Thermoforming automation reaches for more
Canadian PlasticsCanadian Plastics Plastics Processes Robots & Automation
As thermoformers look for faster production rates with higher capacities while also grappling with labour shortages, automation has become a necessity. And virtually all automation suppliers now have enhanced equipment offerings.
For manufacturers, the COVID-19 pandemic created whole new sets of problems – such as supply chain issues – but it also accelerated, and expanded, challenges that existed before. The skilled labour shortage that predated the global crisis became a shortage of workers in general, for example, and continues today even as other effects of the pandemic recede. Indeed, workforce issues impacting the ability to meet production output and deliver customer orders now feels like a permanent problem.
One solution is to automate the factory floor as much as possible, since automated systems are by definition less labour-intensive – instead of requiring one or more operators per production line, a single operator can cover multiple lines. Which is why, since the pandemic, there’s been a high global demand for automation among all types of manufacturers.
In plastics, this means more robotic automation in injection molding, extrusion, and blow molding operations, as processors look for automation solutions to improve efficiencies and mitigate ongoing worker shortages. And also – and this doesn’t get as much notice – in thermoforming, where automation is an increasingly central trend. And not just because of labour shortages, but also because of increasing hygiene requirements for the production process; and because a new generation of higher speed thermoforming equipment is being at least partially hampered by the inability of human workers to handle parts at high speed. For high-volume production, robotics is increasingly employed to automatically perform part inspection and downstream packaging and palletizing functions.
Automation has always been a benefit by facilitating higher, more predictable throughput, but a popular pre-pandemic perception was that some shops resisted installing automation for fear of having to let employees go. To the extent it was ever true, the pandemic has probably killed this concern for good. “The obvious problem nowadays isn’t letting workers go, it’s finding them in the first place and then keeping them, and this has really boosted the number of thermoformers looking for automated alternatives,” said Nate Pelis, sales manager with Ranger Automation Systems. “Before the pandemic, the mentality at many thermoforming shops had been to throw another employee on the line to handle part removal or packaging – I used to see operators climbing around machines, picking very thin parts. I don’t see this as often anymore.”
Also before the pandemic, a typical thermoforming plant would allot space for anywhere from three to five humans for pulling, separating, and counting stacks of product. And this has changed too. “The need to keep lines running during the pandemic while also following social distancing requirements created a perfect storm – suddenly we had customers that needed automation immediately, especially on the back end of the machine,” Pelis continued. “And the demand has kept up, because they’ve seen the efficiencies – which are immediate and impactful – and the attractive return on investment.” Besides that, the need for a more hygienic manufacturing process is a driving factor. “This requirement was especially visible during the pandemic in recent years,” said Mehmed Handanagic, sales manager for automation with Kiefel Technologies.
Which is why virtually all automation suppliers have enhanced equipment offerings launched within the last couple of years.
The drive towards automation is taking place throughout the thermoforming process, beginning with new fully integrated systems. Riverside Medical Packaging Co. Ltd., the manufacturer of Shawpak thermoforming machines, during the height of the pandemic last year introduced one such fully integrated system for automated packaging of medical devices. The turnkey solution features the company’s thermoforming machine, a robot to load the injection molded devices into it, inline printing of the packaging, and visual inspection of the goods. Built around Shawpak’s standard 32-20 rotary machine, the system includes an inline thermal transfer printer, a vision inspection and rejection system, and robot loading of injection molded medical devices into the thermoforming machine. Shawpak also incorporates a multi-lane slitter that slits or perforates the packs containing the individual devices after they are formed and sealed. The entire system’s footprint is about 4 feet wide by 6.5 feet long – a big space saving, given that a traditional thermoforming line is anywhere from 10 to 30 feet long.
