April 30, 2013
Fabricating know-how and modern machine tool technology help Tie Down Engineering, Atlanta, balance its made-to-stock and made-to-order product line operations with a growing contract fabrication operation.
Sloan MacKarvich remembers eating at downtown Chicago’s Firehouse Restaurant, an all-too-appropriate venue considering the cellphone call he received there. This was 2011. MacKarvich had just spent the day at FABTECH®, and he was meeting with the president of a machine vendor. His team at Atlanta-based Tie Down Engineering sounded frantic. One of the company’s buildings was on fire—later believed to be caused by a lightning strike (though the source of the strike was never found). No one was in danger, but it looked as if it would be a total loss.
“The president [of the machine tool company] asked if we needed a ride to the airport,” MacKarvich said. “And I said, ‘Why? We’re here at FABTECH. Let’s find the equipment we’re going to need to replace.’”
Most equipment in the facility was relatively new, purchased in 2009. Investing during downturns had become a tradition at Tie Down ever since Sloan’s father, Chuck MacKarvich, launched the business in the 1970s in Miami.
After FABTECH in 2011, Sloan returned to Atlanta and witnessed devastation. “I had never seen destruction like this,” Sloan said. “In Miami, we were hit by the worst of Hurricane Andrew—which actually led to the family moving up to Atlanta. But this plant fire was worse. Chuck MacKarvich never even visited the facility after the fire. All the tooling and custom machines that took years of work and design on his part were too much to see utterly destroyed.”
Was this the final straw? After all, company revenue had dropped by half during the recession, and now this. Still, the fabricator already had some market diversity, providing products for the transportation, construction, and marine industries, among others. This was why Tie Down had survived previous downturns without significant drops in revenue. But 2009 was different—all of the company’s markets went south. To get through, Tie Down stepped up its investment in manufacturing technology and, to use its excess machine capacity, launched Industrial Laser Solutions, a contract fabrication division.
Then came the fire. Officials proclaimed it was one of the worst they had seen in more than a decade. As it turned out, though, the company rebuilt—and didn’t lose any customers in the process.
Tie Down breaks with convention in several respects, one being its shop layout. It employs 265 people who work in about a half-million square feet of manufacturing space, but all that is split among seven buildings. The one that burned was dedicated largely to welding axles for trailers, a product family that makes up a significant portion of company revenue. It wasn’t a good place to have out of commission for long.
For years Sloan and his father knew this wasn’t ideal. But after the fire, the campus layout turned into the company’s saving grace. As the company rebuilt after the fire, managers sent jobs to other buildings. For instance, the company had lost several band saws in the fire, so schedulers diverted these jobs to its four tube lasers in another facility. Within 45 days, workers were back in the building welding axles, and within four months the operation returned to full capacity.
Considering all the natural disasters of recent years, be it tsunamis and earthquakes or wind and tornadoes, risk reduction has become more important. As Tie Down President Dean Samuelson explained, “Because we have multiple proc-esses, capabilities, and buildings, we were able to recover quickly. We have a lot of redundancy and risk reduction built into the way we manage the business.”
After enduring the dot-com crash and then an epic financial crisis, metal fabricators can be a skeptical bunch. Sloan MacKarvich, who two years ago became president of Tie Down’s Industrial Laser Solutions division, doesn’t fit the stereotype.
MacKarvich doesn’t stroll or meander. He strides almost as fast as he talks. Quick to smile, he describes the company’s technology with earnest enthusiasm. He recalled talking to some of his childhood buddies who complained about their boring summer jobs. For his summer gig he got to work around lasers. “How cool is that?”
In the 1980s and 1990s, any outside industry analyst would have looked at Tie Down’s product line and said it wouldn’t have long to live, thanks to cheap overseas labor. That’s because its original product was, and remains, simple. Its development can be traced back to mobile homes. Decades ago the government had no rules about how to secure mobile homes to the ground. “Without regulation, people used stakes, cable, and all sorts of crazy things to prevent the home from tipping over during a windstorm,” MacKarvich said.
In the 1970s, as a resident of Miami (a city that has had its share of storms), Sloan’s father found a way to overcome it: a tie-down, or ground anchor—basically an auger attached to a metal rod (see Figure 1).
