DSI investigates the use of flexible heaters


Die slide injection (DSI) might have been first reported by us in 1992 but that's not to say that its developer The Japan Steel Works (JSW, Tokyo) has not continued refining it. Occupying pride of place at the recent IPF show was the latest iteration of the technology, employing flexible heaters to heat the entire interface surface of both sides to be heat welded.

Previously, an additional shot was employed to bond the two halves of the part together but this was only achievable over the parts' exposed surfaces. A simulation of the conventional DSI process can be found at this link.

At IPF, DSI was employed to mold a sample comprising a 30% glass fiber-reinforced blue-colored polyamide (PA) component injected from an auxiliary cylinder and a 30% glass fiber-reinforced natural PA component injected from the main cylinder. QCH-Heaters (Quartz Carbon Hybrid) from Covalent Materials Corporation (Tokyo, Japan) are then inserted between the slightly open mold halves, their temperature is raised to 1000°C in the space of three seconds, and the interfaces are melted in order to weld the surfaces together upon subsequent mold closure.

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