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For cut-sheet thermoforming, a novel mold-clamping system from Lenzkes reportedly is attracting attention from machine builders because it offers major reductions in mold-change times.
A new automatic roll-fed thermoformer from Eletro-Forming in Brazil produces refrigerator door liners at a rate of up to 130/hr.
The industry’s first quick-release mold-clamping system for cut-sheet machines made its debut this fall at the SPE’s 15th annual Thermoforming Conference in Milwaukee. This development offers big improvements in mold-change times and overall productivity compared with current clamping arrangements. Other conference highlights included one of the largest rotary machines in North America, a new automatic roll-fed former for refrigerator door liners, a larger series of continuous thermoformers, a flexible in-line extrusion/forming system, and an economical single-station machine.
For the first time, cut-sheet thermoformers have a mold-clamping system that is quick and efficient, according to Lenzkes Clamping Tools Inc., whose new system is said to be a major advance over “homemade” tooling based on C-clamps, U-irons, or other standard tools. “While they may be inexpensive, these remedies are time-consuming, complicated, and inefficient,” explains Lenzkes v.p. Michael Brocher. “Today’s focus on lean manufacturing operations requires quick and safe set-ups.” Mold changeovers that now take up to 90 min can be reduced to about 10 min, according to Brocher. Lenzkes is a German firm with an office in Virginia.
The quick-release clamping system is stepless and adjustable both horizontally and vertically by simply sliding the clamping arm up to the mold and turning the ball pressure screw in the back. The clamping arm can be adjusted with an Allen wrench (supplied), torque wrench, or air ratchet. No bolts, step blocks, or washers are required. The clamping system is made of forged steel and special alloys instead of cast metal. Clamping forces up to 17,600 ft-lb will hold any large, heavy mold in place, says Brocher.
This patented technology has drawn interest from several thermoforming equipment makers who are considering it for their ma chines. Thermoformers such as McClarin Plastics Inc., Hanover, Pa., have adopted the system with good results. McClarin says the tooling has significantly reduced set-up times and shortened lead times and run sizes. McClarin has large machines up to 8 x 16 ft and mounts molds weighing nearly 4000 lb. “Our set-up team has confidence in this system,” says Roger Kipp, McClarin’s v.p. of marketing and engineering.
The mold-clamp system starts at $1000 and can go up to $26,000. Lenzkes is adapting the system to other processes including injection molding and structural foam.
The latest development in rotary machines comes from custom manufacturer Modern Machinery of Beaverton, Mich., which has built its largest rotary unit yet. Said to be one of the largest rotaries in the U.S., its Model 223R is a three-station unit with a 10 x 18 ft forming area. It has electric-driven platens and precise servo-driven indexing that takes less than 6 sec. The 12 x 20 ft infrared oven built by Solar Products Inc., Pompton Lakes, N.J., has 418 zones. The machine handles sheets 0.06 to 0.5 in. thick and weighing 300 to 350 lb.
The unit was sold to heavy-gauge thermoformer Ray Products Inc., Ontario, Calif., which plans to produce large custom thermoformed parts with a range of materials. Winton says the technology could be suitable for large parts such as boat hulls and spas.
Continuous forming machines are also getting bigger, evidenced by a new automatic roll-fed former for large parts. Model TC-CP from Eletro-Forming in Brazil produces refrigerator door liners from PS or ABS at 130/hr and makes transverse and longitudinal cuts to separate parts from the rest of the web.
Servo motors position the guillotine and move the transport chains, ensuring high speed and precision. Longitudinal cutting is done by motorized rotary slitters. The unit has an automatic unwind with a pneumatic lift for rolls weighing up to 1200 lb. The ceramic oven has 30 individually controlled zones.
The mold table has a pneumatic transfer that slides molds on and off. Sheet-width adjustment is made by motors with auto-centering screws, and automatic mold-length adjustment is made by servo motor. An ultrasonic sensor and servo motor adjust for the final part length.
The machine has a forming area of 71 x 31.5 in. It produces parts up to 0.08 thick. Eletro-Forming has sold one machine to Electrolux.
Brown Machine has also added larger continuous formers with its new CS Series, which handles molds from 54 to 70 in. square. A Brown spokesman says makers of food packaging and disposable products are looking for “more platen area to get more products off the line.”
The CS Series has newly designed platen drives that improve precision, and repeatability, Brown says. Platen stabilization is enhanced with four-point linear guides and four-toggle actuation. The third platen is now driven by servo motors and a single roller screw instead of a ball screw. The roller screw is said to take heavier loads and last longer.
A versatile new sheet extrusion line from PTi allows processors to switch easily from rollstock extrusion to in-line extrusion and forming. The line includes a 5-in. extruder (Trident Series Model 5000) and a “J-Stack” roll stand (Revolution Series J 12 20 20) with individual roll drives, motorized height adjustment, and convertible conveyor.
Benefits of the Revolution J-Stack are said to include improved handling of low-melt-strength resins and 25% longer web wrap around the chrome rolls compared with standard vertical or inclined roll stacks. The roll drive has distributed gear reduction for easy changing of the speed/torque range. It also facilitates quick, easy, tool-less disengagement when removing rolls.
Maac Machinery has upgraded its Comet line of single-station thermoformers to include an economical vacuum former designed to handle most cut-sheet applications. Comet Model C64S is a 6 x 4 ft machine with a starting price of $77,000. This “plug-and-play” unit ships in one piece and saves time and money for installation.
Key features are programmable, variable-speed, direct-driven platens; electric indexing; a new color touchscreen PLC control; multi-zoned “instant-on/off” quartz ovens; and fully adjustable clamp frames. Controls are more cost-effective, and the framework is smaller and lighter, than on standard equipment, says Maac.
Maac also announced a partnership with used-machine dealer Stopol to produce five-axis CNC routers designed for high productivity in heavy-gauge thermoforming. According to Maac, most routers used today in thermoforming are general-purpose models designed for wood or aluminum. The new Royce routers available from Maac and Stopol reportedly offer thermoformers better speed, precision, and reliability. The routers operate at 2500 in./min and cycle times are said to be shortened by up to 80%. Prices start at $187,900.
Another new development in trimming comes from Robotic Production Technology, which introduced a portable router trimming or knife deflashing system. The Robo-Trim RT-400 features a servo-controlled table that turns the part as it is trimmed, which makes for a compact work cell. The modular system is mounted on a single base and can be moved with quick set-up.
The robotic trimmer uses the Fanuc/RPT R-44A six-axis robot and a servo-controlled rotary table. The table turns at 60°/sec and holds parts and fixtures weighing up to 250 lb. The system accommodates parts up to 45 x 45 x 42 in.