The e-cigarette industry is evolving rapidly. When e-cigs first came on the market, production rates and volumes were low – the earliest e-cig manufacturing lines had a production goal of about 30-50 e-cigs per minute. As demand for e-cigs has increased, manufacturers have been pushing production volumes dramatically – production goals of 300 or more e-cigs per minute are now being required. As production rates increase, new technologies are needed to support a robust manufacturing process that can keep up with the growing volumes while maximizing yield and reducing scrap.
The first generation laser solutions developed for the e-cig manufacturing process included welding an AISI 304 (SUS 304) grade stainless steel terminal to a Ni-chrome wire using a lap weld from the top. The goal was to capture as many wires as possible, without cutting any wire between the two terminals. The width of the terminal was about 750 microns and the spacing was 4 millimeters. The solution used a 25W pulsed Nd:YAG laser with fixed focus head and a spot size of approximately 400 microns (µm). There was limitation in throughput, and a single shot was not quite wide enough. See Figure 1:
Since then, several second generation solutions have been designed to improve product throughput. For example, using a pulsed Nd:YAG laser that divides the beam into two evenly powered spots with a maximum separation of 0.03-inches. A 25 or 50W pulsed Nd:YAG with fixed focus head and dual spot output is used, with a spot size approximately of approximately 700µm wide. This dual spot capability allows the weld to match the joint configuration; it also provides a more optimal weld across the joint area. The system is tunable, so users can find just the right spacing. This solution provides a better capture of wires; the only limitation is energy loss, so it requires the use of a higher powered laser.
Another second generation solution is using a pulsed Nd:YAG laser welder combined with a galvo-based scan head. Here, the spot size is approximately 500µm (similar to the first generation); however, the galvo scan head can be used to rapidly and precisely position two spots. By overlapping two pulses, the total weld width can be approximately700µm. This option gets you flexibility in the positioning and number of spot welds per terminal. Movement of the galvo mirrors is extremely rapid and translates to a position at the focal point of meters per second (m/s). This enables a rapid fire welding; pulses can be fired at a rate of close to 20 hertz (Hz) for any spots within the working field size of the f-theta lens. Figure 2 shows the galvo laser setup. Read more about galvo laser welding (scan head welding) in our blog "Scan heads for micro laser welding: “Ham n’ Eggs” of laser industry."
The demand for second generation solutions is just beginning to grow, but several systems have been put into production, and many more are in the pipeline. Amada Miyachi now provides basic laser componentry to a variety of the largest machine builders and integrators who are building e-cig processing lines and supplying an integrated manufacturing system. End users include several large US-based tobacco companies and a variety of Asian companies.