A filter disc is a round of wire cloth cut to fit a holder. Nobody looks at it, nobody thinks about it, and it catches whatever isn't supposed to get through. The only time anyone notices a filter disc is when it's the wrong one. We cut discs, rings and multi-layer packs from the wire cloth on our own shelves, and Howard Wire has been doing this kind of work since 1938, first on Howard Street in San Francisco and now in Hayward.
What We Cut
Send a drawing, a sample or the old part. If it's round and made of wire cloth, it probably belongs on this list.
Solid Discs
A full round of cloth cut to your diameter, in any mesh we stock.
Rings
Discs with a hole in the middle, cut to your outside and inside diameter.
Disc Packs
Several discs stacked and run as one unit. The fine layer filters and the coarse layers carry the load.
Framed Discs
Discs welded into a frame, for holders that need a stiff part instead of loose cloth.
Bound Edges
Plain cut, or with a U-edge channel crimped over the rim so cut wires can't work loose.
Other Shapes
Rectangles and odd shapes too. If it's on the drawing, send us the drawing.
How A Disc Pack Works
Fine wire cloth filters well and bends easily. Push enough pressure through it by itself and it bulges, then it tears. A pack fixes that by putting coarser mesh behind the fine layer, so the coarse cloth takes the pressure and the fine cloth only has to filter.
Some packs add a coarse layer in front too, to keep big debris off the fine cloth. Packs are usually written as mesh counts in flow order, like 20-100-20. Write yours that way and we'll know exactly what to stack.
Stack order is the thing people forget to put on the drawing. Tell us which way the flow runs.
Pick The Cloth
Most discs we cut are stainless square weave. The opening is plain geometry, so you get the number before you order. Here's what we stock, finest at the bottom.
| Mesh | Wire | Opening | Micron | Open Area | Stocked In |
|---|---|---|---|---|---|
| 20 | .020" | .0300" | 762 | 36.0% | 304 |
| 30 | .011" | .0223" | 567 | 44.9% | 304 |
| 40 | .0095" | .0155" | 394 | 38.4% | 304 |
| 50 | .0055" | .0145" | 368 | 52.6% | 316 |
| 60 | .0075" | .0092" | 233 | 30.3% | 304 316 |
| 80 | .0055" | .0070" | 178 | 31.4% | 304 |
| 100 | .0045" | .0055" | 140 | 30.3% | 304 316 |
| 120 | .0026" | .0057" | 146 | 47.3% | 304 316 |
| 150 | .0026" | .0041" | 103 | 37.2% | 316 |
| 200 | .0021" | .0029" | 74 | 33.6% | 304 316 |
| 250 | .0016" | .0024" | 61 | 36.0% | 316 |
| 325 | .0014" | .0017" | 43 | 29.7% | 304 |
| 400 | .001" | .0015" | 38 | 36.0% | 304 316 |
| 500 | .001" | .0010" | 25 | 25.0% | 316 |
Openings are calculated from mesh count and wire diameter. Woven cloth carries normal weaving tolerance.
Look at 100 and 120 mesh. The 120 opens wider, because its wire is thinner. Mesh count alone isn't a spec. Give us the wire diameter too, or give us the micron you need and let us pick.
Screening isn't filtering. A 140 micron opening won't reliably stop 140 micron particles in a liquid. Particles come in at angles, squeeze through and pile up into a cake. If you're filtering instead of sizing, plan on going finer than the particle.
When Square Weave Runs Out
That's where Dutch weave takes over. The wires pack so tight there's no straight-through hole to measure, so a Dutch cloth gets its micron rating from testing, not from math. We'll give you the rating for the exact cloth when we quote it. We'd rather not guess at it on a web page. Plain Dutch is the strong one. Twilled Dutch goes the finest.
Pick The Metal
Getting the disc welded into a frame? Ask us about 304L or 316L. The low-carbon grade holds up better at the weld.
What To Send Us
Missing a few of these? Send what you have and we'll ask about the rest.
- DiameterOutside diameter, plus the inside diameter if it's a ring. Add the tolerance you need.
- ClothMesh and wire diameter, or the micron you need to stop.
- Metal304 stainless if you're not sure.
- LayersFor a pack, list the mesh counts in flow order.
- EdgePlain cut, bound, or welded into a frame.
- QuantityHow many you need now, and how many a year if it's a repeat part.
- Drawing, sample or old partA sample beats everything. A drawing with the intended use is next best.
Send The Drawing. We'll Do The Math.
Diameter, cloth, metal and quantity is enough to start a quote. Want to hold the cloth first? Samples are free.
Before You Spec It
Mesh, Opening Or Micron?
How the three numbers relate, and when to spec by each. Read the guide ›
Mesh To Micron Chart
Every common mesh count with its opening, side by side. Open the chart ›
Filtration Cloth
Weaves, alloys and uses for the cloth behind the disc. Wire mesh for filtration ›
Common Questions
Can you copy an old disc or pack?
Send it in and we'll quote it. A used pack shows us the diameter, the layers, the stack order and the edge all at once, which beats a drawing.
What micron rating will my disc have?
For square weave, the opening in the table above is the number, because it's geometry. For Dutch weave, the rating comes from testing and we'll give it to you with the quote. Either way, if you're filtering a liquid, go finer than the particle you need to stop.
Is 200 mesh the same as a No. 200 sieve?
Not quite. A No. 200 test sieve is built to ASTM E11 and opens 75 micron. Our 200 mesh in .0021" wire opens 74, so that one lands close. At 40 it doesn't. A No. 40 sieve opens 425 micron and our 40 mesh in .0095" wire opens 394. If your spec says sieve, tell us.
How should the edge be finished?
Discs can go out plain cut, with a U-edge channel crimped over the rim, or welded into a frame. The right one depends on how the disc seats and seals in your holder, so tell us about the holder.
Do you make screen packs for extruders and screen changers?
Yes. Send the diameter and the mesh counts in flow order and we'll quote the pack.