Ultrasonic Energy Welds Beryllium Copper Spring to Copper Frame Ultrasonic metal welding provides a sound solution to a productionproblem with superior performance, improved throughput and reducedmaintenance. W.L. Gore & Associates, Inc. improves its competitiveadvantage by reducing 'Cost of Goods Sold'
Attempting to weld nonferrous, conductive materials such as Beryllium Copper (BeCu) to Copper (Cu) and BeCu to Brass through the use of resistance welding is difficult and can result in an unreliable weld. The amount of thermal energy required to melt the components together typically deteriorates the spring properties of the BeCu. Additionally, the process technician must contend with weld splatter and high electrode maintenance. The result is higher 'Cost of Quality' due to required mechanical and visual part inspection and frequent electrode maintenance which reduces productivity and adds cost.
Manufacturing engineers have grown accustomed to the inherent problems of resistance welding nonferrous metals. Constant inspection of mechanical integrity, electrode maintenance and weld splatter is required. The lack of a clean, controlled process has, in many cases, become accepted as a fact of life. This paper will present the reader with an efficient and reliable solution that also lends itself to high production rates.
Background (A Sound Process) Ultrasonic energy is mechanical, vibratory energy in the form of sound that operates at frequencies beyond audible sound (18,000 cycles per second and greater).Ultrasonic metal welding joins parts by applying this energy (in shear) onto the interface area between components.50/60 cycle electrical energy is transformed, by a power supply, into 20,000 (20 kHz) or 40,000 (40 kHz) cycles per second high frequency electrical energy.
This high frequency electrical energy, delivered to a piezoelectric crystal, is converted to high frequency ultrasonic mechanical energy. This mechanical vibration is transferred to a welding tip through a tapered, acoustically tuned, metal tool called a horn - (See Figure 1)
One component is held stationary while the other is 'scrubbed' against it at 20,000 (20 kHz) or 40,000 (40 kHz) cycles per second - (See Figure 2.) This high frequency vibration, coupled with force, disperses surface films and oxides creating a clean controlled diffusion weld.
As the atoms between similar or dissimilar metals combine at the part interface a true metallurgical bond is produced without the creation of intermetallics and brittle alloys - (See Figure 3.) Furthermore, the ultrasonic diffusion process does not generate the high temperature that can anneal mechanical springs nor does it require consumables such as solder, flux or braze materials
Excerpted from "Ultrasonic Energy Welds Copper to Aluminum", Welding Journal, January 1997
This high frequency electrical energy, delivered to a piezoelectric crystal, is converted to high frequency ultrasonic mechanical energy. This mechanical vibration is transferred to a welding tip through a tapered, acoustically tuned, metal tool called a horn - (See Figure 1) 
One component is held stationary while the other is 'scrubbed' against it at 20,000 (20 kHz) or 40,000 (40 kHz) cycles per second - (See Figure 2.) This high frequency vibration, coupled with force, disperses surface films and oxides creating a clean controlled diffusion weld. 
As the atoms between similar or dissimilar metals combine at the part interface a true metallurgical bond is produced without the creation of intermetallics and brittle alloys - (See Figure 3.) Furthermore, the ultrasonic diffusion process does not generate the high temperature that can anneal mechanical springs nor does it require consumables such as solder, flux or braze materials 
