Machine detection is a very crucial aspect of industrial automation processes. Prior to carrying out a task, the control mechanism would need to identify the presence of the component in a certain location, if the guard is closed or if the object has arrived at a specific location.
The two most popular detection technologies include mechanical limit switches and proximity sensors. They are both capable of providing reliable detection although they operate in different ways.
The Schmersal Limit Switches are popular in detecting the positions and the end of travels, whereas proximity sensors do not require any physical contact when detecting the objects.
How Do Limit Switches Work?
Limit Switch is a mechanism that changes the electrical condition of the switch upon the action of the moving part of the machinery.
For instance, take the example of a conveyor whose moving platform reaches its end point. At this point, the platform may act on the actuator of the limit switch and send signals to the control system.
Schmersal Limit Switches can be employed in any application requiring detection of mechanical positions. They can be applied in machine guarding and other industrial applications, depending on the type of switch and the application needs.
Mechanical feedback is an advantage that comes with using limit switches. But because of the interaction between the actuator and the machine component, proper installation and testing are necessary.
What Makes Proximity Sensors Unique?
Proximity sensors are able to sense the presence of an object without coming into physical contact.
As an illustration, when an inductive proximity sensor senses the approach of a metallic element within its sensing area, it will send a signal to the PLC.
Such contactless functioning may be desirable in systems that involve frequent motion or high cycle operations where any physical touch may lead to wear.
Proximity sensors have been commonly used in product counting, machine positioning, and the sensing of the presence of elements and processes that are automatic.
Nevertheless, the range of the sensor and ability to detect the object may depend on the type of sensor and the nature of the detected material.
What Technology Should You Select?
This question doesn’t have a one-size-fits-all solution as different machines require different technologies.
Use the Limit Switch:
- If contact operation is acceptable.
- If you need positive mechanical position feedback.
- If there is an established end-point of travel.
- If you need a reliable mechanical switching mechanism.
Use the Proximity Sensor:
- If contactless operation is required.
- If moving parts operate often.
- If you need detection of metal or other proper material.
- If switching frequency is high and mechanical contact is not preferable.
Many other factors will play their role such as dust, oil, vibration, temperature, machine speed, installation space and others.
However, first of all, a typical position sensor cannot be viewed as a safety component per se.
Making The Right Choice For Your Machine
Prior to selecting any detection technology, one must analyze the whole application and not select any product based only on price.
These are some easy questions: What does need to be detected? Is contact acceptable? What is the operational frequency of the machine? What material needs to be detected? What kind of environmental conditions do you have?
At Shikhar Automation, we assist the manufacturers in analyzing all these real-life parameters while selecting automation and detection solutions. And when using Schmersal and other industrial automation systems, the key is to find the appropriate sensor for the actual machine application.
Conclusion
Limit Switches and Proximity Sensors both play an essential part in automation. While limit switches provide reliable mechanical detection, proximity sensors are more versatile, contactless detection devices.
Which one to use largely depends on what machine, what operating environment, what detection need and safety functionality are there.
Correct selection even at the initial stage of designing the machine will improve its performance and reduce maintenance.
