Spure bushing guide is one of the injection mould componets not hot runner system parts. using between with the injection machine nozzle and the plastic mould cavity.
The spure bush(also called spure bushing) is defined as that part of mould connecting member between the machine nozzle and the mould face,and provides a suitable aperture through which the material can travel on its way to the impressions or to the start of the runner systm in multi-impression' moulds.
Note that while initially the nozzle many have been set up correctly(according to the makers's instruction),an increasing in the injection cylinder temperature will cause a fairly high force to be applied to the sprue bush because of the expansion of the injection cylinder.
Providing the alignment between the nozzle and the bush apertures is perfect,a leak-free joint is achieved with the spherical seaing.It should be noted that the radius on the nozzle is slightly less than that in the bush,which ensures both parts are in physical contact at the apertures.However,if the nozzle and the sprue bush are slightly out of line(due perhaps to wear on platen bushes) a gap will result and leakage behind the mould will develop.This drawback is not present if slight misalignment occurs at the seating of the sprue bush and flat-faced nozzle.No leakge can occur if the two apertures are slightly out of line and no restriction to flow will occur either,providing that the sprue bush has an aperture slightly larger than that of the nozzle.
If you have some questions or requrement about the spure bush or any other hot runner confusion,please do not hesitate to contact me.Tina is still here help you solve all these problem.
Written by Tina