Common problems of mold opening

During the injection molding production process, if there are phenomena such as excessive clamping force, misalignment of the lock core, wear of the guide pin, and the mold being in a high-pressure clamping state for a long time, the mold is deformed and the “bite force” is generated, and the mold cannot be opened. Phenomenon, this phenomenon is collectively referred to as difficulty in mold opening. The above-mentioned undesirable phenomena are more likely to occur when large-sized plastic parts, molds with deep cavities, or injection molding machines adopt toggle-type clamping mechanisms.

Table Causes of Difficulty in Mold Opening and Analysis of Causes of Improvement Methods

Re-adjust the mold to reduce the clamping force

Clean/lubricate the guide post or replace the guide post and guide sleeve

Manual mold clamping when stopping (do not increase the pressure)

 Re-install the mold and tighten the pressure plate screws

Increase the mold opening force or remove the mold to replace a larger machine

Clean up oil or foreign matter in the exhaust groove/thimble hole (unblock the air inlet)

Replace the stronger hook

Compression mold and solution

During the injection molding process, if the product or nozzle material (runner aggregate) is not completely taken out or the product sticks to the mold and the operator does not find out in time, the product or nozzle material left in the mold after closing the mold will cause crush injuries Mold, this phenomenon is called compression molding. Compression mold is a serious safety production problem in injection molding production, which will cause production to stop, requiring mold removal for maintenance.

Some mold cores that require high dimensional accuracy cannot be repaired and need to be replaced, causing great losses and even affecting the delivery time of the order. Therefore, it is necessary to prevent the occurrence of compression molding events in injection molding production. It is necessary to set the low pressure protection parameters of the mold reasonably and install the mold monitoring device.

In summary, the reasons and improvement methods of compression molds are shown in Table

Improve the phenomenon of plastic parts sticking (same as improving sticking measures)

Reasonably set mold low pressure protection parameters

Install mold monitoring device in fully automatic production

Additional reset device for thimble plate

Conduct operational training for operators and strengthen their sense of responsibility

Products with row positions and deep cavity structures are not suitable for fully automatic production and change to semi-automatic production mode

Clean the wire drawing and completely eliminate the nozzle wire drawing phenomenon