In Tokyo, a Feas for Injection Molders
JP 90 was a cornucopia of new product introductions for injection molders. Many of the new press designs take into account molders' needs for lower energy consumption, space savings, reduced inventories, and decreased reliance on scarce labor. Besides presses, the 625 exhibitors presented ample news in robots, control systems, and hot runners.
There was also less extensive, but still significant news in blow molding, extrusion, compounding, thermoforming, auxiliary equipment, and materials, which appear in Part II of this report next month.
COMPACT
INTEGRATED
CELLS
Making the workplace more comfortable and attractive to workers was a theme that gained in prominence at this year's show. It showed up in schemes to "clean up" the environment in a processing plant by physically integrating presses and auxiliaries into a neat, compact unit. This goal was particularly evident in four exhibits, two of which are pictured on the following pages. Matsui Mfg. Co., Ltd. showed what a spokesman described as "the future of molding," dubbed the Jet Cell. A Toyo molding machine, and Matsui dryer, loader, mold-temperature controller, and a robot were integrated into a neat, compactly enclosed unit, controlled from a single computer, and intended to be quiet and clean for "worker comfort and convenience." Some Jet Cells are said to be already operating in Japan.
In a similar vein, Kawaguchi showed a KM180B machine with a Matsui mold-temperature controller built into the machine base, and a Matsui dryer and loader built into a cabinet flush against the injection end of the machine. Controls for the auxiliaries were mounted on the machine side under the injection unit.
Niigata Engineering Co., Ltd. showed a similar system on an AN100 precision injection machine, with the mold-temperature controller in the machine base, dryer/loader in a separate, wheeled cabinet fitting snugly against the clamp end of the machine, and control panel for the auxiliaries on the machine side under the injection unit.
ALL-ELECTRICS HUM
The number of suppliers offering all or partially electric servo-driven machines continues to grow, as do the model ranges of existing suppliers.
Sumitomo SHI Plastics Machinery Ltd. joined the all-electric club, which previously included Nissei, Fanuc, Toyo, Japan Steel Works and Niigata. Sumitomo's SE-Alpha Series of all-electric toggle machines comes in 27.5-, 82.5-, and 165-ton models, which will be available here after NPE in June. The machines each have four servo motors regulating injection, clamping, plasticating, and ejection. The line has patented hydraulic tiebar balancers and a small accumulator for uniform clamping. Also, the company uses its own servo motors, which it developed to provide superior reliability and speed.
Also inaugurating an all-electric servo line was Kawaguchi, whose Kjecton line has 5.5-, and 16.5-ton models, with a 33-tonner planned. All have three a-c servos and vertical clamp and injection. The lower mold shuttles forward for insert loading and parts removal. They're not yet offered for export.
Among those expanding their electric-servo lines, Funuc, Ltd., joint developer and builder of Cincinnati Milacron's ACT line, introduced a 16.5-ton unit, the smallest in the line, which now includes eight models extending up to 330 tons. It has all of the features of the 33-ton model, including the "crank-type" monotoggle clamp, which is said to increase cycle speeds. Its monochrome CRT is mounted on a swing arm on top of the machine, making it even more compact. Open machine base allows three-way parts removal.
Toyo Machinery & Metal Co. introduced a 33-ton all-electric press (Plastar TU-30), which joins a series of 5.5, 11, 16.5 and 55 tons.
Japan Steel Works introduced the J55ELD 60.5-ton toggle press (complementing previous 82.5- and 165-ton models), employing five servo motors for injection, plasticating, ejection, mold opening and closing, and clamping. The company bills this machine as capable of "the world's highest molding precision"--e.g., 0.1-micron accuracy on an optical mirror (also a function of mold design).
CIM FOR ALL-ELECTRICS
Fanuc showed off a comprehensive, plantwide computer-integrated manufacturing concept for its all-electric servo injection machines (Cincinnati Milacron's ACT series), which Fanuc calls by the popular Japanese term "FA" for Factory Automation. The system has been sold to two Japanese firms as beta test sites, and could become available in the U.S. within six months, according to Milacron's Bob Kadykowski. The heart of Fanuc's FA Molding System is one of the company's System F--Model D cell controllers, programmed in the Unix operating system, with operator CRT displays programmed in BASIC. The system has four main parts:
* Production control--scheduling up to a year, inventory control, order entry and shipping> it keeps track of materials, tools and purchased parts, even writing purchase orders when inventories are low.
* Molding technology--storing "best" mold setups based on past reject-rate history, as well as other historical data on mold and materials characteristics.
* Expert syste--first previewed at JP 88, this artificial intelligence program adjusts the machine to solve molding problems, based on a dialogue with the operator.
* Quality control--on-line statistical process control (SPC) of the past 1000 shots of all machines in the network> preventive maintenance alerts to operators based on checks of machine running condition and maintenance history> monitoring plant ambient temperature and automatically adjusting molding conditions or actuating alrams if conditions warrant.
HYBRIDS MIX IT UP
Two other firsm introduced so-called "hybrid" machines that combine electric servo drive with conventional hydraulics on some functions for maximum cost-effectiveness (servos are expensive). Nissei Plastic Industrial Co. added a 44-ton companion (PS40F5E) to its first hybrid machine, an 80-tonner (PS80F12E) introduced at K'89. Screw rotation and injection are driven by two electric servomotors, while the clamp is straight hydraulic. Servo-driven injection is said to provide superior precision and reproductivity, especially in the lower speed range> and hydraulic mold clamping reportedly offers greater reliability and durability, as well as stable clamp force unaffected by thermal expansion.
Mitsubishi Heavy Industries, by contrast, showed a new line of hybrids with the servo drive on the clamp end. More precise positioning is said to result, as well as energy savings of 50% (about as much as are claimed for all-electrics). Three models in this MSS series have clamps of 16.5, 33, and 55 tons.
