We too have to crimp solid wire and back solder using 63/37. We have numerous applications that require, capacitors, diodes, resistors, and noise suppressors be attached to terminal boards using standard T&B tinned lugs. Most of the wires range in the 18-20 gauge range with a few in the 16-18 range. Our engineering has written a specification and a procedure that states how it must be done, basically the lug is crimped on the single wire and then soldered to fill all voids, we use a standard calibrated T&B ratchet crimper with the correct nest for non-insulated sta-kon terminal being used. If the wire is of insufficient size to crimp correctly then filler strands may be added and the lug crimped in the normal manner, without soldering.
We have found that if the solid wire in the lug is not soldered and is worked, it will eventually work loose, even with the correct crimp.
I would not recommend boring out the barrel to get a larger wire in a smaller barrel, I would get the correct size lug, or have a special crimper built that does a hex crimp or circumferential crimp on the thinner barrel to obtain a better boundary area, the thinner barrel if dimple crimped may not have sufficient material strength to provide tight enough contact on the magnet wire.
Pat Goodyear
Control Technician
Pacific Gas and Electric
-----Original Message-----
From: TechNet [mailto:[log in to unmask]] On Behalf Of Gerald Bogert
Sent: Wednesday, October 24, 2012 7:26 AM
To: [log in to unmask]
Subject: [TN] Crimping to AWG 8 solid magnet wire
October 24, 2012
IPC/WHMA-A-620 includes the following requirements pertaining to crimping to solid wire.
a. Crimping to solid wire is not allowed except for connector center
contact.
b. Crimp tool cycle must be completed.
We have an OEM who crimps a solid AWG # 8 gage magnet wire (stripped to remove insulation) to a standard AN-8 (T&B) NAVY type terminal lug using a manual hydraulic crimp tool that has adjustable pressure settings. If the crimp is performed at 90 PSI, one gets a complete tool cycle which leaves a deep crimp impression on the top surface of the lug and the # 8 impression on the reverse side of the lug. One can see a bell-mouth at both ends of the lug. If a 60 PSI setting is used, the crimp forms and one can see two small crimp impressions on the top of the lug but nothing on the back side of the lug. Both settings result in the lug barrel forming around the OD of the stripped magnet wire. The OEM uses the 60 PSI setting because of the concern of over crimping at the 90 PSI setting resulting in possible damage to the wire. At one time the lugs were brazed rather than crimped but this process caused some lugs to crack so they changed from braze to crimp.
The contract drawing also mandates that the lugs be soldered after crimping and that the solder must flow to fill any voids inside the lug barrel.
Based on the above, I have the following questions that I would appreciate a response to:
1. What is the technical basis for not allowing crimp to solid wire
for any solid wire other than for connectors and why would we not have the same concern for connector crimp?
2. Would one expect solder to flow into the ID of the lug with the
60 or 90 PSI settings?
3. Assuming the 60 psi crimp is pull tested and passed, is this a
technically acceptable crimp? If not, why not?
[log in to unmask]
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask] ______________________________________________________________________
PG&E is committed to protecting our customers' privacy.
To learn more, please visit http://www.pge.com/about/company/privacy/customer/
______________________________________________________________________
This email has been scanned by the Symantec Email Security.cloud service.
For more information please contact helpdesk at x2960 or [log in to unmask]
______________________________________________________________________
|
