May 19, 2009
Tough economic conditions have hit the construction industry as hard as they have many other industries. These problems in commercial construction are affecting structural steel fabricators. New technologies are especially benefiting four important structural steel fabricating processes by reducing labor costs. These represent some of the bigger developments in recent years.
Tough economic conditions have hit the construction industry as hard as they have most other industries. A study by Longbow Research stated that rental and utilization of construction equipment continues to decline "with utilization rates in excess of 75 percent reported by just 3 percent of respondents, versus 25 percent in December, 29 percent in September, 41 percent in August, and 46 percent in July." And according to Steel Market Intelligence©, the Architecture Billings Index forecast an all-time low in new commercial construction projects.
The slump in commercial construction is affecting structural steel fabricators. A recent article by the American Institute of Steel Construction (AISC), Chicago, cited the cost of labor as the biggest expense facing structural steel fabricators. That expense has remained far more consistent than the cost of materials.
But reducing the cost of labor is far easier now than it was just a few years ago, thanks to some innovations in fabricating technology. These upgrades can help structural steel fabrication shops better utilize labor, saving them money that can be invested in other facets of their businesses.
The new technologies are especially benefiting four important structural steel fabricating processes. The question is: Can your current operations meet these new benchmarks?
1. Drilling: How close can your drilling operations get to 50 inches per minute?
The main upgrade in drill lines is the use of carbide tools that allow fabricators to achieve drilling rates of up to 50 inches per minute without coolant, according to Tom Boyer, president, Ficep Corp., Forest Hill, Md. New drill lines use a ball-screw feed, like those in milling machines, as opposed to a hydraulic cylinder to feed the tool through the material. Running carbide tools requires a more precise feed.
In the past one of the biggest problems with running carbide on a beam or a column was that fabricators couldn't clamp the members properly. New technologies allow them to clamp beams and columns from underneath the web, firmly in each flange, so that the shape doesn't affect the project like it used to.
"It was slow before because the shapes you're dealing with are different," said Lyle Menke, vice president of marketing, Peddinghaus Corp., Bradley, Ill. "To effectively drill with carbide, you need to support the material extremely well."
Beams and columns are both processed in the same production run, according to Menke. The sections need to be clamped firmly so that the carbide tool does not chatter and cause damage. The sections are clamped using a six-point clamping system with an underneath support to immobilize the section.
The feed rate is dependent on the drill diameter, Menke added. For example, fabricators using a 13/16-in. drill should be able to drill at 20-25 IPM with a carbide insert drill. Patented spindle technology employs spindle-specific motors that monitor electronic amperage to help ensure fast, effective hole creation.
2. Material Handling: Can you claim material handling costs of less than $50 every time you move a beam?
The biggest improvement in material handling is the use of product control packages that help create an automated factory. In this scenario, the flow of the material throughout the various work centers and corresponding conveyor and transfer lines is fully automatic.
"No longer is an operator having to decide what location to convey a part or move it subsequently farther through the shop," Boyer said.
"Every time a fabricator lifts a beam with a crane, it costs them about $50," Menke said. "By the time he grabs a chain, fiddles with the beam, makes sure he has the centerpoints so it doesn't lean down one way or the other, he picks up a beam and starts to move it down a shop bay. Then everybody else stops and steps back out of the way and it becomes a spectator sport until he lands it and starts over again. That's one of the reasons material handling, like roller conveyors and lift/carry transport systems, became more prevalent in fab shops."
With the advent of measuring systems, like a roller-feed measuring system, shops now can move material handling outdoors, Menke said. This helps save space on the shop floor. Many large shops store all of their steel outside because the members are long—40 to 60 feet in many cases. Shops can use a roller conveyor and a cross-transfer conveyor, which intersects the conveying line. The machines take a beam out of the yard and place it on the cross-transfer, which is about 60 ft. long. The cross-transfer then moves the beam to the conveyor line, which runs the beam into the building through a small "window" opening.
3. Plasma Cutting: Can your plasma cutting system deliver a cut with a tolerance of 0.010 in.?
Advancements in high-definition plasma cutting have enabled structural steel fabricators to use the technology in plate applications for reinforcement, base plates, and connection plates. High-definition plasma cutting provides a good edge condition, which helps facilitate the welding process, according to Menke. Higher amperages allow the systems to process more plate thicknesses with minimal changeover time.
