Canadian Plastics

Notes from NPE

In the injection molding field, Cinpres seems to have hit the nail on the head with their phrase "assisted injection molding". Whether it's gas-assisted, water-assisted or whatever the next breakthrou...

August 1, 2003   By Cindy Macdonald, associate editor



In the injection molding field, Cinpres seems to have hit the nail on the head with their phrase “assisted injection molding”. Whether it’s gas-assisted, water-assisted or whatever the next breakthrough is, modifications of the basic molding process were everywhere at NPE.

Water-assist was demonstrated by Engel, Cinpres, Krauss Maffei and Alliance Gas Systems.

As Krauss-Maffei describes it, the water flow front acts like a piston to force melt out of the interior of the molded part.

Compared with gas-assist, explains Joachim Kragl of Engel, water-assist removes a larger volume of material, and the temperature of the water can be controlled to speed part cooling. The technique is suitable for larger diameter, hollow-core, rod-like, geometric shapes.

Cinpres was using its water-assist process at the show to mold a chain saw handle in 30% gas-filled nylon with an outside diameter of 1.25 in. at cycle times of only 40 seconds.

Developments in in-mold decorating promise some interesting effects. Proell produces specialty inks that can be used to print the in-mold decorating film. One sample part was designed so that certain portions could only be seen when backlit. Proell also has inks to produce a metameric, color-shift effect on an IMD film.

Rotating platens made an appearance as a new option for insert and multi-material molding. The Freedom Series machines from Taylor’s Industrial Services HPM Division with Rotator option are one example. “While multiple rotating dies are not uncommon, what makes the Rotator unique is that the moving platen rotates on its centre,” explains Ken Eichhorn, director of engineering for HPM Division. “This allows the platen’s back side to be available so the cured part can be removed by a robot, and films and inserts can be inserted into the die while another part is being molded.”

According to HPM, the Freedom Rotator machines have the potential to shorten cycle time by 30-35%. The company expects much of the early demand for the Rotator to be for large tonnage sizes.

In Krauss-Maffie’s Revolution machines, two injection units are lined up on the machine’s longitudinal axis, with a sliding table between the fixed platen and the moveable platen. On the sliding table is a vertical swivel platen on which the mold half is mounted. The swivel platen revolves 180 or 90 degrees around its vertical axis so that the mold cavities can be filled alternately by the two injection units.

Progressive Components has good news for blow molders. The company has introduced a line of standard components for blow molds, and is now offering an in-mold deflashing technology. “Off-the-shelf components for blow molds have been scarce,” says Craig Hasselberger, Progressive’s business development manager. “There hasn’t been a comprehensive program with nationwide coverage.”

Progressive’s blow mold tooling line includes blow needles, ejector pins, cylinders, in-mold punches, pins and bushings.

For in-mold deflashing, knife blades are incorporated into each side of the mold. This eliminates a secondary fixture and a separate downstream operation.

The emergence of large all-electric machines was also touted at NPE. Ube Machinery Inc. has had all-electrics in the large tonnage range since NPE 2000. The company upped the ante at this show by introducing the Ultima UN2000, a 2000-ton all-electric said to have platen size equivalent to a 3000-ton hydraulic machine. (Ube’s new in-mold painting technique is covered on page 10.)

Milacron now produces a 1,125-ton model of its Powerline all-electric presses. The machine has maximum shot size of 220 oz. It builds full clamping force tonnage in 4.3 seconds, but allows injection to begin before it reaches full tonnage to reduce cycle times.

Negri Bossi has also jumped up to the larger sizes. The Elma all-electric, direct-drive line now includes a 935-ton model.

Laser assembly systems are coming of age, with many of the traditional ultrasonics suppliers adding laser capability. Dukane’s Tom Kirkland explains that laser welding offers high precision, no flash and no generation of particulates.

Branson’s Laser IRAM systems are capable of two operating modes — simultaneous and scanning. They are available with 100, 125 and 750 Watts of power. Branson also partnered with Gentex to demonstrate laser welding of clear-to-clear assemblies using Gentex’s Clearweld process.


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