Hybrid or all-electric: can either one pay off for you?Energy savings aren't the only benefit of a hybrid or all-electric molding machine (Woodworking) A planing machine for making moldings (Founding) A machine to assist in making molds for castings. See also: Molding Molding . Speed, precision, quietness, and cleanliness may be more important to most users. Here is another view of these issues, which were explored in April's PLASTICS TECHNOLOGY. The electric screw-drive option has been available on injection molding machines Injection molding machine (also known as injection press) - a machine for making plastic parts. Manufacturing products by injection molding process. Consist of two main parts, an injection unit and a clamping unit. for many years, offering a well-recognized potential for energy savings. Battenfeld began supplying machines with two-speed electric screw motors in Germany back in the 1960s. Servo-electric screw drives have been available since the beginning of the Eighties and have been supplied in North America North America, third largest continent (1990 est. pop. 365,000,000), c.9,400,000 sq mi (24,346,000 sq km), the northern of the two continents of the Western Hemisphere. since 1994. Yet the electric screw-drive option has remained less popular than conventional hydraulic screw drives because of the additional cost (up to 15%) for an electric screw drive. If you consider the average power cost in North America, the increased investment for the servo-electric screw drive, and typical return-on-investment (ROI (Return On Investment) The monetary benefits derived from having spent money on developing or revising a system. In the IT world, there are more ways to compute ROI than Carter has liver pills (and for those of you who never heard of that expression, it means a lot). ) goals, the servo-motor option often makes no sense if based on energy savings alone. Leaving energy aside, however, hybrid machines can still have their place in modern injection molding injection molding n. A manufacturing process for forming objects, as of plastic or metal, by heating the molding material to a fluid state and injecting it into a mold. operations. The case for hybrids Molders have selected servo-electric screw drives for several reasons, but the most important motivation has been the ability for simultaneous operation Noun 1. simultaneous operation - the simultaneous execution of two or more operations parallel operation operation - (computer science) data processing in which the result is completely specified by a rule (especially the processing that results from a of the extruder and other machine functions to shorten the overall cycle time. In applications where very high recovery rates are required, a servo-electric screw drive allows the standard oil reservoir An oil reservoir, petroleum system or petroleum reservoir is often thought of as being an underground "lake" of oil, but it is actually composed of hydrocarbons contained in porous rock formations. size to be retained instead of increased, due to the installed hydraulic power. The hybrid approach means that oil residence time will be increased and oil-heat build-up will be reduced, resulting in less wear and tear on hydraulic-system components and a higher level of oil cleanliness. Servo-electric motors with power ratings suitable for screw drives can also enhance a machine's ability to achieve precise control of screw speed. What about servo pump drives? Replacement of standard AC motors with AC servo motors to drive the hydraulic pump of an injection machine is another hybrid electric/hydraulic solution offered by several machine manufacturers. In this case, the pump servo motor will slow down to an idle speed Idle speed is the minimum operating speed (generally measured in revolutions per minute, or rpm, of the crankshaft) of a combustion engine. At idle speed, the engine generates enough power to run reasonably smoothly and operate its ancillaries (water pump, alternator, and, if when no machine motions are taking place - such as during the time between the end of screw recovery and the start of clamp opening. Actual energy savings will depend on the length of the machine idle time The duration of time a device is in an idle state, which means that it is operational, but not being used. relative to the overall cycle time. Justification of the required investment for a servo-motor pump drive may vary from case to case, but under average conditions it will seldom result in a short payback period Payback Period The length of time required to recover the cost of an investment. Calculated as: . On the other hand, the servo-electric pump drive can reduce the machine's noise level substantially, which is certainly a desirable feature for the equipment user. All-electric for peak precision While hybrid machines retain conventional hydraulics for injection and clamping, all-electric machines perform all movements through servo-electric motors. All-electrics thereby achieve a level of precision and repeatability required for extremely close-tolerance parts. Compared to hydraulic and hybrid-electric machines, the major benefit of all-electric machines is their process capability. The most stringent tolerance levels - and some commercial molding tolerances are now measured in microns - may be difficult to reach with either open- or closed-loop controlled hydraulic injection on a hybrid machine. In addition to their precision-molding capability, all-electric machines offer the greatest reductions in energy usage and noise levels of any type of molding machine. And due to the absence of hydraulic fluids, electric machines are environmentally friendly Environmentally friendly, also referred to as nature friendly, is a term used to refer to goods and services considered to inflict minimal harm on the environment.[1] and clean-room compatible. Even though early predictions of sweeping hydraulic-machine replacement have not materialized, the number of all-electric machines sold continues to increase at a moderate pace. The cost of servo motors requires that all-electric machines be sold at a premium, and major cost reductions are not expected soon. Time will tell which markets are receptive to paying such a premium in order to benefit from the very high molding precision available with all-electric machines. |
|
||||||||||||||||||
Printer friendly
Cite/link
Email
Feedback
Reader Opinion