OT: Sanyo Vacuum Cleaner Failure

S

Sylvia Else

Guest
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?

Sylvia.
 
Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?

Sylvia.
Click to expand...
Must have been designed by the Comet Jet roof hatch engineers. It's been
a long time since such things were an issue for appliance engineers and
it's a foreign concept for appliance "Designers" obsessed with style.
 
Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?
Click to expand...
At the same time when all layouters and engineers learn not to use sharp
corners in their PCB artwork for mission critical stuff. Which probably
means never because it doesn't look cool :)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
"Sylvia Else" <sylvia@not.here.invalid> wrote in message
news:8gvueeF67gU1@mid.individual.net...
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?
Click to expand...

When are consumers going to learn that most manufacturers *design* products
so they won't last forever?
I'm betting the vac was out of warranty, right?

MrT.
 
"Joerg" <invalid@invalid.invalid> wrote in message
news:8h19btFf3hU1@mid.individual.net...
Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?


At the same time when all layouters and engineers learn not to use sharp
corners in their PCB artwork for mission critical stuff. Which probably
means never because it doesn't look cool :)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
Click to expand...

Sharp track corners don't look cool!

I spend years listening to a SW engineer in our office criticising me for
spending time laying out boards correctly. He just didn't get it that the
layout had consequences even for lower speed stuff.
 
On 6/10/2010 12:52 PM, Mr.T wrote:
"Sylvia Else"<sylvia@not.here.invalid> wrote in message
news:8gvueeF67gU1@mid.individual.net...
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?


When are consumers going to learn that most manufacturers *design* products
so they won't last forever?
I'm betting the vac was out of warranty, right?
Click to expand...
Yes, but I'm sceptical of the idea that a part could be designed to
suffer this failure mode in anything like a predictable time. I'll stick
with the hypothesis that this was due to incompetence, not planned
obsolescence.

Sylvia.
 
"Sylvia Else" <sylvia@not.here.invalid> wrote in message
news:8h2gbtFtlgU1@mid.individual.net...
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?


When are consumers going to learn that most manufacturers *design*
products
so they won't last forever?
I'm betting the vac was out of warranty, right?


Yes, but I'm sceptical of the idea that a part could be designed to
suffer this failure mode in anything like a predictable time. I'll stick
with the hypothesis that this was due to incompetence, not planned
obsolescence.
Click to expand...

Of course it's not predictable, it's just guesswork. IF they get too many
coming back under warranty they fix the design, otherwise it's a "feature".

MrT.
 
On 6/10/2010 5:41 PM, Mr.T wrote:
"Sylvia Else"<sylvia@not.here.invalid> wrote in message
news:8h2gbtFtlgU1@mid.individual.net...
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?


When are consumers going to learn that most manufacturers *design*
products
so they won't last forever?
I'm betting the vac was out of warranty, right?


Yes, but I'm sceptical of the idea that a part could be designed to
suffer this failure mode in anything like a predictable time. I'll stick
with the hypothesis that this was due to incompetence, not planned
obsolescence.


Of course it's not predictable, it's just guesswork. IF they get too many
coming back under warranty they fix the design, otherwise it's a "feature".
Click to expand...
It's an expensive thing to get wrong.

Sylvia.
 
Sylvia Else wrote:
On 6/10/2010 12:52 PM, Mr.T wrote:
"Sylvia Else"<sylvia@not.here.invalid> wrote in message
news:8gvueeF67gU1@mid.individual.net...
The cleaning head fell off my Sanyo vacuum cleaner while I was
using it today.

A 3cm plastic tube has sheered all he way round. I looks like a
typical crack propagation failure, with the break completely clean
for 2/3 of the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp
corners in load-bearing plastic components?


When are consumers going to learn that most manufacturers *design*
products so they won't last forever?
I'm betting the vac was out of warranty, right?


Yes, but I'm sceptical of the idea that a part could be designed to
suffer this failure mode in anything like a predictable time. I'll
stick with the hypothesis that this was due to incompetence, not
planned obsolescence.
Click to expand...
**There is an apocryfal tale told about Henry Ford. It goes something like
this:

During the run of the Model T, Henry Ford sent investigators all over the US
to wrecking yards. They were told to investigate old Model T cars and report
on what components had failed on the vehicles.

The investigators reported that most of the components of the Model T failed
at more or less similar figiures. Except one. One component was surprisingly
reliable on the Model T. The king pins.

Henry Ford then, allegedly, instructed his engineers to make the king pins
cheaper.


--
Trevor Wilson
www.rageaudio.com.au
 
Dennis wrote:
"Joerg" <invalid@invalid.invalid> wrote in message
news:8h19btFf3hU1@mid.individual.net...
Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?

At the same time when all layouters and engineers learn not to use sharp
corners in their PCB artwork for mission critical stuff. Which probably
means never because it doesn't look cool :)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.


Sharp track corners don't look cool!
Click to expand...
It's a matter of taste I guess. Young engineers like those sharp 45
degree turns. Totally rounded ones are better, of course, but I've heard
people say "Eeuw, that looks like the old Rubylith spaghetti layout".
Well, yeah, it does but it'll last.


