Weighing The Pros And Cons Of Horizontal, Vertical, And Brush-Type Dedusters
By Andre Petric, President, Kraemer USA
There are a number of things to consider when integrating a deduster into your manufacturing line. Before contacting a supplier, be sure to assess your needs by gathering the following four pieces of data:
Once you’ve collected the above data, it’s also important to familiarize yourself with the types of dedusting methods available. Horizontal, vertical, and brush-type dedusters all come with their own challenges and advantages that should be analyzed before making your choice.
Horizontal, Vertical, Or Brush Type: What’s The Difference?
Horizontal Dedusters: Horizontal dedusters consist of a perforated stainless-steel plate that vibrates side to side, and the tablets basically fall from the press to that plate. The plate isn’t actually horizontal — it has a slight slope — so the tablets slide down as they are moving with the vibration for about a meter in length.
The biggest “pro” for a horizontal deduster is that it is inexpensive. However, choosing to buy a deduster based on price point is not always the right decision. You might save on cost up front, but horizontal dedusters do come with the following “cons” that could impact your facility:
Vertical Dedusters: There are two different types of vertical dedusters to consider:
Brush-Type Dedusters: Brush-type dedusters consist of a helically wound brush located inside a stainless steel tube, driven by a motor. The tablets enter from the side of the tube, and the brush turns and vertically raises the tablets up the tube, until they reach the exit at the top of the unit. Two upsides to this method are its inexpensive up-front costs, and vertical conveying, which is not possible with horizontal type. On the downside, it uses plastic brushes, which can statically charge a product. And, the brushes can wear, which poses the problem of where those worn particles and broken brush fibers are going. Some of the particles exit with the dust, and some stay with the tablets, which is a definite negative. The brushes also can be difficult to clean. Like the horizontal method, the residence time is rather short — up to a couple of meters.
Before considering brush-type conveyors, it’s important to note that they are generally a better solution for conveying capsules. Manufacturers like to see their capsules polished and shiny when they come out of the system. Brush type, because of the friction of the brush on the capsule, is a good solution for that.
You Have The Information, Now What Should Drive Your Decision?
Aside from cost, the deduster decision should be based on dedusting efficiency and the physical ability to have larger containers in place. With the industry trend towards larger batch sizes and continuous manufacturing, the ability to collect a large volume of tablets is important. If, for example, your press tablet chute is at the height of 36 inches and your drum is 36 inches — if you didn’t have a deduster or a metal detector — you could put the drum right next to the press. However, with the horizontal deduster, you need to dedust and metal detect, so you’re dropping through the deduster roughly 8 to 10 inches. Add the metal detector, and you are dropping 10 or more additional inches. As mentioned earlier, this limits the size of the container that can be used. With a vertical conveying deduster you can go upwards from those 36 inches, in increments of about 10 inches, and then drop through the metal detector. The tablets can be discharged into large containers, even higher than the press outlet height. Many manufacturers use stainless steel and plastic IBCs (intermediate bulk containers), as well as flexible IBCs, so that they don’t have large quantities of small tablet collection containers to handle, store, and track. By minimizing the number of tablet collection containers, it makes those tasks much easier.
Tablet deduster choices are numerous, but with the information outlined above you will have the knowledge to make an informed decision.