Structural shops need to rethink how material flows through the facility
August 3, 2012
Structural steel fabricators now realize what their sheet metal counterparts have known for several years: It doesn't make sense to pay people for the non-value-added activity of handling beams. That's why these shops are investigating automated material handling, but before they do that, they need to answer some important questions.
Structural steel fabricating used to be thought of as a totally different world when compared to sheet metal fabricating. That’s not totally the case nowadays.
Sure, the material for the most part is different. (It’s hard to argue that when you compare the capabilities of a drill line with a laser cutting machine.) It’s the business environments that are similar, no matter where folks find themselves in the fabricating universe. Shops are looking to minimize labor costs while simultaneously attempting to address the impending retirement of valuable veteran workers.
Over the last decade the sheet metal world warmed up to the idea of automated material handling as a way to address those two major concerns. Many shops no longer pay machine operators to load blanks and unload parts, and with operators freed up from that mundane chore, they can spend time sharing their knowledge with newer workers. Pallet systems that continually whisk new blanks onto cutting tables and sophisticated tower systems that not only store a variety of blanks but also cut parts are regular sights at shops across North America.
But what about the structural steel shops? Although the adoption rate hasn’t been as high, their desire to acquire automated material handling equipment is growing stronger by the year (see Figure 1). The simple truth is that shops have to process beams more efficiently if they want to be more competitive in their bids.
Also, the layout specialists that play such an important role as the beams exit the machine tools are a dying breed. Mammas aren’t letting their babies grow up to be structural steel fabricators.
Automated material handling technology is helping some trailblazing shops to solve this dilemma (see Figure 2). These structural steel fabricators are increasing the tonnage of metal processed through the shop without adding resources. But before other shops start off on a similar trek in search of material handling efficiency, they need to keep a few things in mind.
Automation can be introduced to just about any existing roller conveyor system. Electric motors replace hydraulic drivers, and electronics are put in place so that controls can automate material flow to a machine tool.
Getting modern material handling automation to work with older measuring equipment, such as gripper carriages, is almost an impossibility. Roller feed or roller measurement types of systems work best with faster-paced automation.
Measurement that is facilitated at the machine also lends itself to easy equipment relocation, according Nick Hajewski, marketing manager, Peddinghaus Corp. If the equipment had onboard measurement capabilities, new CNC machine tools can be moved into its place without needing to replace existing conveyors. This cuts down on the price of the new machine and has no impact on production accuracy. Older gripper- or cart-feed devices relied on machined gear racks.
“As soon as you start tearing apart an older measuring system by either removing some worn rack and then adding a new rack, you have calibration issues,” Hajewski said. “Also, by co-mingling an older gear rack and new gear rack, you have two surfaces that measure differently. When two different measurement surfaces come into play in a single part program, you are exposing yourself to the potential for error.”
Adrian Morrall, president, Voortman Corp., recalled an equipment upgrade his company did for a structural steel fabricator in the mid-2000s. The company had a 30-year-old measuring system and a 1-year-old band saw at the time. Voortman technicians upgraded the band saw’s controls and added automated measuring capability to the equipment. At the same time, the fabricator purchased a drill line, which sat 60 feet away from the band saw. Automated material handling fed the band saw, where accurately measured beams were cut, and conveyors then fed the drill line. One operator now was supervising two machines, which in the past would have required at least two individuals and perhaps more depending on the pace of the drill line.
Of course, for that type of structural steel fabricating system to work, the material handling has to be planned perfectly. As much as shop management may want to dictate how much steel exits the door, the machines on the shop floor determine the pacing of parts flowing through it (see Figure 3).
For example, a drill operates much faster than a band saw. To keep the drill operating at an acceptable rate, a fabricator might want to have a buffer of cut-to-length structural parts between the band saw and the drill. This allows the drill to churn out parts, and the band saw to keep operating at an optimal speed that doesn’t jeopardize the quality of the cuts.
Greg Carpenter, Peddinghaus’ systems project manager, added that planning is essential not only for current needs, but also for future plans. Good decisions made today will make changes in the future easier to implement.
