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All-electric injection molding machines gaining, key to future of molding for the packaging industry

All-electric injection molding machines gaining, key to future of molding for the packaging industry

An all electric injection molding machine offers several important benefits, mostly related to the fact that individual motors control each function, as opposed to a control system consisting of a complicated arrangement of hydraulic hoses. The motors increase the control and amount of coordination among all of the machine's functions, increasing repeatability and reducing cycle times. Other advantages of an all electric injection molding machine include lower power consumption, lower usage of chilled water, lower scrap, increased up time, decreased housekeeping and preventive maintenance, lower environmental impact. An all electric injection molding machine allows the operation to become more competitive, with better part quality. All electric injection molding machines are quickly gaining ground for high performance and fast running applications in the packaging industry. Along with a high degree of process integration, these are the future of molding for the packaging industry. Few of the developments displayed at NPE 2012:

ENGEL North America demonstrated how to use these trends to increase cost efficiency and competitiveness. Two manufacturing cells for the packaging industry were on display, demonstrating the current industry challenges: highest throughput rate at lowest unit costs on the one hand, and the efficient production of attractively decorated thin walled products on the other. Thin walled lids for newly developed ice cream containers were produced by an all electric ENGEL e motion 740H/310W/200 T US combi injection molding machine using two component injection molding and in mold labeling (IML). Once the label is inserted into the mold, the cover is injected from clear polypropylene. Immediately following, a colored edge - also from polypropylene - is added as a second shot in the same mold. In series production, the color used varies depending on the type of ice cream: a red edge for strawberry ice cream, a yellow one for banana. The two component injection molding, combined with IML, allows packaging manufacturers to easily switch from one type of ice cream to another, making it possible to produce even small batches in a highly economical way. The manufacturing cell is fully automated. The all electric ENGEL e cap 3440/460 US injection molding machine used a 96 cavity mold, with an hourly production rate of almost 130,000 HDPE water bottle caps. This output is achieved by operating at a cycle time of 2.7 seconds. Cycle times of less than 3 seconds and injection speeds of 450 mm per second can be realized. Until now, this performance class was dominated by energy intensive accumulator machines, though this will change as the high precision, low energy all electrics prove themselves. Designed to achieve maximum output and process stability, the all electric injection molding machine is able to save energy and cooling water requirements at the same time. The machine bridges this challenging gap thanks to its all electric drive technology, combined with a series of sophisticated features, such as the latest powerful, premium quality injection unit, increased ejector force and a reinforced clamping drive. Compared to a hydraulic machine, the ENGEL e cap reduces energy consumption by more than 40%. Delivering clamping force of between 100 and 420 tons, the e cap is available across a comprehensive range of sizes.

Haitian introduced a new all electric line for medical molding that is the fruition of a seven year German based development project to break into the Japanese dominated field of high tech, all electric injection molding machinery. The innovations are coming from Zhafir Plastics Machinery GmbH. Zhafir Mercury 1000 35/35 is a tiebarless, all electric machine that uses side plates rather than tiebars to create 70% more mold space, allowing use of larger tools on smaller machines. The machine design is described as 30% slimmer than previous models, boosting productivity per square foot. The toggle clamp mechanism has just two levers and a central servo direct drive. The simplified design is aimed at smoother machine operation in an effort to boost repeatability. There is no lubrication requirement. The melt quality is improved by separation of plastification from injection in a two stage injection unit. A unique rinsing process is said to eliminate melt residue. Plastification occurs immediately via a high torque motor. The injection process is controlled by a central spindle driven by a servomotor, which shortens response time and achieves speeds of up to 500 mm/sec with acceleration of over 10g. There are three screw drives and three screw diameters available for each machine size. In an interesting, energy saving feature, the central power supply to the drives and a new generation of inverters from KEB GmbH recirculates the braking energy back into the power grid. Servo motors with low inertia reduce energy consumption during heavy acceleration.

Arburg's fully electric Allrounder E machines significantly expand the fully electric machine range. These machines are primarily designed for the efficient manufacture of standard items, such as technical molded parts, making them the electric alternative to basic hydraulic machines. This new fully electric series comprises a total of four machine sizes, which can each be equipped with a variety of injection units. The spectrum ranges from the Allrounder 370 E with a clamping force of 600 kN (66 tons) and size 170 (3.7 oz) injection unit to the Allrounder 570 E with a clamping force of 2,000 kN (220 tons) and size 800 (15.3 oz) injection unit. The new electric machines provide an economical, cost effective electric solution as an alternative to basic hydraulic machines. These machines offer advantages in terms of cycle times thanks to their rapid and simultaneous execution of the most important machine movements and their potential with regard to energy efficiency. With all the fully electric Arburg machines, the high efficiency of the servo electric drives and the toggle type clamping unit ensure extremely energy efficient operation. Servo motor energy recovery during braking also has a beneficial effect on the machines' overall energy consumption. Together, these factors combine to reduce energy consumption by up to 50% compared to standard hydraulic machines.