“It also has a slotted bolt and steel strapping,” MacKarvich said. “So we take this metal strapping and hook it on to one of two I-beams underneath the mobile home. It’s out of sight and out of mind. The company got off the ground by making about 50 of these a week with arc welders. If we have a major hurricane and FEMA has a lot of mobile homes to erect, we can crank these products out quickly. If we have to, we can make 10,000 a day.”
To produce such volume, the company doesn’t need to employ umpteen welders and assemblers, nor does it use a bank of welding robots. Instead, rods and augers are fixtured onto a vertical conveyor, which moves slowly in a semicircle in front of a team of four or five welders. Another three or four people stand upstream on the conveyor and fixture components into place (see Figure 2).
The welded products, affixed to the line, are transported to a cleaning tank, then (still on the line) move upstairs for coating. The coated products travel through the oven and are offloaded to be palletized and packaged for shipment. No welder can work at such a high speed for long, so the team switches jobs regularly—between material handling, packaging, and welding—to keep fresh and focused.
“It’s a continuous rotation, with a welded anchor coming off the welding line every three to four seconds,” MacKarvich said. “You’re barely even arcing off before you go off to the next part. To this day we can manufacture these parts for less money than what overseas can do.”
Welding here isn’t automated because of the varying demand cycles, which sometimes can be dramatic, and because of the nature of the application. A major storm or natural disaster brings significant demand spikes. For instance, after the oil spill in the Gulf of Mexico several years ago, the shop got a call requesting 30,000 tie-downs to hold the massive containment booms integral for the cleanup effort. Tie Down made the delivery within a few days.
“We depend heavily on robotics for much of our production welding, but robotics could not get our labor inputs lower on a per-ground-anchor-basis than our custom manual setup,” MacKarvich explained. “Most ground anchor models require three relatively short welds, but two of those welds are downhill helical welds. Although completely programmable, these welds can be a little tricky for a robot. Also, robots implemented in a moving production line generally require the line to stop in a programmed position.
“Robots are great, but they will never be as flexible and intuitive as a skilled manual welder,” he continued. “We need such qualities for our ever-changing volume requirements and product mixes related to our ground anchor line.”
The company does employ some cutting-edge robotic welding, including one cell that welds hot-dipped galvanized trailer frame components, complete with a metal-cored wire and tweaked process parameters that can efficiently penetrate the zinc coating.
The wire isn’t what makes this system stand out, though. The cell handles a broad product family. Order quantities are anywhere from one to more than 1,000, and jobs can entail structural tube shapes that can be round, square, or rectangular and of various widths and depths. How the cell accomplishes this exactly is proprietary.
The cell welds product families for one of Tie Down’s many product lines (see Figure 3). Beyond the original earth-anchor line, the company makes products for the manufactured housing sector, marine sector, as well as construction. The entire product catalog is thick: dock ladders and boat trailer components; leaf spring axles, bearings, and frames for commercial trailers; and platform hoists for roofers. That’s just a sampling.
The company had dabbled in contract work but, with the start-up of its Industrial Laser Solutions, sought to expand it. Since its launch, the division has handled a variety of contracts, including a few major ones in the defense and transportation sectors. In a small showroom outside one of the plant floors, MacKarvich pointed to a bolt-on component for a defense vehicle designed to handle the challenging, mountainous battle zones in Afghanistan.
The success of this project led to Tie Down’s formal contract fabrication effort, which concentrates on work ordered repeatedly. Subassemblies, not simple piece parts, represent the fabricator’s niche.
The fabricator has spent decades designing its own product lines, performing finite element analysis on specific models and testing prototypes. The firm has even built a fair number of custom machines designed specifically for its product lines, like a bending machine that forms the structural tube for frame components of trailers. The company’s conference room is lined with plaques showing Tie Down’s various patents and design awards.
So it made sense to approach the contract market by selling this kind of design service, though because the products are someone else’s, engineers act more as consultants and offer suggestions. As MacKarvich explained, early in the relationship the company’s engineers analyze designs and suggest changes. This often involves discussions about material type and weight, critical in sectors like the marine industry and transportation.
In one building, MacKarvich pointed to a structural component that eventually will support a section of a fuel tanker trailer. He then demonstrated the advantages of the Huck fastener, a swage- and collar-lock system that fastens components without torque, a fastening method needed because of the tight positioning tolerances of the mating components, all of which are DOMEX®, a wear-resistant, high-strength steel (see Figure 4).
