An alumina ceramic classifier wheel is the rotating ceramic part inside an air classifier, classifier mill or jet mill. It works with the airflow to separate fine powder from coarse powder, and it is supplied as a wheel body with slots or blades and a bored hub, made to the geometry your equipment uses.
Dense Alumina Material Performance for Classifier Wheels
The six wheel references above list 95–99% Al₂O₃. The columns below support grade comparison; the grade and inspection criteria for the ordered wheel are set in the accepted specification.
Composition and Mechanical Reference
| Property / basis | 99.9% Al₂O₃ | 99.7% Al₂O₃ | 99.5% Al₂O₃ | 99% Al₂O₃ | 96% Al₂O₃ | 95% Al₂O₃ |
|---|---|---|---|---|---|---|
| Nominal Al₂O₃, wt% | 99.90 | 99.70 | 99.50 | 99.00 | 96 | 95 |
| IEC 60672-3 composition grouping | C799 | C799 | C799 | C795 | C795 | C795 |
| Density, g/cm³; typical | 3.94 | 3.94 | 3.90–3.92 | 3.80–3.91 | 3.70 | 3.75 |
| Flexural strength, MPa; 20°C; typical | 315–340 | 330 | 320–350 | 300–320 | 300 | 280 |
| Compressive strength, MPa; 20°C; typical | 2558–2900 | 2500 | 2400 | 2400 | 2000 | 2000 |
| Young’s modulus, GPa; typical | 359–375 | 370 | 365 | 355 | 275 at 20°C | 340 |
| KIC, MPa·m½; method-dependent | 3.8–4.2 | 3.6 | 3.5 | 3.3 | 3.5 at 20°C | 3.0 |
| Color | Ivory | Ivory | Ivory | Ivory | White | Ivory / white |
| Water absorption, %; selection limits except 96% | ≤0.01 | ≤0.05 | ≤0.10 | ≤0.10 | ≈0; typical, rounded | ≤0.20 |
| Mohs hardness; typical | 9 | 9 | 9 | 9 | — | 9 |
| Vickers hardness; HV1, 1 kgf; typical | — | — | — | — | 1600 | — |
*IEC C795/C799 identify material composition groups. Values are material-level; the ordered wheel drawing defines dimensions and acceptance. A dash marks a property to request when it governs selection.
Thermal Material Selection
| Property / basis | 99.9% Al₂O₃ | 99.7% Al₂O₃ | 99.5% Al₂O₃ | 99% Al₂O₃ | 96% Al₂O₃ | 95% Al₂O₃ |
|---|---|---|---|---|---|---|
| Thermal conductivity, W/(m·K); typical | 35–42 at 25°C | 35–40 at 25°C | 30–38 at 25°C | 24 at 25°C | 25 at 20°C | 18–25 at 25°C |
| Mean CTE, 10⁻⁶/K; stated interval | 7.6; 25–800°C | 7.6; 25–800°C | 7.6; 25–800°C | 7.2; 25–800°C | 8.2; 25–1000°C | 7.6; 25–800°C |
| Material service-temperature guide, °C; application-dependent | 1750 | 1700 | 1650 | 1600 | 1600 maximum in air | 1400 |
*The temperature values guide material selection. Set the operating envelope for the wheel, hub, joints, shaft and bearings using the actual load, atmosphere, gradient, dwell and cycle; the 96% column's 1600°C value is a maximum-in-air material reference.
Electrical Material Selection
| Property / basis | 99.9% Al₂O₃ | 99.7% Al₂O₃ | 99.5% Al₂O₃ | 99% Al₂O₃ | 96% Al₂O₃ | 95% Al₂O₃ |
|---|---|---|---|---|---|---|
| Dielectric strength, kV/mm; typical; specimen conditions | 10; 5 mm | 10; 5 mm | 10; 5 mm | 10; 5 mm | 8.3; AC, 6.35 mm | 10; 5 mm |
| Relative permittivity; 1 MHz; typical | 9.8 at 25°C | 9.8 at 25°C | 9.7 at 25°C | 9.6 at 25°C | 9.0 at room temperature | 9.4 at 25°C |
| Dissipation factor; 1 MHz | <0.0001 at 25°C | <0.0001 at 25°C | <0.0001 at 25°C | 0.0006 at 25°C | 0.0002 at 20°C | 0.0004 at 25°C |
| Volume resistivity, Ω·cm; 20°C | >10¹⁴ | >10¹⁴ | >10¹⁴ | >10¹⁴ | 10¹⁴; typical | >10¹² |
*For an electrical duty, define the finished component or assembly test, temperature, specimen or part geometry, method, sampling and acceptance limit.
