Blow molding: big changes to come.
Coextrusion, recycling, CAD/CAM/CAE, and use of new resins for everything from oriented bottles to large automotive and other industrial parts will set the pace for blow molding in the next decade.
New opportunities for plastics blow molding to compete with paper, metal, glass, and also with injection molding, will expand rapidly in the 1990s, adding major challenges to machine versatility and efficiency, processors and machinery people say. In containers, the opportunities and the challenges will come from new food applications like retortable jars, and competition between plastics materials for existing applications such as water bottles. The result will be a proliferation of container shapes, sizes and materials, all vying for brand identification. They'll require larger blow molding machines, more cavities, faster cycle times, and quick-change capability--not just for colors and molds. Even dies and screws will have to be designed to accommodate a variety of resins.
Recycling and environmental regulations will also cause profound changes in blow molded packaging, shifting the emphasis in coextrusion technology from sophisticated five- to seven-layer barrier applications toward simpler two- and three-layer heads designed to bury waste inside new parts rather than in landfills.
The push to recycle will also influence large-part applications, like trash cans and drums, where multilayer accumulator-head and continuous-extrusion blow molders are being introduced by several machinery makers.
Automation in secondary operations will also be an important trend in industrial blow molding, applying lessons learned from high-speed bottle lines. By the end of the '90s, blow molding plants could look much more like advanced injection molding installations today--"lights-out" operations with 10-15 machines supervised by a handful of operators at a central control station. The driving factors will be a shortage of low-priced labor and market demand for parts uniformity and documented quality not possible with manual trimming and finishing.
Automotive applications are expected to be a major growth area in the next 10 years, thanks to improved resins and design and mold-making capabilities. Just in its infancy now, computer-aided process analysis will take guesswork out of blow molded part design. Large parts in development for mid-'90s cars include instrument-panel retainers and seating components.
Auto fuel-tank production will likely shift completely to plastics--mostly HDPE, possibly with nylon or EVOH barrier--by the end of the '90s, in consequence of the transition to less-polluting fuels. "Within 10 years fuel tanks will all be blow molded," predicts Andrew Stoll, manufacturing engineer at Ford Motor Co.'s Milan, Mich., plastics plant. "By 1995 we'll see varying levels of alcohol in fuels, and steel gas tanks corrode badly in contact with alcohol." Also, revolutionary technology like the Japanese "horizontal" blow molding systems could soon make commercial inroads on fuel intakes for U.S. cars.
Blow molding of engineered materials will continue to challenge injection molding for office-machine and computer housings. And new super-large blow molders will take over more production of room-sized parts, like 350-gal intermediate-bulk shipping containers (see PT, June '90, p. 13). New applications and new resins will spur evolution of machinery--screws, heads and molds--to match.
COEX RETROFITS FOR RECYCLING
"Recycling and environmental issues will be the most significant thing in our lives in the coming years. This is not to be taken lightly," says John Antonopoulos, president of Krupp Kautex Machines Div. in Edison, N.J. The effect on blow molding so far has been to generate a lot of interest in coextrusion, but less capital spending. The trend among the few coex pioneers has been to retrofit or modify equipment in-house, not to buy new machines. The big bottle blowers have all followed this do-it-yourself approach for three-layer regrind coextrusion--including Continental Plastic Containers, div. of Continental Can Co., Stamford, Conn.; American National Can Co., Chicago; Sonoco Graham, York, Pa.; Owens-Brockway Plastic Bottles Div. of Owens-Illinois Inc., Richmond, Va.; and Plastipak Packaging Inc., Jackson Center, Ohio.
Retrofitting will continue. Blow molding consultant Meredith-Springfield in Springfield, Mass., recently hosted a three-day demonstration on retrofitting coex heads from Willi Muller Co. of Donrath, W. Germany, which drew 60 people from 30 companies from Mexico to Canada, and a 100 more had to be turned away. Muller offers a package (see PT June '90, p. 13) of a two- or three-layer coex head with vertical satellite extruder, applicable to smaller machines.
