News from Interplas.

News from Interplas

Coming one year after K'89, Interplas '90 in Birmingham, England, couldn't hope to match the mammoth Dusseldorf show for shear volume of news. However, with 1300 exhibitors, there were nonetheless plenty of new machinery introductions to interest of North American processors. Some of these were briefly previewed last month in our Technology Newsfocus section (pp. 13-14).

Materials and additives news at the show was relatively skimpy, and is not included in this report (see last month, p. 14.)

Injection Molding 

With many predicting gas-assisted systems to be the next wave in injection molding, several suppliers prominently displayed their versions of this new technology. Gas-injection molding uses an inert gas, usually nitrogen, to hollow out the thickest sections of large parts. It has made possible injection molding of items such as computer housings, copier covers and large auto body panels with lighter weight, lower warpage, and faster cycles.

The already announced gas-assisted methods from Battenfeld, Cinpres Ltd., Klockner Ferromatik Desma, and Mannesman Demag were all shown (see PT, Oc. '90, p. 37). A new system that injects nitrogen gas into the mold was introduced by Engel, and a spokesman for Sandretto said the company is developing a version of gas-assist technology that it hopes to unveil later this year (see PT, Jan. '90, p. 72).

Engel's Gasmelt system injects nitrogen gas into a partially filled mold cavity to complete the filling. After venting, about 92% of the gas is recovered and reused. The system is run bya special "Gasmelt" computer program. Klockner's "Airpress III" technique is unusual in that it does not inject the gas until the cavity is completely filled with melt> to "make room" for the gas, Klockner proposes opening up subsidiary wells with slides in the mold, or permitting backflow into the injection barrel.

SERVO-DRIVEN SCREW

As at the JP 90 fair, held a week earlier in Tokyo, Interplas featured a number of machine builders touting electric servo-driven units. Newest amont the electri machines was Battenfeld's BK-T 1800/800 toggle press with Unilog 4000 control. This is actually a hybrid machine, with a servomotor screw drive and conventional hydraulic power for all other functions. Servo drive on the screw alone is less expensive than an all-servo machine and still yields up to 20% energy savings, Battenfeld says. The servo-driven screw also gives the molder the advantage of stepless control of screw speed, allowing full torque to be available in the lowest speed range. Speed of the screw can be controlled with greater accuracy, Battenfeld says, resulting in more accurate and reproducible shot weights.

Battenfeld Austria also introduced the first three toggle-clamp units in its CD line. The BA 500 CD-5, BA 750 CD-K and BA 850 CD-5 (60, 91 and 103 tons, respectively) are designed for fast cycling (42 dry cycles/min is reportedly typical). They use a five-point double toggle, with an optional clamp-force control system that reportedly protects against mold damage. A highly sensitive sensor is installed in one of the tiebars, reportedly guaranteeing precise clamping force during automatic operation. A new Unilog 2040 control is standard> Unilog 4000 is optional. These machines are expected to make their North American debut this spring.

MAGNETIC MOLD CLAMPING

A new approach to quick mold clamping and unclamping was unveiled by MIR of Italy. Intended as an alternative to external blocks or hydraulic cylinders. MIR magnetic platen systems consist of a set of permanent magnets, which once polarized are reportedly able to guarantee retention of the dies even if the machine power supply fails. The magnets are embedded in the platens, so there is no reduction in maximum daylight, as there is when external magnetic platens are used. This system is said to be more economical than other mold-clamping devices, and does not require the use of standardized mold-retainer plates like other systems do.

UPGRADES AND ADDITIONS

The remainder of the injection molding news at Interplas centered on upgrades to existing machines and systems and additions to already established product lines.

* Nuova Plactis Metal of Italy (represented here by NPM Inc.) showed one of the upgraded machines from its PM series. The company has added accumulators to 108-, 151- and 216-ton toggle machines in this line, which doubles their injection speeds.

* Mannesman Demag upgraded its NCIIIsystem with the latest microprocessors technology. The system now includes what the company calls an "intelligent" IBED 90 terminal, giving the user a level of process monitoring "previously only available in a process laboratory." Four pressure profile curves of cavity or hydraulic pressure can be overlaid with a graph of screw stroke. Statistical monitoring of process time, temperature and cushion has been supplemented with average temperature range for any zone, two mold temperatures, switchover pressure and stroke, and energy consumption per cycle. Automatic startup/shutdown sequences, good/bad cycle discrimination, and job queuing for automated tool changing are also provided.

