In 2012, HUACHEN Screw pioneered the development of a conical twin screw barrel with tool steel SKD sleeve or bush inserts to enhance resistance to corrosion and wear. The wear-resistant material SKD is used to create a conical-eight-shaped bore sleeve, which is then integrated into the bore of the conical twin barrel to ensure a tight fit with the inner wall. This design is particularly suited for producing high-filled PVC products due to the conical twin barrel’s superior wear resistance.
This highly wear-resistant base material is typically crafted from tool steels SKD11 (equivalent to D2) and SKD61 (equivalent to H13). In the Chinese market, these are known as SKD screw barrels or SKD sleeve fitted barrels, used in complete sets of twin screw conical barrels with an SKD barrel.
SKD sleeve fitted barrels are high-performance barrels that require precise machining. The entire barrel bore must remain flat and smooth to prevent sticking and ensure optimal plasticization of polymers. The inlay plane of the SKD inner bushing must be flat and smooth, presenting a significant technical challenge. The SKD11 sleeve is embedded in the inner wall of the barrel extruding section, which is prone to wear when producing highly filled PVC products. Depending on the required wear resistance area, the SKD11 sleeve fitted barrel is available in three different lengths: one-zone SKD barrel, two-zones SKD barrel, and full coverage SKD barrel.
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