The number I have heard attached to the term "Worlclass" for an SMT
operation is running at fewer than 50dpmo (defects per million
oportunities).
What I know about that number is that few companies know where they stand
with respect to it, fewer companies even want to talk about it. But the
companies that open up a little when this subject comes up are indeed
shooting for a number around 50dpmo and very few, that I know of, have
reached that point yet. Some have!!
Have fun getting there (it is even more fun savoring it when you do get
there),
Ahne.
PS: You cannot produce "Worldclass" garbage, unless garbage is your
business.
-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Charles Caswell
Sent: Wednesday, November 06, 2002 11:53
To: [log in to unmask]
Subject: Re: [TN] Efficiency / Effectivity of your SMT lines
I had it explained to me once. World Class is anything you want it to be.
You can produce "World Class" good stuff as well as "World Class" garbage.
Charles Caswell
-----Original Message-----
From: Steve MacDonald [mailto:[log in to unmask]]
Sent: Wednesday, November 06, 2002 1:24 PM
To: [log in to unmask]
Subject: Re: [TN] Efficiency / Effectivity of your SMT lines
Greetings all. I'm not sure if I'm side tracking here, but...
As a Quality manager burdened with PWB Fab, Assembly, and among other
things, ISO systems, the idea of a Benchmark that defines "World Class" is
intriguing to me. I have heard the phrase used. Can anyone enlighten me to
ANY set of guidlines, in any kind of business, that define, demarkate,
outline, or otherwise identify the point at which any part of any process,
or output can be "officially" quantified as "World Class?"
(Just as a side note: I have asked Quality Consultans about it, and they
don't seem to know either. We might all love a point of reference. I just
hope it's not another ethereal, unquantifiable, Buzz term)
Thanks,
Steve MacDonald
QM / ISO MR
Mass Design Inc.
----- Original Message -----
From: Howard Watson
To: [log in to unmask]
Sent: Wednesday, November 06, 2002 1:08 PM
Subject: Re: [TN] Efficiency / Effectivity of your SMT lines
Thanks Ryan, very accurately stated. It has been my experience that
the machine manufacturers like to use the third method of stating cycle
time. While this is the target, I have not seen this achieved often,
because there are those machine stoppages that seem to occur way more than
desired. You are right on target regarding the "mother lode", and this is
an area that I have been trying to optimize. For example, we had
significant part rejects, 40 - 50%, on a dome LED, and the final solution
was to ream out the nozzles to obtain a seating on the flat part of the
body. Rejects dropped to .2%. We have issues with tube parts that require
a lot of attention and are a big contributor to the mother lode. Reloading
feeders is still an issue to be resolved.
I'm curious if there are machine run time numbers that are a standard
for "World Class". It seems like the term is used often these days, but
what exactly does it mean from the perspective of operating efficiency?
Anyone?
Howard Watson
SMT Manufacturing Engineer
AMETEK/Dixson
rgrant <[log in to unmask]>
11/05/02 05:27 PM
To: "'TechNet E-Mail Forum.'" <[log in to unmask]>,
"'Howard Watson'" <[log in to unmask]>
cc:
Subject: RE: [TN] Efficiency / Effectivity of
your SMT lines
Ehem...(clearing my voice as I climb on the soap box)
With tracking efficiency, you are essentially trying to get the most
amount of product out of a set of machines that you possibly can. To figure
that, you want to know what is theoretically possible and how close you come
to theoretical. Since many brands of pick and place machines keep a record
of what state they are in, you can query that data and get some eye opening
results.
I have found that cycle times can be figured three different ways,
giving very different results. First, looking at a 24 hour period, how many
boards came out of that machine. This is real world cycle time planning
should use, and is the ultimate bottom line. This time includes set up time
and any decreases in change over will positively affect you cycle time.
Second, looking at the time that the line is actually running divided
by the number of board produced. This is the cycle time that determines
your constraint and paces the line.
Third is the time it actually takes for the machine to assemble the
board. This is the theoretical cycle time.
I'm guessing here, but you probably do 2-3 change overs per 24 hour
period. Not using docking carts, change overs could be as high as two
hours. Assuming you get it down to 10 minutes, that means you gain 5 1/2
hours of number two time. That would be awesome, and would improve
efficiency by 25%. This is probably an extreme case, so adjust the numbers
accordingly.
However, if you look at the numbers between number two time and number
three time (theoretical time), you will typically find a difference by a
factor of three or more. This is the "mother load". Your efficiencies are
lost by not focusing all attention on your constraint and keeping that
machine fed, up and running. In other words, any time the constraint
"waits" for product to arrive so it can start working, you have lost time.
Any time the machine stops for any kind of error, you have lost time. Any
time the machine stops for a feeder to be reloaded, you have lost time.
These time losses are only a dozen seconds or a minute or two, but they add
up over a 24 hour period. As a constraint, there is no reason that machine
shouldn't be able to run continuously at near its theoretical limit. I'm
not talking about improving the placement time, just keep that machine busy.
! By improving the "working" time on your constraint, there is an easy 100%
improvement in line efficiency, and it doesn't cost anything. Just an
attitude change from management down to the production line to identify the
constraint and focus on keeping it working.
I have worked in factories where this concept has improved output by a
factor of three, therefore I'm extremely sold on it. As far as what is
possible, I have seen lines where the constraint was "working" 80% of the
time the machine was plugged into the wall. What is realistic... I have
heard reports from machine manufactures that the CM industry is at about
20-40% machine working time. Of course, those at 80-90% working time are
not high mix, low volume.
Not that improving change over time is bad, I just think that
attention should be focused on the place with the greatest potential for
improvement.
Ryan Grant
-----Original Message-----
From: Howard Watson [mailto:[log in to unmask]]
Sent: Tuesday, November 05, 2002 3:47 PM
To: [log in to unmask]
Subject: [TN] Efficiency / Effectivity of your SMT lines
Dear TechNet subscribers,
I am curious about the level of productivity of your SMT lines,
particularly for those in a high mix environment. We are getting pressure
to reduce changeover and cycle times, as I am sure most of you are too, and
I am curious as to what level of effectivity (hours available in the day do
you actually build product) that you are at. Would 80% be reasonable?
Also, how efficient are you at building your product to standards, for those
who track efficiency?
As far as changing over from one job to the next, what are your
average times? It was suggested to me by management that the goal for
changeover should be 1 minute or less. I am a reasonable person, and I
believe that single digit (SMED) changeovers, like 8 or 9 minutes might be
reasonable, but 1 minute is a stretch that I can't see happening, even when
using docking carts for the feeders. Thanks in advance for your input.
Howard Watson
SMT Manufacturing Engineer
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