I spend years listening to a SW engineer in our office criticising me for
spending time laying out boards correctly. He just didn't get it that the
layout had consequences even for lower speed stuff.
Click to expand...
And it has reliability consequences if rough handling is to be expected.
There's a reason why bush pilots drill a hole at each end of a tear.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
"Trevor Wilson"
**There is an apocryfal tale told about Henry Ford. It goes something like
this:

During the run of the Model T, Henry Ford sent investigators all over the
US to wrecking yards. They were told to investigate old Model T cars and
report on what components had failed on the vehicles.

The investigators reported that most of the components of the Model T
failed at more or less similar figiures. Except one. One component was
surprisingly reliable on the Model T. The king pins.

Henry Ford then, allegedly, instructed his engineers to make the king pins
cheaper.
Click to expand...

** Then there is the *non apocryphal* story involving the famous Rolls Royce
" Merlin " V12 aeroplane engine of WW2 ( used in Spitfires, Hurricanes,
Mustangs and Lancaster bombers) that goes the OPPOSITE way.

Quote:

The first production version Merlin I was assigned for Fairey Battle
production. Only 175 had been built and these were considered to be rather
unreliable. As a result, Rolls-Royce introduced an ambitious
reliability-improvement programme to fix the problems. This consisted of
taking random engines from the end of assembly line and running them
continuously at full power until they failed. Each was then dismantled to
find out which part had failed, and that part was redesigned to be stronger.
After two years of this programme the Merlin had matured into one of the
most reliable aero engines in the world, and could sustain eight-hour combat
missions with no problems.

http://spitfiresite.com/2010/04/the-development-of-rolls-royce-merlin-engine.html



...... Phil
 
On 6/10/2010 4:18 PM, Dennis wrote:
"Joerg"<invalid@invalid.invalid> wrote in message
news:8h19btFf3hU1@mid.individual.net...
Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?


At the same time when all layouters and engineers learn not to use sharp
corners in their PCB artwork for mission critical stuff. Which probably
means never because it doesn't look cool :)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.


Sharp track corners don't look cool!

I spend years listening to a SW engineer in our office criticising me for
spending time laying out boards correctly. He just didn't get it that the
layout had consequences even for lower speed stuff.
Click to expand...
I'd have thought you'd just have to remind him that he's a software
engineer, not an electronics engineer.

I've seen recommentations from board manufacturers that one avoid 90
degree bends, but I took that to be more about manufacturing tolerances
that stress concentration. Neither of the two layout programs I've tried
provided the option of curved traces, as far as I can remember.

I'm surprised if track fracture shows up as a significant cause of
failure, but if it does, it wouldn't be the first true thing I've been
surprised about.

One would also have to consider the corners formed where traces become
component mounting pads.

Sylvia.
 
On 7/10/2010 7:27 AM, Joerg wrote:

And it has reliability consequences if rough handling is to be expected.
There's a reason why bush pilots drill a hole at each end of a tear.
Click to expand...
I've used the same technique on a plastic pedal-bin in the past :)

It can be hard to judge where the end of the crack actually is :(

Sylvia.
 
On 5/10/2010 5:21 PM, Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?

Sylvia.
Click to expand...
Sanyo initially replied to my initial complaint by reference to the
warranty period, and that I'd have to buy a new part if the machine was
out of warranty.

I sent a rather caustic second email pointing out that I wasn't making
an inquiry about spare parts, but was making a complaint about a design
flaw. I said that such a flaw meant that the goods were not of
merchantable quality from day one, and that this meant that there
existed the theoretical option of my suing them. However, I indicated
that I didn't consider it worthwhile.

I didn't expect any response. But instead Sanyo have said that they'll
send me a new part.

Sylvia.
 
On 11/10/2010 11:08 AM, Sylvia Else wrote:
On 5/10/2010 5:21 PM, Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?

Sylvia.

Sanyo initially replied to my initial complaint by reference to the
warranty period, and that I'd have to buy a new part if the machine was
out of warranty.

I sent a rather caustic second email pointing out that I wasn't making
an inquiry about spare parts, but was making a complaint about a design
flaw. I said that such a flaw meant that the goods were not of
merchantable quality from day one, and that this meant that there
existed the theoretical option of my suing them. However, I indicated
that I didn't consider it worthwhile.

I didn't expect any response. But instead Sanyo have said that they'll
send me a new part.

Sylvia.
Click to expand...
Oops - my mistake. On seeing the copy of the receipt, they've said it's
out of warranty.

Sylvia.
 
On 11/10/2010 11:38 AM, Sylvia Else wrote:
On 11/10/2010 11:08 AM, Sylvia Else wrote:
On 5/10/2010 5:21 PM, Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?

Sylvia.

Sanyo initially replied to my initial complaint by reference to the
warranty period, and that I'd have to buy a new part if the machine was
out of warranty.

