Faster, More Efficient Laser Welders

Since their introduction to the jewelry industry, laser welders have been lauded for their speed, accuracy, and convenience of use. Retail stores and job shops have made sizable investments in these machines, which are guaranteed to simplify day-to-day repairs such as fixing damage next to stones and cleaning up porosity in castings.

But it has only been in the last few years that the technology has started to turn up in higher volume production settings. Now, however, as laser welders become faster, more user-friendly, and suitable for a wider range of jewelry applications, they are finding new homes as standard equipment on the manufacturing shop floor.

"We're seeing people who are allowing themselves to change the way they produce their products," says James E. Gervais, executive vice president of Crafford-LaserStar Technologies, with offices in East Providence, Rhode Island, and Los Angeles. "They're designing jewelry for laser assembly they've always wanted to do, but in the past were restricted creatively by traditional torch soldering, brazing, or furnace bonding methods." They're also finding the benefits of being able to use less metal, cut down on solder use, and drastically lower reject rates-all thanks to these new and improved machines.

The Speed of Light

Perhaps the biggest factor turning manufacturers toward lasers is their increased speed-that is, how rapidly the beam can be pulsed, with each pulse equating to one "hit" on the metal. Henry Barney, co-owner of B&D Sales Corp. in Cranston, Rhode Island, notes that when lasers first came out, they generally operated at 2 Hz, or 2 pulses per second. "Now you can get machines in the 20 Hz to 25 Hz range," he says. "It's incredibly fast." Gervais notes that some of the models his company produces can fire at up to 70 Hz. "But that's too fast for the average operator," he says, noting that those high-fire rates are more suited to industrial uses. Instead, Crafford limits the output to an easier-to-handle 30 Hz maximum, which is still considerably faster than models available just a few years ago.

The real benefit of the higher-Hz machines is that they allow greater control over how rapidly the metal is heated. When a laser pulse hits a piece of metal, it creates three distinct "bombardment" zones. Think of three concentric circles. The outermost circle is heated metal-hot, but not substantially changed. The middle circle is liquefied metal. This is the preferable state, where the material essentially becomes its own soldering agent and can be moved and shaped. In the center of the three circles, where the beam's heat is most heavily concentrated, the metal is vaporized; in other words, it's lost.

With the early one-shot-at-a-time lasers, operators had to take what they got-one fast burst of hot light. If that was enough to do the job, perfect. If not, it would have to be fired again. And if the burst turned out to be too much for the metal, it left a hole in the piece. With newer lasers, the chances of damaging a piece are lessened greatly. You can achieve successful welding results using a lower hot-light power setting, says Gervais. The power can literally be low enough where firing a single shot would do nothing to the metal. "But if you take that low power setting and fire it at fast intervals, you actually heat the metal at a slower rate. It gives the operator more control."

That degree of control is vital-especially on pieces made of thin metal. Take for example East Providence, Rhode Island-based Carla Corp.'s electroformed jewelry, which is just 0.004 inch thick. When Carla initially considered turning to lasers, the company worked with Gervais to find a setting that would enable the bonding of findings to electroformed pieces while not completely burning through them. Firing at low power and a high rate of speed allowed Carla to do so, and to continue to do so with complete repeatability. "Once we got to the right power levels and beam diameter settings, we made them pre-sets," says Ralph Fleming, president of Carla Corp. And they've been using those pre-sets ever since.

In a Flash

Laser welding is typically done in three stages. First there is core welding, where the piece is bonded together. The second stage is filling, where an alloy laser wire is used like solder to fill any gaps created by the original weld. The final stage is smoothing, where the weld joint is laser-hammered until only minimal polishing and cleanup, if any, is necessary. And it's in the filling and smoothing stages that higher Hz capability truly comes in handy.

"[Auto-pulsing] provides a tremendous advantage because you have the ability to run a bead [of metal] or make a puddle and maintain the metal in a molten state," Gervais says. "In that state, you can shape [the metal] with a light pulse." In some cases, the filling step can be skipped. "[Some] users only perform the two steps of core welding and smoothing. If they've designed their pieces successfully with a nice clean fit, they can get away without having to add any extra material."

But pulse speed does not necessarily equal productivity speed. In fact, while a laser can create a bond faster than a torch, it has to be done one piece at a time. Operators generally weld pieces by holding them either in their hands or in jigs that they've rigged up. Fleming says that although his company benefits from using laser welders, they have had to accept a slight loss in production time.

"You can't set up as easily," he explains. "When we set up for soldering, we have sand pans that we'll line up 40 pieces in. The employees go one by one, left to right with the torch. With the laser, you're handling them one at a time. No sand pan, no jigs." He adds that most laser welder chambers are not large enough to handle a number of parts at once.

Barney admits that the lack of adequate fixturing, whether for single or multiple pieces, has been a sticking point in getting more lasers into mass production. But it's the nature of the product, he says. "Every piece is a little different, even something as simple as a ring shank," he says. "If you've got a piece with modulation in it, that becomes a problem with aligning the beam so it follows the shape of the object. There's no universal jig that's going to work with every piece."