And Kiefel’s newest automation solution is the Kiefel Speed Automation (KSA), a modular system that’s matched to the Speedformer KMD series and can be integrated into both new and existing systems. “One KSA module forms full stacks from partial stacks, for example of food trays and lids; another module takes cartons from a box magazine, erects them, and inserts a protective bag for hygienic packaging if required; a third also includes an automatic labeling unit and palletizing unit consisting of two stations, making it possible to palletize in one station while the other is being emptied,” said Mehmed Handanagic.
Automating part handling can create a gap in the inspection process traditionally done by operators, which is why another area being targeted by new thermoforming automation is quality control through vision inspection technology. And it’s reversing a trend, some OEMs say, since until recently it was assumed by many shops that costs would outweigh the benefits of vision inspection systems in thermoforming. A true accounting of costs will include quality – for example, reject rates, part failure, and scrap rates – but what’s more difficult to measure is reputational cost associated with bad lots. In truth, some OEMs say, quality control was always a particular problem for thermoforming. “Thermoforming can be vulnerable to imperfect parts, for example parts with stacking features such as the stacking shoulder on cups that aren’t properly formed,” said Mark Strachan, chief innovation and technical officer with thermoforming machine builder OMV Technologies. “It seems like a miniscule problem, but when 30 imperfect cups are nested in a box, that stack length variation could be up to an inch shorter than the other stacks, leading the end customer to think they’ve been shortchanged on the number of parts in a box. These stack features also ensure parts are easily de-nested from each other at the automated filling lines and not causing any costly stoppages.”
To automate the process and improve efficiency and effectiveness, computer vision and artificial intelligence techniques are being applied. “An example of the use of a vision inspection system is the ability to measure the overall length of a row of cups before boxing and triggering an eject system that would push the short stack aside for regrinding,” Strachan said. “These systems also check for ovality, flange thickness, sidewall accuracy, black specks, and for the right printing so the right SKU goes in the right box.” And while reject rates most certainly increase initially, Strachan said, the use of these systems will ensure higher output efficiencies and more quality parts in the box. “Identifying imperfections or flaws before parts are packed and shipped can substantially insure the bottom line,” he said.
The drive for more automated quality control is due also to the rise of the need for downgauging, which allows thermoformers to offer the same products with higher product-to-package ratios by using thinner materials. “A cup that used to be 20 grams now weighs 15 grams, which affects the final functionality of the part – it might collapse more easily when the lid is applied,” Strachan said. “Automation can weigh the cup and kick it out if its weight doesn’t fall within the required range. Currently, we can run 200 cups through a camera in just a few seconds.”
THE BACK END
Perhaps the key focus for thermoforming automation is at the back end of the process – the otherwise labour-intensive areas of part removal and part handling. Which makes sense, OEMs say, because when most thermoformers are asked about automation, they typically prioritize end-of-line solutions related to part removal. “Thermoformers looking to automate obviously want to eliminate redundant motions and redundant operations, which usually involve human operators waiting around to do packaging,” said Nate Pelis. “These are the areas we spend a lot of time addressing, because it’s what most thermoformers are looking to automate first.”
But the fact that it’s a common concern doesn’t mean there are one-size-fits-all answers. From simple A/B stacking mechanisms to robotic palletizing systems, there are a lot of ways for thermoformers to move parts. Perhaps the most common automation approach is to use a two-axis handling system where formed parts are clamped and broken from the web as part of the basic stacking system, then transferred via linear drives to a conveyor belt. The parameters for the stacking movements are set through a teach-in mode. Through optimization, speeds up to 40 cycles per minute are possible with standard up-stacking motions. Indeed, high-speed automation is widely used in thermoforming sector, period. “High-speed is now a prerequisite, especially because the outputs of the thermoformers are so high due to high cycle rates and the large number of products that are produced in a short time,” Mehmed Handanagic said. Other options include 180° or 90° rotations to create A/B stacks. Linear automation traditionally dominated the thermoforming sector, Handanagic continued, but three- and six-axis robots – which are frequently used in injection molding – are gaining popularity as the need for flexibility is rising.
