Cooling process cuts preform shrinkage
Netstal-Maschinen AG's Calitec cooling technology solves the problem of an extremely short cooling time for PET preforms — where the remaining heat inside the part can cause the preform to soften.
In conventional systems, the molded preform is guided into a cooling sleeve for post-cooling. As the preform shrinks away from the walls of the cooling sleeve and is no longer supported by the mold core, it loses contact with the sleeve around much of the circumference.
That means the cycle time is ruled by the post-cooling process, Netstal said.
With Calitec, compressed air is pumped into the preform, giving a slight air pressure. This prevents the molded part from shrinking away. It is uniformly pressed onto the cooling sleeve, over its entire circumference.
A special device grips the preform and gently closes it off, then routes the low-level compressed air inside.
The calibration pressure slowly increases during the cooling phase, to counteract increasing shrinkage of the plastic.
Netstal is based in Näfels, Switzerland. The company's U.S. unit, Netstal Machinery Inc., is in Devens, Mass.
Tel. 978-772-5100, fax 978-772-5151, e-mail [email protected]
Wolfcraft handles molded on new press
Wolfcraft GmbH, the German maker of hand tools for do-it-yourself projects, has added a multicomponent injection press from Wittmann Battenfeld GmbH for molding a new product.
The machinery maker helped Wolfcraft develop the two-component handles for a manual sanding tool for plasterboard, from the early stages through production. The handles are soft to the touch.
Wolfcraft brought its injection molding in-house five years ago, to its plant in Dunajska Streda, Slovakia, achieving substantial cost cuts. Wolfcraft now has 12 injection presses, with clamping forces from 60-160 metric tons, all from Wittmann Battenfeld.
The new multicomponent press is equipped with Battenfeld's Airmould process for gas injection, and an integrated servo-electric rotary unit.
The first station molds the polypropylene body of the handle, using Airmould. Then the mold is opened and a rotary table moves the preform into the second position, where a thermoplastic elastomer is injected into the hollow part.
Wittmann Battenfeld is based in Kottingbrunn, Austria. Its U.S. operation, Wittmann Battenfeld Inc., is in Torrington, Conn.
Tel. 860-496-9603, e-mail [email protected]
Priamus mold sensors work without contact
Priamus System Technologies AG of Schaffhausen, Switzerland, has introduced a non-contact mold-cavity temperature sensor called Prisolaris, and a new device to test its pressure and temperature sensors.
Priamus also announced that its cavity sensors are now integrated in injection press controllers made by Keba AG of Linz, Austria.
Conventional sensors are flush mounted, so they touch the part. Prisolaris sensors control the injection molding process without touching the molded part because they are mounted under the mold surface. The Priamus Fill system can now be used to balance mold cavities in hot-runner applications where a sensor mark is not acceptable, such as optical or cosmetic parts.
Prisolaris sensors detect the melt front, a key function for the Priamus automatic switchover from mold filling to holding pressure.
The handheld signal tester type 8951A displays the actual pressure and temperature values, for on-site testing of the measuring signals. It includes an insulation test for all piezoelectric sensors and a check of the sensitivity detection of cavity-pressure sensors.
The company's U.S. operation, Priamus System Technologies LLC, is in Brunswick, Ohio.
Tel. 877-774-2687, fax 877-678-5062.
Macro line to produce barrier shrink bag film
Film equipment supplier Macro Engineering & Technology Inc. has developed a DXL series of double-bubble lines to make barrier shrink bag film.
The primary products for DXL machines are five-layer and seven-layer tubing for shrink bags used as food packaging for cheeses and fresh or smoked meats. The barrier layer can be nylon, polyvinylidene chloride or ethylene vinyl alcohol.
The shrink bag film has a barrier against water, oxygen and aromas, shrinkage of 40-60 percent, and superior puncture resistance, Macro Engineering said. The bags also are heat-sealable and printable.
Macro is based in Mississauga, Ontario.
Tel. 905-507-9000, fax 905-507-3000, e-mail [email protected]
Trexel, MuCell team for molding process
Trexel Inc., developer of the MuCell microcellular molding process, is working with injection press maker Engel Machinery Inc. to commercialize the injection/ expansion molding process, also known as the “core back” process.
Core back can mold structural parts with dramatic weight savings by cutting the density and increasing the ratio of stiffness to weight, the companies said. Once the foamed resin has filled the mold, the back of the mold is partially extracted to foam a thick, multilayer structure.
Trexel President David Bernstein said that by combining core back and MuCell, “you can essentially saturate the polymer with supercritical fluid, or gas in its supercritical state, while keeping the mold closed under pressure, and then precisely open the mold to get maximum expansion.”
“You get a much thicker part, but one that is much less dense, in fact as much as 75 percent less dense,” he added.
Customers in North America can conduct trials at Engel's facility in York, Pa. Stephan Braig, president and CEO of Engel's North American operations, said the process has good potential for applications that have a flat surface, such as automotive door panels.
In one recent commercial application, Mazda Motor Corp. has used core back and MuCell to mold parts with weight reductions up to 30 percent. Mazda, which is working with injection press builder Japan Steel Works Ltd., plans to start using the technology on 2011 model-year cars.
In other news, the Woburn, Mass.-based Trexel said Unilever NV's 171/2-ounce Rama margarine tub won the 2008 German Packaging Award (Deutscher Verpackungs Preis), and a WorldStar Packaging Award.
The tub design was developed by Veriplast Solutions of St. Priest, France. It uses Veriplast's super-light injection molding (SLIM) technology, which combines MuCell with the Veriplast Extra Slim Label.
Tel. 781-932-0202, fax 781-932-3324.
Sepro Axess robots offer greater reach
New configurations of the Axess beam robots from Sepro America LLC give molders up to 33 percent greater vertical reach, plus new safety and convenience features.
The new Axess 22 has a standard vertical stroke of 55 inches, with 64 inches available. Sepro America said that's 8 inches of additional stroke previously unavailable on this size of robot.
The Axess 33 has a standard vertical stroke of 64 inches, with 70 inches available.
Telescoping arms, for low-ceiling applications, are also available on both models.
The vertical stroke on the smaller Axess 11 remains 38 inches, which is no change from the previous model, the Axess 10.
Sepro America is based in Emsworth, Pa.
Tel. 412-459-0450, fax 412-459-0470, e-mail [email protected] .com.
Novatec dryer boasts a smaller footprint
Novatec Inc.'s IntelliPET wheel dryer for PET takes up only 55-60 percent of the floor space required for competing wheel-based PET dryers and uses 40-50 percent less energy than conventional dual-desiccant bed dryers.
IntelliPET has a desiccant wheel dryer similar to Novatec's NovaWheel, a two-zone drying hopper, an electric or gas-fired heater, a cyclone and an optional, self-cleaning “pulse” type of dust collector. One key to the efficient, simple design is the re-use of heat in the air returning to the dryer from the hopper.
According to Novatec, the air is filtered within the dryer, then enters a blower, where the air is split into two streams. The air in one stream is cooled before it passes through the desiccant wheel, and then is reheated before entering the lower zone of the hopper. Air in the other stream remains at such a high temperature that it requires only minimal reheating before entering the upper zone, which saves energy, the company said.
By comparison, Novatec said, the competing wheel-based system for PET has an entire additional drying circuit centered on a hot-air dryer, two cyclones, two low-efficiency gas heaters and two dust collectors with cartridges, which require periodic changing.
The competing wheel dryer is more expensive and costs more for maintenance during its lifetime, according to Mark Haynie, dryer product sales manager of the Baltimore company.
Tel. 410-789-4811, fax 410-789-4638, e-mail [email protected]