How a Silicon Carbide Disc Brush Cut Deburring Cycle Time in Half While Improving Edge Finish
Introduction
The customer's original process ran a pair of 55 mm end brushes, one pass forward and one pass back, at 20 seconds each. The whole deburring operation took 40 seconds per part.
After testing a different abrasive specification, the same operation ran at 10 seconds each way — 20 seconds total. The cycle time was cut in half. And the parts came out with a larger corner radius and a better surface finish than before.
This case study documents what changed and why. It is based on an interview with Charlie Chen, our sales engineer who handled the project, recorded on September 18, 2026.
The Customer's Situation
The customer operates a machining shop producing flat metal components that require edge finishing after CNC machining. Their finishing requirements covered three separate objectives:
Deburring the flat surface. The machining process left burrs on the face of the part that had to be removed before the next operation.
Deburring and radiusing the edges. The sharp edges left by milling needed to be broken and rounded to a specified corner radius. This is a functional requirement, not cosmetic — a sharp edge concentrates stress and creates a handling hazard.
Achieving a specified surface finish. The part required a consistent surface texture across both the flat face and the edge radius.
Three requirements, one operation. The customer wanted a single brush setup that could address all three without adding process steps.
The Three Bottlenecks in the Original Process
The customer had been running a two-brush setup — one brush for each direction of travel — at 55 mm diameter. The process worked, but it had three limitations.
Bottleneck One: Cycle Time
Each pass took 20 seconds. Forward and back meant 40 seconds per part. For a shop running production volumes, this was the largest single time cost in the finishing operation.
The customer had looked at reducing the time by increasing the feed rate or the depth of cut, but neither approach worked. Increasing the feed rate reduced the contact time below what was needed to remove the burr. Increasing the depth of cut caused the brush to deflect and produced an inconsistent result.
Bottleneck Two: Corner Radius Size
The specified corner radius was not being achieved consistently. The original brush was removing the sharp edge, but the radius it produced was smaller than the print called for. The customer was running additional manual work on some parts to bring the radius up to specification.
This is a common problem in edge radiusing with abrasive brushes. The radius produced depends on the filament stiffness, the contact pressure, and the number of passes. A brush that is too stiff will cut the edge rather than radius it. A brush that is too soft will polish the edge without removing enough material to create the radius.
Bottleneck Three: Surface Finish Consistency
The finish on the flat surface was acceptable but not consistent. Some areas showed a uniform texture; others had visible variations. The customer's quality team was inspecting 100% of parts and rejecting a percentage that failed the finish check.
Our Diagnosis: Abrasive Filament and Grit Matching
Charlie reviewed the customer's process and identified the problem as an abrasive specification mismatch rather than an equipment or parameter issue.
The customer's original brush was a standard abrasive nylon brush. The filament was functional, but the abrasive type and grit were not optimized for the combination of requirements — burr removal, radius creation, and surface finish on the same part.
The key insight was that these three requirements pull in different directions.
Removing a burr requires cutting aggression. Creating a specific corner radius requires controlled material removal at the edge. Producing a consistent surface finish requires uniform filament contact across the full contact area.
A brush that is optimized for one of these will be suboptimal for the others. The goal is to find the specification that balances all three — and then to test it.
The Solution: Specification and Parameters
We recommended testing a silicon carbide abrasive nylon brush with a different grit specification than the customer's original tool.
Equipment Parameters
The customer's setup was unchanged:
| Parameter | Setting |
|---|---|
| Brush diameter | 55 mm |
| Number of brushes | 2 (one per direction) |
| Spindle speed | 1,500 RPM |
| Depth of cut | 0.5 mm |
| Feed | None (brush held stationary against the part) |
The "no feed" parameter is worth noting. In this application, the brush is not traversing across the part. It is pressed against the surface at a fixed depth while the part or the spindle moves. This is a common configuration in CNC edge finishing, where the brush is programmed like a cutting tool with a fixed depth of cut.
The 0.5 mm depth of cut is the key parameter. This is the compression of the filament against the workpiece. Too little depth and the brush does not contact the surface. Too much depth and the filament deflects and produces inconsistent results.
At 0.5 mm, the filaments are compressed enough to cut consistently but not so much that they lose their conformability.
Abrasive Material Comparison
During the testing, we also evaluated ceramic abrasive filament against the silicon carbide specification.
