Manufacturing on a high fiber diet

Producing parts faster, more accurately, and more efficiently is the goal of every manufacturer.

While the process used to be labour intensive in the past, modern technology has stepped in, allowing manufacturers to achieve high throughput with an increase in quality and a reduced cost per part.

Commercial fiber lasers have been around for about 15 years, and have proven themselves to be an effective tool in cutting thin stock. “It is about parts per hour. With the fiber laser, and thin materials, you can produce parts significantly faster with higher cut rates than you can with a CO2 laser counterpart,” said Jason Hillenbrand, Laser Product Manager for Amada.

“The reason a fibre laser can cut thin material so much faster than a CO2 is because of the spot density - the amount of power it can deliver to such a small spot."

Fiber lasers systems excel on thinner materials.

“Fiber lasers have displaced the CO2 systems primarily in sheet metal and thin gauge cutting,” said Terry VanderWert, President of Prima Power Laserdyne, LLC.

“4-millimeter thicknesses is the number that seems to be a cross over point that we hear from customers and end users. For sheet metal fabricating application, fiber lasers offer benefits in terms of speed and operating costs.”

He explained that the 4-millimeters or under is a rule of thumb, a sort of demarcation point where the fiber laser cutting systems are the most efficient.

“They can cut thick material but it is a matter of speed and finish advantages,” he added. “If you are a job shop that has one laser machine and your business covers a wide range of metal thicknesses, the CO2 system is more flexible.”

However, fiber lasers have some advantages because of the wavelength of the light as compared to CO2 lasers.

“With the one micron range of the fiber laser the absorption of that beam by the plasma that is formed at the surface of the metal is lower than it is for the 10 micron CO2 laser. So it is a more consistent and stable process,” said VanderWert.

“Fiber laser systems rely on multiple solid-state pump diodes to generate a laser beam with a very short wavelength (est. 1 micron compared to a 10.6 micron wavelength for CO2 systems) that is then moved through a flexible fiber optic cable to the laser cutting head,” says Jon Blom, Product Specialist for Hypertherm’s Fiber Laser team.

“A CO2 system, on the other hand, relies on mirrors, installed a set distance apart, to transfer the light beam.”

This difference in the beam delivery method gives fiber laser systems several advantages.

Economy:

Cutting costs are also a prime reason for switching to fiber laser systems.

“A 3kW fiber costs almost 50 per cent less to operate than a 3kW CO2 laser,” said Steve Aleshin, product manager for laser systems at Salvagnini America.

“The main components of this are maintenance, laser gas and energy cost.” For the energy costs the fiber laser is about 25 per cent efficient converting electrical energy in to light energy.

“It sounds bad but in actuality it is very good,” he said.

A CO2 laser's typical efficiency is around 5 per cent to 10 per cent efficient. That means a 4kW fiber uses 16kW compared to a CO2 laser using from 40kW to 80kW, depending on resonator in question. This is not including the increase in chiller size to cool the laser source. This makes a difference in electric cost per year between $13,070 and $4,900 dollars, assuming one shift and a total of 2,000 hours use. It is a modest amount of savings compared to a CO2.

The initial capital invest in fiber laser system might make one sit up and take notice, but the advantages of these systems speak for themselves.

“There is a price premium of about 25 per cent to go from a CO2 to a fiber laser cutting system of the same wattage and configuration,” said Frank Arteaga, Head of Product Marketing, Market Region NAFTA for Bystronics. He added that there is a 50 per cent lower cost of operation with fiber as compared to CO2.

“Certainly the initial investment for a fiber laser is higher than that of a comparable CO2,” says Marc Lobit, Marketing Manager for Mazak Optonics Corporation. “However the overall productivity advantages combined with a 50 per cent reduction in cost of operation can quickly pay profit dividends in a lower cost per part, and more parts per hour.”

Fiber laser systems save money in energy costs because of their inherit energy efficiency.

“Because fiber laser is a completely solid state, monolithic design, the systems have higher wall-plug efficiency,” explains Blom.

“A fiber system consumes about three to five times less energy making it roughly 86 per cent more energy efficient. The benefit of this is not only lower energy consumption (and lower power bills) compared to CO2 systems, but also the associated cooling requirements are significantly reduced.”

Speed & Quality:

While the operating costs of a fiber laser are much less than of a comparable CO2 system, this is not the primary advantage.

“As one customer put it — companies don’t buy a fiber laser because of the money it saves them. They buy a laser because of the money it makes them,” stated Amada’s Hillenbrand.

“With fiber lasers, in certain thicknesses, you can reach higher feed rates than with CO2,” said Stefan Colle Laser Product Sales Manager for LVD Strippit, Inc. “The gain in speed in thin material with a 2 kw fiber laser versus a 4 kw CO2 laser can be as much as four times faster.”

If you are cutting 1/4-inch and down it will be cheaper and faster to produce the part. “And that is the real reason you would get a machine,” said Brett Thompson, TRUMPF’s TruLaser Product Manager.

“The primary advantage is dependent on the workpiece. For the thinner gauge of materials, with a solid state laser you can go considerably faster especially with the more power you have available. You start to lose the speed advantage at about 1/4-inch. With a 5 kw solid state laser as an example 1/4-inch, is where you start losing the speed advantage.”

Part of the speed and quality advantage of the fiber laser is the concentrated beam that produces a thin kerf.

“What the fiber laser gives you is a smaller kerf,” said Hillenbrand. “Generally the cut width is about 4/1,000 of an inch on a CO2, it may be around 8 to 10 thousandths of an inch for a fiber laser.” The

motion controls for these systems are similar to the ones used by the CO2 machines and have a repeatability and accuracy of 4/10,000 of an inch.