SPACE-SAVING LARGE
MACHINES
While electric servo motors proliferate among small machines, a concept growing in popularity for high-tonnage presses is new clamp designs that radically shorten the overall machine. This is done by replacing a large, long-stroke clamp cylinder behind the moving platen with four smaller, short-stroke cylinders that clamp directly on the tiebars--either on the fixed- or moving-platen side. Some type of mechanical tiebar locking mechanism is required, as are small long-stroke cylinders for high-speed platen traversing. Besides saving floorspace, this arrangement moves less oil, thus increasing speed and saving energy. Clamps of this type have been adopted by the Italian producers Sandretto, Italtech and Remu. Toshiba also offers machines of this type from 1430 to 5500 tons. At JP 88 in Osaka, Mitsubishi followed suit (see PT, Jan. '89, p. 61). And three more Japanese builders joined in at this year's show.
Nissei's new 860-ton FH860S420B has such a clamping system, allowing it to take up no more space than a conventional 400-tonner (see diagram). It's 29.2 ft long. Like Mitsubishi's MM Series, this machine has its clamping cylinders on the stationary platen, and the moving platen is supported on roller bearings.
Japan Steel introduced the J1300EE, a 1430-ton press with a new "tiebar-lock" hydromechanical clamp that's available on presses from 935 to 6600 tons. It has telescoping tiebars, with clamping on the stationary platen. It measures only 32.7 ft long and has only 150-hp pump drive.
Meiki also introduced a compact design. Its M-B Series of presses ranging from 935 to 3300 tons has a new DL clamping system with the clamping cylinder built into the tiebar assembly of the moving platen, and tiebar nut locking on the fixed-platen side. And the oil tank that was mounted over the clamping unit on previous models is now housed under the injection unit. It now occupies 40-50% less floorspace and 60-70% less overall volume.
The DL clamping system also improves cycle times. The system performs tiebar nut locking during low-speed closing just prior to the completion of mold closing. This feature is said to make it possible to start boosting pressure as soon as mold closing is completed, a feature of straight hydraulic systems. And unlocking can be performed during initial slow mold opening. These integrated movements eliminate lost time> and, combined with the reduced quantities of hydraulic oil used, the total reduction in dry-cycle time is said to be 30% (10 sec on a 1430-ton model) compared with Meiki's previous line.
The DL clamping system is also said to simlify mold changing, compared with toggle presses. Complicated mold setting due to the toggle mechanism reportedly has been eliminated. Molds can be changed by simply closing the movable platen until it closely contacts the molds, in the same manner as a straight hydraulic clamp.
MOLDING UHMW-PE
One novely at this show was a live demonstration of injection molding UHMP-PE by Niigata Engineering Co. A model NN755C-UHM was molding single disc-shaped drink coasters from Hizex Million, a 3-million-M.W.grade of material from Mitsui Petrochemical Industries. The machine featured a special screw design, and nitrogen-blanketed hopper to prevent oxidation and preserve molecular weight, an injection-compression cycle with a large compression stroke (0.234 in.) to eliminate porosity, and closed-loop servovalve control of both injection and compression stages. Compression is achieved by a movable core that effectively changes the size of the cavity. The Prism Alpha nitrogen system on the hopper (made by Permea, a Monsanto subsidiary in St. Louis) both stucks out 99.9% of the air and introduces nitrogen.
Also featuring UHMW-PE injection-compression molding was Komatsu Ltd. (which is a part owner of, and partner in a technology exchange with, Husky Injection Molding Systems Ltd. of Bolton, Ontario). Although Komatsu's FKS-UH series does not use nitrogen on the hopper, it does have a special screw design with a check valve. The company says a check valve normally cannot be used with UHMW-PE, leading to loss of shot-weight control. Since the Komatsu screw does have a check valve, it not only provides good precision, the company says, but can also be used with conventional thermoplastics. Barrel-temperature profile control can be changed from UHMW-PE to general-purpose molding with a single switch.
Komatsu also claims that its Direct Flow Control (DFC) nozzle valve provides a particular advantage for molding UHMW-PE (see PT, Jan. '89, p. 65). The company claims that it is essential to maintain constant shear rate on the material throughout the injection stroke, which is impossible with a changing injection-rate profile on a standard machine. By opening and closing the DFC valve in the nozzle (using an electric servomotor whose control is keyed to screw position), it is possible to vary the flow orifice size so as to maintain constant shear with changing injection rate.
Komatsu also advocates injection-compression molding with a movable mold core. But for multicavity molding, Komatsu has a variant of the process, in which the mold is injected with the cavity at its final, "compressed" dimensions. If the cavities were extended at first, uniform filling could not be guaranteed, Komatsu claims. Although a slight overfilling initially results, the cavities are then expanded to relieve stresses in the material, and finally compressed again to compact the resin. Using this method, the weight difference between 25-mm diam. gears in a two-cavity mold varied no more than [+ or -] g, or 0.1%, from the average of 2.195 g over 20 shots. This is said to be less than 5% as much variation as was seen with a "conventional process." (The material was Mitsui's Hizex Million 830M, with 8 million M.W.) The company says it also molded 7-mm bearings from Hizex Million 240M in four cavities and found absolutely no change in molecular weight or density between the raw material and molded parts.
QUICK-CHANGEOVER SYSTEMS
The trend toward Just-In-Time manufacturing and reduced inventories has led suppliers to offer systems suitable for quick changeovers and small-lot production. Niigata's new Model NN30DRI is a 33-ton press with twin barrels pointing in opposite directions on a turntable. Together with a mold changer, it constituted a fully automatic flexible production system. While molding with one injection unit, the other can be automatically purged. Idle time traditionally required for resin change and color change can thus be eliminated. Molds were changed by a dedicated robot that lifted a preheated cavity set out of a six-position fixture behind the press.
JSW introduced the JMC 150E, a compact, integrated system for unmanned molding of several different kinds of parts in small lots. The system included a 165-ton press, mold preheating station (for five mold sets, which don't need to be standardized), hopper with five different color feeders, mold-temperature controller with lines for two molds, purged-material take-out device, and controls for automatic scheduled operation of multiple jobs.