"When a fabricator runs a job, he may get a call from the contractor saying, 'On my 10-story building, I'm going to need floor 3,'" Menke said. "So then he can run everything for floor 3: the base plates, connection plates, gussets, and web stiffener plates. He can nest all parts effectively in the software, load the proper size and thickness on the infeed conveyor, and run all necessary plate components."
High-definition plasma has permitted the technology to be used in more applications, especially for thicker material. With plasma cutting, an angle is more prevalent on one side than the other, Boyer explained. In other words, the cut surface is not perpendicular to the top or bottom of the plate. High-definition plasma reduces the angle of the taper.
"Before if I were cutting 1/4- or 3/8-inch-thick plates, it probably wasn't an issue," Boyer said. "But as I got into heavier plates, depending on the product that was being produced, customers may object to that taper, whereas the high-definition plasma gives you a much squarer cut. You can cut thick material and still have a satisfactory product."
4. Software: Can your software packages accommodate the use of CAD models to generate CNC codes automatically?
The most significant advancement in software is building modeling, Menke said.
"You have a multistory building, the architect puts it together, and then the detailer will integrate every beam or column hole, all connection plates, and angle that is used to connect it; the bracing; and all the openings for electrical conduit and piping. That will all be on a model that can be stored on a laptop computer," he said. "On today's software, a fabricator can look at the model and extract individual members to run through the drill line."
An interface program called DSTV takes the data and manipulates it so that fabricators can run material into the drill line—the software determines the correct location for each hole while the beam is on the conveyor. This has helped eliminate errors and the need to program each piece individually.
The current practice for building construction is building information modeling (BIM), Menke explained. The steel frame of the building, including all the connections and horizontal and vertical members, is in a computerized program that serves as the base for many stages of construction, from planning to shop fabrication to erection.
Some software programs can take the data from the BIM, manipulate it, and transmit directly into the electronic Siemens control of the machines. As a result, a beam, column, tube, angle iron, or plate connection can be processed seamlessly from the BIM, with no need for a programmer or operator to re-enter the data.
More than any other technology, software has helped structural steel fabricators streamline their operations, according to Boyer. Some CAD systems are designated specifically for structural steel design, and recent upgrades to the interfaces allow a fabricator to download a 3-D model of a new structure or building to generate CNC codes, cut the beams to length, and add all the holes. During drilling, for example, everything that physically attaches to the beam is automatically laid out on the CNC drill line as it is processed.
"So if I have a plate that's going to go in a certain location, the CNC program is generated automatically so that at the right location, scribing will be generated so that my fitter knows exactly where to place that plate," Boyer said. "In addition to the location, the specific part number of the plate component that is to be located at that position will be generated [to show fitters where to secure the plate]. The same data from the CAD package goes to a plate processing system, where it produces the holes to punch and drill and the contours to plasma-cut.
A new feature that also is available on new software programs is called "4-D." This allows CNC tools to communicate with the 3-D model automatically and enables fabricators to view the model, which shows by color designation the structural components that have been fabricated.
These technologies will continue to develop, which should help structural steel shops streamline their operations even more in the future. For drilling, that development might simply be an increase in the number of shops that use carbide tools.
As domestic shops look for more ways to decrease material handling costs, many will probably look to technologies that are helping to save floor space in other countries. Examples include fork trucks with side loaders that help balance beams during transportation, Menke said.
"They're used prevalently in Europe and other parts of the world, but they will become more seen in the United States in the near future," he said.
Future plasma developments could include machines that can burn virtually any type of slot or structural configuration, as well as the ability to process thick plates with a better quality of cut, according to Boyer and Menke.
Future structural detailing software soon will place welding symbols on sections of structural members so that fitters know what type of weld is required to secure the member to a beam or column, Boyer said. As shops upgrade their technologies, a main challenge will be full integration of XML files with a CAD system. They will need to select a CAD system that integrates with the equipment manufacturer, allowing them to read and utilize the files.
These represent some of the bigger developments in recent years, certainly not all the tools that can help structural steel fabricators. To find out about the newest innovations, visit the FABTECH® Intl. & AWS Welding Show including METALFORM, which will run Nov. 15-18 in Chicago.
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