By Suzhou Krosino Mechatronic Technology Co., Ltd | 21 April 2026 | 0 Comments
Magnetic Polishing for CNC Parts: A Practical Finishing Option
Magnetic Polishing for CNC Parts: A Practical Finishing Option
You get a part back from the CNC machine. Dimensions are spot-on, but the surface still shows tool marks. There's a micro-burr in a blind hole. Or the customer wants a cleaner look than "as-machined." These are everyday problems, and magnetic polishing is one way to solve them.
At Suzhou Krosino Mechatronic Technology Co., Ltd., CNC machining is what we do. Magnetic polishing is a finishing service we offer when customers need better surface quality on complex parts.
How It Works
A machine generates a rotating magnetic field that spins tiny stainless steel pins inside a processing bowl. The pins swirl around your parts, hitting surfaces that are hard to reach by hand or with traditional tools—internal channels, undercuts, corners. The media flows over the part rather than hammering it, so thin walls and fine features don't get damaged.
Two common approaches: magnetic abrasive finishing (MAF) for precision work with bonded abrasives, and magnetic pin tumbling for lighter deburring and brightening.
What It Actually Does
-
Reaches internal geometries: blind holes, channels, undercuts
-
Removes micro-burrs from machining or 3D printing
-
Brightens surfaces for a cleaner look
-
Cleans up oxidation and machining marks
What it doesn't do: remove heavy burrs from worn tooling, flatten large surfaces faster than grinding, or replace CMP for semiconductor-grade work. It's a finishing step, not a cure-all.
Materials
| Material | Notes |
|---|---|
| Stainless steel (304, 316, 17-4PH) | Most common, works well |
| Carbon steels | Straightforward |
| Aluminum alloys | Good; watch for galling with steel media |
| Brass, copper, bronze | Common for decorative parts |
| Titanium & nickel alloys | Medical/aerospace; needs tuning |
| Tungsten carbide, ceramics | Needs diamond abrasives |
The part doesn't need to be magnetic. The media is. The field drives the pins, which then work on whatever you load.
Surface Finish
Standard magnetic pin tumbling on stainless steel usually improves Ra from about 0.4μm down to roughly 0.1μm, with cycle times of 5–30 minutes. Optimized MAF setups can hit Ra 0.06μm—good enough for many medical and aerospace applications where surface quality affects fatigue life.
But you need to dial in the parameters: field strength, abrasive size, working gap, speed, time. Run defaults and you'll get mediocre results.
Impact on Dimensions
-
Minimal stock removal—microns, not millimeters
-
Low heat, so no thermal distortion
-
Preserves edges when controlled properly
-
Uniform finish, no uneven spots from hand pressure variation
Run too long or too aggressive and you will remove material. Gentle isn't zero-impact.
Size Limits
Magnetic polishing works best on small, complex parts. At Krosino, we typically handle parts under 400mm.
For large, simple parts, belt polishing or vibratory finishing usually makes more sense.
Cost
Processing cost is generally competitive with manual polishing once you factor in labor. One comparison showed traditional drum polishing at 1.2 yuan/piece (85% pass rate) versus magnetic at 0.8 yuan/piece with better consistency. A medical device factory cut energy use by 63.8% and consumable costs by 75% after switching, with abrasive life going from 7 days to 90 days.
Labor savings are real—automated magnetic polishing cuts manual work by about 80%.
For customers, the value is straightforward: better surface finish on complex parts without the manual labor bill.
Who Uses It
-
Medical device makers—biocompatible finishes on implants and instruments
-
Aerospace shops—surface integrity for fatigue-critical parts
-
Precision hardware—deburring and brightening small CNC parts
-
3D printing operations—post-processing internal channels and complex shapes
-
Jewelry and decorative parts—aesthetic finishing without losing material
Not ideal for high-volume simple parts where vibratory finishing is cheaper, or applications needing atomic-level flatness.
Bottom Line
Magnetic polishing is a standard finishing process. It won't transform your product, but it will improve surface quality on parts where traditional methods fall short.
At Suzhou Krosino Mechatronic Technology Co., Ltd., we offer magnetic polishing as part of our CNC machining and finishing services. If your parts need better surface finish than as-machined, it's worth talking about. No hype—just a practical option that gets the job done.
Leave a Reply
Your email address will not be published.Required fields are marked. *
POPULAR BLOG
- Precision and Consistency: Solving Core Challenges in 3-Axis & 4-Axis CNC Machining
- How to Optimize Lead Times and Precision for OEM Machinery Parts
- Precision CNC Machining for Semiconductor & Automation Parts: Why Krosino in Suzhou?
- What is Rapid Prototyping Service？
- What kind of parts could be machined by laser cutting？
CATEGORIES