Nissei, continuing its emphasis from the 1988 JP show on cost-effective molding solutions, showed two economical approaches to short runs and quick changes. For rapid color changes, three liquid-color pumps were mounted on a platform beside the press> the machine control is able to switch from one pump to another, feeding colorant directly to the machine throat. And for quick mold changes, Nissei introduced a motorized mold cart that is manually controlled by a man walking behind it.
SPECIAL-PURPOSE PRESSES
Several more new machines are dedicated to particular applications:
* CD Molding--Nissei demonstrated short-cycle molding of 5-in. and 3.5-in. CDs using a new system employing injection/compression molding on its PS30E3ASEC 33-ton press. The system reportedly molds a 5-in. CD in 5.5 sec, and a 3.5-in. disc in 4.5 sec. Quick, "one-touch" stamper changes are facilitated by Nissei's CD-FP molds, which join the stamper and mirror block together on the fixed platen as a unit that can be easily removed.
Meiki demonstrated two-cavity CD molding, probably a first at a show. The system includes its dedicated M-50AII-D-DM 55-ton press, which is faster than Meiki's conventional presses.
* Lens molding--Nissei introduced the TH160-18VSEL injection-compression press with 176-ton vertical clamp and vertical injection, designed specifically for polycarbonate eyeglass lenses. Nissei says vertical clamping and injection are most suitable for multicavity lens molding. Each cavity has independent cores for compression, mounted on the fixed-platen side. The press has a mold-transfer device making it possible to change the molds or cores easily, and a heating-cooling device for regulating temperatures of various parts of molds and cavities at the optimum levels depending on the shape and thickness of the lens.
Sumitomo is offering a series of presses for lens molding based on its SG series. The 27.5-, 55-, and 242-ton units are equipped with Sumitomo/NEtstal Sycap controls.
* BMC molding--Niigata introduced a 176-ton, plunger-type injection machine for thermoset polyester bulk molding compound (NNT160PP-SCH7000), with a horizontal stuffer, closed-loop, servovalve injection control, injection-compression capability, and 14- in. color CRT. Niigata feels that a plunger preserves glass-fiber length better than screw injection machines, such as it has previously offered.
* Insert molding--Nissei brought out a new 100-ton insert molder (TH100R12VSE) with vertical clamp and injection and a rotating mold table. The older model had 60-ton clamp and shot size of 90 cc, vs. 127 cc for the new model.
* Low-pressure molding--JSW introduced the JIP series of low-pressure, vertical-clamp injection-compression presses of 110, 330, 660 and 1100 tons. This approach is said to require injection pressures as low as 1450 psi and clamping pressures of only 435 to 1450 psi. This is particularly suited to molding warp-free, thin-wall, large-area parts for cars and appliances, as well as in-mold laminating of fabric, carpet or other skin materials for auto interiors and furniture. The vertical clamp has servovalve parallelism control and a mechanical locking device that's said to make it shorter and more lightweight than standard frame-type vertical clamps. The press enables parts to be removed in three directions.
* Multi-process molding--Takahashi Seiki Co., Ltd. has developed what it calls the NC Blow Stamping Injector, a vertical-clamp machine that has both an injection barrel and an NC-controlled extruder that moves on x-y-z axes. The latter can either distribute melt over a stamping mold, or drape parison into the cavity of a horizontal mold for so-called "3D" blow molding.
* High-speed, precision molding--Nissei introduced the PSX40-5A, a 44-ton press for ultra-high-speed precision molding, particularly parts made of engineering resins and thin-walled products. This compact, fully enclosed machine is said to have a more rigid clamp, 600-rpm max. screw speed, 210-cc/sec max. injection rate, and simple adjustment of mold thickness and ejector from the control keypad.
Mitsubishi's new 80MSP-5 is an 88-ton hydraulic-clamp press with closed-loop servovalve injection speed and pressure control. IT's the first in a new line of high-speed, precision molding presses that will range as high as 319 tons. This model is said to dry cycle in 3.6 sec. The MSP line has variable-volume pumps for injection control and a-c inverter motor for screw rotation, both of which are said to save energy. Controls offer display options of CRT, LCD or LED.
GENERAL-PURPOSE MACHINES
Kawaguchi introduced the KM Series of toggle presses, which come in two versions. The B line offers CRT- based control, while the C line has a panel-type display. These presses range in size from 55 to 715 tons, with swiveling injection units and what are said to be improved-performance variable-volume pumps. Company sources believe their 495-tonner is the largest in the world with a variable-volume pump.
Toyo introduced the G2 Series of toggle presses ranging from 16.5 to 495 tons. Toyo emphasizes the user-friendliness of the controls. You can set all key parameters in a single screen "page" on the 12-in. CRT. The CRT graphically compares setpoints with actual injection speed and pressure. A program for machine maintenance automatically appears on the screen the first day of each month and displays when and where in the machine you should perform maintenance checks.
Other control features include four pressure changeover modes, PID temperature control, and hopper-throat temperature control. A "slope control" feature allows injection speed and pressure, screw rpm, and back pressure to be increased or decreased gradually. This is said to prevent part warpage while increasing dimensional accuracy. Six-step injection speed and pressure profiling for complex jobs, and three-step profiling for easier jobs are provided.
Sumitomo's new SH line of fully hydraulic presses have a swing-disc type of clamp similar to some Battenfeld machines. They range from 27.5 to 715 tons and included three sizes not previously offered by Sumitomo: 495, 605 and 715 tons. These machines reportedly occupy 25% less floorspace than Sumitomo's SG toggle series, and will cost somewhat less. Although they have no accumulators, they reportedly use no more oil than the accumulator-assisted toggle machines do, thanks to the short-stroke clamping cylinder. Their speed is somewhat less than that of the SG models, however, a company spokesman notes.
New controls provide closed-loop control of clamp position. Other functions are open loop. The presses have one variable-volume pump and one static pump, except on models over 385 tons, which have two variable-volume pumps and one static pump. Sumitomo will take orders for the new line after NPE.