“Some of our bigger customers want to see a five-year plan. They want to see what the system looks like now and how it can be expanded to meet their goals,” he said. “So when they put a piece of equipment in, they know where it is going to go and where the next piece of equipment is going to go.”
With planning completed, it’s just a matter of moving equipment around and placing the conveyors and cross transfers where needed. Of course, the material handling equipment has to be suited for structural steel:
In some circumstances, a structural steel fabricator may want to specify a gap between adjacent roller sections. This arrangement makes adding a cross-transfer table a lot easier down the road.
Also, if a shop wants to move material off to either side of the cross transfer, it will require a much longer length of conveyor than if material were to be unloaded on only one side.
Those shops that simply can’t add on to the existing building might want to consider just adding a small shed to cover the machinery and placing the material handling system outdoors (see Figure 4). The heavy-duty construction of the conveyor rollers, supports, and other ancillary components makes them resistant to most harsh outdoor environments.
The Holy Grail obviously is to run a system without human involvement—no operator is needed to load beams at the start of a cycle nor is one needed to operate the control and sequence the beams through a machine tool. That best-case scenario appears to be a reality for some structural steel fabricators.
“It’s kind of new, but it’s sort of a wake-up call for the industry,” said Tom Boyer, president, Ficep Corp.
Boyer said building information modeling (BIM), 3-D models used by all parties (architects, contractors, engineers, etc.) involved in the structural steel industry, has evolved to the point where it can be used to provide programming data for modern CNC machine tools. This programming isn’t limited to simple holemaking or coping; it can include scribing, such as for part numbers and layout information.
“This [automated fabricating process] starts off with a stock-length material, and it’s bar-coded into the system. And away it goes,” Boyer said. “As that piece processes through the line, the first cutoff operation knows what pieces come out of that stock length. As they are cut-to-length and drilled, depending on the configuration, we know what that piece is, and we route it through the material flow through the system based on subsequent required operations.”
Automated material handling acts as the traffic cop, ensuring that the beams move along to the stations where they are needed.
Martin Lachapelle, owner of Lainco Inc., Terrebonne, Quebec, Canada, can attest to the power of this lights-out approach. His company recently installed a Ficep 1001 DFB rotating spindle drill/saw line, upgraded the material handling feeding the system, and then watched his company’s productivity almost triple. Lainco’s 27 employees were processing an average of 80 tons per week prior to the installation; now the same number of people push about 200 to 250 tons per week.
The major difference, according to Lachapelle, has been that employees are more focused on loading and unloading trucks and feeding stock-length material into the magazine that feeds the drill/saw. The equipment measures and confirms the material stock length; loads the proper CNC program; drills; scribes; saws; and removes trim cuts, remnants, and finished lengths without the need of an operator.
Lachapelle added that at the end of a workday, the last thing they do is load up the magazine with stock-length beams. When they return the next day, the stock lengths have been turned into cut-to-length sections complete with holes and full four-side scribing ready for the fitters.
This type of information exchange is enhanced when the structural steel fabricator is able to incorporate the information into its ERP/MRP software. With the click of a button, the fabricator should be able to see where a particular beam is in production, what has been done to it, and when fabricating work on it will be complete. Depending on the level of information-sharing among project partners, someone such as a general contractor or an erector conceivably can click on the BIM and find out the status of a particular fabrication destined for the work site.
Indeed, automated material handling in the structural steel industry isn’t only about conveyors and cross transfers. It involves advanced machinery and dynamic software tools. It also isn’t done evolving.
Imagine a conveyor leaving the scribing station and feeding a welding area. A robot feeds the beam into a fixture and another robot begins the welding process. A vision system guides the torch, ensuring the proper amount of wire is fed into the inconsistent gaps often found on structural steel beams. When welding is complete, a robot moves the beam to a staging area, ready to be moved on to fitting. The process repeats itself again.
Admittedly, machine tool builders say work remains to be done in this area, but the control software and vision systems are improving at a rapid pace.
“The first person that can crack the software and put this package together with the robotic welding will be on to something huge,” Morrall said.
That’s another area of potential good news for structural fabricators. Just as they struggle to hire experienced layout personnel, they can’t find welders either.