Today’s post is a visual portrayal of how to optimize peak power and pulse width during laser welding.
Topics: laser welding
Laser technology in manufacturing is everywhere, touching our lives in many, invisible ways. For example, lasers are used to cut the material that the airbags in our cars are made of, the glass for our smart phone and tablet screens and the tiny, delicate medical stents used to improve our health and enhance our longevity. Lasers are used to weld airbag detonators, and the batteries in our handheld mobile devices; to drill engine components for planes; and to mark or engrave all of the above.
Lasers create welds by outputting either discrete packets of energy known as pulses or extended output known as a continuous wave. A pulsed laser produces a series of pulses at a certain pulse width and frequency until stopped. Continuous wave (CW) simply means that the laser remains on continuously until stopped. Pulsed Nd:YAG lasers operate in pulsed mode only, diode lasers operate in continuous wave, and fiber lasers can operate in either pulsed or CW mode.
How do lasers weld? When laser welding metal, one must first raise the temperature of the metal to a point where the laser's energy can be absorbed by the material. To do this, the laser is focused on the material much like the sun might be focused by a magnifying glass for a science experiment, only the laser’s power density is many orders of magnitude higher, around 106 Watts per square centimeter (W/cm2).
Topics: laser welding
Microsecond fiber and pulsed Nd:YAG lasers have been used successfully for hypo tube and stent cutting for many years. The only downside is that cut parts often require a number of post processing operations, depending on material and part requirements. These additional manufacturing steps can add significant cost; they also add to the handling logistics burden for what, in many cases, are mechanically delicate parts, not to mention the added problem of having to deal with chemical-based processes and the disposal of hazardous waste.
Once the commercial justification for bringing laser technology in house is complete, new to laser manufacturers may still have some technical concerns. We’ve recently worked on several very successful collaborations with first-time to laser manufacturers to turn their mountains into mole hills. Now each system is on the floor in production and everyone is wondering what all the fuss was about.
Aluminum alloys, are lightweight, possess good thermal and electrical conductivity, and are relatively inexpensive to work with. Therefore, it’s no surprise that they are being used with increased frequency in product manufacturing applications ranging from batteries and electronics packaging, to automotive components and consumer goods packaging. Laser welding aluminum, however, is more difficult than welding steels for three key reasons: high reflectivity, surface oxide layer, and volatile alloying elements.
Miyachi Unitek is no stranger to patented inventions (at last count, I think the company has 19), and the patent recently issued to NASA raises that number by 1...IMHO.
Topics: laser welding
Laser micro welding of conductive materials like copper has always been somewhat of a difficult proposition due to copper’s high reflectivity at the 1064nm wavelength. 532nm “green” laser welders however, remove this barrier, offering a truly viable method for laser micro welding copper (and other conductive materials) in high volume.
One of the great things about working for Miyachi Unitek Corporation is the company’s near-religious zeal for innovation. I feel like it’s really in our “DNA,” - and while it can be frustrating to ‘finish’ a new technical datasheet only to find out that the product has been tweaked/improved in the time it took to print it - it’s something that I’m proud to be a part of. As a company, we have always provided not only equipment, but also complete manufacturing solutions, which require an understanding of both equipment and process. We are always helping people answer the question, “Is there a better way to do this?”
That innovative spirit recently got its just rewards, as Miyachi Unitek was named one of 14 finalists in the Patrick Soon-Shiong Innovation Awards, presented by the Los Angeles Business Journal and NantWorks. We were honored as an organization that “expands the boundaries of its industry and leads the region in impactful innovation.” I have to admit it felt good to get kudos for some of the technical innovations we have spearheaded in the past decade, and recognition for the impact some of these innovations. I’d like to give our readers just a few examples.
- Application of three-dimensional laser cutting for production of arthroscopic surgery devices – This is a method of using a five-axis motion platform to achieve true three dimensional contour cutting for a shaver used to cut away and remove unwanted fragments of the cartilage from a joint during arthroscopic surgery. With this technique, the edge quality of the laser cut tube is nearly flawless, minimizing the extent of secondary manufacturing process steps. This means better shavers, better surgeries, lower risks and ultimately a better quality of life for many people.
- New welding technique enables crack free welding of high silicon Al-Si controlled expansion alloys and aluminum 4047 for aerospace electronic packages – Using a novel concept, we enabled crack-free welding of 70 percent silicon alloys, which are lightweight, high thermal conductivity alloys that are used for RF and microwave packages and other critical heat sinking applications. Miyachi Unitek modified the solidification process without using post weld heat treatment. By using a fillet weld geometry and moving the weld close to the edge of the package the isotherms around the weld are modified such that the thermal gradient is reduced and re-orientated. The result included crack-free welds in the highest silicon content alloy, CE7.
- Advances in laser welding systems and technology for medical device manufacturing – This innovation includes motion and laser control techniques beneficial to hermetic laser seam welding of implantable devices. Using special software to achieve “position-based firing” along the contour, we developed a method that fired the laser in response to its actual position along the contour at any point in time. We also developed new metals joining production methods using “green light” (532nm) pulsed welding lasers, which facilitates precision welding of copper and gold alloys. This offers a true metallurgical weld, consistent high-reliability electrical connections with no long term resistance drift, and a non-contact process that completely eliminates risks of electro-static discharge or physical damage to the parts being joined.
- New force-based bend align increases yield and throughput for manufacturing pump lasers for the telecom industry – This unique force-based algorithm is used for deforming pump laser diode packages back into alignment. The packages are part of fiber laser amplifiers used to boost a telecommunications signal as it’s transmitted over vast distances. With the force based bend align method, the signal is peaked faster and in many cases with increased coupling over position based systems. The increased coupling provides improved amplification of the signal and greater signal to noise ratio.
- Enabling high performance optoelectronic modules using novel gas-conserving resistance welding electrode system – This new projection welding technique dramatically reduces the amount of Xenon gas needed to backfill a package. Xenon has good thermal properties and does not enter into slow chemical reactions with other materials that can cause degraded performance and reliability. However, it is extremely expensive, and many existing processes waste the costly gas during backfilling. The new technique enables packages to be evacuated, and then filled with gas before being hermetically sealed using projection welding. This process consumes as little as 5 cubic centimeters of Xenon gas, costing only $0.75 per part.