Injection moulding control automatically optimizes clamping force

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  • Control ensures optimal mould ventilation & protects against overfilling
  • Software keeps mould breathing constant even under fluctuating process conditions
  • No additional hardware needed

To measure mould breathing manually and to determine the actually required clamping force is a difficult task. As a result many injection moulders work with the maximum available clamping force. In order to address this issue, Engel has launched iQ clamp control, a new software tool that automatically determines and adapts the optimum clamping force for each individual application based on mould breathing.

Control ensures optimal mould ventilation & protects against overfilling

The prefix “iQ” stands for “intelligent quality” which means that the know-how is integrated into the injection moulding machine’s control unit. The goal is to improve the quality of the production process and thus of the finished products. By continuously adapting the clamping force, the software keeps the mould breathing constant even under fluctuating process conditions.

clamping unit with iQ control

iQ clamp control determines the extent of the mould breathing and automatically adopts the optimal clamping force (source: Engel)

What is mould breathing? And why it is important?

During the injection process, the inflowing melt exerts pressure that pushes the two halves of the mould apart by a couple of thousandths or hundredths of a millimetre. This process is known as mould breathing. If the mould breathing is too great or to small, this can cause rejects due to flashes or burn marks (diesel effect). If the clamping force is too high, the mould is also subject to excessive stress and clamping force build-up unnecessarily consumes more energy.

Manual measurement of mould breathing is imprecise

In order to optimise the clamping force manually, the mould breathing can be determined with the help of a gauge. This is however an imprecise approach. The measurement results are heavily dependent on the position of the gauge. In addition, it takes much experience to interpret them. Many injection moulders therefore work with the maximum available clamping force instead of adapting it to the respective process.

To determine the actual required clamping force, Engel has developed the new iQ clamp control software that automatically determines and adopts the optimal clamping force. The CC300 control unit for Engel injection moulding machines is the first machine control unit worldwide that is capable of autonomously determining a process-relevant target value, according to the company.

No additional sensors or hardware needed

Because mould breathing is caused by the pressure acting in the cavity, its curve is very similar to the curve of average cavity pressure calculated for the projected surface of the moulded part. The advantage over measuring the cavity pressure in the mould is the fact that there is no need to add extra sensors or expensive hardware. The company is using the existing sensor system on the injection moulding machine to compute mould breathing during the ongoing process. To this end, the clamping system including the mould is conceived of as a spring, and the stiffness of the spring is determined during clamping force build-up. During injection, the tension in the spring increases slightly due to mould breathing so that the clamping force increases minimally compared with the set value. In order to determine this increase very precisely, dry cycles are performed at the start of production and the changes in clamping force are stored as reference curves. In this way, iQ clamp control ensures optimal mould ventilation, protects the mould against overfilling and increases energy efficiency.

In an initial step, the new software is being offered for Engel injection moulding machines with electrical clamping units up to clamping forces of 2200 kN.

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