Slat fillers vs electronic counters
The goal for any pharmaceutical or nutraceutical tablet counting machine is essentially the same: to take the product in bulk and distribute it into containers in exact quantities. Several methods have been explored by machine manufacturers since the first automated disk counters. Electronic and slat counters are now the standard within the industry. Each technology has its pros and cons, so before implementing a new tablet filling line, it’s important to select the right technology for your application.
5 Points to consider
Speed / Accuracy:
Speed and accuracy may seem like unrelated topics but the two are intertwined, as I will explain.
There have been many claims about electronic tablet counters achieving speeds close to that of a slat counter, with 100% accuracy. While they do have a definite place in tablet counting / bottle filling, often there is a desire to push these machines beyond their capabilities. This is where we can get into trouble.
Any system trying to count multiple falling objects in free flight is susceptible to errors. No matter how sophisticated the electronics, and intelligent the software, the chaos of the tumbling tablets creates potential miscounts. When these machines are pushed too hard the potential for errors increases substantially. Tablets bounce, tumble, ricochet and collide, creating chaos for the various sensing devices, even vision systems. In short, there is no such thing as 100% accuracy!
This leaves us with having to run the electronic counters at a reasonable speed so as to get a smooth flow of tablets through the sensors in order to achieve a highly reliable count accuracy.
Slat counters, on the other hand, are designed to handle up to 50,000+ tablets per minute. More importantly they can handle large tablets, while still achieving up to 20,000 tablets per minute. While you can run a particular product too fast in a slat counter, it becomes visually apparent to the operator and can be corrected immediately. With an electronic counter it is less apparent, and often not notice until you receive market complaints.
Electronic counters generally do not require change parts for counting different products, giving them the edge over slat counters in that regard. Especially when considering the need to run many different products for short runs. However, for almost all operations, electronic counters still need to be disassembled for cleaning between batches. This is still a time-consuming task and generally requires a higher skill level person, often a mechanic. To help speed the process, some companies purchase a second set of product contact parts, diminishing the benefits of “not requiring change parts.”
Slat counters employ product specific change parts that need to be safely stored when not in use. The upside is the change parts are dedicated to a specific product, reducing any potential cross contamination. While older slat counter designs can have many parts, making cleaning difficult, some manufacturers have come up with innovative designs to improve this time-tested technology. These newer designs allow for changeovers in less than 1 hour.
Let’s face it, you are buying a machine to package your products and make the company money. The customer buying your products will never know that your machine has the latest features and technology. So, unless the technology delivers superior performance or reliability, there is no cost benefit for the latest shiny object.
Slat fillers are very straight forward machines that have passed the test of time. It’s not uncommon to see slat fillers still working smoothly after 20 years of service. Most slat counter manufacturers employ commercially available electronics, and mechanical devices that can be maintained by most mechanics experienced in the industry.
By comparison, electronic counters, especially the better ones, use the latest technology and proprietary components to achieve performance and accuracy beyond that of lesser machines that use commercially available photo-electric sensors. These more sophisticated machines do deliver on performance, but at a higher cost and require higher skilled technicians maintaining the equipment to keep it in good running order.
Cleaning and Maintenance:
Again, I am relating two separate points here as proper cleaning of any piece of equipment leads to better maintenance in the long run.
Between each production cycle, all machines must be cleaned, regardless of technology. This applies, of course, to components directly in contact with the product, but can also extend to other parts of the machine. It is important to choose equipment with flat surfaces that are easy to clean, with wide accessible areas. A machine that has many small parts and cavities is difficult to clean thoroughly and can create problems in the long run. Worse still, is if a rogue tablet gets left behind in a small crevice of the filler.
As for maintenance, most machines will have recommended preventative maintenance schedules. The number of parts, and the simplicity of the machine design, can be indicators for evaluating the level of maintenance that will be required.
Slat counters generally are more susceptible to mechanical wear and require periodic inspections to items such as chains, sprockets and chain guides. This is easily done during the cleaning process.
Electronic counters do have some mechanical wear items, especially the small trap doors that intercept the falling tablets when the proper count is achieved. It is these small actuators and electronic devices that can become problematic and need to be addressed by a trained technician.
All fillers will let in some damaged tablets. Higher end electronic counting systems can offer an all-in-one solution that can determine when a broken tablet is present. Generally, an electronic counter is set to accept any piece of a tablet larger than the smallest cross section of a good tablet.
Slat counters often require an operator in front of the filler to observe the tablets just before release to the bottles. It is surprising how quickly your eye catches something that just doesn’t look right. But this is tedious and therefore potentially unreliable.
When outfitted with vision systems, slat fillers become the gold standard, combining the simplicity and speed of a mechanical counter with the sophistication of modern, vision based, electronic counters, while still being competitively priced. These vision systems can also ensure product quality, and are capable of detecting foreign, broken, chipped, wrong color and oversized tablets.
The IPS Procount Slat Counter
The IPS Procount Slat Counter is an updated version of a familiar slat counter. By streamlining the design, IPS has eliminated hundreds of parts from previous generations, dramatically reducing points of failure, as well as making for a simpler machine, requiring very little maintenance. The result is a cleaner design eliminating potential hiding places for rogue tablets and easier cleaning during changeovers. The IPS Procount can be changed over and wiped down in less than an hour, yielding very high production efficiency. When equipped with the Optel Countsafe Vision System the IPS Procount is the gold standard in solid dose filling.
The best tablet filler for your packaging line remains tightly linked to the number and size of the products to bottle. Slat fillers generally work best with high throughput packaging lines or for larger tablets. For those applications requiring large counts or long campaigns, nothing matches the throughput, efficiency, simplicity and greatest return on investment of a well-designed slat counter.
While this paper obviously has a bias towards the slat counter, it is not without merit. There are very good electronic tablet counters that are relatively fast, accurate and provide years of service. Generally, these are only the most sophisticated, well-engineered and highest priced systems.
However, marketplaces have been flooded with equipment from all over the world and none more so than electronic tablet counters. It is with these lower priced machines that we see our clients having the most trouble.
When looking for tablet counting equipment for your packaging lines, take a long hard look at the machines running, noting how many tablets are being counted each minute, (not the bottles). Note the size and cost of the equipment, the skill level of the people operating and maintaining the equipment. It is when we consider “total cost of ownership” that many of our clients come back to the reliable slat counter.