Two concerns holding processors back from bigger spending are 1) that coextrusion might prove to be a fad, and 2) uncertainties about cost and availability of recycled feedstock, which some expect to remain more expensive than virgin--for top-quality grade. It's also undetermined whether the trend in recycled materials will be toward flake or pellet form. Both are available now, though pellets are expected to win out as the "cleaner" alternative.
Gear pumps could become popular on coextrusion recycle machines, if molders follow the advice of Ed Naureckas, president of Coex Engineering Inc., Libertyville, Ill. He advocates using a gear pump on the recycle extruder to prevent surging and layer nonuniformity. This way, the extruder can run recycle in flake form, and the feed can even contain a mixture of resin types without surging, Naureckas says. He also recommends using a vented screw and a continuous screen changer.
Machinery manufacturers are all developing coex capabilities for large containers and industrial blow molding. Last November's K'89 show in Dusseldorf saw the introduction of three-layer accumulator-head systems aimed at recycling from APV Chemical Machinery, Inc., Edison, N.J.; Johnson Controls, Inc., Manchester, Mich.; and the W. German parent companies of Krupp Kautex and Bekum America Corp., Willamston, Mich.; as well as a continuous-extrusion recycle system from Battenfeld Fischer Blowmolding Machines, Inc., Waldwick, N.J. (PT, Jan. '90, p. 83; March '90, p. 13).
The North American market for such machines has been slow--none have been delivered so far--though machinery makers and automotive processors agree that coextruded industrial parts, for automotive and aerospace, will be important in the '90s. "It's the old problem of `where-can-you-show-me-one-that's-working?'" says Naureckas of Coex Engineering. Kautex claims to have sold the first multilayer machine expressly for recycling in North America, a three-layer KB-150 continuous-extrusion machine, to make a 32-gal trash can.
Battenfeld Fischer has applied recycle/regrind coextrusion to production of drums and jerrycans with a view stripe--an instance of two kinds of coextrusion at once. The view-stripe modification was recently added to a three-layer VK1-30 machine blowing 30-liter drums in Italy. A fourth small vertical extruder and special head were added to insert the view stripe of clear virgin resin, which cuts through all three layers of the wall.
AUTOMATION, HERE WE COME
"The most significant thing in blow molding in the '90s will be total downstream automation, to reduce or eliminate labor at every level in a plant, so that an SPC system can control parts quality in a lights-out environment," says Meredith-Springfield's O'Leary. "Blow molding right now, be it for industrial parts or packaging, is far too labor-intensive for the capital expense. Compare a $300,000 injection molding machine and a $300,000 blow molder. One operator can run 10 injection machines, while one blow molding press generates four or five low-skilled jobs." The day is passing, processors say, when they'll be able to find low-cost labor for those jobs.
The technology to automate bottle lines is available now, and more and more companies will convert to it, says Dieter Wunderlich, v.p. of FGH Systems Inc. (representative for Hesta blow molders) in Denville, N.J. "Labor is the second biggest expense in bottle production after raw material. You need a packer for every machine to eliminate moils and tails, but with automatic trimming and discharge, one packer can take care of three machines." The next step will be in-line flame treating, he adds, whereas now, "People load the bottle into a box and carry it to another part of the plant, where it's flamed and printed."
Krupp Kautex sees greater interest in full automation for blowing drums. The first U.S. order has been placed for Kautex's latest drum machine line (KB 150), which makes a 55-gal drum using new technology for fully automatic deflashing, cutting, drilling, weighing, and leak detecting.
Paul Rothschild, president of Fremont Plastic Products Inc. in Fremont, Ohio, a Q-1 blow molder of consoles and other parts for Ford Motor Co., is spending R&D money to study robotic cutting with lasers and water jets, because "the secondary machinery people didn't seem to be addressing the automation issue." Automation for smaller parts exists, but the high-speed automatic trimming and deflashing on bottle lines isn't easily adapted to the short runs of custom industrial blow molding, Rothschild says.
