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(PlasticsToday) -- Injection
molders stand to benefit from new products recently introduced including
temperature control units from Conair and a Universal needle valve unit from
Hasco. Extrusion systems manufacturer Davis-Standard, meanwhile, reports on a
customer pleased with its HDPE recycling systems.
Conair is introducing two new mold temperature control units (TCUs). The
TW-HT Series TCUs use superheated water instead of hot oil to achieve mold
temperatures as high as 392°F (200°C). The TW-ALT temperature control unit sends
sequential bursts of hot and then cold water through a mold to help reduce cycle
times and improve quality and surface finish in injection molded parts. This
sort of pulsed heating/cooling of a mold often makes sense when a mold is made
of high-thermal-conductivity steel and includes contoured cooling channels.
For molders running PEEK, polyetherimide (Sabic Innovative Plastics'
Ultem is the best known) and other materials that may require mold temperatures
as high as 435°F (225°C), a special TW-HTM model is available.
The closed-loop TW-HT and TW-HTM systems operate under pressures to 218
psi (15 bar) and 250 psi (17.24 bar) respectively, so the circulating water
remains liquid even at temperatures that are twice as high as the sea-level
boiling point. Any leak in the closed-loop system rapidly depressurizes and the
water evaporates immediately on exposure to the atmosphere, so there is very
little risk of injury.
Also new from the company is its TW-ALT alternating TCU, which shoots
bursts of alternating cold and hot water through a mold. These are marketed
especially to molders of parts used in appearance-critical applications and
components requiring optical clarity.
mrcplast.com
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