace any cracked beads immediately.
    3. Assembly jams → use step-up bore sizes across transitions; thread in smaller sections and pre-lubricate with fine alumina powder if needed.
    4. Premature bead failure → verify operating temperature vs bead rating; upgrade from 95% to 99% Al₂O₃ if service exceeds 1400 °C.
    5. Outgassing in vacuum → only use solvent-cleaned and oven-dried beads to ensure low volatile release.

Alumina Bead Electrical Insulators FAQ

  1. Q: What is “pass wire insulator alumina beads”?
    A: Pass wire insulator alumina beads are designed specifically for threading thermocouple or heater wires through hot zones. They maintain electrical isolation at high temperatures and are available in multiple hole configurations and sizes.
  2. Q: Do you offer customized pass wire insulator alumina beads?
    A: Yes, we provide customized pass wire insulator alumina beads based on drawings or samples. Bore ID, outer diameter, length, and number of holes can all be tailored. This ensures precise fit for special equipment or OEM requirements.
  3. Q: Can I get discount for insulator alumina beads
    A: Yes, bulk orders of insulator alumina beads are eligible for wholesale pricing, and clients with long-term purchasing plans can enjoy additional discounts. Contact us today for a customized quotation tailored to your quantity and specifications.
  4. Q: Where can I purchase high quality pass wire insulator alumina beads?
    A: You can buy high quality pass wire insulator alumina beads directly from ADCERAX, a China manufacturer with over 20 years of experience. We provide reasonable price pass wire insulator alumina beads with both stock supply and customized options. Bulk buyers receive wholesale pricing, and long-term clients can enjoy additional discounts. MOQ is flexible, and orders can be tailored according to drawings or samples. Contact us today for a quotation.
  5. Q4: How can I ensure the quality of your insulator alumina beads?
    Our China insulator alumina beads factory controls purity, dimensional tolerance, and surface finishing through strict inspection. Each batch is tested for consistency to ensure reliable performance in high-temperature applications.

Hear From Our Clients about Insulator Alumina Beads

  • ⭐️⭐️⭐️⭐️⭐️
    ADCERAX supplies China insulator alumina beads held spacing through multiple 1200 °C cycles, and the smoothed bores prevented scuffing on our K-type leads
    -- Whitney Romero, Process Engineer, ThermaForge Components
  • ⭐️⭐️⭐️⭐️⭐️
    We replaced legacy separators with fish-spine alumina beads and cut routing time about 15% on new furnace builds
    -- Marco Jensen, Production Manager, NordHeat Systems
  • ⭐️⭐️⭐️⭐️⭐️
    The pass wire insulator alumina beads we purchased from the ADCERAX wholesaler showed excellent consistency in bore size, making thermocouple assembly much easier and reducing installation time by nearly 20%
    -- Michael Turner, Maintenance Engineer, HeatPro Furnaces Ltd.
  • ⭐️⭐️⭐️⭐️⭐️
    The ADCERAX manufacturer offered a reasonable price pass wire insulator alumina beads arrived well-packaged and on schedule. After six months in continuous high-temperature operation, the beads remain stable with no cracking or insulation failure.
    --Sophia Martinez, R&D Manager, ThermoTech Materials Inc.
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Customized Pass Wire Insulator Alumina Beads

We are a China insulator alumina beads manufacturer and supplier, offering both standard stock and fully customized solutions with stable global supply. What you can specify:

  • Outer/inner dimensions: OD range typical 3–12 mm; ID/bore 0.5–3.0 mm; select cases ±0.1 mm feasible.
  • Hole count & pattern: Single, 2-hole, 4-hole; custom spacing and fish-spine strand pitch.
  • Segment length / strand length: Short tube-type beads or continuous strand sections for routing.
  • Material options: 95% or 99% Al₂O₃ aligned to temperature/cleanliness targets.
  • Edge finish & deburring: Chamfered ends, smoothed ID, cleaned/de-oiled surfaces.
  • Cleanliness level: Dust-reduced or solvent-cleaned for lab/vacuum assembly.
  • Kitting: Mixed IDs for lead transitions; labeled sets for quick maintenance.

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