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June 2009

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Subject:
From:
Rex Waygood <[log in to unmask]>
Reply To:
TechNet E-Mail Forum <[log in to unmask]>, Rex Waygood <[log in to unmask]>
Date:
Mon, 1 Jun 2009 08:25:07 +0100
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I don't think I could give you a step by step approach to Taguchi but I
recommend it as an experimental method.
We were waving 50,000 assemblies a week when the customer introduced a
new design. There was an RF can surrounding the pcb which had to be 100%
soldered to the edge of the pcb. Initial work showed that the board was
too small for the can and we had 8 people per shift hand soldering the
bits the wave missed. The can was manufactured using a progressive tool,
megga money to change, the pcb was punch and crunch, expensive to
change. Attempts to improve the wave process failed so we called in two
wave consultants. One was kind enough to say it was impossible at the
start of the day and didn't charge, the second spent a day, did charge
and said it was impossible.
So we did a Taguchi and our first attempt got us down to 1.5 reworkers
per shift. Further honing of the Taguchi plus some other improvements
got us to 0.5 reworkers per shift.
In terms of understanding the wave process and being able to improve the
process, Taguchi is fantastic.
I recommend that you carefully tell your operators why you are doing the
Taguchi and how it works. We had a later Taguchi sabotaged by a wave
operator who didn't like running the machine on settings he knew would
produce rubbish, he doesn't work here now!
You have to gain the co-operation of your production department as to
get points on your graphs you will have to build product that is 'bad'.
You must carefully decide what your attributes are to be so opens,
shorts and pull through might be your choice. On our first one we were
only concerned with the % of the frame soldered to the board. The beauty
of Taguchi is that if you change your mind about the importance of the
attributes you can change the machine settings in line with a paper
exercise on the Taguchi.
Picking your independent variables for a wave is not easy and is best
done in a brain storm once your team realise the definition of
independent variable. I.e. preheater setting is not independent, topside
pcb temp, is as conveyor speed would change topside temp for a given
preheat setting.
We have some software which helps with the arithmetic and array choice.

I really do think Taguchi is a great tool.
Rex

Rex Waygood
Technical Manager
 
Hansatech EMS provides value manufacturing through engineering and
quality
 
Hansatech EMS Limited
Benson Road
Nuffield Industrial Estate
Poole



-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of John Queen
Sent: 24 May 2009 13:55
To: [log in to unmask]
Subject: [TN] Taguchi

Guys have any of  you used the Taguchi process for optimisation of Wave
Solder Process. I am pretty interested in this,  and can you direct me
to examples of this process. 

 

 

 

 

 

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