Efficiency of the Clamp in Injection Molding Machines
– By Zafar Kamal
The nominal clamp-force ratings are approached but rarely reached in actual molding machines. A particular unit may be designed for a specific strength factor but more than likely it will not have the exact force indicated.
Since, in the course of any design calculation, there are many add-on factors which will indicate the need for more clamp force than the theoretical value, any loss i efficiency can usually be neglected . Also, as the machine is used its efficiency will continue to fall off from its original rating. Therefore, any machine that has been in operation for any length of time should be considered as having a lower clamp force than when it was new. If calculations indicate that the clamp force of a machine may be taxed by a particular job, other avenues should be sought for the running of this job.
One approach can be redesign of the mold to require less clamp force by reducing the projected area. The other one might be the choice of a material grade with a lower flow rating or less resistance to flow. The final choice may mean choosing a larger press having a greater available clamp force.