Shinwa Seiki introduced the CN line of presses, whose biggest difference from the preceding line is that the microprocessor controller has been upgraded from 8-bit to 16 bits. This reportedly provides enhanced performance (full closed-loop control is optional). Speed of the 160-tons press exhibited has been increased by 20%, owing to faster pressure buildup and decompression.
Ube Industries introduced the PZII450, a 495-ton toggle press that is forerunner to a new line ranging from 385 to 935 tons, to be introduced this year. The press accepts greater max. die height (35.5 in.) than Ube's previous line. A variable-volume pump that reportedly provides 30-40% energy savings is optional.
Toshiba Machine Co., Ltd., which can return to business in the U.S. in December of this year, introduced the IS-F series of presses from 110 to 935 tons. Three levels of Injectvisor control with LED or electroluminescent display are offered. These machines are said to offer a wider range of functions, higher speeds, greater precision, improved user-friendliness, and better quality control.
NEWS IN CONTROLS
Barber-Colman introduced its new MACO 4000 at JP 90, although it won't be available here until NPE in June. This closed-loop controller is exclusively for injection molding. It's less expensive and more compact than the MACO 8000, though it reportedly packs much the same power and features, except for the new clamp-control module available only on the MACO 8000VA. The 4000 has a Lumitech flush-mountable, electroluminescent operator station (also available as an option for the 8000) measuring just 11 in. wide, 15.5 in. high and 3 in. deep. It has graphics capability and is said to be user-configurable in much the same way as the MACO 8000's CRT.
Besides the compact display, the control unit consists not of several booksized modules, but rather a single enclosure 18 in. wide x 14 in. high x 8 in. deep contains plug-in circuit cards for temperature, sequence, hydraulic control, process control, linear positioning, multi-pump pressure flow, and communications. Six zones of full PID auto-tuning temperature control are standard. Process control includes ramping and closed-loop control of injection pressure or velocity, pack, hold, and backpressure, and cushion. Communication capabilities include RS-485, RS-432, printer port and MACO-NET. An internal SPC package is also available.
Barber-Colman sees the MACO 4000 as primarily aimed at injection machinery OEMs, but it will be offered directly to molders. "We're very excited about it," says Steve Schroeder, president of machinery remanufacturer Epco Div. of John Brown, Inc. Epco plans to introduce it as its E4000 retrofit control on a working machine at NPE. Schroeder believes it will be most cost-effective for machines in the 375-1000 ton range.
HOT-RUNNER NEWS
One unusual hot-runner development was shown by Ju-Oh Inc. (maker of the Part Watcher video mold-protection system sold here by Comet Automation Systems, Inc., Dayton, Ohio). Company's Model 614 hot-runner system uses induction-heated probes, which are said to give very quick response.
Another unusuals systems was unveiled by Seiki Corp., maker of Spear System hot-runner components. Its patented Supercycle Natural Hold Pressure System is said to enable greater molding precision while providing faster cycles. The device fits on the end of the injection barrel between the end of the screw and the nozzle. It contains a valve that can shut off flow from the screw and permit flow from a small melt reservoir in the device, held under independent pressure control. Here's how it works: After initial mold filling, the valve closes off flow from the screw, and hold pressure is maintained in the mold cavities by pressure on the melt in the Supercycle reservoir, rather than the screw. This permits immediate screw recovery for faster overall cycles. A "pressure relief valve" in the Supercycle system is set to accurately control hold pressure independently of hydraulic fluctuations of the machine. A third component of the system is the patented filtration system, said to ensure that only completely clean material enters the mold, with no pressure drop. Cleaning of the system is said to take only 10 min, with no disassembly required. The system will be available in the U.S. 12-16 weeks after NPE, and will cost approx. one-third as much as a new machine, according to Spear System, Inc. in the U.S.
Seiki also introduced a controller that will be standard for all Spear hot-runner systems, replacing a variety of controls for various systems. The AXC Controller is a general-purpose digital controller primarily for use with Spear's systems, but when combined with the proper power unit is said to be capable of controlling hot probes from other suppliers as well. The controller can store 15 mold recipes, although an optional data card can expand upon that. The AXC Controller has a CRT display, a printer, floppy-disc storage, a personal computer to gather data, and a hand-held digital remote unit for 24 Spear probes and eight manifold zones, which can be removed from the mold after it is up and running. It's less expensive than Spear's AMC controller.
Also new from Seiki is the Spear "G" bushing. This is an open-pipe bushing, externally heated with no obstruction in the center. The gate orifice cycles on/off, freezing the gate shut and melting it open. However, Spear has improved the heating rate at the gate to almost double that off the original tip. Initial test data show the same pressure curves as with valve gates, but with no moving parts, says Spear, as well as faster cycles in molding microfloppy discs.
Seiki also has a new Side-Gate Probe, aimed at connector molding. The probe has two tips at right angles to the body that cycle on and off. It's said to run glass-filled engineering materials. (Spear also just recently released in the U.S. the "M"-type probe with two, three of four tips.)
Also new is Spear's EH Busing. This probe was developed especially for high-heat materials and has reportedly run successfully GE's Ultem polyethermide and ICI's PEEK and polyethersulfone (PES). It can be made with Spear's 80Rc tip for glass-filled materials.
Other recent Spear developments include a modular manifold that takes up much less space in the mold than before and consumes 60% less power. Also, Spear has expanded its original Fixed-Pitch multicavity block-type system design into a Free-Pitch System. This means that Spear will manufacture the system to any gate center distance the customer wants.
IN-MOLD
DEGATING
SYSTEM
A novel concept shown by Nissui Kako Co. LtD. was an in-mold degating system that's said to allow use of thicker gates for easy filling of mold cavities--especially with older machines. The system uses servovalve-controlled hydraulic cylinders in the gate area of the mold, which vibrate at 20 Hz to break the gate while the mold is still closed (see diagram). An acrylic test part with a 31-mil-thick gate was vibration-degated in 2.5 sec, and the surface of the break area was much smoother than the same part degated with an end-mill cutter or a laser.
