New Engel Software Attacks ‘Mold Breathing’ Variations

Clamping force is automatically optimized in Engel’s inject 4.0 program, which was introduced this week at the Fakuma trade show in Germany.

The iQ weight control software introduced at Fakuma 2012 optimizes the injection process, while the new iQ clamp control focuses on the injection molding machine’s clamping unit. By continuously adapting the clamping force, the software keeps the mold “breathing” constant even under fluctuating process conditions.

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

While the clamping force is being built up, the mold height and the volume of the cavity are slightly reduced (picture middle). Part of this compression is compensated for by the opening pressure exerted by the melt during injection (picture below). The resulting change in the mold height is referred to as mold breathing. (Engel)

While the clamping force is being built up, the mold height and the volume of the cavity are slightly reduced. Part of this compression is compensated for by the opening pressure exerted by the melt during injection . The resulting change in the mold height is referred to as mold breathing. (Engel)

Use of a gauge can roughly determine the extent placement of the gauge. Many injection molders just use maximum clamping force available instead of attempting to adapt to specific processes.

The new Engel system uses the existing sensor system to compute mold breathing during the ongoing process. The clamping system including the mold 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 mold 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.

The new software is being offered on machines with electrical clamping units up to clamping forces of 2200 kN.

 

About Doug Smock

Former Chief Editor at Plastics World and Senior Technical Editor Design News
Europe, Injection Molding , ,

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