High-tech molds speed milk jug production

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Smith Dairy Products Co. has cut cycle times by 14 percent — from 7.1 seconds to 6.1 seconds — for its blow molded gallon milk jugs by installing mold blocks with water-cooling channels that are contoured to fit the shape of the bottle.

In mid-March, technicians from ThermaForm LLC added the final section of the bottle mold, the center block with a handle. ThemaForm installed the top block for the neck finish in February 2008. Smith Dairy got a return on that initial investment in just eight days. The bottom block, for the base of the jug, came later.

The complete mold can pay for itself in 30-45 days because of increased production, said Rick Roberts, a blow molding consultant who is working with ThermaForm.

The mold blocks use so-called “conformal cooling” by directing chilled water close to the bottle shape, which is a major improvement over traditional, gun-drilled cooling channels that run in a straight line, ThermaForm said.

Smith Dairy runs two Uniloy four-head blow molding machines. Both were built in the early 1970s. The dairy began blow molding its own milk jugs in 1972, the year it stopped using glass bottles.

The savings are substantial. Each blow molding machine now can produce 336 more bottles an hour, an improvement in productivity that saves $50.40 an hour, based on a cost of 15 cents for each high density polyethylene container.

Located in small-town Orrville, right next to the city hall, Smith Dairy is a rarity: It is one of the last independent dairies in Ohio.

Each penny counts, said Smith Dairy's maintenance supervisor, Dave Caldwell. “It helps us on a cost-per-unit [basis] in a competitive market,” he said.

Independents go up against units of mammoth Dean Foods Co., which after years of consolidation is a huge national player in dairy products. But Smith keeps chugging along, now celebrating its 100th birthday. The company is owned by the third generation of the founding Schmid family.

During the last 10 years, Smith Dairy has upgraded its two Uniloy machines with Allen-Bradley programmable logic controllers, air-cooled barrels and air-exhaust controls for quickly removing air from the blow molded bottles, Caldwell said.

The conformal cooling molds mark the latest investment to increase cycle times. Caldwell said the molds also allow a fast start of just 15 minutes. Lower mold temperatures also reduce bottle neck ovality.

Smith Dairy's plastics molding department is housed in a tightly packed area. After molding, the bottles go through a trim press and leak-detection station. Then they are conveyed over to the adjoining milk processing building, where they are staged prior to labeling and filling.

“It's great when you can improve production of an existing machine,” said Caldwell, who pointed out that the plant has no extra room to add a third blow molding machine.

Roberts said mold cooling has been the limiting factor for cycle time on blow molded packaging for 40 years. “There's been no advancement in the technology for blow molds for decades,” he said.

Rather than cutting the blow molds from a solid block of aluminum, ThermaForm uses a high-speed laser to cut a series of thin plates. Using a patented brazing process, the aluminum plates are fused together, with the curved cooling channels already in place.

“When you get done with this, it's one solid block,” Roberts said.

Smith Dairy's use of ThermaForm conformal cooling is really two stories — one about a venerable Ohio dairy increasing bottle output on machines more than 35 years old, and another about a mold-technology company that tried, without success, to interest automotive customers and made the switch to packaging.

Cars to packaging

ThermaForm of Troy, Mich., is a subsidiary of FloodCooling Technologies LLC. The company began in 1999 when Mark Manuel and two other Michigan automotive executives started a company called Fast4M Tooling LLC (pronounced fast form), to make conformal cooling molds.

Tom Clark, a retired executive from advertising agency BBDO Worldwide Inc., bought majority ownership in Fast4M in 2003. Clark formed a holding company called FloodCooling Technologies, which purchased the patents.

Clark said he attracted some high-profile investors, including Jim Holden, former president of Chrysler Corp.; George Simon, president of used-machine-tool seller U.S. Equipment Inc.; and Jerry York, former CEO of Chrysler and IBM Corp.

The target was injection molds for large automotive parts, at Tier 1 suppliers and directly to Chrysler and General Motors Corp. But Clark said that proved a tough market. Potential customers wanted Fast4M to first make prototype tools — at its own cost. That got expensive.

Clark said automakers were having financial problems, and decision makers also balked at investments for new technology. “Between product designers who liked the concept, and purchasing agents who had to approve the financing, we had some difficulty in finding the money,” he said.

In 2007, Clark scaled way back, reducing the company to a handful of engineers and consultants to adapt the technology to blow molded packaging.

Roberts, a 40-year blow molding veteran, said the technology has great potential in HDPE packaging. He worked for 17 years in field service at Uniloy in Michigan, when the machinery company was a division of Hoover Ball & Bearing Co. He was head of maintenance and engineering for Emplas Inc., a blow molder in Puerto Rico, and later co-founded former blow molding machine maker Allied Plastics Systems LLC.

Packaging outlook

Clark's company created ThermaForm to push into the packaging market.

ThermaForm works with a blow molder's designated tool shop and uses a three-dimensional computer model to cut the aluminum plates. The fused, solid block is called a ThermaBlock.

Currently, the company is working with two major blow mold makers: Mid-America Machining Inc. in Brooklyn, Mich., which supplies Smith Dairy's milk jug molds; and Heise Industries Inc. of East Berlin, Conn., which makes molds for consumer products. The toolmakers machine the blocks into finished molds.

The company's sales representative is Hollo Plastics Equipment Inc. in Northfield, Ohio.

ThermaForm has test results to back up its claims. Metallurgical studies by Wayne State University in Detroit showed the ThermaBlocks are a unified, solid mass. “We've done that to prove that these plates, they're not coming apart,” Roberts said.

CMS Solutions Ltd. in Windsor, Ontario, did thermal imaging at the milk bottle molding operation in Orrville, Roberts said, proving that the conformal-cooling blocks significantly reduce temperatures in the mold.

According to Roberts, the fast return on investment for milk jugs will apply to the broad HDPE packaging market, since the jugs fall into the middle of the range of shot-size weights and average cycle times for the entire sector.