JP 90 was a cornucopia of new product introductions for injection molders. Many of the new press designs take into account molders' needs for lower energy consumption, space savings, reduced inventories, and decreased reliance on scarce labor. Besides presses, the 625 exhibitors presented ample news in robots, control systems, and hot runners.
There was also less extensive, but still significant news in blow molding, extrusion, compounding, thermoforming, auxiliary equipment, and materials, which appear in Part II of this report next month.
COMPACT
INTEGRATED
CELLS
Making the workplace more comfortable and attractive to workers was a theme that gained in prominence at this year's show. It showed up in schemes to "clean up" the environment in a processing plant by physically integrating presses and auxiliaries into a neat, compact unit. This goal was particularly evident in four exhibits, two of which are pictured on the following pages. Matsui Mfg. Co., Ltd. showed what a spokesman described as "the future of molding," dubbed the Jet Cell. A Toyo molding machine, and Matsui dryer, loader, mold-temperature controller, and a robot were integrated into a neat, compactly enclosed unit, controlled from a single computer, and intended to be quiet and clean for "worker comfort and convenience." Some Jet Cells are said to be already operating in Japan.
In a similar vein, Kawaguchi showed a KM180B machine with a Matsui mold-temperature controller built into the machine base, and a Matsui dryer and loader built into a cabinet flush against the injection end of the machine. Controls for the auxiliaries were mounted on the machine side under the injection unit.
Niigata Engineering Co., Ltd. showed a similar system on an AN100 precision injection machine, with the mold-temperature controller in the machine base, dryer/loader in a separate, wheeled cabinet fitting snugly against the clamp end of the machine, and control panel for the auxiliaries on the machine side under the injection unit.
ALL-ELECTRICS HUM
The number of suppliers offering all or partially electric servo-driven machines continues to grow, as do the model ranges of existing suppliers.
Sumitomo SHI Plastics Machinery Ltd. joined the all-electric club, which previously included Nissei, Fanuc, Toyo, Japan Steel Works and Niigata. Sumitomo's SE-Alpha Series of all-electric toggle machines comes in 27.5-, 82.5-, and 165-ton models, which will be available here after NPE in June. The machines each have four servo motors regulating injection, clamping, plasticating, and ejection. The line has patented hydraulic tiebar balancers and a small accumulator for uniform clamping. Also, the company uses its own servo motors, which it developed to provide superior reliability and speed.
Also inaugurating an all-electric servo line was Kawaguchi, whose Kjecton line has 5.5-, and 16.5-ton models, with a 33-tonner planned. All have three a-c servos and vertical clamp and injection. The lower mold shuttles forward for insert loading and parts removal. They're not yet offered for export.
Among those expanding their electric-servo lines, Funuc, Ltd., joint developer and builder of Cincinnati Milacron's ACT line, introduced a 16.5-ton unit, the smallest in the line, which now includes eight models extending up to 330 tons. It has all of the features of the 33-ton model, including the "crank-type" monotoggle clamp, which is said to increase cycle speeds. Its monochrome CRT is mounted on a swing arm on top of the machine, making it even more compact. Open machine base allows three-way parts removal.
Toyo Machinery & Metal Co. introduced a 33-ton all-electric press (Plastar TU-30), which joins a series of 5.5, 11, 16.5 and 55 tons.
Japan Steel Works introduced the J55ELD 60.5-ton toggle press (complementing previous 82.5- and 165-ton models), employing five servo motors for injection, plasticating, ejection, mold opening and closing, and clamping. The company bills this machine as capable of "the world's highest molding precision"--e.g., 0.1-micron accuracy on an optical mirror (also a function of mold design).
CIM FOR ALL-ELECTRICS
Fanuc showed off a comprehensive, plantwide computer-integrated manufacturing concept for its all-electric servo injection machines (Cincinnati Milacron's ACT series), which Fanuc calls by the popular Japanese term "FA" for Factory Automation. The system has been sold to two Japanese firms as beta test sites, and could become available in the U.S. within six months, according to Milacron's Bob Kadykowski. The heart of Fanuc's FA Molding System is one of the company's System F--Model D cell controllers, programmed in the Unix operating system, with operator CRT displays programmed in BASIC. The system has four main parts:
* Production control--scheduling up to a year, inventory control, order entry and shipping> it keeps track of materials, tools and purchased parts, even writing purchase orders when inventories are low.
* Molding technology--storing "best" mold setups based on past reject-rate history, as well as other historical data on mold and materials characteristics.
* Expert syste--first previewed at JP 88, this artificial intelligence program adjusts the machine to solve molding problems, based on a dialogue with the operator.
* Quality control--on-line statistical process control (SPC) of the past 1000 shots of all machines in the network> preventive maintenance alerts to operators based on checks of machine running condition and maintenance history> monitoring plant ambient temperature and automatically adjusting molding conditions or actuating alrams if conditions warrant.
HYBRIDS MIX IT UP
Two other firsm introduced so-called "hybrid" machines that combine electric servo drive with conventional hydraulics on some functions for maximum cost-effectiveness (servos are expensive). Nissei Plastic Industrial Co. added a 44-ton companion (PS40F5E) to its first hybrid machine, an 80-tonner (PS80F12E) introduced at K'89. Screw rotation and injection are driven by two electric servomotors, while the clamp is straight hydraulic. Servo-driven injection is said to provide superior precision and reproductivity, especially in the lower speed range> and hydraulic mold clamping reportedly offers greater reliability and durability, as well as stable clamp force unaffected by thermal expansion.
Mitsubishi Heavy Industries, by contrast, showed a new line of hybrids with the servo drive on the clamp end. More precise positioning is said to result, as well as energy savings of 50% (about as much as are claimed for all-electrics). Three models in this MSS series have clamps of 16.5, 33, and 55 tons.
