Testing Our New Ceramic Fiber Disc Brush on Stainless Steel: Parameters and Ra Results
Full parameters, full results — nothing held back except the formula. We put our new-generation 35 mm ceramic fiber disc brush — the resin-injected standard model — on a stainless steel workpiece and ran it at 8000 rpm with a 4 mm/s feed and 1 mm engagement under coolant. The surface came down from Ra 1.6–3.2 µm to Ra 0.2–0.4 µm, with one test group measuring Ra 0.3 µm from a Ra 1.6 start. This article publishes the complete setup so you can judge — and reproduce — the result on your own line.
Ceramic fiber disc brushes occupy a quiet corner of the finishing world: no grit ratings, no nylon carrier, no abrasive grains glued into a filament. The working element is the ceramic fiber itself. That construction is exactly why the numbers below are worth reading — the same brush that starts at Ra 3.2 finishes at Ra 0.4 without changing tools.
1. What a Ceramic Fiber Disc Brush Actually Is
Most "ceramic" brushes on the market are abrasive filament brushes: nylon filaments with ceramic grains embedded in them, sized by grit number. Our ceramic fiber disc brush is a different animal. Each bristle tuft is a bundle of continuous sintered ceramic micro-fibers — pure ceramic fiber, no nylon base — and each tuft contains hundreds to a thousand individual fibers that act as cutting edges. The tufts are locked into a resin-injected steel disc base, which gives the brush its rigidity and clears chips out of the working face.
Three consequences follow from that structure:
- Self-sharpening. As the fiber tips wear, fresh micro-fibers are exposed, so the brush cuts consistently from first use to last instead of dulling into polishing-only action.
- No grit rating. Because there are no bonded abrasive grains, "grit size" does not apply. The cut is defined by the fiber structure itself — which is why our specification tables list diameters and trim lengths, not mesh numbers.
- A rigid, chip-clear base. The resin-injected base holds each tuft at full column strength, so engagement depth stays true instead of collapsing — and swarf escapes rather than packing between tufts.
The test unit was a 35 mm outside-diameter standard model — the first size in the standard series — mounted in a machining center spindle.
2. The Test: Workpiece, Setup and Conditions
The workpiece was a stainless steel block. Stainless is the honest test material for a finishing brush: it is tough enough to expose any tendency of the fill to glaze or dull, and its surface responds visibly to both effective cutting and smeared "polishing."
| Parameter | Value |
|---|---|
| Brush | Ceramic fiber disc brush, 35 mm OD, resin-injected base, standard model |
| Workpiece | Stainless steel |
| Spindle speed | 8000 rpm |
| Feed rate | 4 mm/s |
| Engagement depth | 1 mm |
| Coolant | Yes (flooded) |
All runs were performed in our factory on standard machining equipment — no custom fixtures, no instrumented spindles. That is deliberate: if a result only appears on a laboratory rig, it will not survive contact with a production floor.
3. Why These Parameters Work
8000 rpm on a 35 mm brush. Disc brushes are defined by peripheral speed, not by the spindle number. At 8000 rpm a 35 mm brush runs a peripheral speed of roughly 14.7 m/s — the band where ceramic fiber tips cut cleanly rather than rubbing. The same spindle speed on a large wheel brush would be reckless; on a 35 mm disc it is where the construction comes alive.
4 mm/s feed. The feed sets how long each point of the surface stays under the brush. Too fast and the pass count is too low to level the peaks; too slow and you burn filament life without gaining roughness. At 4 mm/s the workpiece received enough overlapping passes to plan the profile down uniformly.
1 mm engagement. Engagement depth is the parameter most often abused with disc brushes. Press too deep and the tufts buckle, the cutting tips stop presenting edges and the brush smears instead of cuts — while generating heat that coolant then has to fight. At 1 mm on this body, the fibers work in their stiffness sweet spot: enough deflection to conform to the surface, enough column strength — thanks to the resin-injected base — to keep the tips cutting.
The three parameters are a set. Raising speed while deepening engagement, or slowing feed while lightening contact, moves the result away from what we measured. Treat the table in section 2 as a starting point and change one variable at a time.
4. The Results: Ra 1.6–3.2 Down to 0.2–0.4
Surface roughness was measured before and after brushing:
| Surface | Ra before | Ra after |
|---|---|---|
| Test range across runs | Ra 1.6 – 3.2 µm | Ra 0.2 – 0.4 µm |
| One measured group | Ra 1.6 µm | Ra 0.3 µm |
Two things in that table deserve attention. First, the starting condition barely mattered: surfaces entering at Ra 3.2 and surfaces entering at Ra 1.6 converged into the same narrow band. A single brush pass structure leveled the profile instead of merely brightening it. Second, the finish sits firmly in the precision-finishing class — Ra 0.2–0.4 µm is the territory usually reached with stone or abrasive-filament sequences, not with a single brush in one setup.
For contrast on the opposite problem — bonded contamination rather than surface profile — our article on multi-step wheel brush sequences shows the same material family taking off quench scale in four stations. Here, one brush and one setup did the whole job because the enemy was only the profile.