* Presma S.p.A. of Italy, which specializes in rotary, multistation machines, introduced its new Trio 60 vertical-clamp insert molder. With a maximum of three stations, the new machine has a rotary table carrying duplicate lower mold halves, and a single stationary upper mold half. The table can rotate either clockwise or counter-clockwise, permitting the combination of two different robots--one for insert loading and one for parts extraction.

* Butler Designs of England (represented in Canada and the northern U.S. by Barwell Inc., and in the southern U.S. by Louis P. Batson) also launched a new insert machine, the 10/90V. With a shot capacity of 0.3 oz, the 10-ton machine can reportedly process most thermoplastics.

* Sandretto has expanded its new Series Eight machine line, inaugurated at K'89, to six models of 60, 95, 150, 200, 270 and 360 tons.

* Boston Matthews of England added a 55-tonner to its small-machine line. The new model has tiebars that retract to leave 12 in. of space to mount an oversized mold.

* Fortune Machinery Ltd. of england (Victor Plastic Machinery in the U.S.) added a 275-ton machine to its Victor series. The Taiwan-built machine complements Fortune's 121-, 154- and 198-ton presses with five-point double toggles.

NEWS IN ROBOTS

Wittmann Robot Systems of Germany and Sepro of France (newly represented in North America by Conair Martin) were among the few suppliers showing new robotic systems. Wittmann demonstrated its new W 40 sprue picker with advanced microprocessor control. The compact robot has rotation and tilt movement integrated into one block for easier adjustment. Rotation can be adjusted from 60[degrees] to 90[degrees] and the kick stroke is adjustable up to 2 in. As many as 20 programs can be stored and recalled in the unit's hand-held microprocessor control.

Sepro's P.I.P. 350, for parts removal from injection presses and loading and unloading of auxiliaries, and the M.G. 350, aimed at more general loading and unloading applications, are the latest additions to its line. Each is a single-beam, three-linear-axis robot with 59-in. horizontal traverse stroke (electric-driven), 39-in. horizontal pickup stroke (electric), and 55-in. vertical stroke (electric or pheumatic). Maximum loads are 33 lb with air or 44 lb with electric drive.

Extrusion

A number of new developments were exhibited in blown film, sheet, and profile extrusion. Some of these innovations, such as quick-change blown film dies and improved air rings, are still under development, but provide a glimpse of what should be on hand at Chicago's NPE '91 in June.

BLOWN FILM NEWS

Improvements in dies and air rings promise more flexibility and better film quality. Brampton Engineering exhibited its new Slimline die that's said to provide exceptionally quick flushing capabilities, important for frequent color or resin changes. The monolayer model shown was precursor to a multilayer version to be unveiled at NPE. The multilayer version will reportedly allow interchangeability of layer configurations from monolayer to five- and seven-layer barrier structures.

Brampton also had on hand a new noncontacting Air Cushion stabilization cage, which is said to reduce bubble drag and distortion associated with conventional stabilization cages. The system eliminates physical contact between the bubble and traditional roller or iris contact cages and guides, by means of a thin film of directed air flow between the bubble and air-supply arms. The unit is aimed at producers of high-gloss, high-clarity film.

Future Design is currently testing two air-ring improvements that should soon become commercial. The first is a Positive Heath Transfer (PHT) air ring, for thin laminating film. The PHT is designed with an extra ring around the circumference of the air ring, which is said to eliminate interference of ambient air with the cooling effect of the air ring. The key is positive heat transfer, which draws the frost line down close to the surface of the air ring and allows the film to be run at close tolerance.

So far, the PHT has achieved better than [+ or -]2% gauge variation when running 1-mil LDPE of 2 MI at a rate of 6 lb/in. of die circumference, according to the company. During the run, the frost line was no higher than 3 in. above the air-ring surface. Future Design is now experimenting with Du Pont Canada's Sclair LLDPE. Because of the excellent optical properties achieved so far, Future Design president Robert Krycki says the laminating-grade film produced with the PHT is competitive with that normally produced on cast film lines.

The second development is an air ring for HDPE, aimed at the commodity film market, which is claimed to combine good gauge control with high output rates. The ring design moves the air entry back away from the die diameter to a new lip design intended to deliver the air at high speed across the bottom lip. It relies on the distribution within the company's Saturn air-ring chamber, which achieves an air column that delivers more air volume to the stalk without disturbing the drawing process. Tests running HDPE at a rate of 12-13 lb/in. reportedly achieved [+ or -]7% or better gauge performance while maintaining strength of material and stability.

So far, the air ring has been limited to external cooling systems. The next stage is to use it with internal bubble cooling, and Future Design is reportedly talking with a number of extrusion OEMs about adapting it to their IBC systems. The target output rate of the air ring with IBC is 21 lb/in. with a 7-in. die.

