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Machinery and controls.



Injection molding manufacturers are concentrating on making their machines strong, lean, targeted to meet customers' present needs, and adaptable for future requirements. The generic sales motto is "Don't pay for what you don't need today."


Total sales, foreign imports and domestic, of injection molding machines in the U.S. in 1989 were 4893 units. Of these, 2197 were domestically produced, or 44.9%. Total imports in Canada were 494 units, about 80% of the total sales in that country.

North American sales have remained stable for the past several years, hovering around 5500 units. In 1985, U.S. shipments of injection molding machinery numbered 2332; in 1986, 1987, and 1988, the numbers were 1709,1748, and 2016, respectively. For the first nine months of 1990, however, shipments of U.S. units are running 18.7% below 1989.

Market observers are predicting little or no growth in the near future. Wolfgang Meyer, president, Battenfeld of America, Inc., comments that "success, not to mention survival, depends upon product offerings that are strategically suited to specific markets." With a very limited number of U.S. machine manufacturers controlling almost half the domestic market, the remaining 50plus, mostly foreign, large and small suppliers are faced with a highly competitive environment. Some established companies have ceased manufacturing (such as Reed Plastics Machinery Div. and Natco), or are scaling back their U.S. production (such as Klockner Windsor inc.). Meyer suggests that given the unfavorable exchange rate for European manufacturers, Far Eastern suppliers will become increasingly competitive in North America as they establish reliable support services.

PRICE IS CRITICAL The trend toward buying more features than are immediately needed has essentially ended. Price is now the critical factor in most purchasing decisions.

A 1990 market research study, funded by Battenfeld, predicts that certain market segments (electronics, medical devices, automotive) that require high precision injection molded parts will see substantial growth, even in current economic conditions. Industries requiring low precision, commodity-level parts probably will stay level or even decline.

Lifetime cost considerations (purchase price, energy, maintenance, need for future enhancements); capabilities tied to current processing needs; and increased, but simplified, control of the molding process are areas the machine manufacturer must address. "If processors do not require SPC now," Meyer says, "they do not want to pay extra for it, on the possibility it may be needed later."

Built-in modularization as a hedge for the future is the preferred route to higher value. Several manufacturers have introduced modulat designs with interchangeable components that allow functions to be added or capacities upgraded without modifying the basic machine.

Battenfeld's CDPI,s series, as one example, offers options in injection capacity, clamping force, opening stroke, mold height, tie-bar distance, ejector stroke, power packages, and control systems. Flexibility is built-in for the future.


Automation has not caught on as quickly as some predicted. "Fully automating a line may be more expensive than the results justify," Meyer says. "Machines that lend themselves to the addition of automated peripherals on a piece-by-piece basis may be more logical."

The most demanding markets will continue to press for maximum precision. This drives development, of artificial intelligence, real-time controllers, and simplified symbolic language systems that promote understanding of the more complex control. Most such developments probably will come from the computer industry. Machine suppliers will compete on their ability to incorporate the enhanced control technologies into their systems, ideally on an optional basis.

Meyer believes that operators' capabilities are essentially remaining constant as control systems advance, leaving significant machine potential unrealized. The response is two-tiered. Some manufacturers continue to develop highly sophisticated control systems for computer-literate operators. At the same time, they also are selling more user-friendly controls for those with less training. For system integration, requiring high levels of operator input and monitoring, user-intensive alpha/numeric keyboard controls will continue to provide solutions. Injection molding machines may be designed to accept interchangeable modularized control systems for particular production runs. To help plastics processors meet the challenge of sophisticated new controls and the shortage of highly skilled labor, video-based technical training courses (such as Paulson Training Programs, for one) are becoming more available as a means of upgrading the knowledge and skills of production floor personnel.

Especially in today's tight economic situation, threshold cost-reducing molding technologies are expected to come forward. Meyer predicts that there will be growth of gas injection molding of structural panels with reduced stresses or hollow parts without core molds. Onestep production of multiple-material structures by coinjection, and growth of powdered metal parts by injection molding also are projected.


