Mold cavities and opening force

In plastic injection molding, how do cavities affect the clamping force? Those who deal with injection molding machines already know that the more cavities in the mold, the greater the required mold opening force.

In the previous article, we already talked about how the thickness of magnetic platen affects the opening stroke (click to read). And the opening stroke will affect the mold opening force of the IMM (injection molding machine). Accordingly, it will affect the magnetic force of the magnetic mold clamping system. Now we know the mold opening force is proportional to the clamping force of the magnetic plate. So today we will talk about the positive proportional relationship between the mold cavities and the clamping force of the magnetic platen.

HVR MAG has come across such cases before. The customer requested to do a magnetic quick mold change. The original number of openings was 16, and we had no problem doing it. However, when the number of openings doubled to 32, the same magnetic template could not lock the mold and caused it to fall off. Why?

Mold cavities and contact surface

The mold size is almost the same for 16 and 32 holes. However, the increase in the number of cavities leads to a corresponding increase in the opening force. Therefore, the magnetic clamping force should be increased accordingly. But the magnetic platen is still the same as before, without any tonnage added. We need to notice that when the cavities double, the magnetic clamping force should actually be far more beyond the doubled tonnage.

Therefore, we design the magnetic force of the platen for our customers according to your specific requirement at the beginning. Please follow certain guidelines in the actual operation.

In this case, we can also conclude that the contact surface between the mold back and the magnetic platen determines the magnetic force to some extent. So next time you know why we should ask you about the cavities, the mold size, mold back cavity size, mold temperature (we have a sharing on this, too. Click to read!), etc.

You are interested in the plastic injection molding and the mold clamping system? If there are any inaccuracies in the above expressions about how cavities affect the magnetic force, you are welcome to leave your comments. Or send your questions to HVR MAG: export@hvrmagnet.com