Laser cutters direct a beam from a laser head on to a workpiece to melt, vaporize, or burn through the material. The cleanness of the cut depends on the power of the laser and the properties of the material.
A wide range of manufacturers use laser cutters, from small specialty shops to major electronics and automotive parts makers. There are almost as many laser cutting options available as there are applications for the technology.
The appropriate power for a laser depends on a company’s production goals, says Stefan Colle, laser product manager at LVD North America.
“It’s not true that a guy who cuts 14 gauge material would benefit, per se, from going with the fastest or the highest power laser. There is a very good medium for people that do a lot (with) light gauge materials. For instance, there is a benefit for them to go with a 6 kW compared to a 3 kW,” says Colle.
LVD, a Belgian firm founded in 1952 as a precision press brake manufacturer, builds laser cutting machines that operate at between 3 kW and 20 kW. LVD has been making laser cutting machines for close to 25 years. It has developed many laser cutting technologies along the way, including fiber lasers, tube laser cutting machines, and flatbed lasers.
Colle says small job shops may benefit from purchasing an entry-level or used machine. More basic models start between $200,000 and $300,000. Larger and more specialized companies often need more advanced features, which means they will need to purchase higher-priced machines.
Prior work informs current use
Helpful tips for a company that frequently uses a laser cutting machine include reviewing its current roster of clients, its five-year plan, and the laser cutting jobs it has previously outsourced or now needs to outsource going forward. A laser cutting machine provides a good return on investment when a company needs to run it for three to four hours a day. Most laser cutting manufacturers can help a customer understand the capabilities and limitations of different pieces of equipment. For example, LVD has a spreadsheet with different speeds of machines.
Upgrades in machinery usually mean increases in power and automation. This allows a company to cut pieces that are thicker and bigger more cleanly without having a person tending the machine.
“Higher-end models have some peripheral instruments that load and unload sheets automatically. That gives them the option to run unattended during night shifts 24-7,” says Colle.
The material to be cut is a key factor when selecting a laser cutting machine. The production of large parts requires large laser machines. A standard blank, or metal sheet for fabrication, is 5 feet by 10 feet. A blank can be up to 13 feet wide.
Companies that make heavy-duty road-building equipment like excavators and bulldozers typically put multiple large plates side by side on a large table. Welds of thick plates are usually better made when they use beveled edges, which slope out. Beveled edges offer a larger amount of welding surface than squared edges.
Challenges and solutions for laser cutting
Selecting the right laser cutting machine for the material, application and end use of the part is the best way to avoid problems like burrs, the formation of rough edges or ridges on a metal piece. Usually a burr will not form unless an engineer exceeds the capacity of the laser.
“A 12 kW (laser) can cut with nitrogen up to a certain thickness. If you exceed that thickness, you will have to accept a burr on the bottom. The only way to reduce that burr is by going with more power,” says Colle.
The problem with more power is it requires significant expertise. One of the difficulties in creating a higher-powered laser is cooling the optics in the cutting heads. Cooling needs to come from outside the head. The machine cannot cool the optic from inside because that is the section through which the laser beam travels. Fiber laser cutting, a hot cutting method that uses the laser beam to heat and illuminate the workspace, eliminates the problem of how to transfer power to the cutting head.
“Inside the cutting head is still a challenge. When we cut with a laser, we need to install a focal point somewhere in or above the material to process it correctly. If you cut thick steel, you will most likely use oxygen as an assist,” says Colle.
Using a higher power of machine allows an engineer to work with nitrogen to cut thick pieces. The disadvantage is that high-power machines are more expensive. A laser cutting engineer can start out cutting thinner pieces of metal with nitrogen. Nitrogen is an inert gas that will not explode or leave black soot on the edge of a cut part. Cutting with nitrogen allows the part to be taken right to a paint spray booth with no need for cleanup.
Thicker pieces need to be cut with oxygen, an active gas which enhances burning. An engineer working with oxygen has to be careful of the amount they use. They also cannot introduce too much power into the material. More power can lead to striations, or ridges, on the surface of the cut material.
A laser cutting machine manufacturer will be familiar with the power and thickness at which a firm should switch from nitrogen to oxygen. LVD’s laser cutting machines come with a library of cutting settings. For example, on a 6 kW machine, an engineer should switch from nitrogen to oxygen when cutting ⅜ inch steel.
“That’s why people who would cut all the time at more ⅜ inch or thicker steel with nitrogen…would go with at least a 10 or 12 kW machine,” says Colle.
Companies that want to purchase a laser cutting machine benefit from involving the manufacturer early in the selection process. A manufacturer usually uses a consultative sales process to examine a customer’s intended application. They then share options for laser cutting machines that will fit the customer’s needs and budget. At LVD, sales staff perform time studies and evaluate the parts. They review a set of laser cutting machines with the customer to see what will work best.
A purchaser of a laser cutting machine can also note that the machine cannot be utilized for every task. This means the company must reserve money to send certain jobs. For example, a company building a crane has to make some thick parts and some thin parts.
“Not everybody cuts all their parts on a laser, plasma, or flame-cutter. People outsource certain jobs because they can’t do it all in-house,” says Colle.