I sent a rather caustic second email pointing out that I wasn't making
an inquiry about spare parts, but was making a complaint about a design
flaw. I said that such a flaw meant that the goods were not of
merchantable quality from day one, and that this meant that there
existed the theoretical option of my suing them. However, I indicated
that I didn't consider it worthwhile.

I didn't expect any response. But instead Sanyo have said that they'll
send me a new part.

Sylvia.

Oops - my mistake. On seeing the copy of the receipt, they've said it's
out of warranty.

Sylvia.
Click to expand...
However, after my further comment regarding the Trade Practices Act and
design flaw, they have, without conceding my point, said that they'll
send me a replacement.

Sylvia.
 
Sylvia Else wrote:
On 7/10/2010 7:27 AM, Joerg wrote:

And it has reliability consequences if rough handling is to be expected.
There's a reason why bush pilots drill a hole at each end of a tear.

I've used the same technique on a plastic pedal-bin in the past :)

It can be hard to judge where the end of the crack actually is :(
Click to expand...
True. Sometimes it helps to shine a really strong light through there.
Most plastic, even dark stuff, is to some extent translucent and that
way faults can show themselves.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
Sylvia Else wrote:
On 6/10/2010 4:18 PM, Dennis wrote:
"Joerg"<invalid@invalid.invalid> wrote in message
news:8h19btFf3hU1@mid.individual.net...
Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?


At the same time when all layouters and engineers learn not to use sharp
corners in their PCB artwork for mission critical stuff. Which probably
means never because it doesn't look cool :)

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.


Sharp track corners don't look cool!

I spend years listening to a SW engineer in our office criticising me for
spending time laying out boards correctly. He just didn't get it that the
layout had consequences even for lower speed stuff.

I'd have thought you'd just have to remind him that he's a software
engineer, not an electronics engineer.

I've seen recommentations from board manufacturers that one avoid 90
degree bends, but I took that to be more about manufacturing tolerances
that stress concentration. Neither of the two layout programs I've tried
provided the option of curved traces, as far as I can remember.

I'm surprised if track fracture shows up as a significant cause of
failure, but if it does, it wouldn't be the first true thing I've been
surprised about.

One would also have to consider the corners formed where traces become
component mounting pads.
Click to expand...
That is one reason why good layout software offers things such as
teardrop pads as a feature, meaning you don't have to write your own
macros to create those:

http://www.moodle.ee.ttu.edu/file.php/1/layout/lay_ug.pdf

The main area where stress fracture play a big role is connectors. No
matter whether they are additionally secured via screws there will be
forces tugging at the pins. That tugging continues into the board to
some extent. Especially if a right-angle connector has the pins in the
board but is then bolted to a panel.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
Sylvia Else wrote:
On 11/10/2010 11:38 AM, Sylvia Else wrote:
On 11/10/2010 11:08 AM, Sylvia Else wrote:
On 5/10/2010 5:21 PM, Sylvia Else wrote:
The cleaning head fell off my Sanyo vacuum cleaner while I was using it
today.

A 3cm plastic tube has sheered all he way round. I looks like a typical
crack propagation failure, with the break completely clean for 2/3 of
the way round, before it obviously failed in overload.

And the origin of the crack? Yup, you've guessed it. A sharp corner.

When are designers going to learn that you cannot have sharp corners in
load-bearing plastic components?

Sylvia.

Sanyo initially replied to my initial complaint by reference to the
warranty period, and that I'd have to buy a new part if the machine was
out of warranty.

I sent a rather caustic second email pointing out that I wasn't making
an inquiry about spare parts, but was making a complaint about a design
flaw. I said that such a flaw meant that the goods were not of
merchantable quality from day one, and that this meant that there
existed the theoretical option of my suing them. However, I indicated
that I didn't consider it worthwhile.

I didn't expect any response. But instead Sanyo have said that they'll
send me a new part.

Sylvia.

Oops - my mistake. On seeing the copy of the receipt, they've said it's
out of warranty.

Sylvia.

However, after my further comment regarding the Trade Practices Act and
design flaw, they have, without conceding my point, said that they'll
send me a replacement.
Click to expand...
Another useful hint in such letters can be that the matter is currently
being discussed on the Internet. This often results in a sudden outburst
of courtesy :)

I usually try to find the name and valid email address of one of the
higher-ups. VP or quality control, CEO, or similar. And if I really have
my druthers I tend to always find that kind of information.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
 
On Mon, 11 Oct 2010 10:07:55 -0700, Joerg <invalid@invalid.invalid> wrote:

Sylvia Else wrote:
On 7/10/2010 7:27 AM, Joerg wrote:

And it has reliability consequences if rough handling is to be expected.
There's a reason why bush pilots drill a hole at each end of a tear.

I've used the same technique on a plastic pedal-bin in the past :)

It can be hard to judge where the end of the crack actually is :(


True. Sometimes it helps to shine a really strong light through there.
Most plastic, even dark stuff, is to some extent translucent and that
way faults can show themselves.
Click to expand...
Drill the hole a bit further away from apparent end of cut and then work
the crack to see it hit the hole. Repeat if you misjudged end of crack ;)

Grant.
 
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