Roundtable Q&A: Slitting, Winding & Unwinding
- Published: February 17, 2020
What new capabilities are being added into machines to provide operators with ease of use in slitting, winding & unwinding?
Pappas: In slitting it’s definitely the auto knife positioners for the three main types of slitting. In shear slitting, auto knife positioning is very popular.
In score slitting, it’s extremely popular as well, primarily for tape customers who do narrow slitting and need to get in and out of short jobs. For razor slitting, we’re seeing trends that it’s becoming more of a player for certain applications.
On the winding side, I would say what’s new and exciting is the advanced cut transfer capability. We have ways of managing a wide variety of products in order to achieve a secure last wrap as well as a solid first wrap with either self-wound tape products or by adding a tabber or gluing system. The ability to turn the process into a machine paced cut transfer system compared to traditionally an operator cutting and taping by hand saves valuable time and increases throughput. Of course, things like unloading trees and roll pushers also have value when it comes to ease of use.
On the unwinding side, the trend for the last decade has been the shaftless floor pickup. It’s not new, however, it’s still the most popular style primarily for its ease of use. In addition to that, depending on the application, turret unwinds or dual unwinds are becoming more of a factor in machine design. You can decrease the changeover time from around 10 minutes down to as little as one minute, or the time it takes to do a proper splice, which proves to be a big benefit at the end of the shift.
Taylor: Along with the more intuitive controls, slitter and knife positioning systems are one of the most notable new capabilities. From position feedback systems to fully automatic systems, in which the knives are individually positioned by servo motors that are more accurate and consistent than any operator performed manual positioning. Not to mention the decrease in operator safety concerns from manually positioning the slitters. These systems are more affordable and come in more offerings than ever before. Any system that helps to reduce or removes human error, while also increasing productivity is a benefit all around.
We are also providing more feedback capabilities into our HMI to make it easier to operate the machines and troubleshoot when needed. This helps to have greater machine uptime which leads to better ROI.
How are control systems for slitting, winding & unwinding evolving based on customer feedback?
Pappas: Today’s control systems are a lot more powerful than they were a decade ago. It is the heart of the machine and allows us to do high-level functions that were never done before. Auto knife positioning, for example, requires a higher level of sophistication in the slitting system for accuracy and repeatability.
In winding, sequential functions for loading cores, unloading and pushing off to the tree certainly make the machines much more productive and advanced. And in unwinding, as I said previously, there are dual unwinds and stacked unwinds, the control system with the advanced safety allows us to add new levels of versatility but still make it friendly and powerful all at the same time.
Taylor: The workforce is changing rapidly, and as an OEM we must adjust and provide machines that are easier to operate and to maintain. Gone are the days where the machine operator intrinsically understands the process of a slitter rewinder and the subtleties of each machine. Modern operators may have to rotate between different machines or are be asked to run a wider variety or products on a machine with less training or experience than ever before. At Associated Machine Design (ADM), we have focused on improving the ease-of-use operation of our machinery by focusing on operator input, diagnostics and help screens. Many newer operators are more accustomed to a touchscreen interfaces (i.e. smart phones and tablets), so our machines have evolved as well. Our larger touchscreen interfaces look and feel more like smart phones and provide the operator with the pertinent information in a more intuitive format. Taking a complex machine process, like a center-surface slitter rewinder, and providing controls in a manner that a machine operator can use to produce good product more consistently.
Are improved control systems helping with waste reduction? Please explain.
Pappas: Control systems have improved waste reduction in two ways. First, when you drive an unwind you get tremendous benefit in quality of unwind tension compared to a brake. Driven unwind tension control is much more reliable and consistent which leads to a considerable reduction in waste. On the other side of that, when I think of waste and control systems, I think of giving away too much material. Improved control systems and the addition of servos on the pull rolls provide very accurate position loops to calculate exact lengths on finished rolls. You no longer need to “add a little” just to be safe. Even on long runs – say 20,000 ft - you can lock down and get consistent, precise position measurement with improved control systems.
A second way to reduce waste is by having the machine set up consistently every time and recipes add some of that value. Recipes really allow you to put the right parameters into the machine the first time and get the results you want off the machine every time and that definitely reduces waste.
Taylor: Identifying and eliminating waste in real-time is a great way to reduce waste. Advanced process controls are becoming more integrated on our machines. These systems can monitor slit width, caliper variation, tension, etc. in real-time. Many of these systems can provide a digital or printed readout of these measurements. Allowing the operator, or the machine, to flag areas with out of spec conditions, make adjustments as needed to correct the error, and then flag the product again when good product is being produced. This is more efficient than running a full shift of out of spec product before quality control can run a test and discovers an entire production run is bad.
How has technology made slitting, winding & unwinding processes and training easier for your customers?
Pappas: In the old days, an operator really had to learn the materials and keep an eye on the job as it was running. There was not an automated system leading the way, so they would be watching the tension control to make adjustments during the run. Today, with automated systems, the machine is in control once you hit the start button. The machine is managing the unwind tension, rewind tension, and in most cases, it’s closed loop so it’s making real time adjustments consistently every time. The art of watching and learning the materials is not as crucial anymore, technology has really helped us get there. This advancement has helped the learning curve and it’s definitely simplified the training process in most cases.
On the slitting side, traditional knife setting was always a difficult job to teach someone. Now to make an accurate setup, with the right technology in the machine, the operator simply needs to tell the knife placement system what the parameters are, and the machine does the rest. We can measure the efficiency and reliability of the knife positioner so much so that it’s made traditional methods unnecessary.
Taylor: Any process steps that can cost effectively be automated from a manual setup and done automatically with precision and repeatability will make the overall winding process easier. The key is to properly integrate these systems into the slitter rewinder in such a way that it is easy for the operator to use and makes the machine easier to operate with consistently better results.
Complex automatic solutions, when not implemented wisely often require many variables in order to operate correctly. It should not take an advanced degree to be able to operate or setup these systems. The use of newer technology certainly aids in training and troubleshooting as well. Including a web camera and remote internet connection port with our new machines help allow us to better communicate with operators and maintenance personnel while they are at the machine to aid in both training and troubleshooting as well when we cannot be on-site with them.
Are preventive maintenance programs proving themselves to be effective?
Pappas: The answer is definitely yes. It’s not uncommon for our service people to go out to visit customers to check in on their machines and at the end of their trip, find that they bring it back to its full potential. For a number of reasons, machines are out there running every day and small things happen here and there that can affect the performance. Over time those small things can result in a change of quality or typically reduced speed. With just some simple preventative maintenance we can eliminate those factors and get the machine dialed in again.
Taylor: Having a proactive maintenance plan is the best way to keep the machine running worry free. Understanding the proper intervals for maintenance is important but also quickly taking care of small deficiencies on a timely basis rather than waiting for a total failure helps reduce downtime and cost. (You have to sharpen your ax if you want to be able to cut the most amount of wood.)
