Thermoset molding news from K'89.

Thermoset Molding News From K'89

Last month (p. 38), we reported on developments in polyester SMC molding technology. This month, we wrap up our K'89 report with news in general thermoset injection and compression molding, including a novel in-press deflashing system, a new thermoset injection press series, and new wrinkles in thermoset controls and tooling.

IN-PRESS COOLING/DEFLASHING

The photo on p. 51 shows an innovative auxiliary device for automatically cooling and deflashing parts in a compression press. It was shown operating on the new four-station automatic compression press from Battenfeld Duroplasttechnik (formerly Battenfeld Berges, and represented by Marvel Equipment), described in our show preview (PT, Sept. '89, p. 64). The post-molding operations are accomplished with a rotary-indexing metal drum. A robot takes the part--in this case a circuit-breaker lid--from the mold and places it on the drum, where it is held in place by vacuum. The metal surface of the drum is internally cooled. While on the drum, the part is pushed against a metal plate that breaks off most of the flash, especially the thicker sections.

Two remaining stations on the drum could be used for drilling holes or other operations. The machine at the show was the second system of this type ordered by a major W. German electrical-parts manufacturer.

THERMOSET INJECTION PRESSES

Also new from Battenfeld Duroplasttechnik is the BE series of five thermoset injection machines of 145, 200, 275, 350, and 440 tons. They're said to have been completely redesigned according to the Compact Design (CD) approach used on Battenfeld's smaller thermoplastic machines. The new modular hydraulic system is said to make them extremely fast and incorporates a servovalve on the injection unit for closed-loop control. Two accumulator systems are provided for the injection and clamp units. Newly developed valves reportedly ensure deceleration for gentle mold locking, even at fast-closing speeds over 1400 in./min. Unilog 4000 controls are standard.

CONTROLS AND TOOLING

Our January report on injection molding news at K'89 (pp. 67, 69) included discussion of new controls and SPC reporting functions for thermoset machines from Bucher-Geyer (Bucher, Inc., Buffalo Grove, Ill.). One of the more interesting features of the Mannesmann Demag CAS/CAP information system now available on the Bucher presses, according to a company spokesman, is the ability to measure and record the area under the injection-pressure curve as a quality-control variable (see graph). Using it as a measure of the work put into the material can indicate a change in lot-to-lot consistency of the compound.

In addition, Bucher has a new, exclusive relationship with Acrolab Instrument Ltd. of Windsor, Ontario and Detroit for improving productivity of thermoset tooling. Under this agreement, Bucher represents Acrolab in the thermoset field; Acrolab makes heat pipes and designs heating/cooling systems for molds (previously, Acrolab has been mainly involved with thermoplastic applications). Using heat pipes together with Calrod-type electric heaters reportedly allows distributing heat uniformly over the cavity surface, including deep into cores, resulting in faster cycles and more uniform curing. One customer molding polyester BMC head-lamp reflectors reportedly achieved 10% average improvement in cycle time.