Machine developments could spur IBM growthMachine developments could spur IBM growth

Interest in injection blowmolding machinery is rising as machine makers meet processors'' wishes for more machines able to process polyethylene terephthalate (PET)—the in-demand polymer for many applications—and as more moldmakers begin to serve the market. The end of a U.S. patent also freed potential injection blowmolding (IBM) processors there from concerns about legal battles when processing PET.

Typically IBM is a three-station process: preform molding, rotation of preforms to a blowing station, and parts removal from core rods. Parts formed, usually for packaging, offer excellent appearance, tight and consistent tolerances, and the process creates no scrap. Nonetheless, the global market for IBM machines is only 120 to 140 machines a year, according to Luca Bertolotti, technical manager at manufacturer Uniloy Milacron, in its Magenta, Italy, plant.

But as processor interest grows, he says Uniloy is expanding its range to include larger machines with preform mold clamp force range increasing from the current 45 to 75 tonnes, to new machines with 90 to 150 tonnes of clamp force. "This will allow higher cavitation" for increased outputs, he explains. He expects most processors will continue to process the same small (to 200 ml) products and not use the additional force for larger parts.

Some already offer such large machines, including Novapax (Leer, Germany), with IBM machines having preform clamp forces of 40, 65, 85 or 125 tonnes, and blowmold clamp force up to 65 tonnes. Its machines also are PET-capable. Novapax''s machines have four stations instead of three, which Novapax claims lets processors more easily run existing molds with the extra fourth station and makes for more efficient hydraulics. Ossberger (Weissenberg, Germany) makes large IBM units but these typically see use in automotive parts processing (see August 2002 MP/MPI).

Jomar Corp. (Pleasantville, NJ) offers IBM units with preform clamps from 12 to 170 tonnes. President Bill Petrino notes the firm recently added proportional hydraulics to its larger models, something it already offered on the smaller ones. Proportional hydraulics allow for more precise process control. "In the U.S. [proportional hydraulics] proves a good selling point; outside the U.S., processors often are not so keen to spend the additional $15,000 or so," he says.

Adds Petrino, "Jomar machines have always had vertical plastifiers, but in the last year we''ve added horizontal" for those customers more accustomed to horizontal extruders, as used on competitors'' models. Still, Jomar claims vertical extruders help processors save up to 33% on energy consumption. Uniloy argues for horizontal as a means of improving pack pressure, and easing maintenance and services.

Jomar began work on a PET-capable IBM unit in 2000 as processor Wheaton Plastics'' (Millville, NJ) U.S. patent on injection blowmolding of PET expired. Wheaton had made its own IBM machines, with electric servodrives, for processing PET. "We think we''ve got this [IBM of PET] down," Petrino says, as the firm has developed its own extrusion screw for plastifying PET and uses closed loop controls to control temperature of core rods so that temperatures remain within the narrow range suitable for PET processing. Higher temperatures can cause the material to crystallize and lose its clarity. "The PET kit can be retrofitted to other IBMs," he says.

Bertolotti says one of the biggest developments in the past few years has been the increase in the availability—and the decrease in the price—of the injection molds used on these machines. "It''s possible now to buy much better molds at lower cost" than a few years ago, he says.

Last year the world''s largest independent manufacturer of blowmolds, Wentworth Technologies Co. Ltd. (Burlington, ON), acquired IBM moldmaking leader Jersey Mold (Millville, NJ) to get its hat into the expanding IBM ring. Tooling is a major financial issue with these machines since, generally, two sets of molds cost as much as the machine itself. He says that as the selection and quality of tooling has improved, an increasing number of applications are shifting from extrusion blowmolding to injection blow, as the latter offers processors greater flexibility to fill more smaller orders.

Others question that assertion, among them Joe Spohr, Sr. VP global business development at extrusion blowmolding machine Graham Machinery Group (York, PA), who responds: "Hardly. I think injection blowmolding had its heyday 10 years ago. IBM cannot do multilayer and it doesn''t offer the outputs required." Uniloy is a major supplier of extrusion blowmolding equipment and ranks among Graham''s fiercest competitors.

Though the trend is clearly from PP or polyethylene (PE) to PET, the latter material still accounts for a small share of the market, says Petrino. When processing PP or PE, Bertolotti recommends specifying injection molding grades rather than extrusion blowmolding ones. "The good thing is, [materials] research is increasing for this process; there has been a lot of development with barrier resins, especially Barex," he says. Barex, supplied by BP and based on acrylonitrile co-monomers, is used to make single-layer bottles with high barrier performance.

Demand for IBM machines has been solid enough to attract the attention of more manufacturers. Novapax entered the market in 1998, and more recently Parker Plastic Machinery Co. Ltd. (Taichung, Taiwan) did so. In May, Meccanoplastica (Campi Bisenzio, Italy) exhibited the first commercially available electric-servodrive-powered injection blow machine (see July 2003 MP/MPI). There have also been some novel attempts at combining preform injection and blowmolding in a single step. Merle Norman Cosmetics (Los Angeles, CA) molds preforms and blows them in one step to transparent bottles using copolyester supplied by Eastman Chemical (Kingsport, TN), making bottles with walls .20 inch thick.

Matthew Defosse [email protected]