Many times, a customer’s problem with product throughput can be solved with some simple solutions. I am not going to discuss screener ball decks, screen rings, or ultrasonic sieving but rather some simple solutions for those applications where the powder wants to sieve but is just not going through the screen! First, let’s discuss on size sieving.
What is On Size Sieving?
On Size Sieving is a problem that occurs when the actual particle that should pass through your sieve or screen is just a hair too big or too small for the screen you’re using.
For example, the lab indicates that your sieve analysis shows 70% of your powder is passing through a 53-micron sieve (270 mesh), but you can only achieve 45% passing through the 270 mesh in production.
Things you’ve done to address the issue:
- Check for screen blinding – nope, not seeing any.
- Slowed the rate down – no luck.
- Messed with your screener’s weights – still nothing.
- Blamed the screener manufacturer – it happens more than you think…
The Problem Could Simply Be Wire Diameter
Perhaps your wire diameter on the 270 mesh is a .0016 inch but by simply changing to a .0014 inch wire (still a 270 mesh), this could open up the micron size ever so slightly enough, allowing those powder particles that are just a hair too big to pass through. All of a sudden, you are seeing your yields increasing from 45% to 70%!
When customers approach me with these issues, I advise them to compare the wire diameter on the test sieves versus the wire diameter in production. The opposite can also apply with on size screening as well. It is possible for the hole or aperture to be too big. Switching to a slightly smaller wire diameter could solve this process issue.
TBC vs. U.S. Sieve Cloth vs. Market Grade
Another problem that arises is using TBC (tensile bolting cloth) instead of market-grade cloth or US sieve cloth. All three may say they are 30 mesh, but the actual opening of each one varies slightly. Sometimes this variation does not matter, but other times it may be the difference between passing QC (quality control) and failing. See our graphic below:
Many times, a customer calls up and requests, for example, a 30 mesh. We ask, “Is this a 30 mesh market or a 30 mesh TBC?”. The customer then tells you 30 mesh market. We make the screen frame and ship it only to be told, “This mesh is way too big.” The customer doesn’t realize that TBC is being used, which has larger openings than standard 30 mesh market-grade.
Not many screener manufacturers pay attention to the quality of the wire and or the exact sizing they are passing on to their customers (unless instructed to), so it pays to ask these questions. HK Technologies only use one main supplier of our wire cloth, which keeps us from guessing what we are passing on to our customers. There are many very inexpensive wire cloths on the market, and the lack of quality and hole size will show over time. We also often provide histograms of the wire mesh upon the customer’s request; however, there is a small charge. The histogram provides a detailed inspection of the wire, the hole size, and the wire size. To learn more about our fine mesh sizes, click here to check out our Mesh Chart.
In closing, we urge you to pay attention to your holes and wire diameters as well as your microns and meshes.
Do you have any further questions? We can help! Contact us today.
Jeff Hochadel has over 25 years of experience building and selling vibratory screening equipment. Jeff is responsible for handling fine mesh screening applications for The Cleveland Vibrator Company. His expertise is utilizing our Ultrasonic Deblinding System to solve difficult screening problems. When Jeff is not visiting customers promoting our products you can most likely find him fly fishing.
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