The finding was that grinding force was comparable between the two materials. Both removed the burr and created the radius at the same depth of cut and spindle speed. The difference was in the surface finish.
Ceramic abrasive produced a better surface finish than silicon carbide in this application. However, ceramic filament is more expensive, and the customer's finish requirement was met by the silicon carbide specification. For this reason, silicon carbide was the recommended production specification.
The ceramic option remains available if the customer's finish requirement becomes more stringent in the future. For applications where surface finish is the primary constraint, a ceramic abrasive end brush is often the better choice.
The Results
The customer tested the new specification on their existing equipment.
Cycle time dropped from 20 seconds per direction to 10 seconds per direction. Total operation time went from 40 seconds to 20 seconds per part.
The corner radius achieved specification without additional manual work. The radius was larger and more consistent than the original process produced.
The surface finish on the flat face improved. The variation that had been causing rejections was reduced, and the customer was able to reduce inspection frequency.
The improvement in cycle time came from a specification change, not a parameter change. The customer did not increase spindle speed, did not increase depth of cut, and did not change their equipment. They changed the brush.
Why We Test Before Adding to the Order
The customer's initial request was for a quotation on a replacement brush matching their existing specification.
We recommended testing first. The reason is that the customer's original specification had been established years earlier, and the process had evolved since then. The part geometry, the machine setup, and the finishing requirements had all changed. The brush specification had not.
A specification that was correct five years ago may not be correct today. Testing a sample against the current requirements costs the customer a small amount of time and confirms whether the specification still applies. In this case, it did not — and the difference was measurable.
We also test ceramic against silicon carbide in edge finishing applications where surface finish matters. The grinding force may be comparable, but the finish is not. Knowing which material produces the required finish prevents the customer from over-specifying an expensive filament when a standard one will work.
FAQ
Q: Why does the brush run without feed?
A: In this application, the brush is held against the part at a fixed depth while the part or spindle moves. This is common in CNC edge finishing where the brush is programmed like a cutting tool. Feed rate is not relevant because the brush is not traversing across the surface.
Q: What does the 0.5 mm depth of cut represent?
A: It is the compression of the filament against the workpiece. Too little compression means no contact. Too much compression causes deflection and inconsistent results.
Q: Can I use one brush instead of two?
A: The two-brush setup is used because the application requires contact in both directions of travel. A single brush can be used in some applications, but the geometry of this part required bidirectional contact.
Q: Is ceramic abrasive always better than silicon carbide?
A: No. Ceramic produces a better surface finish, but it costs more. If the silicon carbide specification meets the finish requirement, there is no reason to pay for ceramic. The correct choice depends on the specified Ra.
Q: What grit should I use for edge radiusing?
A: The grit depends on the required corner radius and the surface finish specification. For general edge radiusing, 180 to 240 grit is typical. For finer finishes, 320 grit or higher.
Q: Can you provide a sample for testing?
A: Yes. We provide samples so you can evaluate the specification on your own equipment and parts. Contact us with your part details, material, and finishing requirements.
Conclusion
The improvement in this case came from a single change: matching the abrasive specification to the actual requirements of the part.
Three requirements — burr removal, corner radius, and surface finish — were all being addressed by one brush specification that had been written years earlier. Testing a new specification against the current requirements produced a 2x cycle time reduction, a larger and more consistent corner radius, and a better surface finish.
For machining shops working with edge finishing operations, the lesson is straightforward. The brush specification should be tested against the part requirements, not inherited from a historical drawing. The cost of a sample test is small compared to the cost of running a suboptimal process for years.
For applications where edge finishing is a critical requirement, our end brush series includes options for abrasive nylon, ceramic, and wire filament. A twisted knot end brush may be appropriate for heavier burr removal, while an abrasive bristle end brush is often used for lighter finishing passes.
For a broader view of how precision edge finishing is applied across industries, see our precision engineering page.
Running an edge finishing operation where cycle time or finish consistency is a problem?
Contact our team for a specification review. Send us your part details, required corner radius, and surface finish specification, and we will recommend a brush for testing.
Henry Zhu
International Sales Manager
Phone / WhatsApp / WeChat: +86 13818514531
Email: info@shlgbrush.com
Email: zhulei@shlgbrush.com
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