Battenfeld Gloenco demonstrated its new Auto Profile Control System for blown film thickness control ona line producing 67-in.-wide three-layer LDPE/LDPE/PPDPE converting film at its Droitwich plant. Developed by Battenfeld Gloucester Engineering, the system consists of a number of air-heating/cooling units located radially within a Polycool air ring. By varying the heating/cooling effect of individual units, the temperature of air exiting the ring can be raised or lowered in a particular circumferential zone. The temperature change locally increases or decreases film gauge.

This sytem is one of four now on the market for automatic blown film profile control. The others--from Windmoeller & Hoelscher, Reifenhauser and Filmaster (see Technology Newsfocus)--accomplish this at the die, rather than air ring> but the W&H Optifil P system has the similarity of utilizing a series of cooling-air jets around the die.

Battenfeld's new system was controlled by an Extrol 6032 computer, which prevents the system from over-reacting to minor variations in film thickness by staggering heating/cooling around the problem area. In tests, the Auto Profile Control System has achieved a 50% reduction in transverse gauge variation, although actual gauge tolerances are dependent on process parameters.

Plast-Control (represented by Control and Metering) is also working on an automatic control for a blown film die, which it hopes to have ready for exhibition at NPE. At Interplas, the company exhibited a new capacitance sensor that can either be fixed of rotate 360[degrees] around the bubble.

FILM CENTER/SURFACE WINDER

Egan Machinery Div. of John Brown has developed a new center/surface winder for cast film. The winder is said to be capable of handling a wide range of product thicknesses and provides a choice of winding modes. It can be used for center or surface winding or a combination of both. In the combined mode, the percentage tension contribution of the center and surface drives, as well as total tension, can be varied during the reel buildup. Other features include the ability to vary the surface drum nip pressure, or run in gap mode to control the density of the reel.

WEB SENSORS & CONTROLS

Measurex Corp. exhibited its Model 2283 Z-Laser non-contacting thickness sensor, which it developed jointly with a tire manufacturer to provide direct measurement of the thickness of rubber on a calender roll close to the nip. It's also said to be applicable in plastics, particularly for thick, opaque products such as foam sheet and composites. The unit combines a laser triangulation technique with a radio-frequency Z-axis distance measurement, which, unlike laser-only designs, provides thickness measurement that is unaffected by roll runout and is insensitive sensitive to temperature and vibration. Advantages for direct measurement of thickness include high measurement precision independent of material composition, eliminating the need to recalibrate for each compound. Because of its short measurement integration time, the Z-Laser provides faster measurement, enabling high-speed calender control.

Measurex has also signed on OEMs for distribution of its FasTrack flat-web extrusion gauging and control system (see PT, Nov. '90, p. 15). In the U.S., it has reportedly reached agreements with Egan Machinery and Black Clawson.

Infrared Engineering introduced its MM55-LF system for on-line measurement of coatings on foils. The unit uses low-energy infrared light that is sensitive to coating thicknesses of 1 to 15 microns. wavelenghts can be chosen to suit the thicknesses being measured. Accuracy is unaffected by the supporting sheet or foil, and over a typical thickness range of 1-10 microns, accuracy is said to be better than [+ or -]0.2 microns. A curtain of air is available to protect the head under difficult processing conditions. Coatings that can be measured include polyesters, PS, and PVC on substrates of aluminum foil, metalized film, and tin plate.

FOR PIPE AND PROFILES

Battenfeld Extrusionstechnik, sister company to Battenfeld Gloucester, exhibited its complete range of twin-screw extruders for profiles, from 50 to 107 mm. The new 65-mm BEx 2-65-18-V unit is for 110-265 lb/hr production of PVC glazing beads, foam, and other structural profiles. The unit has parallel screws with 18:1 L/D. New for window profiles is a 90-mm unit, providing high torque within a low speed range for a maximum output of 550 lb/hr.

In addition, improved screw design has significantly increased output for Battenfeld's 90-mm BEX 2-90-22V pipe extruder. Output rates for rigid PVC reportedly have reached 770 lb/hr (990 lb/hr with force-feeding). Also contributing to better output is an improved gear box that's said to increase the unit's motor efficiency.

Corma Inc. presented an expanded size range in its ribbed pipe systems. Standard Ultra-Rib pipe systems, for production of single-layer HDPE, PP, and PVC pipe with radial or spiral reinforcing ribs and a smooth interior wall, are available from 0.8 to 32 in. Extrusion Technologies, Denver, Colo., which has produced Ultra-Rib pipe in 24-in. diam., will reportedly move up to 32-in. this year.