“Laser will produce tolerances between +/–0.002 to 0.005 of an inch. This compares with plasma tolerances in a range from +/–0.015 to 0.030 and oxyfuel ranges between +/–0.020 to 0.030,” said Blom.

“Another consideration is the thickness of material to be cut. Fiber lasers are generally best suited for cutting thinner materials. Though a 3kw fiber laser can cut thicker materials (up to 3/4 inches), fiber laser cutting speeds are faster on thin materials compared to CO2, but the cutting speeds decrease faster with thickness compared to CO2. It is important to consider the volumes of each thickness that are needed to be cut, then balance the run cost with productivity to choose the correct system.”

Flexibility:

Flexibility of a fiber laser comes in the way the light is delivered via a flexible fiber and not a static light source. “There is no practical limit to a solid-state laser’s table size,” said Blom.

“A larger cutting table requires merely a longer delivery fiber. In fact, it is even possible to install a fiber laser head right next to a plasma cutting head on a plasma cutting table, something that is not an option for CO2 laser. At the same time, the ability to bend or coil fiber optics means the systems are relatively compact when compared with gas systems of comparable power. This is especially beneficial to shops with limited floor space.”

Some job shops might opt for a CO2 laser, as they work better on thicker material, but Hillenbrand maintains, “you can cut it with fiber laser as well, but generally it will be slower and the edge quality will not be the same as with CO2 — at least not with the technology that we have in place today.”

“One of the applications where fiber lasers have made a big splash in the last few years is cutting of three-dimensional hot formed steel components,” said VanderWert. “Those are up to two millimetre thick so perfect for fiber lasers. These are structural components for A-pillars and B-Pillars.”

The ability to cut reflective metals is another strong suit of fiber lasers.

“Fiber lasers feature positive light properties such as a shorter wavelength, which improves beam absorption into the material being cut, and enables the cutting of reflective metals such as brass and copper,” said Blom.

“A more concentrated light source creates a smaller spot and longer depth of focus so fiber laser can cut thin materials fast and medium thickness materials more efficiently. With stainless steel and thinner mild steel, up to est. 6 mm (1/4 inch), a 1.5kW fiber laser can cut just as quickly as a 3kW CO2 laser.

"This very high power density translates to increased output, yet with lower business costs because the operating costs for fiber cutting are lower than that of traditional CO2 systems.”

The ability to etch, mark, clad and weld also lends flexibility to a fiber laser system. “For cladding you would use different optics to focus and control and manage the beam profile and on top of that you need a means of delivering the cladding material to the focus point of the beam so that it melts and deposited on the surface,” said VanderWert.

Maintenance and consumables:

CO2 laser systems require regular maintenance with mirrors that need to be maintained and calibrated. Resonators and turbines that move the laser gas need to be inspected and replaced when needed. “All of this maintenance adds up,” said Blom.

“A CO2 system can cost up to $20,000 per year to maintain. Fiber lasers on the other hand, require little to no maintenance since they don’t rely on mirrors or turbines.” Bystronic’s Arteaga concurs.

“There is virtually no maintenance as there are no mirrors in either the fiber laser unit or the beam path delivery as it is a monolithic fiber to fiber design,” he said.

“Fiber lasers does not use laser gas, gas turbines, laser mirrors, delivery mirrors, bellows beam path, beam purge. The only maintenance is in the mechanical aspects of the machine and also the cutting head consumables like nozzles.” Colle states that typical long-term preventative maintenances, which you face with CO2 lasers, are no longer required with a fiber laser.

“The only daily maintenance we see now with fiber lasers is the cleaning of the protective window. This is small piece of glass that protects the lens from getting contaminated by back splatter.”

While there is less maintenance required to the cutting head, Al Bohlen, National Sales Manager Mazak Optonics Corp. said, “There is a chiller system, which is smaller than a CO2 but still requires periodic water changes and also

filter replacement. Otherwise the machine aspects are very similar, but with a CO2 machine there are many more maintenance items related to the beam delivery system as well as the CO2 Laser unit itself.”

“The largest portion of the consumable that have been eliminated are the optical components,” said TRUMPF’s Thompson.

“There are no optical components inside the laser that need to be maintained or replaced. That has really dropped down the operating costs even more so than the efficiency of the actual machine itself.”

The fiber laser systems eliminated the need for laser gas but did not remove the need for assist gas.

“The assist gas can be significant cost. The assist gas is that used to help remove the laser’s melted materials. It can be compressed air, compressed oxygen, or compressed nitrogen,” said Prima Power’s VanderWert. “In cutting, the goal is to melt material and with the assistance of the gas jet, remove the material from the cut. In welding you want to melt the material but you don’t want to remove it. You want to protect it from the oxygen in the air. Therefore you shield it with a low flow. In cutting it is a high flow rate of gas.”

“The fiber laser really shines when using nitrogen as assist gas,” said Colle. “There is almost no gain with using oxygen as assist gas. A 2kW CO2 laser versus a 2kW fiber laser cutting mild steel with oxygen will produce very similar cutting speeds.”

A stronger bottom line:

While there are many benefits of a fiber laser cutting system, manufacturers are looking at this technology because it can process parts at a high rate of speed while maintaining high quality. If a company primarily cuts thin gauge material, “they can generate higher profit or reduce their cost per part to secure a higher volume of bids. Basically you can drive a stronger bottom line,” said Bystronic’s Arteaga.

“The reason a company would switch from a CO2 laser to a fiber is for three reasons. One is to increase capacity, two to replace worn equipment, and three reduce operating cost,” said Salvagnini’s Aleshin.

“It is usually easy and universal, that is the reasons for replacing a machine. One precursor is to make sure that a fiber laser will cut the material in question, and to the quality that the part needs to be cut.”

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