OT: "We didn't do ANYTHING"

[Freddie]

Well of course, an E-Stop button should not be covered, this is unquestionable.
But if you can break the machine by using an E-Stop, this is something I would not accept as a customer.

 

[Jeebs]

Well of course, an E-Stop button should not be covered, this is unquestionable.
But if you can break the machine by using an E-Stop, this is something I would not accept as a customer.

Using the E-Stop as a normal stop.
I don't think we have any machine that won't show some accelerated wear and tear due to such abuse.

 

[Clay B.]

Let me clarify a bit here

Well of course, an E-Stop button should not be covered, this is unquestionable.
But if you can break the machine by using an E-Stop, this is something I would not accept as a customer.

The machine was not broken because the E-stop was used. The problem is when you use an E-stop it stops everything instantly so the conveyours can not empty themselves out.

The conveyors move powdered material. When the conveyors stop any powder left settles to the lowest point. You have access hatches on the conveyor to cleanout this excess material in times of E-stops power failure etc.

The issue we had was they would Not clean out the material. They would just restart the system. If you stopped the system normally the conveyors would shut down in series to allow themselves to be empty for the next start.

An E-stop is a safety device and should never be used for normal control of a machine. That why we create Start and Stop buttons. E-stops are safety overrides to protect personal and equipment in "unusual" circumstances.

Side note. Since that time our newer systems have an added feature. If the E-stop is used the access doors must be oppened and closed before the safety relay will reset. Ironicly one of our first customers who got the system with the new safety circuit asked us if we would retrofit a competter's controls to have this feature. He had this problem in the past and repairs had costed him.

 

[OkiePC]

Using the E-Stop as a normal stop.
I don't think we have any machine that won't show some accelerated wear and tear due to such abuse.

If it comes down to a choice between machinery destruction or protecting humans, I will go ahead and choose machinery destruction.

I have had similar issues with abusing the e-stop button because it is more convenient than a normal stop. Often, the only reason they used the e-stop button is because of its mushroom head. there was a normal stop button right there to, but the big e-stop button is easier to hit, and that saves the operator a few milliseconds. They don't have the comprehension to understand the consequences, but they automatically and unconsciously form shortcuts into habits.

This can result in minor mechanical wear or the certain demise of motor controllers, depending on how many times they do it and how the controls are designed.

What we did, in certain situations, was make e-stop recovery a little more involved for the operators.

Machine operators will always find the path of least resistance. I no longer get mad about it, I just try to use that fact in my design and modifications.

Make it harder to recover from an e-stop and they will quit abusing it almost immediately.

 

[Peter Nachtwey]

It depends.

We have ramping stops and immediate hard stops. The ramping stops are smooth. The immediate hard stop are where we just set the control signal to the valve to 0. This can cause pressure intensification on the rod side of the piston and caviatation on the cap side it the system is extending at the time. I have seen cases where the cavitation sucked the o-rings out of the system. Cavitation isn't good for the cylinder lining or the seals.

BTW, it amazes me that stupid people are think others are even more stupid to believe their lies.

 

[Clay B.]

We have ramping stops and immediate hard stops. The ramping stops are smooth. The immediate hard stop are where we just set the control signal to the valve to 0. This can cause pressure intensification on the rod side of the piston and caviatation on the cap side it the system is extending at the time. I have seen cases where the cavitation sucked the o-rings out of the system. Cavitation isn't good for the cylinder lining or the seals.

BTW, it amazes me that stupid people are think others are even more stupid to believe their lies.

What is really bad is when you know they are lieing but you can not say anything because it will make the situation worse.

 

[theDave2]

What is really bad is when you know they are lieing but you can not say anything because it will make the situation worse.

Yeah. Like when I just took my car in for service and also asked them about the alternator output voltage (15.3v - it's a 2004 GM) and they said it's higher in the winter because more load is drawn. And he said it with such a straight face, I had a hard time holding back until I got out of there.

 

[panic mode]

One customer complained few weeks ago that machine is not safe to operate because it is not guarded properly. We agreed because we all stood in front of the running machine and while safety gates were closed, clearly some of the lexan panels were missing (they removed them).

Same customer called again just few days ago. They were complaining was that they had problem starting up the same machine after it was powered over weekend. They said that everyone was there including shift leader, maintenance crew with their own programmer, production manager etc. They all 'tried everything they could' but there was 'nothing wrong' showing on an alarm screen and machine refused to start.

While on the phone, an email arrives with attachment. Same comments on urgency etc. but nothing to point to potential issue so we looked at the attachment. It was photo of the alarms screen showing two alarms:
- Master not On, press Master On button
- Air Pressure Low
(the later one is result of first alarm because air was dumped)

 

[mgvol]

Waste heat boiler for a large incinerator was coming out of an unplanned outage. I get called in at 6 p.m. because of a low steam drum pressure alarm, to find that one of the mercury pressure switches had been stepped on and bent, preventing the mercury from closing the switch. Get it repaired and make the 20 min. drive back home. Get called back in at 8:30 p.m. because "the boiler has no alarms but is not making any steam pressure". Find root valve for PT closed and said a prayer of thanks that the boiler was not yet up to sufficient pressure to start lifting relief valves. Make the 20 min. drive home. Get called back in at 2:00 a.m. becuase "your stupid control valve is not maintaining steam flow setpoint". Climb up on the mezzanine above the steam drum, only to find "my stupid 12 in. control valve" stroking madly, trying to maintain flow. It was at this point I noticed both of the butterfly valves on the bypass line (around the control valve) wide open. Of course, no one had any knowledge of who stepped on, closed or opened any valves...

 

[TConnolly]

Machine operators will always find the path of least resistance.

Ain't that the truth!

You would be amazed at the combinations of button sequences operators will discover that the machine designer never intended or even anticipated.

I just dealt with this one: Final part of machine cycle opens slowly at first to protect the tooling die, then changes to rapid once the die is clear. Operator discovers that if he switches to setup mode, then holds down the jog reverse button while switching back to auto mode that he can skip the slow open step and go straight to rapid retract. Saves him five seconds, and since maintenance changes broken dies, its not his problem.

 

[milldrone]

We don't know what happened. It just stopped working.

Said the millwright, still holding a screwdriver with a burned off tip in his hand.