Fremont is developing a programmable, automated x-y-z router, which will increase parts uniformity by correcting the inevitable variations in hand finishing and even some of the part-to-part variations imposed by the molding process itself. Eventually, Rothschild wants to develop a programmable deflashing robot with die sets, using machine vision of some kind to sense where the edge is to be trimmed. For now, he says such a system may not be cost-effective, but he expects the economics to change. "If you look at the trade-off between capital and labor, you'll be able to afford more capital for doing some of these things in the '90s than you were in the '80s. The time to do it is now, and not wait until you have to ask, `Oh my gosh, where am I gonna get somebody to do this.'"
Rothschild's ultimate dream is to design a part on a 3D CAD system, transfer the design information to a moldmaker, who generates a tool path and cuts the mold, then take the same CAD file to another supplier to build a robotic trimmer.
COMPUTER PROCESS SIMULATION
"Toward the end of the decade you could see the time to develop a major automotive part reduced to six months from several years now. A blow molded part might go through only three or four stages: pre-prototype, prototype, pre-production, and full production," says Charles Taylor, former coordinator of GE Plastics' Polymer Inflation Thinning Analysis (PITA) program in Pittsfield, Mass., and now at General Electric Co.'s corporate R&D center in Schenectady, N.Y. PITA is GE's pioneering software for blow molding process simulation, which GE uses to help customers "design for manufacturability" (PT, June '89, p. 15).
"It's surprising how little we really knew about what happens inside the mold," muses Taylor. "With process analysis, we look at the part design and the material distribution. We simulate the mold closing and inflation of the part, and we can make a prediction within 10% of the final wall thickness in different areas of a part. The previous rule-of-thumb methods couldn't come within 50%."
PITA was derived from blowing hundreds of parts under different conditions into a "step mold," a series of telescoping box shapes from small to large, fitted with thermocouples. "Using high-speed video equipment, we're also filming the parison as it's being extruded before the mold closes, and using computer analysis to model the rest of the physical process that takes place inside the mold," Taylor says. The intent is to eliminate the risk of designing costly engineering-resin blow molded parts that end up using more resin than necessary and fail the test of cost-effectiveness.
In the past, industrial designers who weren't familiar with blow molding would base material cost estimates on unrealistic expectations, like "uniform wall thickness," which doesn't happen in blow molding. Because designers couldn't anticipate how nonuniform the part would be (10:1 variation in wall thickness is possible), they had to build in excessive "safety factors." Some bumper beams, for example, turned out to use two to three times more material than planned, Taylor says, causing cancellation of some projects, and even delays in car introduction.
MOLDS BUILT OVERNIGHT?
Computer-aided process simulation isn't the only new technology that will speed development of new blow molded parts. So-called "desktop manufacturing" methods, such as stereolithography and selective laser sintering, for rapidly converting CAD data into 3D objects, are beginning to be considered for blow molding. "We just made an injection mold in a week using stereolithography to prototype the part. We're somewhat restricted in size now, but this technology is very new and can be used for blow molds too. Anything you can imagine can be done," says Jerry Hobson, owner of Hobson Bros. Aluminum Foundry & Mould Works Ltd. in Shell Rock, Iowa. He also has his eye on laser sintering: "Who's to say you can't put a powdered metal into a laser beam and build a mold? With such technology, I think you'll see molds being built at night when nobody's there."
Hobson may not have to wait long for laser sintering of metals into molds from CAD designs. Laser sintering of metals is being done now in a lab at the Mechanical Engineering Dept. of the University of Texas in Austin, which holds patents on a process being commercialized by DTM Corp. in Austin (PT Jan. 90, p. 23). DTM (majority owned by BFGoodrich Co.) is commercializing a selective laser sintering machine, the SLS Model 125, which builds wax models of molds for lost-wax casting, as well as mock-ups or prototypes of ABS or other plastics. DTM marketing manager Kent Nutt says building a wax mold can take 2-6 hr, depending on complexity. DTM just opened a service bureau in Brecksville, Ohio, where customers can bring "a 3D CAD file, or actual design drawings, which we would then input into our engineering workstation, using solid-modeling CAD software. Then we transfer the CAD file to the SLS Model 125, which builds the design represented in the CAD file," Nutt says. "The idea of the service bureau is to be sure we fully understand customer design needs before we put the SLS machine on the market in 1992."
