bernardg
Computer
- Nov 19, 2002
- 47
Hello all,
In one of our applications, we attach the "metal-graphite brushes" to the "brass terminals" by ultrasonically welding the brush shunts (or pig tail - made of copper braided strands) to the terminals.
This is being a bottle neck operation, because we are having repeated instances... where we couldn't weld the brush braids to the terminals consistently.
After a careful analysis of this problem, we found out that, there are a considerable amount of brushes whose pigtails are contaminated with brush dust.
As with the ultrasonic welding machine… the parameters (energy level, power & amplitude of vibration) were customized for the copper braids /pigtail. So, while using the contaminated pigtails, the machine couldn’t weld it because the energy level required welding it changes due to the inclusion of brush dust.
FYI. We nuggatize the end of the pigtails using resistance-welding to bundleup the braids to ease the assembly process. The speculation at this point is that the brush dust gets deposited in the pigtails and is embedded into it during the resistance welding. So during the actual ultrasonic welding process, the energy it takes to complete the weld increases because of the contamination. Then, when we increased the weld energy, though it gave us a good weld on the contaminated pigtails... but when the brushes with good pigtails were used, it over-welds it... resulting in a fracture at the transition.
(1) How to set the parameters, so that it would work for both (good and contaminated pigtails).
(2) Have anyone experienced a failure in the ultrasonic metal weld process do to the contamination? If so, how did you overcome it?
Also, kindly shed me some light on the different parameters and how they are related during the welding operation.
Thanks in advance for being generous with your time and expertise.
bernie
In one of our applications, we attach the "metal-graphite brushes" to the "brass terminals" by ultrasonically welding the brush shunts (or pig tail - made of copper braided strands) to the terminals.
This is being a bottle neck operation, because we are having repeated instances... where we couldn't weld the brush braids to the terminals consistently.
After a careful analysis of this problem, we found out that, there are a considerable amount of brushes whose pigtails are contaminated with brush dust.
As with the ultrasonic welding machine… the parameters (energy level, power & amplitude of vibration) were customized for the copper braids /pigtail. So, while using the contaminated pigtails, the machine couldn’t weld it because the energy level required welding it changes due to the inclusion of brush dust.
FYI. We nuggatize the end of the pigtails using resistance-welding to bundleup the braids to ease the assembly process. The speculation at this point is that the brush dust gets deposited in the pigtails and is embedded into it during the resistance welding. So during the actual ultrasonic welding process, the energy it takes to complete the weld increases because of the contamination. Then, when we increased the weld energy, though it gave us a good weld on the contaminated pigtails... but when the brushes with good pigtails were used, it over-welds it... resulting in a fracture at the transition.
(1) How to set the parameters, so that it would work for both (good and contaminated pigtails).
(2) Have anyone experienced a failure in the ultrasonic metal weld process do to the contamination? If so, how did you overcome it?
Also, kindly shed me some light on the different parameters and how they are related during the welding operation.
Thanks in advance for being generous with your time and expertise.
bernie
