In injection molds, mechanical microswitches are often used to confirm the position of hydraulic cylinders.
When a switch fails once, replacement may appear to be the simplest solution.
But what happens when the same type of microswitch fails repeatedly, and several switches installed on different cylinders show similar problems?
In that situation, replacing individual components may only treat the symptom.
A real technical case analysed by the Vega Team demonstrates why repeated microswitch failures require a structured investigation of the component, its sealing system and the manufacturing process.
The Customer’s Problem: Repeated Microswitch Failures
The Customer was using hydraulic cylinders equipped with mechanical microswitches identified as MS1 and MS2.
The problem was not limited to a single switch.
The Customer reported frequent failures in the microswitches installed on the molds. New switches could also stop working after a certain number of production cycles.
The situation became particularly significant when the Customer clarified that a large number of switches were affected.
The order involved 44 microswitches in total: 22 MSA and 22 MSB. The two switches initially sent to Vega were therefore samples intended to represent the wider problem, rather than the complete population of affected components.
This immediately changed the engineering approach.
The question was no longer simply:
Why did this microswitch fail?
The more important question became:
Why are multiple microswitches experiencing the same type of failure?
The First Clue: Fluid Inside the Microswitch
The investigation became more interesting when the Customer’s end user opened one of the failed microswitches.
Liquid was found inside the component, and the internal parts were reported to be seriously damaged.
Another microswitch was found with a damaged spring. The Customer also questioned whether the sealing method used between the two metallic parts of the microswitch was sufficiently robust.
This was an important observation.
If a microswitch is expected to operate in an industrial mold environment, the protection of its internal electrical and mechanical components from the surrounding environment is critical.
The presence of liquid inside the switch therefore required further investigation rather than simply replacing the failed component.
IP66: The Difference Between a Specification and a Field Failure
During the investigation, the Customer referred to the IP66 protection rating indicated in the product documentation and asked Vega to confirm the applicable protection level.
The supplier had previously tested the switches and declared them to be IP66.
However, the field evidence showed that liquid had entered at least one of the switches.
The Vega Team therefore asked an important diagnostic question: was the liquid actually hydraulic oil, and where exactly had it entered the switch?
Opening and analysing the failed component was considered useful for identifying the entry point and understanding what had happened in service.
This distinction is important in failure analysis.
A component can comply with a specified protection level under defined test conditions, while a production failure may still indicate a problem in a particular manufacturing batch, assembly process or sealing operation.
The field failure therefore had to be investigated rather than dismissed simply because the component had been tested to IP66.
The Investigation Reaches the Manufacturing Process
The supplier’s technical investigation eventually identified a specific problem.
The infiltration was attributed to an assembly defect.
More precisely, the quantity of sealing glue applied around the closing cap was not uniform at all points.
This meant that the sealing between the metallic components was not consistently effective, creating a possible path for fluid infiltration.
This finding was particularly significant because it explained how apparently identical microswitches could experience similar failures.
The problem was not necessarily the microswitch mechanism itself.
The critical factor was the consistency of the sealing process during assembly.
Corrective Action: Modifying the Sealing Process
Once the cause had been identified, the supplier checked and modified the automatic sealing process.
The original process was not completely automatic: sealing was automatic only during one phase, while another part of the operation was performed by an operator using a dedicated glue dispenser.
This created the possibility of variation in the amount and distribution of sealing material.
The sealing process was therefore checked and modified to improve consistency.
After the modification, permeability tests were performed on samples of the switches.
According to the supplier’s report, the modified switches showed no fluid infiltration during the tests.
This was the key corrective action documented in the case.
Why Vega Did Not Immediately Replace All the Switches
Because the Customer had reported a large number of failures, there was naturally an expectation that all affected switches should be replaced.
However, Vega did not immediately replace all 44 units.
The Vega Team first wanted to analyse the returned samples and understand the real cause of failure before defining the appropriate warranty action.
This is an important principle in industrial technical support.
When many components fail in a similar way, replacing everything without understanding the root cause can simply reproduce the same problem.
A proper failure investigation should first establish:
- what actually failed;
- how the failure occurred;
- whether all failed components have the same failure mechanism;
- whether the failure originates from the component or from its manufacturing process;
- whether a corrective action has eliminated the cause.
Only after these questions are answered can a reliable replacement strategy be defined.
Alternative Microswitches Were Also Considered
During the discussions, the possibility of replacing the existing MS1/MS2 solution with MS5 or MS6 was also considered.