5. What "New Generation" Means — and What We Can Say
This brush is the successor to our standard ceramic fiber disc brush, and the honest summary is: the finishing effect is clearly better, and the construction changes behind that improvement are proprietary. We will not publish filament treatments or base bonding details that took real development work to find.
What we can publish is the data above — and we deliberately did. Parameters and results are what a process engineer needs; construction secrets are what a manufacturer owes its customers. If the result matters for your part, the fastest path is a sample test on your own workpiece, which we arrange routinely.
6. Reproducing This on Your Line
If you want to try this setup, the checklist is short:
- Match the brush to the feature. 35 mm suits open faces, edges and gentle contours; the standard series continues through 45, 55, 65 and 85 mm for larger surfaces. Smaller end-brush formats reach pockets and internal features — the diameter defines where the brush can go, the parameters define what it does when it gets there.
- Start from the measured set. 8000 rpm, 4 mm/s, 1 mm on a 35 mm disc, with coolant. Scale spindle speed with diameter to keep peripheral speed in the same band; keep engagement at or below 1 mm until you have a feel for the fill.
- Keep coolant in the loop. Our test ran flooded. Coolant carries swarf out of the tufts and keeps the ceramic fiber working at stable temperature — running dry is a different process and should be sample-tested first.
- Measure Ra, not shine. A bright surface can still be rough. Judge the brush by profilometer numbers against your drawing, the way we did.
7. Ceramic Fiber or Ceramic Abrasive Filament?
Because both carry the word "ceramic," the two product lines are often confused — and choosing between them is easier than it looks:
| Ceramic fiber disc brush | Ceramic abrasive filament brush | |
|---|---|---|
| Filament | Pure sintered ceramic fiber tufts, no nylon base | Nylon filament with ceramic grains |
| Cut definition | By fiber structure (no grit number) | By grit size (e.g. 240, 320) |
| Best at | Fine finishing and micro-deburring of hard alloys | Grinding tasks where stock removal is defined by grit |
| Typical finishes | Ra 0.2–0.4 µm (this test) | Application-dependent |
If your target is a precision finish on stainless, titanium or another hard alloy — and your enemy is the profile, not bonded scale — the ceramic fiber disc brush is the shorter road. The same ceramic fiber construction is also available in an end brush format for pockets, slots and internal features, and our earlier article on ceramic abrasive end brushes covers the abrasive-filament side of the family in depth. For the disc brush family as a whole, see our disc brush guide.
FAQ
Q: What spindle speed should a ceramic fiber disc brush run at?
A:Size the speed by peripheral speed, not by the spindle number. Our test ran 8000 rpm on a 35 mm disc — a peripheral speed of roughly 14.7 m/s. Larger diameters should run proportionally lower spindle speeds to stay in the same peripheral band. Ask us for a speed recommendation matched to your brush diameter.
Q: Why don't ceramic fiber brushes have a grit size?
A:Because there are no bonded abrasive grains to grade. Each tuft is a bundle of continuous sintered ceramic micro-fibers — pure ceramic fiber without a nylon base — so the cutting action comes from the fiber structure itself. Specification is by disc diameter, trim length and shank, not mesh.
Q: What surface finish can a ceramic fiber disc brush reach?
A:In this test on stainless steel: Ra 0.2–0.4 µm, down from Ra 1.6–3.2 µm, with one group measuring Ra 0.3 from a Ra 1.6 start. Your result depends on the starting profile, the feature geometry and the parameters — but this is the class of finish the construction reaches.
Q: What does the resin-injected base do?
A:It locks each ceramic fiber tuft at full column strength and keeps the working face true under engagement, while letting chips clear instead of packing between tufts. A soft or loosely filled base lets tufts buckle — the brush then smears rather than cuts, and the finish suffers.
Q: Can I run the brush dry instead of with coolant?
A:Our published test ran with coolant, which carries swarf out of the tufts and keeps cutting temperature stable. Dry running changes filament wear and thermal behaviour, and we would not assume the same parameters transfer — send us the workpiece and we will sample-test dry conditions before you commit a production parameter.
Q: What should I send to get a brush and parameter recommendation?
A:Four things: the workpiece material and target Ra; the feature to be brushed (open face, edge, slot or bore); your machine's speed range; and whether coolant is available. We match the brush diameter and return a starting parameter set like the one in this article.
Let the Data Pick the Brush
The fastest way to know whether this finish transfers to your part is to run it. Start from the ceramic fiber disc brush product page for sizes and shank options, browse the full ceramic fiber brush series and disc brush series for other diameters — or send us your target Ra and workpiece, and we will return a starting parameter set with the sample.
Note: Longguang is a manufacturer and exporter of industrial brushes. We do not provide on-site deburring services or local installation.
Henry Zhu
International Sales Manager
Phone / WhatsApp / WeChat: +86 13818514531
Email: info@shlgbrush.com
Email: zhulei@shlgbrush.com
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