Guide post

Generally speaking, when the precision requirements for cold‑die guide rails are particularly stringent, it is advisable to determine the mating dimensions of the guide rails according to the H6/h5 fit; manual grinding can achieve even higher accuracy. On the market, guide posts and guide bushings are typically sold as matched sets, but do you know how to assemble them? Below, we will briefly outline the main assembly steps for guide posts and guide bushings for your reference.

First, deburr the workpiece, then carefully inspect the tolerances of the assembly and the valve seat bore.

The operator must then check the perpendicularity of the pilot hole and the mating surface, typically using a dial indicator for verification and adjustment. If the clearance is small, tap the part by hand after finishing; if the clearance is substantial, use a press for assembly.

After completing the above steps, the sliding template must also be checked with a push rod; if necessary, the guide bushings should be properly adjusted. Under normal conditions, there should be no mutual interference during sliding.

Causes of damage to guide posts and guide bushings:

1. Poor quality

Poor material selection, insufficient hardness, or improper heat‑treatment of guide posts and guide bushings can all compromise the surface hardness of the guide posts, leading to damage. Additionally, excessive clearance between the locating pin and the guide bushing can shorten the service life of the locating pin and pose a potential hazard.

2. Fit clearance between the guide post and guide bushing

The fit clearance between the guide post and the guide bushing also has a certain impact on the service life of the guide post.

3. There is a problem with the design.

When designing guide posts and guide bushings, the issue of venting must be taken into account; otherwise, the guide posts may end up functioning as a locating mechanism. Additionally, the guide bushings should be equipped with vent holes to prevent vacuum formation during mold closing, which can generate substantial suction forces upon mold opening.