New Physical Foaming Process for Injection Molding

At the NPE2018, Linde LLC  is introducingPlastinum foam injection molding, described as a less expensive, more flexible process for lightweighting molded plastic parts than currently available foaming processes. This physical foaming process is particularly suitable for automotive, white-goods, and medical parts manufacturers who are using conventional injection machines and are looking for an alternative to existing chemical and physical foaming methods.  

In the Plastinum foam injection process, plastic pellets are impregnated with carbon dioxide (CO₂) in Linde’s new equipment prior to the injection molding machine. This system allows for physical foaming in conventional injection machines without retrofitting for foam, other than adding a shutoff nozzle. What distinguishes this approach from other processes is that pellets are impregnated with gas in a pressurized autoclave and then transported to the machine hopper, which is not pressurized. Thus one autoclave can feed two machines or be moved on a cart from machine to machine. Gas is said to remain in the pellets for 4 to 6 hr at ambient conditions.

In addition to its new foam technology, Linde is also featuring its Plastinum portfolio of CO₂ gas technologies including the enhanced gas-assist injection molding (eGAIM) system; spot-cooling technology for injection molds; and inert gas-metering equipment. Also featured is Linde’s automated Cryoclean “CO₂ snow” cleaning technology.

Linde’s Plastinum GAIM C (also known as Enhanced Gas Assist Injection Molding - eGAIM) system will be demonstrated at the Yizumi-HPM Corporation booth (W3343) during NPE2018. The eGAIM system can reduce cycle times up to 35 percent compared to nitrogen systems. The patented Plastinum GAIM C system reportedly also produces better surface characteristics and enables more consistent part quality.

Linde also will feature a spot mold cooling demonstration unit at its booth. The Plastinum Temp S-CO₂ spot cooling technology is used to internally cool cores as small as 0.025 in. in diameter. It distributes cooling to difficult-to-reach parts, decreasing cycle time up to 50 percent while maintaining or improving part quality, Linde says. It can also be used to eliminate sink marks on Class A surfaces.