However, this was not simply a matter of replacing one microswitch with another.
For some compact hydraulic-cylinder applications, installing MS5 or MS6 required a special cylinder configuration.
The Vega Team explained that special solutions were available for installing these mechanical switches on the rear side of the cylinder, using specific configurations identified in the cylinder catalogue.
This is an important design consideration.
A microswitch cannot always be treated as an independent component. Its dimensions, operating mechanism and mounting position must be compatible with the hydraulic cylinder and with the available space inside the mold.
Vega’s current product documentation confirms that mechanical switches are available for specific hydraulic-cylinder configurations. For example, the V450CM range uses mechanical switches because its all-steel construction is not suitable for magnetic sensing.
Mechanical switches for Vega hydraulic cylinders
What This Case Teaches About Microswitch Reliability
This case demonstrates several important principles for injection-mold applications.
1. Repeated failures are rarely random
When many identical components fail in a similar way, the probability of a common root cause increases.
The investigation should therefore move from individual replacement toward systematic failure analysis.
2. Protection ratings must be considered together with manufacturing quality
An IP rating defines performance under specified test conditions.
It does not eliminate the need for a robust and repeatable manufacturing process.
In this case, the investigation identified non-uniform sealing during assembly as the cause of fluid infiltration.
3. The sealing process can be as important as the component itself
The microswitch mechanism may be correctly designed, but inadequate or inconsistent sealing can compromise the entire component.
For this reason, manufacturing-process control is an essential part of component reliability.
4. Alternative sensors may require a different cylinder design
Changing from one microswitch to another is not always a plug-and-play operation.
The switch must be mechanically compatible with the cylinder, the available space and the mold design.
5. Root-cause analysis should precede large-scale replacement
When dozens of components show similar failures, replacing all of them without identifying the failure mechanism can be expensive and ineffective.
The better approach is:
failure observation → sample analysis → root cause → corrective action → verification → replacement strategy
Mechanical Switches for Hydraulic Cylinders
Vega currently offers dedicated mechanical-switch solutions for hydraulic cylinders, including the MS5, MS6 and MS7 families.
Depending on the configuration, the switches are designed for different temperatures, mounting arrangements and cylinder versions. The official Vega documentation also specifies applications with up to millions of operating cycles.
Hydraulic cylinder end-stroke switches
Mechanical switches for hydraulic cylinders
For applications where position monitoring is critical, sensor selection should therefore be considered together with the hydraulic-cylinder design and the requirements of the injection mold.
Monitoring hydraulic cylinder position sensors on injection molds
Conclusion
The repeated failure of a microswitch is not necessarily evidence that the switch itself is fundamentally unsuitable.
In this case, the investigation showed that the critical issue was related to fluid infiltration caused by non-uniform application of sealing glue during assembly.
The supplier modified the sealing process and subsequent permeability tests on modified switches did not show infiltration.
The case therefore provides an important lesson for injection-mold engineers and maintenance teams:
When several sensors fail in a similar way, do not stop at replacement. Investigate the failure mechanism and identify the process that created it.
For hydraulic cylinders operating inside injection molds, reliable position detection depends not only on the electrical switch itself, but also on the mechanical integration, environmental protection and manufacturing quality of the complete solution.
URL da inserire nell’articolo
- Hydraulic Cylinders – End-Stroke Switches
Panoramica dei sensori magnetici, induttivi e meccanici:
https://www.vegacylinders.com/en/10-end-stroke-switches-hydraulic-cylinders - Mechanical Switches for Hydraulic Cylinders
Pagina specifica per MS5, MS6 e MS7 e relative configurazioni:
https://www.vegacylinders.com/en/12-hydraulic-cylinders-mechanical-switches - MS5 Mechanical Switch – V450CM
Pagina specifica del microinterruttore MS5:
https://www.vegacylinders.com/en/end-stroke-switches-hydraulic-cylinders/30-ms5-mechanical-switch-80-hydraulic-cylinders-v450cm-q-p-versions.html - Monitoring Hydraulic Cylinder Position Sensors on Injection Molds
Articolo tecnico Vega sulla gestione dei sensori di posizione negli stampi:
https://www.icvega.com/support/monitoring-hydraulic-cylinder-position-sensors-on-injection-molds - Mechanical Switch Operating Range in Hydraulic Cylinders
Approfondimento tecnico sul corretto posizionamento e campo di intervento dei microinterruttori:
https://www.icvega.com/support/mechanical-switch-operating-range-in-hydraulic-cylinders