One area that’s traditionally been challenging has been automating part handling at the trim press and end-of-line wrapping, case packing, and palletizing, due in part to the wide range of products, limiting “universal” automation designs. For thermoformers running non-servo-eject trim presses, BMG recently introduced what’s being called a first-of-its kind automation solution – the Mantis Robotic Trim Press Handler, developed by NAS Nalle Automation Systems, a BMG company. Described as the industry’s first robotic system that reliably handles the flow of parts ejected from any non-servo trim press, including those made by BMG competitors, the fully automated system reportedly can reduce labour requirements by up to 75 per cent, and the modular robotic design allows for tool changeovers in under an hour.
Ranger Automation’s TR series robots have ultra-high-speed servo drives that allow part extraction and stacking at cycle times as fast as two seconds, and can fit any new or existing thermoformer, with configurations available to stack parts off the side or at the end of the line, or with the Downstacker option, to stack directly under the line onto indexing conveyors.
However it’s accomplished, once the thermoformed parts are stacked, they can be moved to final packing stations, which can be as simple as automated sleeving systems or as complex as fully articulated robotic arms that place stacks of nested product into pre-made boxes. “Technically, the automation for the back end of thermoforming is actually very similar to robotics for injection molding or blow molding,” said Mark Strachan. “The IML injection molding automation has been so good for so many years now that all types of geometries can be done. In the thermoforming IML space – called TIML – the OEMs have been behind the ball, but we’re catching up and can now offer much more sophisticated TIML automation, in part because of the drive to single-source materials like PET, which favours thermoforming over injection molding because thermoforming can thin-gauge it much better and with more cavitation.”
A factor for thermoformers to keep in mind – particularly for first-time automation buyers – is the level of training and experience required of the operators as well as the level of comfort and ability to interact with and support the automation. Depending on the application, this is where a collaborative robot – or cobot – might prove useful. Compared with industrial robots, cobots’ ease of use and smaller sizes make them accessible, even for thermoformers that previously might have rejected automation due to concerns over cost or the perceived hassle of handling high-mix, low-volume work that would require constant reprogramming. “I’ve seen many thermoformers use cobots for simple, light-duty tasks that need accuracy, like applying adhesive labels,” said Nate Pelis. “Since thermoformers tend to be experimental by nature, some shops are buying a cobot just to try it out, and usually they find a good use for it; it’s the only instance when I might recommend buying the robot first and finding the application second.”
Even as more thermoformers look to automate more areas of their production process, it’s important to remember that the old adage of buyer beware still applies. “I receive many calls from thermoformers that have bought used automation and can’t get it to work the way they want,” Mark Strachan said. “Sometimes we can tweak it to fit into a particular thermoforming line, and sometimes it’s a lost cause because there are too many components that would need to be changed. I’ve also seen it happen with new automation, which I think is attributable either to poor communication between the customer and the OEM, or because the customer changed the geometry or stack height of the parts after ordering the automation.” One reason this latter scenario risks happening is because of supply chain problems currently wreaking havoc with delivery dates, which make it more likely than ever that a process might change between the automation order and its delivery. Nor are lead times necessarily getting any shorter, even as the pandemic recedes from view. “The reliance on overseas electronics is definitely impacting our lead and delivery times,” said Nate Pelis. “There are a lot of logistical steps that go into building an automation system, and we have very little control over them.”
In the end, it feels as though the genie is finally out of the bottle: automation is gaining major importance for thermoformers not only as a solution to labour shortages but also by offering more precision and control for higher repeatability, higher quality and increased hygiene requirements, fewer defects, and less waste. There’s no going back, but it still has to be approached the right way: by the thermoformer doing a deep dive into its manufacturing process with the OEM, with detailed conversations and clarifying expectations during the design phase of any project, including in-depth discussions about operating scenarios along with the benefits and potential process changes expected with automation.