With Plastics, It’s Good to Use More Gas

With gas-assist molding, users can achieve 30 percent per unit savings compared to structural foam or a 20 to 30 percent tool savings compared to straight injection. Those savings normally are sufficient to get any customer’s attention. However, with gas-assist molding that is just one aspect — one very important aspect. In most cases, improved product texture and the ability to eliminate other processing steps such as painting provide additional incentives. For example, a gas-assist molded and silk-screened cover for an industrial application meets all the visual and structural requirements of the customer while providing an extremely durable and cost-effective alternative to painted metal panels. “In recent years we have seen our customer base move away from painting and use gas assist to accomplish a similar cosmetic finish,” says Jeff Rodgers, president and CEO, DeKalb Molded Plastics. Steve Langen, program manager at Mack Molding’s Southern Operations, also views replacing paint with molded-in texture as one of the advantages of an external gas process. Three examples show the beauty of using gas-assist molding.

Better Bezel

Sajar Plastics Inc. gas-assisted process combines the best aspects of structural foam and straight injection that has opened new markets. “We are experiencing significant growth with gas assist for parts requiring high cosmetics, increased design freedom and cost savings such as metal to plastic conversions,” says Mark A. Zumerling, vice president sales & engineering, Sajar Plastic Inc. Some of the engineered resins processed at Sajar include: PCABS, ABS, polypropylene, HDPE, nylon, acetal, polyester, polystyrene, HIPS, ABSPBT, PBT and glass-filled. One example is a bezel molded for industrial machines. Sajar Plastics also made gas-assist molded products for electronic data storage units, gaming machines and other applications in industrial, consumer and even medical markets.

Award-Winning Design

A gas-assist molding product won the Building & Construction category at the recent Alliance of Plastics Processors Conference & New Product Design Competition. Molded by Mack Molding Co., the cover of Trane’s top-of-the-line residential air conditioner (AC) system uses a single-molded unit that replaces one with five separate glued parts. External gas used in the injection-molding process provided cavity texture replication and improved part ejection. Using a lower injection pressure to fill the part reduced press size requirements and costs. A UV-stabilized polycarbonate resin provides the strength, impact, longterm aging, cosmetics and the color stability required for the outdoor application.

ATM Cashes In

Using the external gas injection technology developed and licensed by Cinpres Gas Injection (CGI) Inc., Mack Molding manufactures a front fascia on the money dispenser for Triton’s ATMs. The external gas-assist process eliminated sink marks and solved cost issues. Initially, Triton used a product made from a structural foam process to obtain the impact and stiffness the application required. “With external gas, they can produce a large cosmetic part that is structurally strong at a lower cost,” says Steve Langen, program manager at Mack’s Southern Operations.