Semi-Gloss Polished Finish for MJF & SLS Parts
Our newest option for MJF and SLS nylon parts is a semi-gloss polished finish. We produce it in-house at our West Michigan facility using an automated impact polishing process. In one step, parts go from depowdering to a smooth, semi-gloss surface. As a result, end-use parts get the look and feel of a finished product instead of a raw print.
In the industry, you may also hear this finish called shot peening, peening, semi-gloss, or satin finishing.
Standard bead blasting leaves the matte, slightly grainy texture most people associate with powder bed nylon parts. Polishing, on the other hand, closes up that texture. Because of this, parts feel smoother in the hand, hold up better to scuffing, and take black dye more evenly. If you are not sure this is the right finish for your project, reach out to one of our Sales Engineers and we will help you choose.
How the Polishing Process Works
Polishing works by impact, not by cutting or melting. For example, sanding removes material to knock down the surface, while vapor smoothing uses a chemical process to melt and reflow it. Polishing does neither. Instead, parts tumble inside an enclosed blast cabinet while high-pressure air fires plastic polishing media at them.
Each impact presses down the peaks of the powder-fused surface. This is the same principle as shot peening on metal parts. Since the process compacts the surface rather than cutting it away, surface roughness drops without removing material from the part.
STEP 1 | DEPOWDER
First, we remove parts from the build and clean off the loose powder.
STEP 2 | POLISH
Next, we clean and polish the parts in an automated, controlled cycle matched to the part geometry and the finish required.
STEP 3 | INSPECT & FINISH
Finally, we inspect each batch and ship the parts in their natural color or dyed black.
Polished Finish vs. Standard Bead Blast
| Standard Bead Blast | Polished Finish | |
|---|---|---|
| Appearance | Matte, uniform | Smooth, semi-gloss sheen |
| Feel | Slightly grainy texture | Smooth, closed surface |
| Scuff resistance | Standard | Improved |
| Dyeing | Available | Available, with a more even color |
| Best for | Prototypes, fixtures, internal components | Customer-facing, handheld, and end-use parts |
| Availability | Standard on all MJF / SLS parts | Optional upgrade |
Why Choose a Polished Finish
- Consumer-ready appearance: Parts look like a finished product rather than a 3D print. That matters for anything your customers will see or hold.
- Better feel: The smoother surface suits grips, handles, housings, and other parts that people handle every day.
- Lower friction: The compacted surface slides more easily than a bead blast finish. This helps with sliding fits, snap features, and parts that move against each other.
- Scuff resistance: Polished parts hold up better to handling, assembly, and packaging.
- Dye-ready: Polishing pairs with our black dye finish for an even, consistent color.
- Repeatable results: Polishing runs on automated, controlled cycles, so parts match from batch to batch. In addition, our ISO 9001:2015 certified quality system makes it a strong fit for low volume production runs.
- No chemicals, no material removal: Polishing is a mechanical process. It smooths the surface without solvents and without sanding material away.
Design Tips for a Polished Finish
- Line of sight matters: Deep pockets, internal channels, and narrow slots receive less media than outside surfaces. As a result, they may come out less polished than the rest of the part.
- Narrow slots and holes: Slots narrower than 0.050″ (1.27 mm) can trap blast media during polishing. If your part has features this small, let us know so we can plan for it. Alternatively, consider widening them in the design. Our MJF design guide has more tips on feature sizes.
- Semi-gloss, not high-gloss: If you need a fully sealed, glossy surface, vapor smoothing is still the better choice. For a specific color or coating, see our part coating options.
- Delicate features: Very thin walls and fine details may not be good candidates for tumbling. Send us your model and we will let you know.
Polished Finish Part Gallery
The photos below compare the polished finish to our standard bead blast. You will also find a selection of polished MJF and SLS parts we have produced. For comparison, you can browse our raw gray and black dyed MJF part galleries.
Before & After
Polished Parts
Frequently Asked Questions
Is a polished finish the same as shot peening?
Yes. Both terms describe blasting a part with media to compact and smooth the surface rather than remove material. You may also hear it called a peened, semi-gloss, or satin finish.
How is polishing different from vapor smoothing?
Polishing is a mechanical process that gives a semi-gloss surface. Vapor smoothing, by contrast, is a chemical process that gives a glossier, fully sealed surface. So if you need parts that are watertight or easy to wipe clean, vapor smoothing is the better fit.
How is it different from tumbling or vibratory polishing?
Tumbling grinds parts against abrasive media in a vibrating bowl, which wears the surface down over time. Our polishing process, however, smooths the surface by impact without abrasion. The result is a more consistent semi-gloss finish.
Can polished parts be dyed?
Yes. We can dye polished parts black for an even, consistent color.
Which materials can be polished?
We currently offer polishing on nylon (PA12) parts from our MJF and SLS machines. If you are working with another material, contact us and we will let you know what is possible.
Not Sure Which Finish Is Right?
Send us your files and tell us how you will use the parts. Our Sales Engineers will then recommend the finish that fits your application and budget. You can also compare every option on our post processing page.
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