Alumina Ceramic Classifier Wheel Specifications
| Alumina Grading Wheel | ||||
| Item No. | Outer Diameter（mm） | Inner Diameter （mm） | Height （mm） | Purity |
| AT-SM-A001 | 50 | 30 | 70 | 95%-99% |
| AT-SM-A002 | 80 | 65 | 90 | 95%-99% |
| AT-SM-A003 | 100 | 75 | 80 | 95%-99% |
| AT-SM-A004 | 155 | 135 | 95 | 95%-99% |
| AT-SM-A005 | 250 | 220 | 100 | 95%-99% |
| AT-SM-A006 | 260 | 240 | 120 | 95%-99% |
Download the Product Catalogue
How to Choose an Alumina Ceramic Classifier Wheel
Most enquiries come from five situations. Find yours in the table below, then check the two columns that matter for it. If you are not sure which one applies, send the wheel drawing or a photo of the worn part and we will tell you what we need.
| Your situation | What decides the wheel you need | What we will ask you first |
|---|---|---|
| You build air classifiers, classifier mills or jet mills and need the ceramic wheel as a bought-in component | The drawing revision, the rotation, the bore and hub fit, and the wheel envelope inside the housing. | Equipment model and the drawing or 3D model; the direction of rotation; whether the wheel is supplied alone or as part of a rotor assembly. |
| You run a powder line and a wheel is worn out and needs replacing | The part number or the worn wheel itself, plus the slot and blade geometry that changed during wear. | Photos of the worn wheel, the part number if it is visible, and how long it lasted; whether anything else changed before it failed. |
| You classify an abrasive mineral or ceramic powder | Where the wear appears — slot edges, blade leading edges, the disc or the rim — and how you measure it. | Powder type, typical particle size, throughput, and the wear measurement you already use. |
| You classify a powder where metal pickup must stay low | The alumina grade and the full powder contact path, not only the wheel body. | The elements you monitor, your current analytical method and detection limits, and your allowed increase over the incoming powder. |
| You buy spare parts or maintain powder equipment for others | A repeatable specification: the accepted drawing, grade and sample kept on file. | Your expected quantities and whether you want one size or several; the parts you normally keep in stock. |
| You need a size that is not in the listed table | The drawing-based custom route, approximately 80–600 mm OD. | A sketch, drawing or sample with the main dimensions; the machine model; and any speed or balance requirement you already know. |
Two things decide whether a ceramic wheel fits your machine: the bore and hub interface, and the slot and blade geometry together with the direction of rotation. The same outside diameter does not make two wheels interchangeable — slot count, slot width, angle, effective height and the hub fit all have to match.
Alumina vs Silicon Nitride, Zirconia and Metal Classifier Wheels
| Wheel material | Normally chosen when | What to watch |
|---|---|---|
| Dense alumina (Al₂O₃) | Abrasive powders, and powders where metal pickup must stay low. Widely used for mineral, ceramic, pigment, chemical and battery-material classification. | Edges and thin blade sections are the first places to inspect. Dense alumina has good hardness and wear resistance but less tolerance for impact than some other ceramics. |
| Silicon nitride (Si₃N₄) | Where impact and thermal shock are the concern and edge chipping drives replacement. | Different grade family and a different price level. Request the grade data for the actual material if you compare it with alumina. |
| Zirconia (ZrO₂) | Where a dense, high-strength ceramic is wanted and the powder is sensitive to contamination from the wheel. | Considerably heavier than alumina, which changes the rotating mass and the balance work on the assembly. Confirm the grade family, because zirconia grades differ a lot. |
| Steel or alloy wheels | Low-abrasion powders, or where a metal wheel has been acceptable and cost drives the decision. | Metal is removed at the blade and slot edges by abrasive powder, and that material enters the powder stream. Wear changes the geometry, so the cut size drifts between replacements. |
Alumina Ceramic Classifier Wheel Packaging
- Each alumina ceramic classifier wheel is wrapped with soft cushioning material around the blades and bore to minimize impact and edge chipping during transit.
