Cobot Cuts Cost and Risk While Boosting On-Time Delivery

Los Angeles-based plastics contract manufacturer Kal Plastics deployed UR10e trimming cobot for a fraction of the cost and lead time of a CNC machine, cut trimming time nearly in half, and reduced late shipments to under one percent — all while improving employee safety and growth opportunities.

As the first known plastics thermoformer to use a collaborative robot for trimming, Juliet Oehler Goff, President and CEO of Kal Plastics, knew she was blazing a trail for others. “It was arguably kind of crazy because no one had ever done it before, so I took a huge risk,” she said.

Thermoforming uses sheet plastic that is heated to become soft so it can be vacuum-formed in or around a mold. Excess plastic is then cut off to create final products whose dimensions range from a few inches to the size of a room. Over the years, five-axis CNC routers replaced hand-trimming for most thermoformers. More recently, Goff had watched her peers explore the use of large industrial robots to finish-trim molded plastic parts, but she wasn’t convinced.

For a business like hers, the initial price point of industrial robots and their required safety caging was too high, not to mention the programming costs. “You end up having to have a skillset under your roof that’s very expensive. That’s a risk for a small business,” she said. After talking to colleagues, she heard behind the scenes that many of those who had tried industrial robots found that they didn’t work well for their applications and that they wouldn’t buy them again.

Goff is also a director and member of the R&D committee for the national industry association, the Society of Plastics Engineers (SPE) Thermoforming Division. In that role, she had been involved in numerous discussions about the state of robotics, particularly collaborative robotics, and their application in the industry. When Kal Plastics needed to replace a CNC machine that was nearing the end of its useful life, Goff was presented with an ideal opportunity. She set out to research the use of cobots for her own business and agreed to share her findings at the organization’s national conference.

Goff looked for low-hanging fruit for the initial cobot deployment: parts that presented safety or productivity issues with hand-trimming, and that could be produced on less-expensive equipment to boost competitiveness.

“I did my homework and found that Universal Robots was the global leader in the collaborative robot space,” Goff said. “They came out and gave us a demonstration, and when I looked at the numbers, they were really attractive. I was looking at getting another five-axis CNC router, and at the time it would have been a quarter-of-a-million-dollar investment and I would have waited 12 months to take delivery. When I met with UR, I was quoted two weeks to get the equipment, and the entry point was a quarter or a fifth of the cost.”

Dan Sproles, a consultant and another director for SPE Thermoforming help improve overall operations at KAL Plastics. From his initial skepticism, Sproles has also become a champion of UR cobots.

According to Sproles, “If you’re a thermoformer that’s been in business for 50 years or five months, if I look at the cobot, it’s a perfect fit — because I can’t afford a new CNC, but I can afford this. And I can afford someone that’s going to basically take a tablet and program it. So your bang for your buck — it’s the robot.”

Prior to installing the collaborative robot, the forming and rough trimming took place in the thermoforming cell, and then the parts had to be transferred to the CNC router in another part of the plant. Moving parts was disruptive and added production time.

The initial task identified for the cobot is a complex trim of a four-cavity mold, in which one sheet of plastic is formed into four parts. The ability to install the cobot into the same work cell alongside the thermoformer inspired Sproles to describe it as a “cell manufacturing dream.” Formed parts come off the thermoformer and are immediately rough-cut to separate them. They are then delivered directly to the cobot, which can trim two pieces in each setup. The cobot takes nearly half the time of hand-trimming and provides greater accuracy and consistency.

The deployment has two routers mounted on the robot arm — one with a standard router bit and one with a larger saw blade. The advantage is that the routers are the same commercial tools used for hand trimming. They are inexpensive and available off-the-shelf at any hardware store. Balancing the two heavy routers as they rotated around the part presented early challenges that were solved by mounting the robot arm overhead on a gantry to reduce pressure on the robot joints and improve accuracy.

The efficiency of the new work cell has already paid off. “The robot has basically taken over all of the overflow that we had to do by hand,” Sproles said. “In the past, we always had to juggle back and forth on the CNCs just to make delivery dates. We introduced the cobot: now there’s no more overtime and we can ship on-time. I would say late shipments have dropped to less than one percent.”

Now that the cobot has been proven, Goff is looking forward to implementing larger cobots in other workstations, and for processes beyond trimming. Unlike a CNC, which requires a large, dedicated space, permanent installation, and a three-phase, 480V power source, the gantry and UR10e cobot along with the fixture table can be moved anywhere in the plant as needed, as long as there is a standard 110V power outlet. Easy programming reduces costs and risks and offers new worker opportunities.

The cobot’s ease of programming was a big deal, said Sproles. “If I bought a regular CNC, regular robot, I’m going to spend thousands of dollars training that person, not knowing if they’re going to be here tomorrow.”

With the UR cobot, José Luis, a valued Kal Plastics operator, was able to learn the basics of programming using the free online UR Academy classes, which he could access in his native Spanish. He then attended two sessions of affordable, hands-on training. That was all it took for him to be able to create new programs, change tools, and make adjustments as needed.

Goff is thrilled to have a way to retain and advance her valued employees. “It gets your workforce excited because it’s different, it’s cool, it’s unique,” she said.

When Goff began her research, her workforce was afraid that robots were going to replace their jobs. She told them, “Listen, you don’t get it, guys. I want you to be safe. I want you to work smart. I don’t want you to just rely on your hands; I want you to rely on your knowledge and skills. If we can get our work environment to a point where you’re more of a QC operator than a machine operator, that’s a win for everybody.”

After working with the cobot, her workers’ attitudes have completely changed. “Once everyone settled down and they saw how this thing worked, it was like, ‘Why didn’t we do this sooner?’” Goff said.

This article was contributed by Universal Robots (Ann Arbor, MI). For more information, visit here  .