What should be noted in the design of push rods in injection molds?

1. In injection molds, the distance between the push rod side hole and other holes (such as screw holes, pin holes, return spring holes, cooling water holes, etc.) should be greater than 2.5mm.

2. The unilateral gap between the push rod and the push rod fixing plate should be about 0.5mm.

3. The unilateral gap between the push rod and the template should be around 0.5mm.

4. In design, standard dimensions should be used as the size of the push rod, and the push rod head should not sink into the push rod fixing plate.

5. The guide holes of the push rod and the insert need to be matched according to H7/F7. But in the injection molding of PA, LDPE, and PP, the gap between the push rod and the push rod fitting hole is less than 0.02mm. If it's too big, there will be flashes.

6. After the installation of the push rod, the push rod fixing plate should be able to slide downward automatically without any jamming phenomenon.

7. The fixed positions of push rods should correspond one-to-one and be marked to avoid installation errors.

8. When the forming part of the push rod is inclined or curved, it should be prevented from rotating to avoid installation errors.

9. When designing the position of the push rod in injection molds, it is not only required to have appropriate demolding force, but also to ensure that the plastic parts are demolded in parallel.

10. If the height or demolding slope of the plastic part is large, smaller contour lines need to be drawn in the plan view, so that there will be no errors in the setting; If the top corner of the plastic part has a large fillet, smaller contour lines need to be drawn in the plan view. In order to ensure the correct setting of the push rod, if the top corner of the plastic part has a large fillet, smaller contour lines need to be drawn in the plan view. When the fillet is large, the tangent line of the fillet should be drawn in the plan view as the boundary line of the push rod position.

11. The distance between the push rod and the plastic part should be accurate, neither too far nor too close.

12. Suggest placing the push rod at the bottom of the plastic part instead of the top.

13. A push rod needs to be added to the inclined surface of the plastic part because the push rod and the plastic part are prone to sliding on the inclined surface, and the pushing force will be distributed accordingly, greatly reducing the thrust. Three or more small steps need to be taken on the end face of the push rod to increase thrust. Meanwhile, the head of the push rod should also be prevented from rotating.

14. For deeper columns (column height greater than 8mm), push rods should be added as much as possible at the bottom of the column. In this way, not only is the spraying effect good, but the exhaust volume can also be increased, which is beneficial for filling the melt. For short columns, two push rods can be added next to the column. Whether it is necessary to add an exhaust rod at the bottom of the column depends on the specific situation.