Injection molded hexagon socket screw assembly drawing and specifications
Injection molding hexagon socket screws are key fasteners in mold assembly, used to connect mold plates, secure parts, and transfer loads. The preparation of assembly drawings and the selection of specifications and dimensions directly impact the mold’s connection strength and stability. Hexagon socket screws, characterized by their small wrench space and high tightening torque, are widely used in compact mold structures, particularly in connecting components such as movable and fixed mold plates and backing plates. They can effectively save installation space and improve assembly efficiency. Assembly drawings must clearly indicate the screw’s installation location, quantity, tightening direction, and coordination with the connected components to ensure a standardized and orderly assembly process.
Assembly drawings for hexagon socket screws must adhere to fastener assembly drawing standards. Use thin solid lines to outline the screws, and thick solid lines to indicate the tightening direction and force points. The screw specification and tightening torque should also be noted. In the assembly drawing, the screw-to-hole fit should be labeled ” M10×1.5-H7/g6,” where H7 represents the tolerance band for the screw hole and g6 represents the tolerance band for the screw’s external thread. This ensures a reasonable fit clearance, facilitating assembly and ensuring connection rigidity. For evenly distributed screws (such as connecting screws at the four corners of a template), the center-to-center distance between adjacent screws (e.g., “hole spacing 150×150mm”) and the diameter of the distribution circle (e.g., “distribution circle Φ200mm”) should be indicated, with symmetry symbols used to indicate the symmetry of the distribution. Furthermore, the assembly drawing should include a partial cross-section view showing the screw’s countersink depth (e.g., “countersink depth 12mm”) and effective thread length (e.g., “thread length 30mm”) to ensure that the screws are fully seated in the hole and prevent loosening due to insufficient threading.
The specifications and dimensions of hex socket screws must be determined based on the mold’s stress conditions and installation space. These primarily include thread diameter, length, head size, and hex socket hole dimensions. The thread diameter (d) typically ranges from M6 to M30, with M6 to M12 being common for small molds and M16 to M30 for large molds. For example, an M16 screw can be used to connect the movable mold plate to the backing plate, while an M8 screw can be used to secure the ejector plate. The screw length (L) must ensure that the threaded portion is fully engaged with the connected component (engagement length ≥ 1.5d) and that the head is in contact with the surface of the connected component. For example, an M10 screw connecting a 20mm thick mold should have a length of 35mm (25mm thread length). The head diameter (D) and thickness (k) must comply with standards (such as GB/T 70.1-2008). The head diameter of an M10 screw is 16mm, the thickness is 8.5mm, the width across flats (s) of the hexagon socket hole is 8mm, and the depth (t) is 5mm. Ensure that the hexagonal wrench can be fully inserted and transmit sufficient tightening torque.
Hexagon socket screws for special working conditions require non-standard sizes or reinforced structures to meet high-strength connection requirements. In molds subjected to impact loads (such as large stamping and injection molding composite molds), fine-thread screws (such as M16×1) are recommended. Their small thread lead angle provides enhanced anti-loosening properties. In molds operating in high-temperature environments (such as thermoset plastic molds), screws made of high-temperature-resistant alloys (such as Inconel 718) are recommended to prevent the material’s strength from degrading due to high temperatures. For connections that require frequent disassembly (such as removable mold modules), hexagon socket screws with a positioning step (the step diameter is 0.5-1mm larger than the thread diameter) can be used to ensure consistent positioning during each assembly. Furthermore, in corrosive environments (such as molds using chlorine-containing plastics), stainless steel hexagon socket screws (such as 316) should be used, and surface treatment requirements (such as “passivation”) should be noted in the assembly drawing.
Technical requirements for hexagon socket screw assembly must clearly define tightening torque, anti-loosening measures, and testing standards to ensure connection quality. The tightening torque should be determined based on the screw specifications and material strength. For example, the tightening torque for an M10 high-strength screw ( grade 8.8 ) is 45-55 N · m . Too low a torque can lead to loosening, while too high a torque can cause the screw to break or the threads to slip. Anti-loosening measures include applying thread sealant (such as Loctite 243 ), installing spring washers, or using locknuts. In molds subject to frequent vibration (such as high-speed injection molds), a double anti-loosening method (thread sealant + spring washers) is required. Testing standards include checking the tightening torque with a torque wrench, checking the clearance between the head and the connected part with a feeler gauge (≤ 0.05mm ), and checking the thread fit accuracy with a thread gauge. These technical requirements should be clearly stated in the assembly drawing, such as ” Tightening torque 40±5 N · m , apply thread sealant to prevent loosening,” to ensure a well-defined assembly process.
