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Precision tools such as injection molds require predictive maintenance.

Sensors for predictive maintenance in injection molding

Mold monitoring

Do you know the condition of your injection mold?

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.

We offer you a unique range of sensors for specific applications:

Temperature sensors 6198A from Kistler for injection molds help monitor the condition of the temperature control system.
Mold temperature sensors
Mold temperature sensors offer a simple way to monitor actual mold temperatures at reasonable cost.
Acoustic emission sensors from Kistler used for predictive maintenance help determine the injection mold’s state of wear.
Acceleration and structure-borne sound (AE) sensors
The mechanical elements of an injection mold (such as sliders and guides) can be monitored effectively with structure-borne sound sensors: the acoustic emission (AE) changes in the worn condition.
Strain gauges and strain sensors measure the surface strain – and also, therefore, the strain in the tool structure. A change in the measurement signal indicates wear or deformation of the supporting assemblies in the injection mold.
Strain sensors
Strain gauges and strain sensors measure the surface strain – and also, therefore, the strain in the tool structure. A change in the measurement signal indicates wear or deformation of the supporting assemblies in the injection mold.
Distance sensors
Distance sensors
Optical or inductive distance sensors detect changes in the interaction between the mold plates. This can be impaired due to contamination or wear, and may lead to issues such as flash on the molded part.
Kistler recommends force sensors 90x1C to track the injection mold’s ejector force for mold monitoring purposes.
Force sensors
As an alternative to strain gauges, a force sensor can also be used – for example, to measure the ejection forces.

Temperature management of injection molds – mold monitoring with temperature sensors

To control the mold temperature during mold monitoring, Kistler is offering specific 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

Strain sensors from Kistler help detect deformations of the injection mold at an early stage.

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

Predictive maintenance based on the measurement of the injector force allows to detect deposits in the cavity.

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. 

Monitoring of inserts during overmolding – mold monitoring with distance sensors

To ensure the correct positioning of the insert, mold monitoring is recommended during insert molding.

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. 

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