Friction increase after coffee and coke spilling?
Friction increase after coffee and coke spilling?
(OP)
Hi everybody.
I experienced a weird behaviour of a steel inertial latch whose reliability is currently doubtful.
We performed a spill test in which the latch:
1) was immersed in black coffee and then allowed to dry for three hours;
2) then immersed in coke and again allowed to dry for three hours;
3) finally immersed in diet pepsi and allowed to dry for three hours.
Well, after this spill test the latch experienced a DECREASE of the friction coefficient. We were expecting an increase due to obstruction of the fluids residues.
How can we explain that??
Catibon
I experienced a weird behaviour of a steel inertial latch whose reliability is currently doubtful.
We performed a spill test in which the latch:
1) was immersed in black coffee and then allowed to dry for three hours;
2) then immersed in coke and again allowed to dry for three hours;
3) finally immersed in diet pepsi and allowed to dry for three hours.
Well, after this spill test the latch experienced a DECREASE of the friction coefficient. We were expecting an increase due to obstruction of the fluids residues.
How can we explain that??
Catibon





RE: Friction increase after coffee and coke spilling?
Am I understanding correctly, was this a sequential fouling of a single latch without evaluating the performance between tests? Maybe the coffee has good lubricating qualities that overcame the stickiness of the soda's?
David
RE: Friction increase after coffee and coke spilling?
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RE: Friction increase after coffee and coke spilling?
Thanks for your reply.
We actually tested the latch after spilling in sequence the three liquids and without evaluating intermediate behaviour. This latch will be part of a seat in such a way that it will be difficult to visually inspect it, unless we take the seat in pieces (which occurs not always).
We want to be sure that dust and dirt or liquids spilled by mistake by the seated person, don't worsenthe latch performance.
I hope now it's clearer
Claudia
RE: Friction increase after coffee and coke spilling?
<tongue-in-cheek>
debodine
RE: Friction increase after coffee and coke spilling?
Matt
CAD Engineer/ECN Analyst
Silicon Valley, CA
sw.fcsuper.com
Co-moderator of Solidworks Yahoo! Group
RE: Friction increase after coffee and coke spilling?
Perhaps the expected results would be obtained with sugared drinks, like Gatorade and V8 Splash, or drinks containing fat and solids, like milk.
Mike Halloran
Pembroke Pines, FL, USA
RE: Friction increase after coffee and coke spilling?
Makes a very good car battery post cleaner... Make sure to wash well afterwards..
RE: Friction increase after coffee and coke spilling?
It is possible that three hours was not suffient to really dry the thing out, so that there was a lubricating film of liquid.
RE: Friction increase after coffee and coke spilling?
TTFN
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RE: Friction increase after coffee and coke spilling?
The latch is subjected to big and time-short forces. I thought that maybe in this case, passed the stickness condition at the beginning, since the speeds involved are very high, the viscosity of the residues on the surface would make the latch more "slippy".
What do you think? Bad science fiction?
Claudia
RE: Friction increase after coffee and coke spilling?
Residues may have an effect, but you need to replicate the surface conditions they impart. Perhaps an eye dropper to apply the product may be better.
Regards,
Cory
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RE: Friction increase after coffee and coke spilling?
RE: Friction increase after coffee and coke spilling?
Mike Halloran
Pembroke Pines, FL, USA
RE: Friction increase after coffee and coke spilling?
RE: Friction increase after coffee and coke spilling?
It sounds like what you need is a test that better replicates your concerns -- perhaps starting off with a test plan. Remember back to grade school and science fair projects (assuming you did those) where you had to come up with a hypothesis before you did your experiment? That's what's needed here. You need to write down what substance you're going to try and why you think it will cause the latch's performance to deteriorate, thinking through the properties of the contaminating substance.
I agree with those that noted that the substances used were all acidic and only one contained sugar. Something you might want to think about (besides using products with milk and sugar) is throwing some dust and crumbs in there (you know, the powdered doughnut to go with the coffee, the Big Mac with the Coke ...) Alcohol (as humerously suggested byscastillo) would also be good as it contains a lot of sugar. Or if the latch is encased by foam, then minute particles of foam that get dried out and brittle because of the liquids. Generally, the liquid is usually only the transport medium. It's the small particles carried by the liquid that will get caught in the latch and stick to it.
Patricia Lougheed
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RE: Friction increase after coffee and coke spilling?
Cheers
Greg Locock
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RE: Friction increase after coffee and coke spilling?
B.E.
RE: Friction increase after coffee and coke spilling?
Actually I'm only the checker for this experiment and I will definetely suggest to lab guys to repeat it again. For example writing a good test plan before.
Hopefully we'll come out with reasonable results.
Claudia
RE: Friction increase after coffee and coke spilling?