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Sherlock Ohms

It's All in the Robot's Timing

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RBedell
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Gold
Re: Do it right vs. do it over ?
RBedell   10/14/2013 12:12:32 PM
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Glenn, my second post, ': A silly millisecond slower', tries to touch on the things you are mentioning.  My counter response is: Why should the engineer notice the problem went away? 

In that situation, what is the engineer's job duties?  I am simplistically assuming to keep the entire line running.  If so, the engineer will not monitor every detail at all the stations down the line.  He is likely monitoring the overall operation of the line and supplies feeding the line.  The details of a dent in a floorplan is below the horizon on his radar unless it caused the line to stall or stop.  Then it would rise above horizon and he would see it.  The task of monitoring the details of each station is given to the people at each station. 

The job you had was to determine if the issue at hand was a 'normal' failure or an 'operational' failure.  'Normal' being - failures not necessarily due to design or usage issues.  'Operational' being - failures that will continue to occur if equipment continues to be used the same way; like using the motor rather than a brake to hold a robotic arm in position for hours.  In other words, that engineer needs to know about operational failures not normal failures.  But, the engineer's definition of operational failure is not the same as yours.  A dent in the floorpan was not an operational failure to the line and there was (assuming) no issues being feedback from the line output so there was no failure.  If the dent in the floorpan caused problems down the line, then the engineer has an operational failure.

It is a matter of perspective.  You are seeing the problem from your angle and the engineer is seeing it from his angle.

 

bob from maine
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Platinum
Re: A silly millisecond slower
bob from maine   10/14/2013 12:10:43 PM
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I'm reluctant to side with the engineer however I can see several scenarios where NOT making the change would be appropriate. First, apparently the dented floor pans were not a critical problem and the assembly process was able to operate without changes. Second, every program controlling a robot should be fully documented and when 'minor' changes are implemented they should be verified to assure they don't cause other errors elsewhere. This verification is often more difficult than dealing with an upset line worker. Lastly, undocumented changes make future troubleshooting or analysis really difficult. It easily could have changed Sherlock Ohms into Made by Monkeys. I'd say some enhanced communications from the engineer would have gone a long way here.

Tom-R
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Gold
Re: Which efficiency
Tom-R   10/14/2013 12:05:59 PM
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I like your point Ron-C. It doesn't assume the Engineer didn't want the problem solved the way it was. The first thing I wondered was when did the denting start? If it didn't do it when first installed, then maybe the grippers were wearing. I've seen entire machine speeds adjusted by maintenance for similar reasons. Then I get called back because the line is slowing down. The worst experience I had was commissioning a line, and as we brought the speed up the controls wouldn't work as planned. Turned out a supervisor kept overriding sensors by taping coins onto the proximity switches. Ya it kept conveyors running and product moving at that moment, but try debugging accumulation cycles or just getting cycle stops to work properly. We finally explained it was costing us more time finding and correcting his "fixes" than we gained in any production he forced through by overriding controls. When I read this story it made me wonder if the line had not reached the final design speed, and the Engineer didn't want the unit ultimately limiting that top speed. I've seen a line designed to run 900 units a minute being run at 600 units a minute for much the same reason. Yes everything is running smoother, but the owners have also been denied 1/3 of their investment's capacity because slowing things down was an easier fix than replacing worn parts or doing a proper change over between unit types. I wonder why we always assume upper management doesn't know what they're doing?

Ron C.
User Rank
Iron
Re: Which efficiency
Ron C.   10/14/2013 11:10:27 AM
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I wonder if this may also have been a case of how the change was presented. "I can fix the problem by lengthing the cycle time" as oposed to "I can solve the problem by shortening the wait time".

 

Same result but could be looked at very differently by management.

GlennA
User Rank
Gold
Do it right vs. do it over ?
GlennA   10/14/2013 10:54:36 AM
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The original complaint was that the robot was denting the floorpans.  Reducing the acceleration while carrying the floorpan prevented the denting.  If your choice was to transfer a floorpan in 15 seconds, or transfer a dented floorpan in 14.8 seconds, while overall cycle time does not change, which would you choose ?  Transfer time may be important, but aren't un-damaged parts and eliminating repairs and rework important too ?

Another point:  the engineer that 'investigated' the dented floorpans, and rejected the suggestion to reduce the acceleration, didn't notice when the problem was corrected.  Shouldn't he have noticed, and investigated why the problem went away ?

RBedell
User Rank
Gold
Re: A silly millisecond slower
RBedell   10/14/2013 10:31:06 AM
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It may not be realistic to expect higher management to make good decisions for lower levels.  They see a different picture than the lower levels do.  Perhaps the lower levels should try to see things differently and explain solutions in a manner that higher levels would understand.  If the higher levels are focused on operations and cost then:  Using the brakes instead of the motors saves power and that save money.  It also saves money by reducing downtime, repair costs and restocking of spare parts.

The entire structure of business, design and production requires different views of the same goal.  Inter-communications between those views are not always easy nor simple.  Explaining in terms they understand but might seem erroneous to us.  One hint, the farther up management, the more money plays the role.

RBedell
User Rank
Gold
Which efficiency
RBedell   10/14/2013 9:59:22 AM
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As pointed out already, a few milliseconds may not matter.  The answer would depend on: Is the line waiting on the robot or is the robot waiting on the line?  If the line is waiting on the robot then does a few milliseconds really matter?  But, if the robot is waiting on the line then a few milliseconds is irrelevant.  As engineers, we can sometimes let our designs integrate into our egos.  Possibly, the engineer rejected the suggestion because it would slow down the robots cycle time.  And the engineer was proud of that quick cycle time.  While the pan got dented, the line didn't shutdown because of it and the engineer could keep his cycle time (and ego).

An alternate view:  Only suggesting a solution may not work well.  In the end, the solution has to be evaluated as to the impact it will have on the situation.  The engineer would have to take the time to evaluate it.  But, providing the solution and how it might affect the situation gives the engineer more information to make a decision and saves him time.  If the robot was waiting on the line then; reporting that because the robot is waiting on the line for 'X' amount of time, the extra time allowed for reduced acceleration would not affect the line.  The engineer might have approved the solution or at least took a closer look.  In terms of ego, he could slow the acceleration and keep the line speed and few would know, thus preserving his ego.

Rob Spiegel
User Rank
Blogger
Re: A silly millisecond slower
Rob Spiegel   10/14/2013 8:35:42 AM
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I suppose that if you watch the milliseconds, the seconds will take care of themselves, but this is ridiculous.

taimoortariq
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Gold
Re: A silly millisecond slower
taimoortariq   10/13/2013 8:53:35 PM
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That is pretty interesting. And it makes alot of sense as well, specially the solution where you proposed to use breaks in idle time. Pity sometimes people in higher management don't use their heads.

taimoortariq
User Rank
Gold
Greed gets to us
taimoortariq   10/13/2013 8:22:20 PM
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Being cautious and careful with the machinery is more important than just blindly maximizing the efficiency. More production although very important might be reckless and cause damage to the parts and the machine as well.

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