The price of sheetmetal precision

New developments in sheetmetal cutting technologies are giving manufactures faster, more efficient options when it comes to cutting materials, but how much accuracy do you really need and how much can you afford? Katherine Crichton looks at the key differences between plasma and laser cutting.

New developments in sheetmetal cutting technologies are giving manufactures faster, more efficient options when it comes to cutting materials, but how much accuracy do you really need and how much can you afford? Katherine Crichton looks at the key differences between plasma and laser cutting.

KNOWING the best tool for the job is essential for efficient manufacturing, but cutting through the sales hype to separate fact from fiction can be diffi­cult, making it harder for manufactur­ers to know exactly which method best suits their application.

There are several key differences separating plasma and laser cutting, and knowing the benefits and limita­tions of each can save manufacturers time and money.

According to Philip Rowse, applica­tions engineer with Farley Laserlab, one trend is to promote thicker cutting with laser machines, but says this can be a false economy.

“While lasers can do the same job as plasma can, in most cases plasma is often cheaper and faster with a similar or better cutting quality for materials of 16mm mild steel and above,” Rowse said.

“The exceptions are decorative stainless steel and specific jobs with special materials like some bullet proof plate that must be laser cut,” he told Manufacturers’ Monthly.

Dale McClelland from Applied Machinery agrees and says while lasers can cut to the same thickness as plas­ma; it is more cost effective to use it with thinner gauge materials or any­thing that requires a high level of pre­cision and accuracy.

“Customers that require multi-func­tioning and need to cut thinner plates with less distortion will automatically buy a laser because of its versatility and ability to cut a range of materi­als,” he said.

“Laser can cut, engrave and weld materials like plastic, glass and wood, whereas plasma is only effective with electronically conductive material, non-ferrous metals such as stainless steel, aluminium and copper,” McClelland explained.

Plasma evolves

With the introduction of high defini­tion plasma, offering enhanced preci­sion, accuracy, better edge quality, reduced bevel angels and dross, manu­facturers have another alternative to traditional plasma and laser cutting.

Rowse says because high definition plasma allows square edges and small holes in thick plate, 8mm holes in 12mm plate are now a reality.

“While laser cutting will give a smaller heat affected zone, this is not always important. In the past if you needed to tap a thread in a hole, your only real choices were to laser-cut the whole part then tap the hole.

“Now you can use a combination of drilling and plasma machines to not only process the part faster, but also complete both the tapping and cutting in one operation,” he said.

“A major breakthrough in plasma has been to get the Kerf width down in size, as well as allowing a square edge to the cut. “Another development is the massive increase in consumable life with improved energy density resulting in faster, cleaner, and better consumable life,” he said.

“With digital control of start-up ramp and gas flow, we are now seeing machines with 260A able to complete a job of a 400A machine.”

While these developments are mak­ing plasma more efficient, Rowse advises manufacturers if overall job accuracy is most critical, then laser will still remain the better option, as it enables jig-less construction and higher precision for detailed jobs.

Comparing the costs

A major deciding factor in whether or not manufacturers use plasma or laser cutting in their operations is the com­parable price of the machinery.

McClelland says the initial capital investment required varies greatly between plasma and laser systems.

“A standard 2kw laser with a pump and a fixed pipe with a standard 8×4” table will cost around $300,000 to $750,000 with the same thing in plas­ma (300A) priced between $90,000 and 300,000 depending on the setup table, controls etc,” he said.

“There are also other factors to take into account including power con­sumption, maintenance and cleaning.”

Both Rowse and McClelland stress the importance for manufacturers to carefully consider their application to determine the value of each particular process in their business.

“This is critical, while there are many applications where laser is the clear choice; often choosing plasma can not only save money but can result in higher production capabili­ties,” Rowse explained.

McClelland advises manufacturers to listen to both sides of the story and get an independent opinion based on what the requirements are before mak­ing a decision.

“This independent opinion may come from industry – don’t be fright­ened to speak to other manufacturers in your field,” he said.

For more information contact:

Applied Machinery sales@appliedmachinery.com.au

Farley Laserlab prowse@farleylaserlab.com.au