Gas-assist injection molding was developed several years ago to overcome the limitations of conventional injection molding. A molding technique that requires special knowledge, like gas-assist, usually takes some time to move into new industries. Accordingly, the gas-assist process has been adopted by several industries during the last few years, and this innovative technology is now making inroads in the medical industry, offering new technical and creative possibilities to device OEMs. The process features a unit that introduces nitrogen gas into a mold cavity after it has been filled with plastic. The compressed nitrogen displaces a portion of the molten plastic when injected into the cavity. The result is hollow parts that are light and relatively inexpensive to make. Designers can use gas-assist molding to create thin-walled parts. Such parts can be molded with low clamp tonnage, which reduces both tooling cost and required injection molding machine size. The gas-assist technique is ideal for adding thick, hollowed-out sections to otherwise thin-walled parts. The process improves upon polymer fill and packing techniques and boosts melt-flow length. A designer can create larger, more-complex parts with fewer injection gates than conventional molding, while minimizing costs incurred with complicated hot-runner systems. In addition, the sections that are cored out cool rapidly, reducing overall cycle time.
Gas-Assist Handles with Attached Thinner Sections. Because of the thick cross section of the molded handles, a gas-assist process is used to mold a hollow, tube-shaped part with a highly cosmetic surface and a consistent internal gas channel. The molding process ensures mechanical and structural integrity.
The handle is sectioned to show the hollowed out center in its tube-shaped portion. It is important to note that the wall thickness is consistent over the length of the handle and around its perimeter. This optimizes the mechanical properties of the molded part.