Polymer Machinery Corp.'s new Arburg M series features control enhancements, proportional hydraulic valving, and fast mold, material, and color changes. Available with clamp force from 28 to 94 tons, the M series has a flexible building block system.

The new Multronica control can store setup data for up to sixty molds on a 3.5 inch diskette. The software automatically makes adjustments to correct for differences in screw size if one mold is moved to another M-series machine of comparable size. Modular injection cylinders with plug-in electrical connections and a new quick-coupling screw are standard equipment. Clamp and injectorstrokes are controlled by precision proportional valves with linear variable displacement transducers. Hermetically sealed spiral heater bands enhance ramping of temperatures for molding temperature-sensitive materials.

An optional sorter unit under the clamp automatically separates good from bad parts. If preset tolerance values for injection parameters are exceeded, the sorter separates the rejects as the good parts are conveyed under the machine base.


Boy Machines Inc., which has offered 24, 30, and 55 ton machines with its Dipronic digitally adjusted control, now looks to increased penetration of the broad 50 to 100 ton market with its new 80T2 (with Dipronic control) and 80M (with the new Mipronic Plus control) 88 ton models.

John Johnson, national sales manager, foresees that some users will opt for smaller machinery and reduced numbers of cavities, as alternatives to larger tonnage, multiple cavity installations. "Some molders have discovered that a reduction in the number of cavities in a tool can facilitate greater precision, faster production rates, and quicker mold changes and startups. "Johnson adds that in many instances, increased production and lower processing costs may derive from using multiple small machines rather than one large one.

The company is especially pushing its new Mipronic-Plus control, now available for the 30,55, and 88 ton models, for the high-tech precision market. The control includes a high-resolution 10 inch visual display; storage capability of thirty setups in an onboard RAM, and 300 additional setups with a 3.5 inch floppy disk; five injection speeds, and two ramped zones for gradual transitions between different speeds and pressure steps. An SPC/SQC package also will be available next year.

The Mipronic-Plus also is designed for computer-intergrated manufacturing with single or multiple machines and tolerance monitoring of ten parameters; it includes optional closed-loop control, a standard seven-day timer for automatic start-ups, and a printer port for reports.


The continuing effort is to provide the machine operator with useful, real-time information for expediting decisions to make the molding process most efficient. Ron Sparer, supervisor, Controls Development, Cincinnati Milacron, reports that the company, building on its current SPC capabilities, is investigating neural networks and "fuzzy" logic techniques as possible control advancements. "These highly sophisticated control technologies will not be available tomorrow, but neither are they solely 'blue sky' concepts. Although they currently would be very expensive, they have real potential as machine control systems in the future."

Neural techniques are suited for the molding process because they handle extensive combinations of input patterns to achieve a desired result. Neural networks try to simulate the brain's operations by providing many paths between the input parameters and the desired outputs. The correct responsive paths are determined by "training" the network with repetitious data sets that describe some of the relationships between the inputs and outputs. If an input data pattern outside its experience is encountered, it makes a best guess based on already recorded inputs. The neural network thus is like its human counterpart, where decisions are made based on past associative experiences. The more experience, the better the decision.

Fuzzy logic, which combines conventional logic practices with the unconventional problem-solving capabilities of a neural network, similarly can handle large input data sets and "learn" from experience. Fuzzy logic, however, relies more on conventional statistical techniques to accomplish a best guess instead of trying to emulate the human brain.

Sparer says both techniques might find use in an injection molding machine of the future because the molding process has many input variables that can affect part quality (such as back pressure, temperature, and extruder rpm). For example, in a future control, as the part weight varies, the neural network initially would monitor and record what the operator does to correct for the variances. The network would learn" from the operator's actions by conditioning itself to respond not only to data it has already recorded but also to interpolate between the already recorded conditions to correct the problem.