SPACE-SAVING LARGE
MACHINES
While electric servo motors proliferate among small machines, a concept growing in popularity for high-tonnage presses is new clamp designs that radically shorten the overall machine. This is done by replacing a large, long-stroke clamp cylinder behind the moving platen with four smaller, short-stroke cylinders that clamp directly on the tiebars--either on the fixed- or moving-platen side. Some type of mechanical tiebar locking mechanism is required, as are small long-stroke cylinders for high-speed platen traversing. Besides saving floorspace, this arrangement moves less oil, thus increasing speed and saving energy. Clamps of this type have been adopted by the Italian producers Sandretto, Italtech and Remu. Toshiba also offers machines of this type from 1430 to 5500 tons. At JP 88 in Osaka, Mitsubishi followed suit (see PT, Jan. '89, p. 61). And three more Japanese builders joined in at this year's show.
Nissei's new 860-ton FH860S420B has such a clamping system, allowing it to take up no more space than a conventional 400-tonner (see diagram). It's 29.2 ft long. Like Mitsubishi's MM Series, this machine has its clamping cylinders on the stationary platen, and the moving platen is supported on roller bearings.
Japan Steel introduced the J1300EE, a 1430-ton press with a new "tiebar-lock" hydromechanical clamp that's available on presses from 935 to 6600 tons. It has telescoping tiebars, with clamping on the stationary platen. It measures only 32.7 ft long and has only 150-hp pump drive.
Meiki also introduced a compact design. Its M-B Series of presses ranging from 935 to 3300 tons has a new DL clamping system with the clamping cylinder built into the tiebar assembly of the moving platen, and tiebar nut locking on the fixed-platen side. And the oil tank that was mounted over the clamping unit on previous models is now housed under the injection unit. It now occupies 40-50% less floorspace and 60-70% less overall volume.
The DL clamping system also improves cycle times. The system performs tiebar nut locking during low-speed closing just prior to the completion of mold closing. This feature is said to make it possible to start boosting pressure as soon as mold closing is completed, a feature of straight hydraulic systems. And unlocking can be performed during initial slow mold opening. These integrated movements eliminate lost time> and, combined with the reduced quantities of hydraulic oil used, the total reduction in dry-cycle time is said to be 30% (10 sec on a 1430-ton model) compared with Meiki's previous line.
The DL clamping system is also said to simlify mold changing, compared with toggle presses. Complicated mold setting due to the toggle mechanism reportedly has been eliminated. Molds can be changed by simply closing the movable platen until it closely contacts the molds, in the same manner as a straight hydraulic clamp.
MOLDING UHMW-PE
One novely at this show was a live demonstration of injection molding UHMP-PE by Niigata Engineering Co. A model NN755C-UHM was molding single disc-shaped drink coasters from Hizex Million, a 3-million-M.W.grade of material from Mitsui Petrochemical Industries. The machine featured a special screw design, and nitrogen-blanketed hopper to prevent oxidation and preserve molecular weight, an injection-compression cycle with a large compression stroke (0.234 in.) to eliminate porosity, and closed-loop servovalve control of both injection and compression stages. Compression is achieved by a movable core that effectively changes the size of the cavity. The Prism Alpha nitrogen system on the hopper (made by Permea, a Monsanto subsidiary in St. Louis) both stucks out 99.9% of the air and introduces nitrogen.
Also featuring UHMW-PE injection-compression molding was Komatsu Ltd. (which is a part owner of, and partner in a technology exchange with, Husky Injection Molding Systems Ltd. of Bolton, Ontario). Although Komatsu's FKS-UH series does not use nitrogen on the hopper, it does have a special screw design with a check valve. The company says a check valve normally cannot be used with UHMW-PE, leading to loss of shot-weight control. Since the Komatsu screw does have a check valve, it not only provides good precision, the company says, but can also be used with conventional thermoplastics. Barrel-temperature profile control can be changed from UHMW-PE to general-purpose molding with a single switch.
Komatsu also claims that its Direct Flow Control (DFC) nozzle valve provides a particular advantage for molding UHMW-PE (see PT, Jan. '89, p. 65). The company claims that it is essential to maintain constant shear rate on the material throughout the injection stroke, which is impossible with a changing injection-rate profile on a standard machine. By opening and closing the DFC valve in the nozzle (using an electric servomotor whose control is keyed to screw position), it is possible to vary the flow orifice size so as to maintain constant shear with changing injection rate.
Komatsu also advocates injection-compression molding with a movable mold core. But for multicavity molding, Komatsu has a variant of the process, in which the mold is injected with the cavity at its final, "compressed" dimensions. If the cavities were extended at first, uniform filling could not be guaranteed, Komatsu claims. Although a slight overfilling initially results, the cavities are then expanded to relieve stresses in the material, and finally compressed again to compact the resin. Using this method, the weight difference between 25-mm diam. gears in a two-cavity mold varied no more than [+ or -] g, or 0.1%, from the average of 2.195 g over 20 shots. This is said to be less than 5% as much variation as was seen with a "conventional process." (The material was Mitsui's Hizex Million 830M, with 8 million M.W.) The company says it also molded 7-mm bearings from Hizex Million 240M in four cavities and found absolutely no change in molecular weight or density between the raw material and molded parts.
QUICK-CHANGEOVER SYSTEMS
The trend toward Just-In-Time manufacturing and reduced inventories has led suppliers to offer systems suitable for quick changeovers and small-lot production. Niigata's new Model NN30DRI is a 33-ton press with twin barrels pointing in opposite directions on a turntable. Together with a mold changer, it constituted a fully automatic flexible production system. While molding with one injection unit, the other can be automatically purged. Idle time traditionally required for resin change and color change can thus be eliminated. Molds were changed by a dedicated robot that lifted a preheated cavity set out of a six-position fixture behind the press.
JSW introduced the JMC 150E, a compact, integrated system for unmanned molding of several different kinds of parts in small lots. The system included a 165-ton press, mold preheating station (for five mold sets, which don't need to be standardized), hopper with five different color feeders, mold-temperature controller with lines for two molds, purged-material take-out device, and controls for automatic scheduled operation of multiple jobs.
