Let's get digital

Wednesday, 02 November 2011 06:46

Fabricators use more software and automation but customization limits use of robotics

By Godfrey Budd

Automation, semi-automation, microcontrollers and other software-supported tools of the digital age are improving productivity and work quality in Alberta's fabrication sector. But the highly customized products that are the focus for many of the province's fabrication shops tend to rule out the use of robotics or semi-robotics.

“We do machine or semi-automatic welds,” says Don McFarlane, president of Cessco Fabrication & Engineering Ltd. “The operator runs the machine as it makes the weld, and turns a digital control that sets the parameters for the weld. We do some CNC machining. But our work is mostly highly customized. Robotics pays only with highly repetitive jobs.”

On the other hand, improvements in the controls and the use of feedback loops have dramatically boosted the productivity of traditional welding technologies. Propak Systems Ltd., which manufactures processing equipment packages and plants for the oil and gas industry, makes pressure vessels with steel thicknesses ranging from 0.25 inches to about six inches. Many of the fabrication processes performed at the company's Airdrie-based plant use submerged arc welding (SAW).

The process has been around for decades but in the last few years, especially since about 2000, as more countries industrialized and competition heated up, SAW has become more efficient with hi-tech makeovers for monitoring and controls.

Today's SAW controls are all digital and provide feedback for monitoring for adjusting voltage, amperage and wire feed speeds. Also, today's machines are no longer restricted to single-phase power, but can connect to three-phase power, and inverters make it possible to a use a modern SAW machine anywhere in the world, according to an article in Practical Welding Today.

An operator can input several programs, so it is unnecessary to remember the precise heat and power ranges for a specific job. With the weld parameters entered and stored, they can be used again in the same application. With deposition and heat ranges programmed, the machine's control system ensures that the operator stays within the assigned parameters.

Also, with dual welding nozzles, which were introduced for SAW about a dozen years ago, “Your deposition rate of filler metal goes up considerably, depending on the size of the joint and the type of metal you're working with and the thickness,” says James McLachlan, the quality control manager at Propak.

“It is important to keep settings very tight, and procedures must be followed precisely. The machine has software that allows the welder to see in an instant where he's at with deposition. Its feedback loop enables a read-out on screen that tells you the volts, amperage and travel speed from which you can derive the deposition amount.”

The digital aspect of today's SAW machines also enables remote programing, monitoring and reporting. Like a CNC machine, the welding power source can be programmed remotely and monitored via a network.

Surface tension transfer (STT) welding, which went commercial in 1994, was little known a decade ago, but is now being used at Propak. According to an article in the Journal of Industrial Technology, published several years ago, the STT process offers several advantages such as “improved weld qualities, reduced operation costs and improved operating conditions.”

The backbone of STT, says the article, “is its revolutionary waveform technology, which controls current precisely and independently of wire feed speed during the entire welding cycle. This precise digital control of the weld current represents the next generation in welding technology and a whole new future in industrial applications.” The article, Assessing the Benefits of Surface Tension Transfer Welding to Industry, estimated that “Up to 75 per cent of the current short-arc sheet metal and pipe welding applications could be justifiably replaced by STT due to its tangible benefits . . .”

What McLachlan terms the automatic readout of the new STT machines from Lincoln Electric enables both operator and inspector to “be on the same page. It means fewer errors and frees up shop floor inspectors for other duties. He has less ongoing monitoring to do and can rely more on spot checks. The system is taking care of things. It tells the welder he's on target within the required parameters. It makes a huge difference.”. The automated readout function was introduced a couple of years ago.

Some fabrication managers, however, are software skepticsat least for now.

Says Marv Kossowan, president of Dacro Industries Inc.: “We don't use anything that uses software. No one can show us where it will benefit. We are a custom manufacturer and every product is different.”

Others see an advantage in software-supported equipment.

Nigel Kucher, president of Kucher Steels (1992) Inc., attributes his firm's reputation for quality, in part, to the use of software-supported equipment. A relatively new automated cutting table that also includes bevelling and other weld-prep functions helps ensure that quality cuts are done in a timely manner. “Anyone in the industry knows our cuts are good,” Kucher says.

It seems likely that the digital revolution will continue its incursions into the fabrication sector–as it has almost everywhere else. One can't help stumbling across the benefits of digital/software-based systems. CNC operations systems that are compatible with design and drafting software can help cut waste, for example.

“Shapes and sizes of pieces to be cut can be downloaded from the design program to maximize usage of a plate on the burning table, so we have minimum wastage,” says Stephen Hutchison, general manager at Altex Industries. “This sort of system has been around for about a decade but it's getting more refined all the time.”

The `company is installing a new machine from Fuji that does both milling and drilling, as it has a live spindle. Having a machine that can perform these two distinct functions saves time in materials handling, Hutchison says.

Although the welder may still have to modify it, a welding power source that uses software results in better arc welding stability, more possible controls, and more process options, says Matthew Yarmuch, program leader, welding and slurry systems engineering, at Alberta Technology Futures, a branch of Alberta Innovates (formerly Alberta Research Council).

Yarmuch and his group are working in partnership with a private company on developing what he calls a hybrid automated welding system. “This is designed mainly for pressure equipment in Alberta,” he says.