In the next several years, DTM also hopes to have a prototype metal sintering machine. Research is being done at the university on a modified SLS Model 125, originally designed for polymer sintering, but substituting a higher-powered laser. According to Dr. Joseph Beaman, professor of mechanical engineering, the modified machine is sintering low-temperature metals such as copper, tin, and aluminum. A higher-temperature oven and more powerful laser for sintering steels is still on the drawing board but should be ready in six months. Beaman hopes to "produce a material of machine-tool strength" applicable to moldmaking.
Automotive applications are seen as one of the burgeoning areas of new opportunity for blow molders, but it will require them to gain experience in running unfamiliar materials, such as nylon, PP, and other polymers not commonly blow molded, says Paul McGill, chief engineer at Hartig Plastics Machinery Div. of Somerset Technologies Inc., New Brunswick, N.J. For example, Himont U.S.A., Inc., Wilmington, Del., is developing new high-melt-strength PP resins capable of hanging large parisons, such as for blow molded seat backs.
McGill expects that extruders may be designed with screws that can be changed easily to run a variety of materials. Press speeds will also have to be faster, he says: "Machines built in the last year or two may be adequate, but not older ones."
And coextrusion will have new applications in high-tech automotive parts, to achieve vapor barrier in fuel tanks, and to insulate against heat and sound, as in the case of a two-layer, foam/solid PP air duct being produced in Europe on a Kautex machine (see photo). Density of the foam layer is 0.42 g/cc--about a 55% reduction, according to Kautex's Antonopoulos, who knows of no other commercial blow molded foam part.
"Accumulator heads will become more specialized to handle automotive resins," predicts McGill. "More attention will be paid to contouring and streamlining heads to handle heat-sensitive polymers like nylon and PP, to ensure against burning inside the head. These polymers run maybe 100 [degrees] hotter than PE would normally run--at around 500 F. Flow surfaces on the insides of heads might be chrome plated--rarely done in blow molding now, though common in extrusion dies."
Extruders and screws will need to be specially designed for running the new tougher, high-molecular-weight resins for automotive parts, machinery makers say. "You'll need grooved feed throats in the extruder and non-compression screws with almost constant root diameter; and the mixing sections of the screw will be only at the end to run at very cool temperatures," says Kautex's Antonopoulos. He adds that it's equally important for the head to deliver melt to the die without adding backpressure, which could further raise the resin temperature.
Processors don't expect major inroads in blow molded auto body panels, largely because they say they can't really get a Class-A surface out of a mold. The mold thermal-cycling approach of Du Pont Co., Wilmington, Del., "improves the surface, but still requires secondary polishing," says Roger Duncombe, general manager of Modern Plastics Corp., Coloma, Mich., one of the largest U.S. blow molders of engineering resins. The Du Pont process also doubles cycle time, he says, "And it can cost another $200,000-$300,000 to retrofit your press."
Nonautomotive large-part applications for engineered blow molding are also developing rapidly. Duncombe says the biggest thing he sees happening is machine housings, like side panels for copiers. "We see more and more applications, mostly because of materials developments. A lot of stamped steel and plastic injection molded or structural-foam parts are going to be blow moldable in the future--and a lot less expensive," he notes. Duncombe also expects more flame-retardant and low-smoke/low-toxicity blow molding materials to be aimed at transportation applications--airline seat backs for example.
NEW TWIST FOR UNDERHOOD PARTS
Horizontal-parison extrusion blow molding machines from Japan represent one of the most novel blow molding technologies to appear recently (PT, May '89, p. 58). With movable extruders, heads and/or molds, these machines can lay a parison into a complex cavity, such as an irregularly shaped duct, virtually without flash. With the mold tilted or horizontal, melt strength of the material no longer is a limitation on large parts. And these machines are able to extrude two different resins--in layers, sequentially, or side by side--so as to place hard and soft materials in a part where they are needed.
