Mesh counts openings per inch on the sieve used to size the material. Micron is the particle size. The two are not interchangeable and the conversion is not linear, which is why the same nominal cut from two sources can behave like two different products.
The table below is the reference we use when a customer says “we run 80#”. It is the start of a conversation, not the end of one.
Going one mesh finer changes four things at once
- Cut speed falls, typically 5–15% per step at the same pressure and plate thickness.
- Edge quality improves: less taper, shallower striations, smaller trailback at the bottom edge.
- Piercing takes longer, and back-spray on thick plate gets worse.
- Oversize contamination starts to matter more — a grain that is harmless at 80# can be a third of the bore at 0.020 in.
That last point is what actually costs mixing tubes. The rule the machine builders use is simple: the largest grain in the mix should not exceed one third of the focusing tube ID. A supplier who sells a mesh number with no oversize figure makes that rule impossible to check. Ask for the residue above 100 mesh, or the +150 μm fraction.
Comparing three quotations that all say “80 mesh”
| Ask for | What it decides |
|---|---|
| D50 by sieve or laser | Two grades with the same sieve cut can sit 25% apart in D50 |
| Residue above 100 mesh | Plugging risk, tube wear and the 1/3 rule |
| Free silica | Abrasive that shatters in the tube produces fines that no longer cut |
| Conductivity, ASTM D4940 | Decides whether a coated part can be coated at all |
| Batch-to-batch span | The figure that shows up on the third container, not the first |
If a supplier can answer five of five, the quotation is comparable. If they can answer two, price is the only thing left to compare.
How to choose the first grade
Work backwards from the acceptance standard, not forwards from the price list. Fix the plate thickness and the edge requirement, land on a grade from the table above, then cut one test plate at 100% of rated speed and inspect the edge. If it passes at full speed you are a grade coarser than you need. If it fails at 60% speed, go finer and accept the slower cut — chasing speed with a grade that will not hold the edge only moves the cost into secondary machining.
One more check before you commit: run the grade against the tube bore you actually use. A 140# in a 0.040 in tube wastes edge quality; an 80# in a 0.020 in tube plugs. The table gives the pairing for a reason.