Three new pipe gauging and control products were introduced by Buhl Automation A/S, represented here by Luwa Corop. For wall-thickness control of gas and water pipe, Buhl has the Rotor Scanner 50/160 for pipe diameters of 2-6 in. (Previously, the rotor scanner had been offered for pipe diameters of 0.6-2.56 in.) A noncontacting ultrasonic scanner rotates continuously in one direction at 60 rpm. A profile of wall thickness is shown in relation to selected limits.

Also on hand was Buhl's Gravimacs gravimetric measuring and control system, which is not just for pipe extrusion. The unit uses the loss-in-weight principle to ensure constant material flow from the extruder and give precise production data. The hopper is equipped with a quick-release mechanism for easy removal, and program function pushbuttons provide atuomatic control of speed and the material feed hopper. The unit has three LCD displays to show actual production values, and a numeric keyboard is used to input setpoints.

Integrated monitoring and control of pipe wall thickness, centricity, and weight are provided through Buhl's PPC 3411 Pipe Extrusion Line Control. The console accepts interfaces from Buhl's wall-thickness scanner, thermal die-centering module, and gravimetric weigh hopper. It combines gravimetric feeding control and wall-thickness scanning to self-calibrate the thickness gauge.

A noncontacting gauge control for profile lines was exhibited by Maplan. The Profitec 01, manufactured by Messund Regeltechnik GmbH of Germany, uses an infrared light beam to monitor the accumulation of extruded material as it exits the die. Changes in amount of material accumulation prompt adjustment in hauloff or screw speed. (Maplan is represented by American Maplan, and Profitec equipment is also marketed by Actual Plastics Technology.)

On-line video monitoring of profile cross-section, introduced at the last Interplas in 1987 by Krauss-Maffei, again made an appearance--this time from Cincinnati Milacron (see PT, Jan. '88, p. 55> July '89, p. 69). In Milacron's setup, as the profile slid down the tipping chute, it was placed against a glass plate to be measured head-on by the video system, then moved away. After each inspection, measurements were compared with specifications, and the data were transmitted to a host computer. Accuracy was said to be better than 1.9 mil. Parameters monitored included edge length and distance between edges, wall thickness, widths of openings, minimum and maximum distances, straightness, inside and outside diameters, concentricity and roundness. Standard measurement area is 2.76 x 3.94 in.

COMPACT

EXTRUSION

LINE

The special feature of new Series 90 extruders from Betol Machinery Ltd. is compactness: the 60-mm unit occupies 20.5 sq ft of floor space--a 30% reduction compared with conventional machines. Space savings were achieved by reducing the size of the control cabinet and fitting it into the base frame of the extruder without sacrificing access to the machine. The Series 90 line includes 32-mm, 38-mm, 50-mm, and 60-mm models

Compounding

New twin-screw compounding extruders and improved process controls were on hand at the exhibition. To start with the extruders, Betol Machinery Ltd, of England exhibited its relatively new BTS60 60-mm corotating twin-screw compounder, said to be a "second-generation" design. The machine uses a trapezoidal, self-wiping screw that is said to be suited for advanced plastics compounding and high-torque requirements. The 80-hp motor delivers a max. screw speed of 300 rpm> outputs exceed 660 lb/hr. The BTS60 complements 30-mm and 40-mm units, and will soon be followed by an 80-mm unit.

Battenfeld Extrusionstechnik (represented here by Purnell International) exhibited a newly designed twin-screw lab extruder, BEX 2-50-16 V, for pelletizing PVC. (With suitable screws, it can also be used for pipe or profile.) The 16:1 L/D machine has a low-speed range infinitely adjustable from 4.8 to 48 rpm. High torque provides outputs up to 330 lb/hr while ensuring gentle handling of the melt, the company says. Also new is a hot-cut pelletizer with infinitely variable rotor drive.

Theysohn exhibited its new TSK Series corotating, intermeshing, twin-screw compounders, quietly introduced at K'89, which will become available in the U.S. this year and shown at NPE. The series ranges fromlab size to production units with output rates of 7700 lb/hr. Modular barrel sections are secured with four tiebars. The gearbox design can deliver high torque and also adjust the screw center axis.

INTEGRATED PROCESS

CONTROLS

In the past, Theysohn has marketed Inoex on-line q-c systems as add-on accessories to its extrusion lines. Now, the company is offering the process controls built into its extrusion lines, enabling users to link the total process control of each individual line to a central computer.