Sparer points out that even at their highest level of sophistication, the training of the neural networks would be dependent upon the inherently limited capabilities of even the most expert processing technician.

He reiterates that these promising control technologies are currently in their infancy. However, although they are costprohibitive in all but their simplest form, the door is ajar for availability of more "intelligent" plastics processing machines.


To compete effectively with offshore machinery builders, Engel Canada Inc., and Engel Machinery Inc., in the U.S., call the current design directions "a new spirit of manufacturing in North America."Taking a leaf from the trend in the automotive industry to rely on qualityand capacity-proven single-source suppliers, Kurt H. Fenske, vice president, sales, says the manufacturer of injection molding machines must become "a partner who shares the customer's goals and concerns. He must deliver sensible solutions for the real needs of today, but without neglecting the user's future interests in new techniques and changing requirements." Zero-reject precision; application-specific solutions without major impact on price and delivery, fostering modularity in machine component design; and product and process know how, with the ability to help customers derive the maximum from the machines, now are fundamentals that will define the competitive relationships of the 1990s.

Engel's new 30 and 55 ton hydraulics, the ES 30 and ES 55, feature a swing-out control panel and screen and full access to all service and maintenance zones. Rail-mounted covers or hinged gates are either simply pulled out or moved aside, which also eases automation with auxiliaries. Clamp, injection, and ejector manifolds mounted on their respective cylinders improve hydraulic response. Quick barrel change and a swing-out injection unit speed product turnaround.

Modular ES 30 and ES 55 injection units ease shot size interchangeability. Engel's EC88 standard microprocessor, with a "distributed intelligence" architecture, allows parallel microprocessors that can be dedicated to individual machine processes.


In a carry-over from Krauss Maffei's 1000 through 4000 ton M-series, quick barrel changing has been made standard for the company's entire machine range, enabling molders to optimize their plasticizing units for engineering plastics.

The 65 to 880 ton B3 series provides higher horsepower and hydraulic volume to plasticize material during clamp opening and closing. Dennis Richmond, business manager in Krauss Maffei's Injecting Molding Division, says the series now features an enhanced MC-3 control, which incorporates SPC, process capacity analysis control charts, and trend analysis.

Richmond adds that there is increasing interest in multiprocessing concepts, such as the Alpha machine, which can create large single structural parts by combining different plastic materials within one integrated production system; and multicolor machines, for molding four or more colors in a single part, such as automotive taillight lenses. DEMANDS FOR QUALITY HPM Corp. has been developing a series of 75 to 500 ton injection molding machines as a response to molders' demands for high quality products at competitive cost. Kemp Shepard, vice president, cites features such as improved energy-efficient hydraulic designs that include variable-volume pumps; more accurate clamp and injection systems; and common injection units for hydraulic and toggle machines.

Shepard says a major company direction, consistent with industry trends, has been to improve overall repeatability and to satisfy molders' requirements for short lead times. "Customers want machines that are easy to set up," he says, "with quick mold changing and comprehensive data storage capabilities. They expect a lot of maturity in the controls. And, service is all important, to keep the machines performing at their optimum levels. The machine manufacturers also must understand process technology, covering an increasingly wide range of materials, to best serve their customers."


Husky Injection Molding Systems, Ltd., has a line of machines with modular design that the company says is easily customized. For example, many applications would require a basic clamp module (pump-based, with no accumulators), with a 20,000 psi injection unit, a 20:1 L/D screw, an injection rate less than 1 kg/sec, and a high torque/low speed drive. By contrast, a thin-wall packaging application would require a high-speed clamp (accumulator-based), a 30,000 psi injection unit, a 25:1 LID screw, an injection rate greater than 3 kg/sec, and a low torque/high speed screw drive. Each clamp is available with at least ten different reciprocating screw injection units and ten different two-stage injection units. Applicable to all machines from 150 to 4000 tons, the line will be competitively priced to reflect only those specifications the customer requests. The robotics line, available with one to five axes with air, hydraulic, electric, or servo drive, and accuracies to +/- 0.004 inch, also is modular. Built not only for Husky machines, but also for all competitive machines from 150 to 4000 tons, the robots can handle speeds up to 13 ft/ sec and payloads of up to 560 lbs. Husky also has developed a line of injection molding machines three, or four injection units, and the option of rotating platens or coinjection units. Advances also are being made in factory automation technology. For example, one model of operator interface is an IBM-compatible PC with a 40 megabyte hard disk drive, which can operate a complete on-line SPC system to monitor up to twenty variables and store 10,000 entries in the data log. This information can then be saved on a 3.5 inch floppy disk for further analysis. Supervisory computer systems and a modem connection to Husky's service department are also being refined.


