Retractable-Tiebar Machine Is 'Americanized' And Toggle Presses Get Upgrades.

* At an open house last month, HPM Corp., Mt. Gilead, Ohio, announced improvements to two injection machine lines. First, the original design of the company's NextWave two-platen, retractable-tiebar presses has been "Americanized." HPM acquired the design when it bought Hemscheidt of Germany in 1997. Second, in response to customer feedback, HPM has made about 20 modifications to its economically priced Universal toggle machines. More than 100 of these presses have been sold since their introduction at NPE '97. Both machine lines will be displayed in June at NPE 2000 in Chicago.

New-generation NextWave

Three main changes have been made to the new version of NextWave presses, which span a size range from 360 to 5000 tons. These machines have a hydromechanical clamp with short tiebars that retract with the moving platen, leaving open access to the mold area. One change is that they now carry HPM's modular injection unit with twin outboard injection cylinders. The result is a shorter machine than the original with a single in-line cylinder. The difference amounted to more than 3 ft on the 1750-ton press shown at the open house.

Also new is a hydraulic system based on HPM's standard approach of using multiple fixed-volume pumps for major machine functions and a small variable-volume pump for hold, eject, and core functions. This arrangement is said to provide faster response and lower cost than the NextWave's previous variable-volume pump system.

The third new feature is the Barber-Colman/HPM Command 4500C controller with color LCD screen and floppy-disk drive as standard. It is said to be user-friendly and easy to reprogram for special sequences. The same controller is used on HPM's modular hydraulic-clamp machines. Michael McKee, the new v.p. of injection molding sales, notes that the Command 4500C is currently offered only on NextWave models of 880 tons and larger. Smaller units still have Siemens controls, but the former S5 model has been upgraded to an S7, which utilizes Profibus field-bus architecture. This design greatly reduces the amount of wiring and is therefore much easier to troubleshoot and maintain, McKee says.

He also notes that HPM offers its cast Parabolic platen as an option for special applications of NextWave machines. Although the computer-designed shape is engineered to reduce platen deflection, McKee says HPM has found that, for most applications, a more cost-effective protection against deflection is the "decoupled" platen/carrier design. Instead of the usual one-piece construction of moving platen and carrier, the two are separate and joined by hourglass-shaped pins that act like variable-rate springs, according to McKee. With this arrangement, there is less tendency for bending of the platen carrier, "so the moving platen stays truer to the stationary platen," he claims.

Toggles get an overhaul

HPM introduced the Universal II series of toggle-clamp machines at its open house. Ranging from 60 to 560 tons, they carry a host of modifications suggested by customers, but their low price has not changed from two years ago. The basic machine "carcass" is built in Hong Kong to HPM design, but the barrel, screw, controls, and options are added here.

The machines have been made sturdier and easier to service, while reliability has increased and maintenance needs have decreased, McKee says. Upgraded controls include the Command 4000 as standard with larger monochrome display (color optional) and screens in four languages. The card rack has been expanded from nine to 12 slots, and it now offers alarm logging and additional capabilities-- like separate analog controls for core/ejector speed and pressure and adjustable pull-in force on the injection-unit sled.

At NPE, HPM plans to demonstrate gas-assist molding of PVC on a Universal II machine in cooperation with Alliance Gas Systems, Inc., Chesterfield Township, Mich.