Such technology has yet to make a major production auto part in the U.S., but that could change soon. Excell Corp. of Japan has set up MES Corp., a custom molding operation in Troy, Mich., using proprietary horizontal blow molding machines (which are not for sale). Excell operates such machines in Japan and Sweden for automotive and other applications from fuel intakes to instrument-panel retainers. MES president Ram Mehta, formerly a research engineer at the General Motors Technical Center in Warren, Mich., says Excell currently supplies eight of 11 Japanese car companies and two Korean auto makers with over 60 auto parts. In the U.S., MES plans to start supplying Subaru in Lafayette, Ind., this year with an air-cleaning duct combining PP and TPO materials, and is quoting on an instrument panel with built-in airbag compartment for the 1992 GM Saturn. Mehta sees a U.S. market potential of up to 10 million parts in three years, he says, which translates into a need for "at least 30 machines." Mehta's goal is to have 50 machines here within four years.
(Placo Co. of Japan--with offices in Torrance, Calif.--makes a machine of this type, though this has been the subject of a patent dispute with Excell.)
MORE VARIETY IN STRETCH-BLOW
Two polyolefin materials have been subjects of speculation that they might challenge PET for at least some segments of the oriented bottle market in the '90s. However, the challengers have a long way to go yet. Oriented PP, for example, looked as if it might be poised for a comeback with the emergence of potentially trend-setting orange-juice application a year ago (PT, Sept. '89, p. 15). Virtually all PP resin producers were looking to exploit this "breakthrough" with new, high-clarity resins for oriented bottles.
Today, some have adopted a more cautious attitude. One is Donald A. Goodridge, industry manager for packaging at Himont U.S.A., Inc., Wilmington, Del. He hasn't seen any major commercial successors to last year's juice bottle, though he says considerable interest and opportunities still exist for PP in applications where moisture resistance is important. "To get these programs from the drawing board to commercial reality, it's important for resin producers, equipment manufacturers, and end users to work closely together," Goodridge says, adding that there's also a lot to be learned about OPP preform design.
Other observers note that some processors' initial interest in PP has been dampened by the high cost of available stretch-blow machinery. And PP's limited market today further discourages new applications because of environmental perceptions. "People think because PP is used in lower volume, it won't be recycled; so they go with PET," says one machine builder.
While PP at least has around 10 [cents]/lb cost advantage over PET, the reverse is true of another new contender, polymethylpentene (PMP). Just two months ago, Phillips 66 Co., Bartlesville, Okla., introduced a new grade that's said to be the first to give crystal-clear bottles when stretch-blow molded (PT, June '90, p. 21). However, this development is still in its infancy; Phillips' first commercial plant won't be on stream until 1992; and Phillips' PMP is priced at $1.75/lb, which is a far cry from PET levels. PMP does have an advantage in heat resistance for hot-fill or retortable containers, but it also suffers from poorer gas barrier than PET, except for moisture.
Thus, there's reason to doubt that anything will unseat PET in oriented bottles during the next 10 years. With big-volume soft-drink markets apparently saturated for the time being, the recent trend has been for development of lower-output machinery systems for custom bottles and shorter runs of miscellaneous food containers. William Mueller, technical manager at Krupp Corpoplast in Edison, N.J., sees a trend to individual, branded container shapes. For example, he says in Europe there are many PET stretch-blown oval, square and rectangular bottles, made with only slight machinery modifications.
Mueller also sees growing interest in wide-mouth PET jars, especially with heat setting. He says Corpoplast is introducing a BW-60 wide-mouth wheel machine, which will be demonstrated at NPE'91 in Chicago next June. In addition, Corpoplast recently shipped its first CorpoTherm heat-setting wheel system to a customer in the Far East.
Shoichi Ichikawa, v.p. of Nissei ASB Co., Atlanta, also believes wide-mouth will be a major area of emphasis for PET in the future. (Nissei introduced several wide-mouth developments at K'89 last fall--see PT, Jan. '90, p. 85). However, he also expects the search for better barrier and heat resistance to be dominant themes of the '90s, leading to more multilayer wide-mouth and other PET containers.
