A company in West Wales design and build Stud and nut feed systems for a wide range of applications.
This project involved a stud feed system that provided a stud into a 600 Ton Sheet metal press for a car parts manufacturer. I became involved when the machine had been out at the customer for several months with ongoing technical issues which had not been resolved on site. At this point the machine was brought back to the UK and I came in to see if I could diagnose the faults and see what could be done.
Due to the ongoing issues the system was only allowing a production process of approximately 500 parts per hour with relatively long restarts afterwards to get back into production.
After spending some time with the designers and electrician, the fault was diagnosed as two distinct problems:
- Firstly, the PLC that had been used was now obsolete and had been unable to detect the cycle go command from the press consistently due to the amount of time the signal was present for. This caused numerous stoppages to the press and therefore production suffered.
- Secondly, when there was a fault the stud feed system had been made in a complicated way for the operator so that if the pressed an incorrect button out of sequence, the system would lock and they would have to clear out the studs and start the process again which proved to be both time consuming and frustrating for them.
- Further to these two problems, there were also small issues with the Pneumatics and some of the sensors in terms of their position and type.
The fix once the problems were identified were relatively simple
- Part one was to put a modern ABB Eco PLC in place of the old PLC. This new PLC has a faster cycle time and so would pick up the small signal from the press each time in ran through its start point.
This also meant that the programme had to be re-written and was done in such a way as to simplify it and allow for future upgrades to the system such as additional feed heads.
- Part two was to simplify the operator interface, the old system had 15 pushbuttons on the control panel, some of which were obsolete but had carried the ability to interfere with the previous program.
- These buttons were removed and the total button count went from 15 to 7. The program was used to make the next button in sequence to flash when an action was required by the operator and significantly simplifying the operator process on start-up.
- The final part was to go through the system completely and look at how the other parts such as the Pneumatics and sensors were working. Through solving the PLC issue it highlighted that some of the sensors were not working in the best way so these were repositioned and a couple of them changed to optical sensors which allowed for greater precision.
- In addition to this I then spent time with the operators of the machine teaching them how to use it effectively and also how to fault find any issues that came up and how to fix them. This means that any issues that do occur can be resolved quicker and allow production to start with much reduced downtime compared to the prior to the changes.
- We were also able to provide phone support as required to them.
As a result of the improvements made over the course of a few days, the system went from running poorly (500 parts per hour) and inconsistently to producing over 900 parts per hour over longer production runs.