Automatically optimise clamping force
At Fakuma show Engel presented their new software iQ clamp control. By continuously adapting the clamping force, the software keeps the mould breathing constant even under fluctuating process conditions, says the company.
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 millimeter (known as as mould breathing). For this Engel has developed the iQ clamp control software that shall automatically determine and adopt the optimal clamping force on an objective basis. The company asserts that 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.
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. According to the company an advantage over measuring the cavity pressure in the mould is the fact that there is no need to add extra sensors or hardware. Engel found a method for 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 shall reduce the risk of quality deficiencies, ensure mould ventilation, protect the mould against overfilling and improve 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.