“This entire frame is just 4 mm thick,” he said, “but it’s 100 KSI.”
This product and many others like it led Tie Down to invest in the new machines within what the company calls its “feeder” building, the operation’s heartbeat. The building has seven sheet cutting lasers and four lasers for tube cutting. Mac-Karvich pointed to the two newest systems: a 5-kW, solid-state (disk) sheet cutting laser from TRUMPF (see lead image) and a tube cutting system from BLM, with its 3-kW IPG fiber laser (see Figure 5).
The solid-state lasers do have the ability to proc-ess thicker plate and thicker-wall tube sections. But of course it’s on the thinner stock that the machines truly fly. The company sends its nonferrous material as well as any mild steel stock less than 0.25 in. to its fiber and disk systems.
Being solid-state and requiring no laser gas, the systems also require much less energy and maintenance, which was a significant benefit for Tie Down, MacKarvich said. On some of its older CO2 lasers, managers found they were spending almost $50,000 a year on replacement parts and other maintenance work.
From the lasers, material flows to the press brakes, including a TRUMPF model that has real-time angle measurement and automatic angle compensation, which uses special punch tooling with two discs inserted into the tip. If the material springs back to an angle that’s out of the required tolerance, the discs on the punch tip can detect this (see Figure 6). For a specified angle, the machine knows that the discs should be a certain distance apart, plus or minus a tolerance window, which can be extremely small with a succession of bends on a workpiece. (A small error in the initial bend can grow into a large error by the final bend.)
These technologies have plenty of internal benefits for the company. The fiber and disk lasers can cut thin stock extremely quickly. They’re solid-state, so they have no laser gas to switch out and no mirrors to maintain. The bending technology improves productivity and reduces setup and tryout time. It also helps with material utilization. For many parts, it doesn’t matter whether it is bent with or against the grain, because the angle correction can account for those changes. This means the laser programmer doesn’t need to orient a certain piece a certain way on a nest, just to attain the desired grain direction for bending.
The automatic angle compensation does add a little to cycle time, so operators usually don’t use angle correction for every part, which can be overkill anyway. If the technician knows a batch is cut from the same sheet and has the same grain direction, he can bend with angle correction for the first piece. From this the machine has learned what it needs to do to bend other pieces in the batch correctly.
Driving such investments is the increased use of high-strength material. “We consider anything that’s 3⁄8 in. thick and less to be sheet metal,” Mac-Karvich said. “It depends on the design, of course, but in theory, when you convert from mild steel to high-tensile 100-KSI material, you can have 40-percent less material thickness and have an equivalent strength factor. So 3⁄8 in. material all of a sudden can be less than a quarter inch.”
And again, on thin stock, the solid-state lasers’ speed really raises eyebrows. With the industry trending toward thinner but higher-strength metal, the company keeps its new lasers busy. “For the thinner material, we’re averaging two to three times the output, compared to what our older CO2 lasers could do,” MacKarvich said.
Some of Tie Down’s product lines still are run through the stamping presses, which take up the lion’s share of floor space in Building One, the original facility. But over the years, the lasers have taken on more work. Those lasers now feed every downstream process in six other buildings, each of which is devoted to a process (such as assembly) or product family, be it truck trailer frames, ground anchors, or anything else. For Tie Down, buying another laser won’t likely create a bottleneck downstream, because downstream has so many distributaries.
The company’s fast cutting and cycle times built excess capacity that has eased scheduling, which juggles the make-to-stock and make-to-order operations (which can involve standard or customizable product lines) as well as contract work. Traditionally, a laser job for a large order of one of the company’s product lines may have tied up the lasers for hours. Now that the fiber and disk lasers churn through the job faster, the laser department can take on unexpected demand coming from, say, a contract customer that calls in a hot job. In a sense, the hot job has turned into, well, just the next job.
The seven buildings act like seven mini-companies, all collaborating in a tight supply chain serving a diverse customer base, which, financial crises aside, provides the stability during economic downturns. MacKarvich conceded that having seven buildings isn’t always ideal for product flow, but the cost of moving everything under one roof just doesn’t make good business sense.
Besides, having seven buildings does reduce risk when it comes to natural disasters and severe weather. If lightning should strike twice, Tie Down is ready.
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