Schaumburg, Ill. — In the age of Industry 4.0, companies are accelerating their drive to automation.
However, that might not be the best idea for everyone.
Dennis Rector, director of engineering at Chicago-based manufacturer Flexan, said that it's important for liquid silicone rubber manufacturers to make sure the numbers add up before deciding to automate a process. And when they don't, there are stronger alternatives.
"There is no straightforward rule for automation," Rector said in a presentation at LSR 2019, held Sept. 10-12 in Schaumburg. "Automation is the most consistent process — I won't argue that — but decisions should be based on return on investment calculations. And when ROI is not favorable, do what makes business sense."
There are a number of factors to consider before automating a production line. Rector said parts that require post-cure or secondary operations are tougher to automate because there is a transfer process from the molding machine to the secondary machine, especially in the case of small parts.
Parts with complex geometries or that require undercutting have limitations as well, and vertical presses generally are more costly to automate.
Rector gave an example using hypothetical numbers. If a manufacturer quotes a part with an annual volume of 1.2 million — which isn't considered high volume — and the target price is 15 cents each, then the firm's projected revenue would be $180,000. If quoted at a 35 percent margin, the company would have $60,000 to work with to automate production.
Rector said the cost of automation easily is $120,000, meaning the payback period for that part would be 1.9 years, which would not be cost-effective to take on. If the volume was 2.4 million, or if the producer could get more margin out of the product, then automation might make sense.
"When you're in upward of 5 million, there's no doubt automation is by far the best process for LSR," Rector said. "But when you're in the 500,000 to 1.5 million, what do you do?"
If the numbers don't come out favorable, there are alternatives. Rector said rotary LIM machines are one of his favorites because they have advantages of cycle time overlaps and consistency. One drawback, however, is that if the manufacturer doesn't have a cold deck, then runner removal can be challenging.
He added that rotary machines are best for insert molding, easy to load and as production volumes increase, the operator can be replaced with a five-axis robot.
"There are some opportunities where you can go to a rotary press, not automate and still save a lot of money in the process," Rector said.
Another route is to install a single operator to run multiple presses, though Rector said this is not an option he prefers. However, it does have distinct advantages in scenarios where manufacturers have presses they are not actively using in their facility. Rector said those can be configured in a 90-degree "L" or side by side and, similar to the rotary press option, the vendor gains cycle time overlap advantages.
"Basically the operator gets the presses out of sync and you don't have any wasted mold open time," Rector said. "Operator fatigue is definitely an issue with this. Operators are moving and a lot of times the out-of-cycle sync just doesn't work."
Semiautomation is another alternative. Rector said in cases where parts require secondary operations, manufacturers can choose to automate half of the process.