Copper Tube Laser Welding
Introduction
Use of laser welding to produce small diameter tubes allows a cost-effective method of production and has been carried out on steel tube for many years. The recent availability of high-power blue wavelength lasers allows quality welding of copper tubes at high speed – which had previously not been possible with infra-red lasers due to poor energy absorption. The Blue wavelength of NUBURU laser is absorbed by Cu by a factor of x1.2 compared that of IR lasers
Current Process
The current process for making copper tubes with diameters under 5mm consists of a billetpiercing step followed by a series of die passes at decreasing diameters. This process is not ideal for all tube sizes as the number of process steps make it less cost-effective for decreasing diameters. A simple, one-step, process exists in laser welding a thin strip of copper into a tube as it passes through a die to form its shape. Larger copper tubes are welded with well-known traditional techniques.
Testing
An AO-200 was integrated into a commercial tube welding machine to demonstrate NUBURUs capabilities in the welding of small diameter, thin walled, copper tubing. In this testing, a sheet of 0.1mm folded copper was welded at the seam to create a 2mm diameter copper tube. Cross sections reveal a clean, defect free, weld between both sides of the copper sheet. (Figure 2). Larger diameter tests were conducted on tubes ranging in wall thickness from 0.7mm to >1mm and diameters between 6 and 12mm. For this testing, 2 x AO-650 were focused down to a single spot for a combined power of 1.2W. This configuration was used to simulate NUBURU’s next product line, the AI-1500 (1.5kW BPP<11). The resulting welds were of high quality and demonstrated a key benefit to welding with blue, little to no spatter. (Figures 3,4)
Summary
NUBURU’s AO-200 provides optimal weld quality for joining thin-walled copper tubes.
As wall thicknesses increase, NUBURU’s AO-650 and AI-1500 provide the same quality and can meet the demand of most line speeds today.
Figure 1. AO-200 & AO-650.
Figure 2. Cross section of 2mm copper tube.
Figure 3. Cu seam weld
Figure 4. Cu butt weld
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