Nissei, continuing its emphasis from the 1988 JP show on cost-effective molding solutions, showed two economical approaches to short runs and quick changes. For rapid color changes, three liquid-color pumps were mounted on a platform beside the press> the machine control is able to switch from one pump to another, feeding colorant directly to the machine throat. And for quick mold changes, Nissei introduced a motorized mold cart that is manually controlled by a man walking behind it.
SPECIAL-PURPOSE PRESSES
Several more new machines are dedicated to particular applications:
* CD Molding--Nissei demonstrated short-cycle molding of 5-in. and 3.5-in. CDs using a new system employing injection/compression molding on its PS30E3ASEC 33-ton press. The system reportedly molds a 5-in. CD in 5.5 sec, and a 3.5-in. disc in 4.5 sec. Quick, "one-touch" stamper changes are facilitated by Nissei's CD-FP molds, which join the stamper and mirror block together on the fixed platen as a unit that can be easily removed.
Meiki demonstrated two-cavity CD molding, probably a first at a show. The system includes its dedicated M-50AII-D-DM 55-ton press, which is faster than Meiki's conventional presses.
* Lens molding--Nissei introduced the TH160-18VSEL injection-compression press with 176-ton vertical clamp and vertical injection, designed specifically for polycarbonate eyeglass lenses. Nissei says vertical clamping and injection are most suitable for multicavity lens molding. Each cavity has independent cores for compression, mounted on the fixed-platen side. The press has a mold-transfer device making it possible to change the molds or cores easily, and a heating-cooling device for regulating temperatures of various parts of molds and cavities at the optimum levels depending on the shape and thickness of the lens.
Sumitomo is offering a series of presses for lens molding based on its SG series. The 27.5-, 55-, and 242-ton units are equipped with Sumitomo/NEtstal Sycap controls.
* BMC molding--Niigata introduced a 176-ton, plunger-type injection machine for thermoset polyester bulk molding compound (NNT160PP-SCH7000), with a horizontal stuffer, closed-loop, servovalve injection control, injection-compression capability, and 14- in. color CRT. Niigata feels that a plunger preserves glass-fiber length better than screw injection machines, such as it has previously offered.
* Insert molding--Nissei brought out a new 100-ton insert molder (TH100R12VSE) with vertical clamp and injection and a rotating mold table. The older model had 60-ton clamp and shot size of 90 cc, vs. 127 cc for the new model.
* Low-pressure molding--JSW introduced the JIP series of low-pressure, vertical-clamp injection-compression presses of 110, 330, 660 and 1100 tons. This approach is said to require injection pressures as low as 1450 psi and clamping pressures of only 435 to 1450 psi. This is particularly suited to molding warp-free, thin-wall, large-area parts for cars and appliances, as well as in-mold laminating of fabric, carpet or other skin materials for auto interiors and furniture. The vertical clamp has servovalve parallelism control and a mechanical locking device that's said to make it shorter and more lightweight than standard frame-type vertical clamps. The press enables parts to be removed in three directions.
* Multi-process molding--Takahashi Seiki Co., Ltd. has developed what it calls the NC Blow Stamping Injector, a vertical-clamp machine that has both an injection barrel and an NC-controlled extruder that moves on x-y-z axes. The latter can either distribute melt over a stamping mold, or drape parison into the cavity of a horizontal mold for so-called "3D" blow molding.
* High-speed, precision molding--Nissei introduced the PSX40-5A, a 44-ton press for ultra-high-speed precision molding, particularly parts made of engineering resins and thin-walled products. This compact, fully enclosed machine is said to have a more rigid clamp, 600-rpm max. screw speed, 210-cc/sec max. injection rate, and simple adjustment of mold thickness and ejector from the control keypad.
Mitsubishi's new 80MSP-5 is an 88-ton hydraulic-clamp press with closed-loop servovalve injection speed and pressure control. IT's the first in a new line of high-speed, precision molding presses that will range as high as 319 tons. This model is said to dry cycle in 3.6 sec. The MSP line has variable-volume pumps for injection control and a-c inverter motor for screw rotation, both of which are said to save energy. Controls offer display options of CRT, LCD or LED.
GENERAL-PURPOSE MACHINES
Kawaguchi introduced the KM Series of toggle presses, which come in two versions. The B line offers CRT- based control, while the C line has a panel-type display. These presses range in size from 55 to 715 tons, with swiveling injection units and what are said to be improved-performance variable-volume pumps. Company sources believe their 495-tonner is the largest in the world with a variable-volume pump.
Toyo introduced the G2 Series of toggle presses ranging from 16.5 to 495 tons. Toyo emphasizes the user-friendliness of the controls. You can set all key parameters in a single screen "page" on the 12-in. CRT. The CRT graphically compares setpoints with actual injection speed and pressure. A program for machine maintenance automatically appears on the screen the first day of each month and displays when and where in the machine you should perform maintenance checks.
Other control features include four pressure changeover modes, PID temperature control, and hopper-throat temperature control. A "slope control" feature allows injection speed and pressure, screw rpm, and back pressure to be increased or decreased gradually. This is said to prevent part warpage while increasing dimensional accuracy. Six-step injection speed and pressure profiling for complex jobs, and three-step profiling for easier jobs are provided.
Sumitomo's new SH line of fully hydraulic presses have a swing-disc type of clamp similar to some Battenfeld machines. They range from 27.5 to 715 tons and included three sizes not previously offered by Sumitomo: 495, 605 and 715 tons. These machines reportedly occupy 25% less floorspace than Sumitomo's SG toggle series, and will cost somewhat less. Although they have no accumulators, they reportedly use no more oil than the accumulator-assisted toggle machines do, thanks to the short-stroke clamping cylinder. Their speed is somewhat less than that of the SG models, however, a company spokesman notes.
New controls provide closed-loop control of clamp position. Other functions are open loop. The presses have one variable-volume pump and one static pump, except on models over 385 tons, which have two variable-volume pumps and one static pump. Sumitomo will take orders for the new line after NPE.
