The injection mold is the most important resource in the injection molding process, because it is usually impossible to replace. Damage inevitably leads to a production stoppage that can put the supply chain at risk. This is why predictive maintenance is so very important. At present, this type of maintenance is controlled depending on time intervals or production quantities, forcing users to maintain their molds more often than necessary so as to ensure production capability in all cases. Sensors placed intelligently in the mold can be used to monitor the operational status of the tool (mold monitoring). Objective measurement data provides a reliable basis to allow extended maintenance intervals.
Sensors for predictive maintenance in injection molding – mold monitoring
Do you know the condition of your injection mold?
Temperature management of injection molds – temperature sensors
Alongside pressure, temperature is one of the most important process values in the injection molding process. To ensure controlled and reproducible dissipation of the heat from the mold, injection molds are kept within a narrow temperature range: this is achieved by a temperature control medium (usually water) and a temperature control device. Different temperatures may also be necessary in one tool.
A maintenance intervention is indicated if the flow of the medium through the temperature control channels in the mold is impeded and the heat transfer to the tool wall is restricted (by deposits, for example). A simple and cost-effective temperature sensor placed in the mold enables prompt detection of malfunctions in this complex system.
Force flow and deformations in the injection mold – mold monitoring with strain sensors
The injection mold is a highly loaded system consisting of a very large number of components. It must withstand the high injection pressures in the projected surface of the molded part and, in turn, is compressed by the clamping force of the injection molding machine. This system of forces requires a very rigid and balanced tool structure.
Any deformations lead to increased wear of the moving components and attrition of the sensitive parting line. Installing strain sensors helps to detect gradual changes so costly damage and downtime can be avoided.
The injection mold ejector – mold monitoring with force sensors
Contamination can cause ejectors to become sluggish or jam. Measuring the ejector force provides information about the ejector's condition so conclusions can be drawn about the presence of deposits in the cavity, which would then require cleaning.
Other applications for force measurement in the tool include monitoring of support plates or sliders.
Mold monitoring – monitoring overmolding of inserts
Overmolding of inserts is a common procedure in injection molding. It is essential to monitor whether the insert was placed correctly so the tool is not damaged if (for example) melt penetrates functional areas of the mold. Optical or inductive sensors can be used for monitoring.