Farrel Corp. exhibited a process control for its CP (Continuous Processor) series mixers, which combine Farrelhs Continuous Mixer with a short hot-feed extruder on a common frame. User interface is provided by a 386-type personal computer with color CRT. Data can be viewed or printed in the form of color trend charts during or after processing. Motor control and various machine functions can be initiated from the CRT and keyboard, reducing the number of pushbuttons needed to drive the machine. High-speed response to chaning process conditions is provided by a PLC that operates independently of the computer but regularly reports significant process data for the computer to display. Functions of the system include automatic process control, recipe storage, data acquisition and storage, and SPC. The unit can be retrofitted.

Leistritz (American Leistritz in this country) displayed a prototype of a new process control for its compounding lines. The Macromatex 12-1 is based on hardware from Philips and is IBM compatible. It's user programmable, with user-definable graphics that can control up to 14 drives. The unit's data-processing capabilities can be used for SPC without interfacing to an outside computer. The Macromatex will complement the more dedicated Micromatex control in the Leistritz product line> cost difference is about 35-40%.

Thermoforming

A new generation of pressure formers that feature an "expert-system" computer control was launched by Adolf Illig, represented here by Plastic Systems and others. The newest unit, known as RDKP/DSB 54d, is run by a programmable logic controller, which calculates necessary processing parameters from oprator inputs of material type, thickness and width, depth of draw, and tool function. Up to 2000 processing programs, making up an expert system that controls heating, hole punching, platen movements, and cycle times, are stored in the controller through program cassettes. The operator can adjust the program on-line once the initial conditions have been set by the computer.

The machine is designed with modular construction, permitting the integration of preheating stations, a cross cutter, punch-and-die systems, and an on-line scrap granulator. Electric servo motors drive the machine's forming and cutting platens. (For example, the RDKP/DSB 72d is the basic 54d model along with a preheat station for processing polypropylene.)

The RDKP/DSB 54d has a forming area of 19.5 x 14.8 in. and max. draw depth of 4.7 in. It has a microprocessor-controlled mold changing device, with full digital and graphic displays of all process functions.

Another new pressure former with sophisticated controls is the KL1SH52 from Paul Kiefel GmbH, said to be the first pressure former with disk-programmable setup capability. It has hydropneumatic drive, quartz heating, 14.8 x 20.2 in. forming area, 4.7-in. draw (upward or downward), speed capability of 55 cycles/min, and quick-tool-change capability. Modular design accommodates options like in-line cutting and stacking. CRT control station stores production data, shows set and actual values, and displays fault diagnostics and tool-change sequences.

Blow Molding

A new series of twin-station, microprocessor-controlled blow molders, commercially introduced at Interplas, will be unveiled to North American processors at this year's NPE show in Chicago by Battenfeld Fischer Blasformtechnik GmbH, Troisdorf, Germany. A primary feature of the new machines, known as the BFB1-D Series, is the capability to change molds, die heads and blow pins in less than an hour. Fail-safe, hydraulically controlled, mechanical springs hold the molds in place, which are removed manually. According to Battenfeld engineers, typical mold-change time for twin-station blow molders is 6-8 hr, which has so far seriously limited their productivity, flexibility and application range.

Battenfeld, having developed its BFB1-3D and 4D models (for 3- and 5-liter containers respectively), this year plans to unveil a new BFB1-6D model, which can blow mold up to a 6-liter container. The new unit is slated for exhibition at NPE. The units have coextrusion capability, as well.

IN-MOLD WALL MEASURING

A new computerized system with ultrasonic wall-thickness measuring built into the mold was shown by Inoex GmbH of Germany. Ultrasonic measuring capability with the USS-IMM system is accomplished when the plastic part contacts ultrasonic sensors imbedded in the mold during blowing. The sensors transmit echo-signal data to a computer, which monitors weight, thickness and dimensional accuracy.

System operation and processing inputs are made through an industrial-hardened computer. Processing options include coextrusion software.

Auxiliary Equipment 

While auxiliary equipment suppliers abounded at Interplas, significantly new introductions were few. Colortronic of Germany showed a new dryer and a granulator larger than any the company now offers. The T92 dryer uses two cells to provide continuous drying and can provide a dewpoint from -58 to -18 F.

Colortronic's new M 252-L granulator is similar to its predecessors except that the company has more than doubled the size of the rotor from 4 in. to 9.85 in., allowing it to ingest large sprues and parts with surface areas of 7 x 15 3/4 in.

K-Tron Vertech introduced the Micro Feeder, an ultra-compact gravimetric additive feeder that can be machine mounted for injection and blow molding production. It's patterned after K-Tron's larger Graviblend feeder and can feed from as little as 100 gm (3.5 oz)/hr to around 200 lb/hr.