However, the time lost in laser welding is more than compensated for by the time savings you get from having virtually no clean-up work, says Tino Volpe of Tiffany & Co. in Cumberland, Rhode Island. Unlike soldering torches, lasers leave no firescale on a product. Therefore, once a piece is out of the chamber, it's done. "You don't have to do fluxing or pickling," he says. "So if you count the clean-up work that comes with soldering, it is faster."

Gervais points to Carla Corp. as a prime example of the post-production speed of lasers. "They do the laser assembly as the last step," he says. "And after it's done, it's so clean from the inert gas environment it was welded in that they put it in a tray and it gets wiped and bagged. It's almost turnkey."

Quality and Quantity

While lasers may be cutting down clean-up time and speeding up post-production in high volume manufacturing, they aren't doing so to the detriment of quality. In fact, in many cases they are helping companies make even better quality jewelry and reduce rejects.

Carla Corp.'s delicate electroformed pieces are made of an alloy that's 58 percent gold and about 42 percent silver. When it's torched, the silver anneals and the overall hardness of the piece drops from around 145 Vickers to roughly half that. "If you drop it on the ground from waist height, it will dent," says Fleming.

With the laser's localized heat and the ability to use rapid-fire, low-power pulses, the pieces never have a chance to anneal. The result is a stronger product. "It's a perfect fit because with the laser there's no extreme heat," Fleming says.

In addition, the company is saving on metal. "We used to manufacture out of 0.007 inch [metal], accommodating for the loss from the soldering process. Now that we laser, we cut the wall down to 0.004 inch because we don't need the thickness for durability."

By reducing the weight of each piece by 35 to 40 percent, the company has saved thousands of dollars each year-a savings that translates into a better price point for retailers. "It's bringing electroform more into the mainstream," Fleming says.

It's not just precious metal that's being saved through the use of lasers. Although the cost of solder may initially seem petty by comparison, companies that have switched to lasers are also saving money by cutting back on solder use. "We have pieces we assemble with the laser that we've switched from soldering," Volpe says. "If you have multiple [joining] operations, you don't have to use different types of solder." This translates into monetary savings in solder, time, and skilled labor, he adds.

Another benefit lasers are bringing to manufacturers is a noticeable reduction in reject rates. Robert Corio of Robert Corio Designs in Johnston, Rhode Island, uses lasers to tack weld pieces together prior to soldering them. This allows his employees to be sure that each piece is perfectly aligned beforehand. "Sometimes soldering can undo a joint, even if it's held in place with a clip. But with the laser, it doesn't move." Corio notes that no piece goes into the soldering stage until it is firmly tacked in place, even if it has to be done several times. "We keep fixing it until we've got what we want," he says. "We don't mind if we put 10 or 15 percent more time into a product if we know it's going to come out right."

In fact, Corio says he has reduced his reject rate to zero thanks to the laser. Because a piece is firmly tacked before soldering and no slippage occurs in the oven, every piece that goes into the oven goes out the door.

Fleming has also seen a drop in reject rates from a different aspect. "After we were done soldering, our reject rates were around 15 percent," he says. "Because the pieces were so soft, when they went into mass finishing there would be a lot of denting just from the handling. Now our reject rate is less than 5 percent because we have the improved hardness in our favor. When we handle the pieces, there's less denting." And it's mighty hard to argue with a lower reject rate.

Beyond Welders

Just as laser welders are improving in performance, broadening manufacturers' design options and often saving them money, so are other forms of laser technology. For example, laser engravers are now more powerful, says Volpe. This makes them suitable for use with a wider variety of metals, including silver.

"Silver has a very high conductivity," explains Volpe. "It wicks [away] the heat generated by the laser impact faster than the laser can supply it, so it takes more energy to melt the contact point." Older, 65 watt laser engravers couldn't generate the requisite heat to melt the silver for engraving before the metal dispersed it. Newer machines, pumping 100 watts of power and the accompanying heat, readily overcome that problem. Plus, automated rotary tables with X-Y-Z axis capability, as well as step programs that allow an operator to touch a button and walk away while 20 or 30 pieces are perfectly engraved, are answering the prayers of many high volume manufacturers.

Other laser-based technologies are likewise being adapted to meet the needs of larger jewelry manufacturing companies. Volpe says that Tiffany & Co. is currently conducting a feasibility study using a laser-cutting machine for platinum tubing; the laser, which is supplied by Rofin-Baasel Inc. in Boxborough, Massachu-setts, would replace its current water-jet-based system. "The water jet is extremely efficient compared to using a lathe," he says. "But we are always looking to take the next step. Laser cutting produces a smaller cut line than the water jet, [removing less metal between slices]. With a smaller cut line, we can get more rings per tube. And with the price of platinum being so high, the savings add up very fast." Volpe adds that the system can be driven by CAD programming, making it ideal for creating samples.

With so much happening in the world of laser technology, it's no wonder more and more high volume manufacturers are beginning to see the light. Lasers have always been about speed and convenience. But with each new generation, as laser manufacturers are listening to jewelry makers' needs, they're getting faster and easier-and they're finding their way into more operations every day.