ADRIAN, MICH. - Quick - name the rotationally molded product that requires teams of seven inspectors working around the clock, five days a week. The answer: Roto Plastics Corp.'s blue, inflatable bladder for football helmets.
Rotomolding is the only way to make the seamless bladder, said President David Mulligan. And Roto Plastics is the only supplier.
Foam parts that are compression molded at the Adrian company fit together with the blow-up bladder to make cushioning systems for football helmets used in junior high school through the National Football League. Football helmets and pads generate about 55 percent of the company's $6 million in annual sales.
Product liability has winnowed the list of customers for the helmet cushions.
``When we started making football helmet components, there were over 20 helmet manufacturers in the United States. There are now two,'' Mulligan said.
Roto Plastics makes about 2,000 bladders a day. The raw material plastisol - liquid PVC - goes through seven tests before it reaches the machine.
After each cycle, the machine operator carries the bladders from the classic rotomolding work environment of hot, strenuous labor through a door into a sedate, air-conditioned testing area. After trimming, they go through a rigorous testing process conducted by seven employees.
Each one gets imprinted with its own serial number. ``From the serial number on the part I can tell you everything you ever wanted to know about that part,'' Mulligan said.
The number ties each bladder to detailed production data including the plastisol lot number, the production date and cycle number, mold cavity number and machine settings.
Every bladder is immersed in water to check for leaks. Employees use gauges and run their hands carefully over each one.
Bladders that make it through the first inspection are set aside for 24 hours, then given a pressure test, visual inspection and a second water test. Cushions that pass that test get a final pressure test and yet another visual inspection. Before packaging, employees seal the valve, which later can be used to adjust the inflation level and give each helmet a custom fit.
That level of testing and traceability is rare in rotomolding. But Mulligan said Roto Plastics has applied what it has learned to other products, such as a seal for a face mask used to inhale anesthetic. The inflated cushioned part has a wall thickness of plus or minus three-thousandths of an inch. The base is thicker and more rigid.
``We do a little over a million of these a year,'' Mulligan said.
Other products include boat seats, parts for floor scrubbers and equipment for handicapped children.
Roto Plastics had 1995 rotomolding sales of $2.98 million. The company recently built a 7,500-square-foot addition to house a new four-arm Ferry 220 E machine with a 105-inch swing diameter. Ferry Industries Inc. of Stow, Ohio, delivered the independent-arm machine in January.
Roto Plastics was founded in 1973. Mulligan, one of the owners, joined the company four years later.
A teacher of sculpture at Siena Heights College in Adrian, he had started a pattern-making company. He rented space at Roto Plastics, then ended up merging his company with Roto. The company still has its own shop to make patterns, the models used to make molds.
That makes Mulligan an artist and a rotomolding executive - a fitting combination for an industry that blends art with science.