In injection molding, the two mold halves are forced apart by a few thousandths to hundreds of millimeters during the injection and the holding phase due to the buoyancy pressure of the melt. This is known as the so-called mold breathing. Too large or too small mold breathing can lead to injection molding defects such as flash or burn marks.
In order to manually optimize the required clamping force, dial gauges can be attached to the mold to determine the mold breathing. Permissible respiration depends on the quality requirements of the injection molded part, the material and the size of the machine.