Shinwa Seiki introduced the CN line of presses, whose biggest difference from the preceding line is that the microprocessor controller has been upgraded from 8-bit to 16 bits. This reportedly provides enhanced performance (full closed-loop control is optional). Speed of the 160-tons press exhibited has been increased by 20%, owing to faster pressure buildup and decompression.
Ube Industries introduced the PZII450, a 495-ton toggle press that is forerunner to a new line ranging from 385 to 935 tons, to be introduced this year. The press accepts greater max. die height (35.5 in.) than Ube's previous line. A variable-volume pump that reportedly provides 30-40% energy savings is optional.
Toshiba Machine Co., Ltd., which can return to business in the U.S. in December of this year, introduced the IS-F series of presses from 110 to 935 tons. Three levels of Injectvisor control with LED or electroluminescent display are offered. These machines are said to offer a wider range of functions, higher speeds, greater precision, improved user-friendliness, and better quality control.
NEWS IN CONTROLS
Barber-Colman introduced its new MACO 4000 at JP 90, although it won't be available here until NPE in June. This closed-loop controller is exclusively for injection molding. It's less expensive and more compact than the MACO 8000, though it reportedly packs much the same power and features, except for the new clamp-control module available only on the MACO 8000VA. The 4000 has a Lumitech flush-mountable, electroluminescent operator station (also available as an option for the 8000) measuring just 11 in. wide, 15.5 in. high and 3 in. deep. It has graphics capability and is said to be user-configurable in much the same way as the MACO 8000's CRT.
Besides the compact display, the control unit consists not of several booksized modules, but rather a single enclosure 18 in. wide x 14 in. high x 8 in. deep contains plug-in circuit cards for temperature, sequence, hydraulic control, process control, linear positioning, multi-pump pressure flow, and communications. Six zones of full PID auto-tuning temperature control are standard. Process control includes ramping and closed-loop control of injection pressure or velocity, pack, hold, and backpressure, and cushion. Communication capabilities include RS-485, RS-432, printer port and MACO-NET. An internal SPC package is also available.
Barber-Colman sees the MACO 4000 as primarily aimed at injection machinery OEMs, but it will be offered directly to molders. "We're very excited about it," says Steve Schroeder, president of machinery remanufacturer Epco Div. of John Brown, Inc. Epco plans to introduce it as its E4000 retrofit control on a working machine at NPE. Schroeder believes it will be most cost-effective for machines in the 375-1000 ton range.
HOT-RUNNER NEWS
One unusual hot-runner development was shown by Ju-Oh Inc. (maker of the Part Watcher video mold-protection system sold here by Comet Automation Systems, Inc., Dayton, Ohio). Company's Model 614 hot-runner system uses induction-heated probes, which are said to give very quick response.
Another unusuals systems was unveiled by Seiki Corp., maker of Spear System hot-runner components. Its patented Supercycle Natural Hold Pressure System is said to enable greater molding precision while providing faster cycles. The device fits on the end of the injection barrel between the end of the screw and the nozzle. It contains a valve that can shut off flow from the screw and permit flow from a small melt reservoir in the device, held under independent pressure control. Here's how it works: After initial mold filling, the valve closes off flow from the screw, and hold pressure is maintained in the mold cavities by pressure on the melt in the Supercycle reservoir, rather than the screw. This permits immediate screw recovery for faster overall cycles. A "pressure relief valve" in the Supercycle system is set to accurately control hold pressure independently of hydraulic fluctuations of the machine. A third component of the system is the patented filtration system, said to ensure that only completely clean material enters the mold, with no pressure drop. Cleaning of the system is said to take only 10 min, with no disassembly required. The system will be available in the U.S. 12-16 weeks after NPE, and will cost approx. one-third as much as a new machine, according to Spear System, Inc. in the U.S.
Seiki also introduced a controller that will be standard for all Spear hot-runner systems, replacing a variety of controls for various systems. The AXC Controller is a general-purpose digital controller primarily for use with Spear's systems, but when combined with the proper power unit is said to be capable of controlling hot probes from other suppliers as well. The controller can store 15 mold recipes, although an optional data card can expand upon that. The AXC Controller has a CRT display, a printer, floppy-disc storage, a personal computer to gather data, and a hand-held digital remote unit for 24 Spear probes and eight manifold zones, which can be removed from the mold after it is up and running. It's less expensive than Spear's AMC controller.
Also new from Seiki is the Spear "G" bushing. This is an open-pipe bushing, externally heated with no obstruction in the center. The gate orifice cycles on/off, freezing the gate shut and melting it open. However, Spear has improved the heating rate at the gate to almost double that off the original tip. Initial test data show the same pressure curves as with valve gates, but with no moving parts, says Spear, as well as faster cycles in molding microfloppy discs.
Seiki also has a new Side-Gate Probe, aimed at connector molding. The probe has two tips at right angles to the body that cycle on and off. It's said to run glass-filled engineering materials. (Spear also just recently released in the U.S. the "M"-type probe with two, three of four tips.)
Also new is Spear's EH Busing. This probe was developed especially for high-heat materials and has reportedly run successfully GE's Ultem polyethermide and ICI's PEEK and polyethersulfone (PES). It can be made with Spear's 80Rc tip for glass-filled materials.
Other recent Spear developments include a modular manifold that takes up much less space in the mold than before and consumes 60% less power. Also, Spear has expanded its original Fixed-Pitch multicavity block-type system design into a Free-Pitch System. This means that Spear will manufacture the system to any gate center distance the customer wants.
IN-MOLD
DEGATING
SYSTEM
A novel concept shown by Nissui Kako Co. LtD. was an in-mold degating system that's said to allow use of thicker gates for easy filling of mold cavities--especially with older machines. The system uses servovalve-controlled hydraulic cylinders in the gate area of the mold, which vibrate at 20 Hz to break the gate while the mold is still closed (see diagram). An acrylic test part with a 31-mil-thick gate was vibration-degated in 2.5 sec, and the surface of the break area was much smoother than the same part degated with an end-mill cutter or a laser.
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