September 2017 Special Advertiser Q&A on Tension Control
Dover Flexo Electronics, Inc.
22 years with the company
Q: What’s new in tension control? Has your company released any new products lately?
Breen: Considering the fact that the mechanics of tension-sensing devices have changed little in recent years, most of the advancements in tension control are coming from electronic features added to digital control hardware or software, and firmware upgrades and enhancements.
A trend in industrial electronics that has mirrored the increased use of smart user interfaces in consumer electronic devices is the incorporation of touchscreen user interfaces into devices. Touchscreens provide a more intuitive user experience and replace the need for separate navigation buttons and switches on controller overlays and front panels. Many current generation web guiding and control products will incorporate touch screens.
Dover Flexo Electronics has just released its new TriView Left-Right-Total Tension Indicator with a large color LCD touchscreen. This tension measurement and display device is used for diagnosing tension differential between both edges of a running web or just to verify that running tension is even from edge to edge. TriView’s touchscreen displays tension in the user’s choice of modes. Total tension is always displayed, and the machine operator can select between viewing the web’s left- and right-side measured tension values or a balance indication that shows any deviation between the left and right edges of the web as measured by an installed tension-sensing roll. Switching between views occurs with a simple tap on the display.
Q: Explain some of the keys to a well-functioning tension control system.
Breen: Although tension measurement and control equipment plays a vital role in the production quality aspect of flexible packaging, converting and web printing, it’s a process variable that production managers want to work invisibly, without having to worry about how or why it’s working. The greatest compliment we hear from customers is that they’re not even aware that their tension control equipment is doing anything. They mount it to the machine and it sits there and it works.
One key to achieving the right web tension for a flexible packaging converting process is the production team’s understanding of their web materials’ physical characteristics, thickness, weight, extensibility and optimum running tensions. For instance, polyethylene runs best at a much lower tension than polystyrene or aluminum foil.
Assuming that management will choose a tension control technology that employs direct tension sensing to achieve the most consistent and accurate running tensions, the converter’s ability to answer these questions about their application is key to them realizing a well-functioning web tension system:
- In which tension zones are problems being experienced: unwind, intermediate or rewind?
- What idler roll locations in the web path are best suited to have tension transducers (load cells) installed on them?
- What are the project budget constraints?
- What tension range will we be running in most of the time? This is important for transducer sizing.
- How versatile do we need the tension control system to be with respect to the range of substrates and material properties the machine will be running?
- Which tension control vendor will best fill our needs?
- What style of transducer mounting hardware will fit best into this location on the machine frame?
- Should we connect the installed tension transducers to a tension readout device only or to a closed-loop automatic tension controller?
Ultimately, the production team will want to select tension transducers that will be accurate over the range of tensions the machine will be running. And they’ll select the best tension controller for the applications they’ll be running within their budget. Fortunately, some tension control equipment suppliers offer a range of controllers with varying feature sets and price points to meet customer needs.
Q: In addition to the key factors, how important are the intangibles when it comes to this type of equipment (i.e., ease of use, ease of installation, etc.)?
Breen: Each user of tension control equipment will place a different value on the importance of a particular product feature to that facility based on the particular application and the people and resources that will be working with the new tension control equipment.
For instance, in a converting plant where there is a shortage of plant engineering talent to install and set up new auxiliary equipment on a press or machine line, ease of installation becomes a top benefit. However, in a plant where the operators all speak English as a second language, ease of use of the equipment and an easy-to-learn user interface becomes paramount. In plants where humidity is high, the anti-corrosiveness of the equipment components is more important. In a plant that is running its machines continuously and downtime is at a premium, reliability and product lifespan may be the most treasured benefits.
Q: How has the trend of “Industry 4.0” and the connected factory floor impacted the design and manufacture of web guiding/tension control equipment (if at all)?
Breen: We have not seen as much of a call for communications protocol upgrades and design changes to our tension control products as one might expect given all the industrial network integration we’ve seen over the past two decades. Most of our customers in the North American marketplace that are needing to network their tension signals into a centralized automated control system request a basic 0-to-10VDC signal output from our devices, or a basic RS232 or RS485 communication capability.
That being said, we do have requests for Ethernet-connected devices from time to time, so we have to be able to offer it. I suspect this is much more of an issue for other controls manufacturers with heavy distribution in Europe and Asia.
Q: Is there anything else you’d like to share about web guiding/tension control?
Breen: The RoHS Directive from the European Commission is having a strong impact on the design and manufacture of products for many electronics manufacturers as they scramble to meet the regulatory compliance to remove lead solder and other hazardous materials from their products and their manufacturing environments. Compliance with the current directive will not be optional for electronic device manufacturers selling into Europe.