PET & PP GO NON-ORIENTED
One of the bigger events of the '90s could be the advent of nonoriented extrusion blow moldable PET. At K'89, Automa of Italy (and Mississauga, Ontario) showed a system that extrusion blow molds ordinary injection-grade PET. Bekum in Germany is working on an inexpensive machinery alteration to allow "slightly modified" PET to be extrusion blown, says Manfred Weiss, technical sales director in Berlin. The equipment modification is "something like a side accumulator between the extruder and the head," Weiss says. It could be available in as little as a month. The resin needs only an "after-condensation" to give it more melt strength, but not making it more than 10%-15% more expensive than standard PET, he says.
Resin companies say that if PET can be extrusion blown on standard equipment, it will find a ready food market, with or without barrier. They say the oxygen barrier issue is overrated, and that food companies often don't know, and may overestimate, what barrier performance they really need.
PP, too, faces growing prospects in unoriented extrusion blow molding. The 1-gal water bottle is up for grabs--a 1.5-billion-gal market in 1988, growing 12%-15%/yr, according to the International Bottled Water Association. Water bottles are blown today out of HDPE, PVC, PET, and even Phillips' K-Resin. PP could be a strong contender against more costly PET over the next 10 years, processors say, except that PP is generally considered to have insufficient melt strength to support a parison for a bottle that big.
However, Himont is looking to change that with its new family of high-melt-strength PP's (noted above), which have already been blown commercially into 1-gal handleware. Himont market development manager William R. Curtis expects the new large-part blow moldable PP to be successful against HDPE because of its lower taste and odor transfer.
A small Texas bottle maker, Western Environmental Plastics Inc., Lewisville, Texas, says it's already testing a 1-gal handled PP bottle for a water bottler. The bottles are extrusion blown "with no difficulty" on a modified two-head Uniloy 2011 machine, says Western Environmental President Kurt Ruppman, using an off-the-shelf clarified PP.
PP water bottles are also being injection-blow molded in Spain and Brazil on machines from Jomar Corp., Pleasantville, N.J. Jomar, by the way, just delivered what may be the biggest injection-blow machine yet built--with 200-ton parison clamp and 28.5-ton blow clamp--to American Plastics Inc., Independence, Mo., for personal-care packaging. Jomar worked 18 months on the "supersize" machine, which includes "advanced technology in the way it opens, closes, and transfers," says C.B. Starks, executive v.p. of American Plastics. Jomar is considering adding such a model to its standard size range.
"I think people will have to become as versatile as possible in order to grow in blow molding," says John Francis, Johnson Controls' director of marketing and product development. He sees many dairy customers with bottle lines dedicated to 1-gal HDPE milk jugs, who want to expand into bottled water. So Johnson Controls is broadening the capabilities of its Uniloy dairy machines to run other resins like PVC, PETG, and PET.
Although the new machine is still in the development stages, Francis says running different materials "will probably entail changing the screw, which we can do in 4 hr in the R&D lab."
In 10 years' time, he also foresees quick-change heads with hydraulic fittings and quick disconnects, not "hard" piping and wiring, to allow switching from single to dual parison heads. Heads might also have a single-point, frontal die adjustment (vs. a four-point adjustment area today), Francis speculates. "You would definitely have to change the head tooling, but probably not the head itself," he says. "The head could be relatively universal, and you would only have to change the die and mandrel."
Cincinnati Milacron Plastics Machinery Systems, Cincinnati, last year bought Hayssen Mfg. Co., a manufacturer of conventional extrusion blow molding equipment, largely because of the simplicity and ease of use of Hayssen's changeover technology, says Gary Harvey, general sales manager. "On Hayssen's 60-65 Autoblow, changing from one quart bottle mold to another quart mold of a different bottle shape can be done in 1 hr and is very easy," he says.
FGH's Wunderlich notes that a prototype quick-change Hesta continuous-extrusion blow molder was demonstrated at K'89. This HM 501 machine runs PVC, HDPE, and PP, Wunderlich says. "We demonstrated changing from a round bottle to an oval handled bottle in 21 min."
Modern Plastics' Duncombe adds that automotive blow molders want future heads developed for quicker and less expensive color and material changes, because in switching from an engineering resin to HDPE, "you can pump several thousand lb of material through, and it has to be thrown away." Purging compounds don't clean out all engineering resins completely and are also expensive, he adds. Hartig, Kautex and APV are all working on the problem.
