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February 2001

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Subject:
From:
David Hillman <[log in to unmask]>
Reply To:
TechNet E-Mail Forum.
Date:
Fri, 16 Feb 2001 12:09:22 -0600
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Hi Ken - there is one other cracking root cause you should explore. What
type of metal is the standoff made out of? Some of the metals used for
standoffs (e.g. some 300 series stainless steels) can undergo workhardening
during forming. Workhardening reduces the formability of the standoffs.
Most standoff fabricators use "annealed" feedstock but if too much
workhardening occurs during fabrication then you can have a splitting issue
during installation.  Good Luck.

Dave Hillman
Rockwell Collins
[log in to unmask]




Ken Bloomquist <[log in to unmask]>@IPC.ORG> on 02/06/2001 08:12:56 AM

Please respond to "TechNet E-Mail Forum." <[log in to unmask]>; Please respond
      to Ken Bloomquist <[log in to unmask]>

Sent by:  TechNet <[log in to unmask]>


To:   [log in to unmask]
cc:

Subject:  Re: [TN] Standoffs



Thanks for the reply Guy,

We have tried a wide range of pressure and speeds using everything from a
hydraulic press to an arbor press. They still split and according to the
standoff people that's to be expected. We have found that making the hole
within a couple of thousandths of the standoff shank diameter helps.

In our case an electrically active terminal is a standoff that a lug gets
screwed to. We don't have any problem with bifurcated and turret terminals.

The bigger questions is how do people address splits like this in a part
that is not directly referred to in the J-STD or 610? Do you worry about
entrapment of processing fluids ad mentioned in J-STD?

Thanks,

Ken
-----Original Message-----
From: Guy Ramsey [mailto:[log in to unmask]]
Sent: Tuesday, February 06, 2001 4:54 AM
To: TechNet E-Mail Forum.; Ken Bloomquist
Subject: RE: [TN] Standoffs


IPC-A-610 says that the performance requirements apply to electrically
active terminals. So they would apply to bifurcated and turrent terminals.

In a former life, we accepted splits as normal for certian types of
terminals. Then we hired a guy with lots of experience and knowledge, a
process engineer. He taught us how to set up the swage tools. The splits
went away.

The secret was speed. We were forming the terminals too quickly. The press
had two adjustments, a regulator for pressure, the other was a valve
controled the speed with which the pressure was applied. The correct
combination of pressure and speed gave target terminals.


 Guy Ramsey
American Competitiveness Institute
Senior Lab Technician / Instructor
610 362-1200 ext 107


-----Original Message-----
From: TechNet [mailto:[log in to unmask]]On Behalf Of Ken Bloomquist
Sent: Monday, February 05, 2001 1:57 PM
To: [log in to unmask]
Subject: [TN] Standoffs


Hi Technetters,

I have a question on threaded standoffs, swaged into printed wiring boards,
that are used for mounting wire lugs and chassis mounting. I'm interested
in both roll swaged and flared flange both soldered and non-soldered.

Using the guidelines of J-STD-001, do the same rules for splits and cracks
apply to standoffs as do for bifurcated and turret terminals? In
discussions with numerous standoff manufacturers they tell me that these
parts WILL split but do not affect form, fit or function. J-STD-001 seems
to be concerned with entrapment of processing fluids and does not address
standoffs.

How do others handle these type of components especially regarding splits
and cracks that extend into the shank?

Ken Bloomquist
General Dynamics
Ordnance and Tactical Systems
Aerospace Operations

P.O. Box 97009
Redmond, WA 98073-9709
425-885-5000
[log in to unmask]
http://www.gd-ots.com/aehome.html



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