Newbury Industries, Inc.'s new 35 and 300 ton units extend the line of MonoToggle clamp machines. Features include up to 40% less floor space than other machines of similar capacities, large platens, and wide tie-bar spacing. The 35 ton machine has 16.5- by 16.125-inch platens, larger than normally found on 55 ton units, and 12.5- by 10-inch tie-bar spacing. The 300 ton unit has large 40- by 34-inch platens and 26.25- by 22.25-inch tie-bar spacing. The designs thus facilitate applications requiring a large mold area and small shot sizes. Clamp force at the center of the moving platen provides high rigidity and speed.


Van Dorn Plastic Machinery Co. has broadened the capabilities and options available for the HT series of toggle clamp machines. Additions include high speed models for all sizes from 85 to 500 tons, and the microprocessor based, hard button, digital-set Pathfinder programmable control, enhanced with open-loop profiling for injection. Van Dorn has also added ability to interact with auxiliary equipment, via the SPI Communications Protocol, to its Pathfinder EL control, available on all HT Series and HP Series machines from 275 to 3000 tons.

To expand and improve processing capabilities, the company now is licensed to manufacture and sell the Willert Barrier II high performance screw for Van Dorn machines. Particularly effective for polypropylene, polyethylene, polystyrene, and nylon, the screw is said to provide improved recovery rates and melt quality.

Van Dorn has been involved in customized large-tonnage installations, primarily for automotive and housewares. The company currently is building its first two 3000 ton machines for an automotive application.

The company reports it is providing an increasing number of mold change systems, involving Van Dorn design as well as the integration of other manufacturers' systems, for just-in-time manufacturing. NEW SIMULATION SOFTWARE Auxiliary aids, related to material processing and mold design, supplement machines and controls to bolster efficiency. AC Technology, for example, has recently made available what it says are the first computer simulations of the gas-assisted and the coinjection molding processes, as well as simulation software for injection molding with reactive materials. Because the filling dynamics are affected by the properties of the gas and the gas entry points, injection molding simulation programs designed for a single material are not adequate. Peter Medina, president, AC Technology Plastics Productivity Center, says the company's CGain gas-assisted injection program simulates the initial filling of a polymer, and then the injection of high-pressure gas through the sprue or other locations in the cavity at a specified time. The software differentiates materials based on the time instant and location of their entry into the cavity and traces the distributions of polymer skin and gas core during molding. The software also accounts for the differences in material properties, and the mass, heat, and momentum interactions between polymer and gas.


Injection molding machinery and controls are being challenged not to give up any precision and evolve to a higher level, while making processing functions easier to set up, easier to monitor, more repeatable, and more cost-effective. The technology thus is at once being required to become more complex in its inherent capabilities and simpler in its practical interaction with operators on the production floor. Cost is all important. But possibly even more, there is a deep rooted desire to link complexity with the security of basics. Modularity and flexibility, standardization, and the ability to visualize more readily the functions that are being performed reflect the quest foreverbetter, more competitive injection molded products. One can only wait with great interest to see how these trends will continue to be revealed in the machines and controls at NPE'91.
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Title Annotation:injection molding equipment
Author:Wigotsky, Victor
Publication:Plastics Engineering
Date:Dec 1, 1990
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