JSW Plastics Machinery introduced all electric models in its J AD series from 220 to 650 tons specifically for high speed packaging. They have reinforced bed frames to support heavy stack molds, along with linear guide rails for the moving platen and sliding shoes for stack mold center plates. Besides 30% higher mold weight capability, they have bigger motors, 50% faster injection acceleration/deceleration response, 24:1 mixing screw with higher rpm (yielding 20% greater PP plasticating capacity), extended daylight, 20% faster clamp movements, 20% less platen deflection, 100% greater nozzle touch force (using a hydraulic cylinder), and greater heater capacity. In addition, the models have 2.5 times greater electrical capacity than a standard machine so they won't overheat during high speed molding. The regenerative braking system recovers around 6% of energy from mold open/close operations.

Milacron's PowerPAK all electric series of 440 to 1125 tons include water cooled drives and enhanced diagnostic and maintenance information on the drives in the control system, which includes a built in energy monitor. Also new is optional high force electric injection, designed especially for PET preforms. These machines offer optional accumulator assisted hydraulic injection and ejection (a 330 ton model is available only in this configuration).The PowerPAK is suitability for high speed, high volume stack mold applications: A 550 tonner with two stage, screw/plunger electric injection unit molded thin wall PP lids in a 2 x 4 cavity stack mold on a 4.8 sec cycle. The machine has stack mold support shoes and "greaseless" tiebars-said to be unusual for all electric stack mold operation, as well as a selectable axis configuration (SAC) with an option of all electric on all four machine axes (clamp, injection, ejection, extruder), or as a combination of the ejector or injection axes as hydraulic. The clamp and extruder remain "all electric" on all model configurations. The machine's speed is a result of several standard features including an electric toggle with rack and pinion direct drive clamps, linear low friction bearings, and a patented two stage electric injection. Additional features include high volume air, water and hydraulics supplied to convenient locations on stationary and moving platens for easy hookup to the stack mold, and easy top or side entry automation access for high speed part removal or in mold labeling (IML) applications. The EJECT GUARD™ protects machine and mold eject mechanism from high force eject conditions. Greatly reduces ejector pin/mold damage.

Toshiba operated a new 200 ton EC200SX all electric press in an automotive cell, showing off special technology developed by Japanese molder Taisei Plas Co. for bonding sheet metal to overmolded plastics. The key is a process for nano texturing the surface of the metal to enhance bonding. Toshiba molded an automotive circuit board holder with the help of its own new jointed arm robot that demolded parts and inspected them with a laser mounted on the robot. Taisei technology is also used in Japan to mold a tablet computer case in which PPS attachments are overmolded onto metal. Tight control of injection pressure afforded by the EC SX series is essential to this process.

Niigata had a new generation all electric line at the show. The MD S6000 series comprises smaller models (55 to 150 tons), while the MD W6000 series is medium to large sizes from 200 to 1100 tons. These units have wider tiebar spacing and updated controls with more user programmable features. These machines are non hydraulic and feature the most compact body in the industry. NIIGATA has a distinctive injection unit structure to minimize machine installation area. Height of the MDS6000 is lower than out conventional model and the operability is improved. This new model is equipped with 50 mm wide mold space than a conventional model. Now it can accommodate even larger molds. In addition, platen rigidity is much increased thanks to CAE analysis. During clamping, this change helps to minimize the deformation of mold. And by adopting linear guide system, mold open/close movement is flawless. Sealed ball screw is applied to injection axis and clamping axis to prevent grease scattering. Grease consumption rate is drastically reduced, and a waste grease recovery port is equipped at clamping side. The Patented M Support System is the new structure of adopting platen support which is attached to the fixed movable platen to create looseness at the lower part of the platen by supporting it from the center of its height at both sides. This will promote the even deformation of platen during clamping force load and prevent platen deflection. The Patented Group Temperature Control system monitors 2 heaters by 3 sensors. By shifting weighted values among sensors, it can change sensor position virtually and change temperature slope freely. This system has the enormous effect on preventing the problem of stringiness, drooling, nozzle freezing and material burn. Another standard feature is "Cylinder Follow up Control" which prevents resin burning within the nozzle. In the MDW6000, The distance between tie bars has been increased 60 100mm and the mold height has been increased more than 100mm. This new machine can mount molds that could previously be mounted only on higher ranking machines. The wider mold height ensures easy compatibility with various types of clamp devices. A newly developed high stiffness injection unit with new servo motor and Niigata's unique control technology enables a long lasting dwelling. Twin Group Thermal Control can be used not only with the nozzle that is contact between resin and mold, but also for the resin feed portion of the heating barrel. The thermal sensors can be virtually installed in desired positions. Using a state of the art CPU results in minimal calculation period. Optical cables, which are highly resistant to noise, are used for communications between servo amps. The high resolution encoder enables precise position control and ultra smooth movement. The pressure feedback control, unique to Niigata Machine Techno, delivers very good response and accuracy of pressure control.

 
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