Many times, a customer’s problem with product throughput can be solved with some simple solutions. I am not going to discuss 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.

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 is indicating 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 rising 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 wire diameter that is slightly smaller could solve this process issue.

Another problem that arises is the use of 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 the 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 customer. There is a lot of very inexpensive wire cloth 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.

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.