PolyJohn Turns to Blow Molding, Doubles Its Productivity

A leading producer of portable toilets, sinks, tanks and other sanitary products and accessories was experienced in almost all of the major plastics processes. PolyJohn Enterprises started up in 1984 with thermoforming of roof and side panels of its portable toilets. Then it expanded into sheet extrusion, rotomolding for bases of portable toilets, and injection molding for accessory parts such as soap dispensers, paper towel dispensers and toilet seats. Resulting growth brought challenges that strained the limits of its existing technology portfolio. 

Currently, the third-generation family-owned firm employs 275 people and has annual revenue around $100 million. The 140,000-square-feet headquarters plant in Whiting, Indiana, houses five rotary thermoformers, one sheet line, five rotomolders and five injection machines from 110 to 500 tons. Another rotary thermoformer is located at its Canadian plant in Orillia, Ontario.

How To Expand Capacity?

By 2022, it became apparent that a capacity expansion had to be considered. Demand had grown substantially for PolyJohn’s largest-volume products —standard construction-grade portable toilets — and the firm was also looking to expand into contract manufacturing for other markets. According to Sam Cooper, president/CEO of PolyJohn since 2022 and grandson of co-founder Ed Cooper, “We were thinking seriously of buying another extruder, but then we said, ‘Let’s take a look at our high-volume products and how to make them faster, better, cheaper.’ We started by looking at issues regarding labor costs and availability for extrusion and thermoforming.”

PolyJohn began working with blow molding specialist Uniloy Inc. “We met the engineering and sales teams, who explained the process to us,” Cooper recalls. “Blow molding is both an art and a science, and Uniloy really helped speed up our learning curve. They presented us with a turnkey solution. They were definitely more a partner than just a vendor.”

Cooper adds, “We saw that, in comparison with thermoforming, blow molding saves inventory, work-in-process and labor. There’s no need to run sheet, cool it down, and then reheat it and form it, and the cycle time for blow molding is as good or better than for thermoforming.”

Once PolyJohn decided to pursue blow molding, the next challenge was where to put it. “Whiting was maxed out in terms of space and electrical power available,” Cooper says of the company’s Indiana headquarters. “We felt hesitant to buy a whole new building for blow molding while knowing hardly anything about the process.” Uniloy offered an unexpected solution: It had 40,000 square feet of unused space in its headquarters plant in Tecumseh, Michigan. So PolyJohn subleased the space right where the machine was built.

As its first step into blow molding, PolyJohn installed a Uniloy Model UAI2900V machine with a 75-lb accumulator head, 325-ton clamp and some custom options, including a quick-mold-change system with magnetic platens and molds on an indexing track beside the press. It was up and running in September 2024.

PolyJohn is now blow molding the roof, side panels and front panel for its flagship construction-grade portable toilet. “We can blow mold two roofs in one shot and cut them apart — all in the same cycle time as for thermoforming one roof,” Cooper notes. “We also blow mold two side panels in one shot — again in the same cycle as thermoforming one panel. So we doubled our productivity in both cases. A bigger challenge was the front panel. It had been twin-sheet thermoformed, but we can blow mold it in the same cycle time.

“In Whiting, we can make 75,000 standard toilets per year with thermoforming. This one machine in Tecumseh can make 40,000 toilets a year with six people.” Automated changeovers have also worked out well. “We can change both the mold and color in two hours versus taking a whole eight-hour shift. We could change either mold or color alone in perhaps 45 minutes.”

All told, blow molding realized substantial savings in the cost of producing a portable toilet. Equally important, Cooper notes, “We were floored by the improved quality with blow molding. We get better part definition — sharper corners — but part-to-part uniformity is even more of a benefit. Thermoforming always had issues with variability in shrinkage, sheet sag, ambient temperature, and there were issues with labor and adequate training to deal with manual fixturing and accurate hole placement.”

The latter has been solved with robotic trimming and hole drilling by a Kuka six-axis robot and a modular fixture table, which came online in November. The robot has a WiFi connection to the supplier for remote troubleshooting. “Before, we didn’t have sufficiently high volume to justify automated trimming and routing for our thermoforming lines,” Cooper explains.

And That’s Not All …

PolyJohn is exploring another unfamiliar process at the Tecumseh site. The firm just installed a 500-ton low-pressure structural-foam molding machine from Milacron. It will be used to make “skids” (bases) of portable toilets, which now are rotomolded. Similar to PolyJohn’s experience with blow molding, the new process provides higher quality and higher productivity.

Cooper says Tecumseh will be the headquarters site for producing the firm’s standard construction-grade portable toilet. The site now employs eight to 10 people, all new hires. That number could grow quickly, especially if PolyJohn adds assembly operations there.

Cooper does not see labor being displaced by the new, higher output processes. PolyJohn established two new divisions in 2024. One, called Cooper Plastics, will offer contract manufacturing services to utilize the thermoforming capacity freed up by blow molding. “We have some interesting bids in the works from large retail companies. So we won’t lose any people.”

PolyJohn also has a new Rapid RPS Division to supply products for disaster preparedness and response — some made in-house and others purchased outside. The new line includes cots, laundry carts, storage containers, tarpaulin kits, hygiene kits, buckets, mops, bedsheets and, of course, portable toilets. “We were active in responding to hurricanes Helene, Milton and Beryl,” Cooper says. “It was one of the most rewarding things we did this year.”

The Rapid RPS Division has also started work on products for wildfire response in Canada and the Western U.S., as well as mobile hospital products, such as a first-aid station built inside the frame of a portable toilet, equipped with instruments to take blood pressure and more.

Cooper sees lots of international potential in these new ventures, and he foresees need for another new facility of perhaps 250,000 square feet in the next few years.