Electric injection machines inspire respect, loyalty

Robbins Scientific, Sunnyvale, CA, originally operated its hybrid-electric Huske Hylectric as a beta machine and in the process decided it was the way to go.

All-electric and hybrid-electric injection molding machines once evoked doubt and reluctance, but they are now becoming entrenched in the market. A sampling of molders tell us why.

Over the last three years, about 29 percent of injection machines sold in North America have been of electric rather than hydraulic design, and that number is growing, according to Agostino von Hassell of The Repton Group, New York, NY.

Since 1985, when Cincinnati Milacron (now Milacron Inc.), Batavia, OH, led the charge by bringing Japanese-built Fanuc all-electric machines to these shores, about 30 other machine builders have gotten into the electric machine business as well. The list provides names and telephone numbers of those companies, along with an indication of whether they supply all-electric machines, hybrid-electric machines, or both.

Initially, all-electric machines were available mostly in small sizes such as 50 or 100 tons. The market is still dominated by small or medium machines, but larger machines are now offered. Several builders make all-electrics in the 1500-ton range, and at least one 2000-ton all-electric, which will be the largest all-electric on the market when it is completed, is on the way from Ube, Ann Arbor, MI.

For the uninitiated, the term "all-electric" implies that both screw motion and clamp motion are actuated directly by electric motors, usually a-c servomotors, without any intervening hydraulics. The "hybrid" machine normally uses an electric motor to drive the screw, but uses hydraulics on the clamp end of the machine. Even hydraulic, toggle, and hydromechanical machines require electricity to operate, of course, but they also require hydraulic oil and hydraulic circuitry.

The usual mantra from suppliers of the all-electric machines is that their units use less electricity than the hydraulic designs, are cleaner because they use no hydraulic oil, run quieter, are more precise, and require less maintenance. Unfortunately, they also cost more, a premium cited by purchasers as ranging from 10 to 20 percent.

To get some other perspectives on all-electric and hybrid electric machines, we went to a number of molders who are using the machines and are willing to share their observations. While not perfect, their experience has been overwhelmingly positive, which bodes well for the future of the electric machines.

Debuting a Hybrid

Inland Technologies, Fontana, CA, settled on JSW all-electrics after putting the machine through a side-by-side test with another brand.

Robbins Scientific, Sunnyvale, CA, has about 100 employees with molding and assembly divisions combined. It runs 20 injection machines and has just dipped into the electric injection technology by acquiring a single 100-ton Husky hybrid machine. (Husky does not supply all-electric machines to date.)

The machine is used to mold medical pipette tips and tubes in PP and other polyolefins. Wittmann (Torrington, CT) robots are used to handle parts from a mold that runs 32 parts per cycle with 16 sprues. According to Jesse Cohen, senior process engineer, the machine was acquired for its tiebar spacing, thin-wall capability,

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