NEW COOLING TECHNIQUES
Efforts to blow mold larger industrial parts and smaller parts at higher output rates will focus in part on improved cooling, which typically consumes 40-80% of today's cycle times. John Mikula, head of the big drum division of Sonoco Products in Lockport, Ill., foresees a "move to cooling molds. A part will be blown and formed in one mold and then transferred almost immediately to an identical cooling mold to speed up production." Agreeing with this view is Stephen Cornell, director of packaging technology at American National Can Co. He foresees that cooling molds mounted on separate "cooling wheels" will be a trend in smaller container molding, both oriented and unoriented.
For big drums, Mauser Werke GmbH recently displayed a prototype "aftercooler" system at June's Interpack show in Dusseldorf. In this system, each drum automatically moves to a cooling station resembling a room-sized refrigerator with glass walls, 12 x 12 x 6 ft high. The drums move on a belt through the cooler, which handles four drums at a time. (Mauser Packaging Ltd. is in Litchfield, Conn.) Krupp Kautex has a number of KB 150 drum machines with a secondary cooling mold operating in Europe.
And mold technology itself will change. Heise Industries Inc., E. Berlin, Conn., is applying for patents on a "jacket cooling" approach, which has been prototyped on a proprietary wheel blow molder. The key is using water-cooling lines that follow the contours of the mold cavity. V.P. Tad Heise says a conventional mold typically has straight-drilled water lines 1-1 1/2 in. apart, which is all right for a straight-walled bottle shape, but yields uneven cooling and shrinkage with the new "designer" bottle shapes.
Quantum Chemical Corp. reports considerable interest in a paper on liquid nitrogen cooling, presented by senior research engineer Morgan L. Gibbs of Quantum's USI Div. in Rolling Meadows, Ill., at last year's SPE ANTEC in N.Y.C. Liquid nitrogen introduced through the blow pin is used in large drum production, but Gibbs sought to prove it cost-effective for containers from 1 pint to 1 gal. Gibbs demonstrated 34% cycle-time reduction on an HDPE Boston round pint, and 21% reduction on an HDPE gallon bleach bottle. Taking into account the nitrogen cost of 6[cents]/lb, this saved 11% on cost per part to the gallon's cost. Gibbs believes that optimized blow-pin design could achieve savings in the latter as well.
PHOTO : Major bottle makers want to utilize recycle with coextrusion but are not yet willing to
PHOTO : replace their existing wheel machines. Retrofits seem to be the answer.
PHOTO : Secondary automation is the trend. Here an 8-gal jerrycan with a view stripe is made at a
PHOTO : rate of 85/hr, deflashed and oriented, on Battenfeld Fischer's VK1-30. What you can't see
PHOTO : through the view stripe is that this is a three-layer coextrusion containing 80%
PHOTO : post-consumer recycle in the middle (close-up, left).
PHOTO : In-mold labeling is another attractive form of automation (here on a Krupp Kautex KEB
PHOTO : machine). PE film labels could help facilitate recycling.
PHOTO : For now, DTM's selective laser sintering device makes models out of casting wax. But
PHOTO : research holds the promise of building steel molds overnight from fused metal powder,
PHOTO : directed by a CAD program.
PHOTO : A Japanese custom molder has set up MES Corp. in the U.S. as the first to exploit novel
PHOTO : "horizontal" blow molding technology for producing complex-shaped auto parts, such as air
PHOTO : ducts. Subaru air duct has rigid PP in the tubular sections and soft TPO at the ribbing
PHOTO : and ends.
PHOTO : Two- and three-layer coextrusion as a means of utilizing recycled polymers will be a major
PHOTO : trend in the '90s.
PHOTO : Coex will find new uses in industrial parts, such as this novel automotive air duct, with
PHOTO : a PP foam sound and heat barrier, covered with a PP skin. It's made commercially in
PHOTO : Europe on a Krupp Kautex machine.
|Printer friendly Cite/link Email Feedback|
|Author:||Schut, Jan H.|
|Date:||Aug 1, 1990|
|Previous Article:||New modeling system makes parts in minutes instead of hours.|
|Next Article:||The right roll for wrinkle-free web processing.|