New machinery expands opportunities for EPS and EPP molders.

Quicker mold changes for short- and medium-run shape molders are provided by the latest expandable bead molding machinery from European suppliers. At last fall's K'95 exhibition in Dusseldorf, Germany, new equipment reflected this and other trends that could broaden bead-foam applications potential. Examples are "skin molding" to provide a moisture barrier or decorative surface on food packaging and durable goods; more high-pressure EPP machines; presses that can run either EPS or EPP; new dual-density or dual-material molding systems; and a prepackaged mobile plant that can be erected quickly near a customer.

MORE PRESSES FOR EPP

Two new lines of EPP machines testify to the growing interest in this material for resilient packaging and durable goods such as helmets and auto parts. Because EPP does not contain a blowing agent, these machines require mold pressures of up to 6 bar, about double the pressure for EPS.

EPS machine builder Plasttechnik Greiz GmbH of Greiz, Germany, has now expanded into EPP machines with the FAH-PP line. It comes with steam-chest dimensions of 780 x 550 mm, 950 x 780 mm, and 950 x 1400 mm.

Another EPS press maker that is getting into EPP is Berndorf Italia of Italy (represented here by TRI Manufacturing, Lebanon, Ohio). Its new VEH 50 machine reportedly is being used to mold EPP sun visors for the Ford Mondeo. It takes mold sizes up to 610 mm square and 250 mm high. Its Siemens controller has new software that reportedly optimizes steam use, providing steam savings of up to 30% as well as faster cycles.

In the next few months, Berndorf plans to come out with a bigger machine to mold 6.6 x 3.3 ft auto bumper cores. Also in the works is a machine that can mold either EPP or EPS. It will have two filler mechanisms for the different materials.

QUICK MOLD CHANGES

Machine suppliers are emphasizing quick-mold-change (QMC) systems that can accomplish changeovers in as little as 5 min. Typically, these systems use an adapter frame (suitable for existing tools) that is fastened to the mold and then clamped by automatic latching devices on the machine platen. Several suppliers mount a movable carriage on top of the machine that carries a winch or rack-and-pinion hoist mechanism. The hoist grabs the adapter frame and, once it is released from the platen, lowers it to the floor or onto a wheeled cart. The systems also involve quick couplings for air, water, steam, and filler guns.

A semi-automatic QMC system is optional on the new HZ series of machines from E.A. Heitz OHG of Germany (represented by Machinery Corp. of America, Allentown, Pa.). Although the filler guns must be coupled and uncoupled manually, the rotary unlocking mechanism leaves part of the gun in the mold so that there will be no misalignment the next time the mold is installed.

The year-old HZ presses are high-end, full-featured machines for general-purpose shape molding. Standard features include proportional hydraulic clamp, parts-handling robot, and microprocessor control with programmable timers and limit switches.

QMC is standard on the new FAH-PP line of EPP molding presses from Plast-technik Greiz. Several other suppliers also offer QMC, including AMD of Filago, Italy, and Promass of Trevi, Italy. Promass says its fully automatic mold-change system takes only 5 min, regardless of mold size or number of filler guns. A QMC system in which the mold is pushed by hand in and out of the press on rails is available on EVH-C machines from Erlenbach GmbH of Germany (represented by Profoam Machine Sales, Lexington, Ky.). Typical mold changes are completed in 30 min, the company says. And Hirsch Maschinenbau of Austria (represented by Casner & Associates, Maineville, Ohio) says mold changes on its Vacutrans machines take 25-35 min.

DUAL-DENSITY MOLDING

A new approach to co-molding of parts with sections composed of different densities or even different materials is provided by a dual-mold system from Hirsch. One application is insulation for home water heaters, in which EPS is overmolded with heat-resistant bead (such as GECET PPO/PS bead from Huntsman Corp., Chesapeake, Va., or Styrotherm from BASF Corp., Wyandotte, Mich.). Another use could be packaging that must support heavier loads in specific areas.

To make such two-layer parts, the machine has two identical female molds mounted side by side. After molding the first layer of material, the mold shuttles into the second molding position, where it joins with a second male mold half to overmold the second material layer.

AUTO STACKER/INSERT LOADER

Hirsch has two other novel uses for its shuttling-mold setup. In these cases, only a single male and female mold half are required. The female mold shuttles to the side in order to eject parts onto a stacking table (or multiple tables for multicavity molds). In addition, an insert-loading frame can be built onto the side of the female mold so that while parts are being ejected and stacked, the male mold can move forward to receive a set of inserts quickly and automatically. During molding, the insert frame extends outside the press, allowing fresh inserts to be loaded with no loss of cycle time. The shuttle-mold system also makes it easy to move the mold outside the press for quick changes, Hirsch officials note.

SKIN MOLDING CATCHES ON

Several machine suppliers report that so-called "skin molding" is a new and growing trend in Europe, even though it hasn't yet aroused much interest in North America. Skin molding involves molding an EPS part, then placing a film of PS into the mold and re-steaming the part to bond the two together. A clear or colored film can be used to create a moisture barrier for meat trays, ice-cream tubs, and even postal shipping boxes. Aluminized film is used on EPS ceiling panels for industrial buildings. Another reportedly successful application is waffle-shaped floor panels for homes. Tubing is laid into the depressions to provide integrally heated floors. Several suppliers are hopeful that auto companies will adopt EPP door panels skinned with TPO film or PP fabric.

Skin molding typically requires a robot to load the film or fabric into the mold. An open machine design facilitates robot access, according to sources at Teubert Maschinenbau GmbH of Blumberg, Germany (represented by Foam Equipment & Consulting Co., St. Louis). Other companies active in skin molding are Erlenbach, Heitz, AMD, and Kurtz GmbH of Germany (U.S. subsidiary is Kurtz North America, Elkhart Lake, Wis.). Kurtz supplies units to precut the film inserts.

Heitz notes that standard machines require die-cut sheets of skin material to be folded into the mold cavity. Heitz also makes special machines that have a horizontal female mold for vacuum forming PS film while a foam part is being molded in a second mold. In the next cycle, the foam part is robotically transferred to the skin mold and re-steamed to bond with the skin.

MOBILE PLANT-IN-A-BOX

Because it's expensive to ship EPS packaging long distances, Hirsch now sells a mobile plant that can be set up near the customer. This turnkey factory-in-a-box comes packed in shipping containers, ready to be up and running in three to six days. It includes one pre-expander, two to six presses, a material-storage system, steam generator, air compressor, cooling-water circuit, and all electrical and water connections.

THINNER CUPS

Thinner EPS cups and lower stacking height are possible with a new mold-filling and steaming system from Thermoware EPS Machinery b.v. of Barneveld, the Netherlands. Average cup thickness now can be reduced from 1.82 mm down to 1.2 mm.

Leak testing cups in the machine is an innovation from Koster Gmbh + Co., Obersulm-Willsbach, Germany. The cup-handler tests for vacuum leaks on the lower one-third of the cup. If it senses a leak, an alarm is sounded and the machine halts. This feature, first shown at K'92 on an eight-cavity machine, is now available for 10 cavities.

Koster says it has also made its machines 10-20% more energy efficient and has improved mold design to cut cycle time for an 8-oz cup down to 6.5 sec.