Remote or on site trouble shooting of modern automated manufacturing equipment is fairly straight forward if one follows a structured approach.

You will need to have a functional understanding and access to

  • Human Machine Interface (HMI)
  • User & maintenance manuals
  • Electrical schematics
  • Hydraulic schematics
  • Pneumatic schematics
  • PLC ladder logic
  • Principle of operation and setup of sensors
  • Spare parts inventory
  • Functional modules of the system
  • Process flow
  • Machine vision systems
  • SPC
  • Have mechanical & electrical skills
  • Be computer literate

Trouble shooting methodology starts with problem definition

  • System has stopped with a fault condition
  • System is running but producing excessive rejects – Got to SPC screen and center process
  • System does not start – Check for input power and air, blown fuses.

System has stopped with a fault condition

This is one of the most common faults

  • Look at the alarm screen on the HMI
  • Check cause and then clear alarm
  • Find the alarm which does not clear

Alarm does not clear

The HMI will give the functional input required to be in an on/off state for the system to go to the next sequential state of operation

These could be

  • Guard doors not closed
  • Processing modules not ready
  • System stopped due to excessive rejects – Check reason for excessive rejects
  • Servo faults – Check servo driver, any mechanical obstructions and clear fault
  • Communication error –  Reset PLC to see if connection is made
  • Waiting for supply of input components – Refill required supply components
  • Air pressure low – Go to source
  • Vacuum pressure low – Go to source or check for blockages
  • Input voltage low – Go to source
  • Functional module not turned on – Turn on
  • Scrap bins full – Empty

Guard doors not closed

  • Step by step trace the guard door which is not closed
  • If alarm is still on check for loose fit condition of guard door
  • Check for guard door lock malfunction
  • If necessary use key to simulate close condition of guard door to check function

Processing Module not ready

  • Inspect the functional module
  • Trace the input the functional module is waiting for to continue
  • If it is a sensor check the function of the by simulating an on off condition and check the state in the ladder logic, HMI or indicating LED’s
  • Replace sensor if defective
  • Check if HMI fault condition still exists and go over the check again till this module is ready.
  • Check for bent brackets, loose sensor mountings
  • Check for air & vacuum within limits

This will continue with more detailed approaches on the various functional areas

Till then happy trouble shooting and feel free to post your problems

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