CHICAGO — Van Dorn Demag Corp. has entered the two-platen injection molding machine market, with its new Caliber Series. At Booth S2300, a 1,760-ton Caliber is molding a part for an automotive door assembly.
Van Dorn Demag also is showing a hydraulic-clamp press with an electric screw drive. Also new: the next generation of its Pathfinder controller, boasting a program that helps an operator set up the machine based on part information and the material used.
Also during NPE in Chicago, the company is displaying 17 injection molding machines.
The two-platen hydromechanical Caliber is available in clamping forces from 1,100-4,400 tons, and shot sizes of 125-600 ounces. Space savings is one main advantage of two-platen machines, which are smaller than machines with the traditional three platens.
Van Dorn Demag said the concept of ``productivity per square foot'' is catching on in the United States, especially in markets that require large-tonnage machines such as automotive, housewares and appliances.
``We didn't hear that in the past, but we're hearing it now,'' said Patrice Aylward, marketing communications manager.
A two-platen machine is about 30 percent smaller than the same-size three-platen machine, according to Kenneth Vaughan, marketing manager.
Vaughan said a team of engineers from Van Dorn Demag and the company's German parent, Mannesmann Demag Kunststofftechnik, began working on the design in the fall of 1995.
The designers wanted to minimize the number of parts and make a less-complex, two-platen machine.
To reduce deflection, engineers made the platens much thicker than traditional hydraulic presses, using finite element analysis.
``The depth of the platen is what keeps it stiff. It's like a beam,'' Vaughan said during a preview of the technology before NPE at Van Dorn Demag headquarters in Strongsville, Ohio.
Caliber's four tie bars are fixed to the moving platen, so they pull out from the fixed platen when the clamp is open, giving unobstructed mold access.
When the mold closes, calipers are engaged that link into notches in the tie bars. The four cylinders mounted on the tie bars build tonnage from the moving platen.
When the mold-open sequence begins, the cylinders release the tie bars.
Having the tie bars pull out of the fixed platen upon mold opening presented alignment challenges. Van Dorn Demag engineers designed a large yoke to support the moving platen and mold. The yoke sits on bushings that nearly encircle the guide rods.
The company also is introducing injection presses with electric screw drives, called the HTE Series.
The machines have a hydraulically driven clamp.
Van Dorn Demag wanted some benefits of electric power, including quiet operation and energy savings, since electric drives produce power on demand only, not during the molding cycle's idle phase.
Company officials decided to go to this ``hybrid'' design, pairing hydraulic and electric power, instead of an all-electric press, after their research showed many all-electrics struggle to maintain accurate injection pressures, especially during the transition phase from shoot to pack and hold.
That transition, according to Van Dorn Demag, requires a complex conversion of the rotary motion of a ball screw into precise pressure.
HTE machines use a servo electric screw drive and variable-speed pump drive made by Reliance Electric Co.
Standard features include a Pathfinder 5000 controller, ceramic heater bands and an energy monitor function, which analyzes energy use.
HTE presses are 60 percent more energy efficient that earlier models, according to Van Dorn Demag. Electric screw drive also allows the screw to rotate while the clamp is moving.
The variable-speed pump drive smooths out machine operation, eliminating shocks to the hydraulic system that can spur oil leaks.
HTE machines come in clamping forces of 85-650 tons.
Van Dorn Demag's Caliber machine also will have the electric screw drive, which is available as an option on the two-platen presses.
The company also redesigned its HP line of midsize hydraulic machines. A side-mounted oil tank gives a lower profile. The press has a much longer open stroke and bigger maximum daylight.
In controls, the company will show its Pathfinder 3000 and 5000 controllers, both with the Scout program.
Set-up operators enter information about the resin and part, such as part weight, and Scout recommends set points as a starting point.
Another standard feature, Machine Expert, suggests corrective action to fix processing problems.
Other functions include Auto-tune Process Control, which automatically sets and adjusts the optimum tuning parameters when using closed-loop control. Auto-calibration checks the hydraulic control valves and recalibrates them.
In smaller-press news, Van Dorn Demag is running a 400-ton Newbury vertical injection press overmolding a gear shift handle with a soft vinyl grip. A Pathfinder control is now available on the company's small press, the ET Pro.
Visitors to Van Dorn Demag's booth also will see high-speed molding of thin-wall parts — polycarbonate minidisc cartridges in a 41/2-second cycle and a 91/2-ounce medical basin every seven seconds.