What Is an Alumina Sand Mill Agitator Disc?
An alumina sand mill agitator disc is a ceramic disc mounted on the agitator shaft of a sand mill or bead mill. As the shaft turns, the discs set the grinding beads in motion, and the beads break down and disperse the particles in the slurry.
Plants switch from steel to alumina ceramic agitator discs when steel discs wear quickly in abrasive slurries, or when iron and other metal wear debris must be kept out of the product. Alumina is a dense, hard ceramic, so the disc surface that touches the beads and slurry is ceramic rather than metal.
ADCERAX supplies the ceramic disc itself, as single discs or as matched sets for a full disc stack. The shaft, spacers, locking parts, grinding chamber and grinding media remain part of your mill. For rotor-type mills, see our alumina ceramic dispersion rotor.
Alumina Sand Mill Agitator Disc – Standard Sizes (mm)
The five AT-SM models below are standard alumina agitator disc sizes. Choose a model by its full combination of outer diameter, inner diameter and height, not by outer diameter alone. Other diameters from Ø40 to 180 mm, as well as keyways, splines and slot patterns, are made to drawing.
| Alumina Ceramic Disc | ||||
| Item No. | Outer Diameter（mm） | Inner Diameter （mm） | Height （mm） | Purity |
| AT-SM-001 | 90 | 30 | 26 | 95%-99% |
| AT-SM-002 | 90 | 36 | 24 | 95%-99% |
| AT-SM-003 | 100 | 45 | 30 | 95%-99% |
| AT-SM-004 | 140 | 80 | 45 | 95%-99% |
| AT-SM-005 | 165 | 85 | 50 | 95%-99% |
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Alumina Grade Properties for Agitator Discs
ADCERAX alumina agitator discs are made in dense sintered alumina from 95% to 99.5% Al₂O₃. The typical values below are measured on material test samples. Use them to compare grades. They are not ratings for disc speed, torque, wear life or contamination, which depend on your mill, beads and slurry.
| Property (typical) | 95% Al₂O₃ AD-ALU-950 | 96% Al₂O₃ AD-ALU-960 | 99% Al₂O₃ AD-ALU-990 | 99.5% Al₂O₃ AD-ALU-995 |
|---|---|---|---|---|
| Bulk density, g/cm³ | 3.75 | 3.70 | 3.80–3.91 | 3.90–3.92 |
| Flexural strength, MPa (20 °C) | 280 | 300 | 300–320 | 320–350 |
| Compressive strength, MPa (20 °C) | 2000 | 2000 | 2400 | 2400 |
| Young's modulus, GPa | 340 | 275 (20 °C) | 355 | 365 |
| Fracture toughness KIC, MPa·m½ | 3.0 | 3.5 (20 °C) | 3.3 | 3.5 |
| Hardness | Mohs 9 | 1600 HV1 | Mohs 9 | Mohs 9 |
| Water absorption, % | ≤0.20 | ≈0 | ≤0.10 | ≤0.10 |
| Thermal expansion, 10⁻⁶/K | 7.6 (25–800 °C) | 8.2 (25–1000 °C) | 7.2 (25–800 °C) | 7.6 (25–800 °C) |
| Color | Ivory / white | White | Ivory | Ivory |
How to Choose an Alumina Agitator Disc for Your Bead Mill
1. Check the complete fit
Match the OD, bore, drive connection, rotation direction, slot pattern, disc spacing and chamber clearances. The same OD does not guarantee interchangeability. Send a drawing or worn disc for review.
2. Confirm the shaft connection
Choose a straight bore, keyway, spline or clamping hub to drawing. Review the fit and locking force when replacing steel—excessive force can crack ceramic.
3. Select the alumina grade
- 95% or 96%: General abrasive wet grinding.
- 99% or 99.5%: Formulations sensitive to additives in lower grades.
- Consider wear contamination from both the disc and your grinding beads.
4. Choose individual discs or a matched set
Use a matched set for a complete stack replacement. Keep disc thickness, spacing and total stack length consistent; mix designs only with engineering approval.
Alumina vs. Zirconia, Polyurethane and Steel Agitator Discs
| Material | Main advantages | Key considerations |
|---|---|---|
| Alumina | Hard, wear-resistant ceramic; generally costs less than zirconia. | Suits abrasive slurries where metallic wear debris is undesirable. Requires careful mounting and impact protection. |
| Zirconia | Higher toughness and impact resistance than alumina. | Heavier and more expensive; often paired with zirconia beads in high-energy mills. |
| Polyurethane | Elastic and impact-resistant. | Produces organic wear debris. Check compatibility with solvents, temperature and process chemistry. |
| Hardened steel | Strong and tolerant of rough handling. | Metallic wear debris may contaminate light-colored coatings, pigments and battery materials. |
Packaging and Inspection for Alumina Sand Mill Agitator Disc
- Each alumina sand mill agitator disc should be separated and protected to avoid edge impact, bore damage and ceramic-to-ceramic contact during transport. Parts with thin walls, keyways, slots or precision hub surfaces require additional foam positioning and reinforced outer packaging.
