Sensor protection

With sensors (optic, inductive, ultrasonic, laser,…) machine developers can manufacture machines that perform multiple and complex functions with high speed and accuracy. The main problem is that many times designing machinery for sensor mounting comes a long time after main machinery design. It seems that designers under estimate the importance of sensor good working condition. How many times many of us we walked in factories observing operating machines with cables and sensors in absolutely bad condition. I¢m not referring to high voltage equipment but to control one. Maintenance personnel are also responsible for this situation. It seems that when a problem appears maintenance personnel in order to solve it immediately make some error and try tests with the equipment. Accidental movements of sensors during operation are the usual problem in high speed assembling machines. If the problem occurs more than one time probably the sensor after many adjustments will finally been damaged. The designers must take seriously the positioning, adjustment and protection of sensors.

 

Consider these few principles when designing for sensor mounting and adjustment.

• Never use sensors in machinery without adequate protection against all possible threats. Remember sensors are sensitive. 
  
• Use sensors built-in threads for adjustment only if they are strong enough. Always remember that probably the sensor will be many times more expensive than the sensor protection.
  
• Design the sensor mounting part with adjusting features (oblong slots, built-in threads) because it is better to adjust the mounting part than the sensor itself.
  
• If it is possible avoid sensor adjustment. Design machinery for standard operation.
  
• Always cover sensor¢s signal cables. The most usual malfunction is damaged sensor cable. For protection use elastic spiral conduits with plastic mounting insert (Pg threads).
  
• Never under estimate the importance of sensor correct mounting and protection.
  
• Standardize for design purpose the different types of sensors which are used by your automation department. Dimensions from sensor¢s manuals are not cover all the necessary information for correct positioning. It is best to observe and keep notes about the special needs of each sensor (indicators, assembly sequence).
  
• Categorize the machinery used for every sensor according to type and size of sensor. Have stock of these parts can help you when there is a special need for additional sensors (this happens often when working with prototypes).