(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.