Jeff / Lou,
This question of SPC comes up from time to time on the technet and it rarely
gets a good answer. I believe this is because the question is flawed (no
offence intended).
To use SPC you must first have a need for SPC i.e. something to control so
the question should not be "How can I use / implement SPC ?" but "What
variables affect the output of my process ?"
I have found attribute charts to be useful in finding out how your process
is operating and as you try to improve the output you should discover the
key variables which affect your output.
Whilst there are many excellent books on SPC the biggest complaint I hear is
that they are not relevant for this industry. Most SPC books work on
measuring widgets X mm long off an automatic machine - easy! But all the
books can tell you is how to use the tools, not how they apply to your
industry, that relies on you getting to know your process and finding out
what makes it tick.
And most important of all don't ignore any variable e.g. quite often the key
variable is not one which is controlled by a knob on a machine but something
in the design, e.g. pad layout, hole to pad ratio etc etc.
I hope this helps, don't expect anyone to give you an ABC of how to do it
but provided you ask the right questions you'll get there!
Good Luck.
Neil Atkinson
Quality Manager
Stadium Electronic Controls
Hartlepool
England
-----Original Message-----
From: Lou Hart [mailto:[log in to unmask]]
Sent: 29 November 1999 17:03
To: [log in to unmask]
Subject: Re: [TN] SPC Information
Jeff, sorry for the delayed response to your posting. Someone earlier
suggested an IPC document on SPC in assembly. I believe it is available
now, based on what I saw in the latest IPC review. I requested it and
eagerly await its arrival (its number I forget offhand).
There have been discussions of SPC earlier in this forum, with people
exhibiting varying degrees of enthusiam. My generic feeling is: if you're
collecting data, use it. Frequently that use will be through SPC. (If
you're not using the data, stop collecting it.) You've heard Deming's
advice - Plot the dots. Individuals control charts may be useful to you.
I don't know if c or p charts would be. It depends on the volume of your
production.
Two books I've come across recently may be worth knowing about. Statistical
Control by Monitoring and Feedback Adjustment, written by Box and Luceno,
deals with basic SPC and also with methods to make adjustments in processes
where that is possible. Another book by Quesenberry treats SPC, adjustment
methods, and SPC for short-run processes. It also seems to have some nice
discussions of general quality techniques. I haven't done more than glance
through it so far.
Please don't hesitate to contact me outside TechNet if you want more
information. I am new to this business as well and would welcome the chance
to work with you on these matters.
Louis Hart
Quality Assurance Manager
Instrumentation Systems Division
Compunetix, Inc. 412-858-6184
Monroeville, PA 15146
"With the chart on the wall, with the figures published, let's emulate and
rouse our enthusiasm in production."
- State Statistical Bureau of the People's Republic of China
----------
From: Isaac Jeff[SMTP:[log in to unmask]]
Sent: Wednesday, November 24, 1999 2:03 AM
To: [log in to unmask]
Subject: [TN] SPC Information
Dear all
I would like to setup a meaningful SPC / SQC system in my production and
test
sections. I have searched the archives and have obtained useful information
and
links to websites offering software to setup / control / monitor an SPC
system.
I don't want to go on a course which will explain how to do this if the
course
tackles all industries. I would like to go on a course which relates
specifically to Electronic Manufacturing as I believe this would show me
exactly
what data I can be capturing and how to capture it which would be helpful to
control and monitor the assembly process.
Does anyone know of an SPC course that relates specifically to electronic
manufacturing in Sydney / Australia ?
or better
Does anyone know of some company / person in Sydney / Australia who would
come
to my company and explain the absolute basics of setting up a meaningful SPC
/
SQC system ? For a fee of course.
As you can tell this is very new to me, but everyone needs to start
somewhere.
To date one of the ways I've been tackling quality problems is by getting
feedback from the testing area as to the reasons for quality problems /
failures. This then highlights a number of factors in the process which I
can
address to prevent these faults (less than 0.04 dppm) from re-occuring. We
also
have inspection points along the way ie. after screenprinting, after
pick&place,
after reflow but I am at a loss to what data I can be capturing, and how to
put
this data into the various formulas out there to calculate Cpk, Cp, Ppm etc.
I
have been doing a lot of reading, but am in need of personal tuition.
Many thanks in advance for the help.
Regards,
Jeff Isaac
Hypertec Australia
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