Aluminium Oxide Abrasive Nylon Filament: Uses and Specs
Material guide · 6 min read · updated 2026-10-24
Aluminium oxide abrasive nylon carries Al2O3 grit through the nylon instead of silicon carbide. The grit is slightly softer than SiC but tougher, meaning it resists fracturing. That changes how the brush cuts and the finish it leaves.
This page explains when aluminium oxide is the better choice, how to pair grit and diameter, and how it compares with SiC and ceramic grain.
What the material is
Like other abrasive filaments, Al2O3 filament is made by extruding nylon with grit blended evenly through it, typically at 20–40 % by weight. The nylon base is often PA612 for its wet stiffness. As the filament wears, fresh grit is exposed along the whole length.
On one filament producer's hardness table, fused alumina is about 2,100 Knoop against about 2,480 for silicon carbide. The same producer notes that aluminium oxide grit is tougher and less likely to fracture than SiC, and that short trials have shown Al2O3 filament to be very effective even on steel parts.
Aluminium oxide vs silicon carbide vs ceramic
Grinding practice generally steers aluminium oxide toward ferrous metals and materials with high tensile strength, and silicon carbide toward titanium, aluminium and non-metals. In brush filament the difference is smaller than on grinding wheels, and one producer notes that comparisons of metal removal between the two are not clear-cut. Treat the table as a starting point and run a trial on your own part.
| Property | Aluminium oxide | Silicon carbide | Ceramic grain |
|---|---|---|---|
| Hardness (Knoop, producer data) | about 2,100 | about 2,480 | aluminium oxide based |
| Grit behaviour | Tough, resists fracture, dulls gradually | Very hard and sharp, more brittle | Microcrystalline, fractures into new sharp edges |
| General abrasive practice | Ferrous metals and high-tensile materials | Non-ferrous metals, stone, glass | Hard steels, stainless and alloys under pressure |
| Relative aggressiveness | Moderate | High | Highest |
Where aluminium oxide filament is used
- Light deburring and edge blending on steel and stainless parts, where a less brittle grit holds up.
- Fine finishing at 320–600 grit on small-diameter filament, such as miniature end brushes, cross-hole brushes and polishing wheels.
- CNC disc deburring brushes for machined parts.
- Cup and wheel brushes for drills and angle grinders where a less aggressive scratch pattern than SiC is wanted.
- Floor-care discs, where Al2O3 is offered as an alternative to SiC at similar grit sizes.
Choosing grit and diameter
Grit and filament diameter are paired: coarse grits need thick filament. Typical commercial ranges run from 36 grit on about 1.78 mm filament to 600 grit on about 0.30 mm, with 80–120 grit on 1.02–1.27 mm and 240–320 grit on 0.56–0.76 mm. The full table is in our silicon carbide filament guide, and the same sizes apply to aluminium oxide.
Two rules of thumb from filament producer data apply to both grits. Finer grit gives more cutting points per filament: 120 grit carries about 50 % more particles than 80 grit. A smaller filament diameter conforms better to edges, which often makes a finer filament more effective than a coarse one on deburring work.
Filament design levers
Before changing grit type, it is worth adjusting the filament itself, because filament design often has a bigger effect than the grit.
- Diameter: for the same filament volume, going from about 1.27 mm (50 mil) to 1.02 mm (40 mil) filament gives about 25 % more abrasive surface in contact with the part. Smaller filaments also tend to last longer.
- Crimp: crimped filament keeps the strands separated and gives a bushy, even face, while straight (level) filament packed densely at a short trim gives the most aggressive tool.
- Loading: 30 % grit has long been standard, and 40 % adds about one-third more cutting particles at some cost in filament durability.
- Blends: abrasive filament can be mixed with other fills. Producers describe tampico mixed with fine abrasive filament for softer floor buffing, and glass fibre mixed with abrasive filament for aggressive cleaning of newly rolled steel sheet.
Pros, cons and how to specify
- Pro: tough grit that resists fracture, well suited to ferrous work.
- Pro: good for consistent, finer finishes at higher grit numbers.
- Con: generally cuts less aggressively than SiC or ceramic at the same grit.
- Con: like all abrasive nylon, it is heat-limited, so control speed and use coolant where possible.
- Specify: grit type (aluminium oxide), grit size, filament diameter, crimp, trim length, brush format, mounting and maximum speed. Include the material and hardness of the part and the edge or Ra target in your RFQ.
Alternatives
For faster cutting on aluminium, brass and stone, use silicon carbide filament. For maximum stock removal on hardened or stainless steel, use ceramic grain filament. For cylinder bores, a flexible hone brush with abrasive globules gives a controlled cross-hatch instead of a brushed finish. Browse abrasive nylon brushes for available formats.
Frequently asked questions
- When should I use aluminium oxide instead of silicon carbide abrasive nylon?
- Choose aluminium oxide for steel and other high-tensile materials, and when a finer, more consistent finish matters more than cutting speed. Choose SiC for aluminium, brass, titanium, stone and glass, and for faster cutting.
- Is aluminium oxide abrasive nylon good for stainless steel?
- Yes, it is a common choice for light deburring and finishing of stainless. For heavy stock removal on stainless, ceramic grain filament usually cuts faster.
- What grit sizes are available in aluminium oxide filament?
- Commercial ranges commonly run from coarse grits around 80 up to fine grits of 320, 500 and 600, with diameter matched to grit.
- Does aluminium oxide filament last longer than silicon carbide?
- The grit itself resists fracture better, but brush life depends mostly on diameter, trim, speed, heat and pressure. Run a trial on your own part to compare.
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