HEIL Environmental Industries Ltd is on a crusade to automate production in its refuse collection vehicle manufacturing facilities. In the past four years, the company has invested in excess of $11 million in its Fort Payne, Alabama, and Phoenix, Arizona plants.
The company's flagship plant got the lion's share this year — $3 million for an array of state-of-the-art equipment that might as well have come directly from the recent Fabtech International exhibition (see coverage, Page 30).
Of course the company is not acquiring these machine tools just for the sake of automating. Heil is putting them to work in order to improve precision, productivity, and quality of its product line, including front loaders, rear loaders, side loaders, and recycling equipment.
“We are committed to investing in manufacturing machinery and processes,” says John Craig, senior vice-president and general manager. “This equipment, combined with our efforts to harness lean manufacturing initiatives and follow the principles of our ISO 9001:2000 system, allows us to design and manufacture refuse collection bodies that are stronger, yet lighter.”
The automation program has been going on since 1998 when the company purchased its first welding robot.
“The time had come for us to begin switching over to robotic welding,” says Wayne Smith, vice-president of manufacturing for the company's refuse equipment group. “The original plan was to add one or two robots per year. It didn't take long to realize that if we added robotic welding, we needed to upgrade other fabrication equipment, too.”
So began a capital investment program that saw the 320,000-sq-ft Fort Payne plant literally pack its plant with automated equipment in 2002. That is because one piece of equipment that the plant received occupies 5,000 square feet, but the plant size remained the same.
To make room for the Bystronic laser and its material handling equipment, Heil had to displace and compress the production line 100 feet. However, the squeezing process involved more than just finding some room. The laser system had to be installed at a point in the plant where it could most easily be integrated into the flow of materials.
“We also had to make sure that we would be able to keep the machine running at the same time we move the parts that it cuts,” Smith says. “We fabricated special carts for that purpose and spent time brainstorming ways to smooth the flow.”
Advantages of lasers are well known: extremely clean cuts that require no additional processing, exceptional accuracy, and localized heat zone that minimizes distortion. However, getting the laser was only half of the power of a laser cell — and only half of the total price. Heil considered it equally important to purchase the material handling system that moves sheet steel in and out of the machine.
“We had a very clear vision of what we needed and what was right for us,” says Richard Mills, corporate manager of manufacturing engineering. “Bystronic worked closely with us to ensure the machine was designed and built to fulfill all of our needs.
“Without the material handling system, most companies only get 30-35% arc time. We are able to get in excess of 85% arc time because of the difference in the material handling system.”
Mills says the material handling system costs approximately as much as the laser itself. However, he considers it money well spent. The return on the investment from the material handling system is higher than from the laser machine.
“It's the material handling system that gives you the productivity improvement,” he explains. “We would not be getting the most out of the system without it.”
The 4-kW laser can slice through one-inch carbon steel using oxygen as the assist gas. Like much of the Fort Payne plant, the gas delivery system also is automated.
The laser has a 20-ft by 8-ft cutting envelope. According to Heil, the only other Bystronic laser in North America with a cutting envelope that size and the automated material handling system is in the other Heil refuse collection vehicle plant in Phoenix. The system is so large that a single operator cannot monitor all the functions simultaneously. Instead, closed-circuit television cameras report what each area of the system is doing.
Most of the steel that the flexible manufacturing system processes is stored in two towers. The two towers combined can hold up to 100 tons of material.
Each storage tower houses a series of shelves — 34 in all. Each shelf is capable of holding 6,000 pounds of steel. The material handling system selects the desired alloy and gauge of sheet from the appropriate tray and delivers it to the laser for cutting. The system also unloads the finished parts.
“About 70% of the material comes in small sheets,” Mills says of the two-meter by four-meter maximum (6.56 by 13.12 feet) of the standard material handling system. “Handling of the high-volume sheets is highly automated.”
Larger sheets (between 12.37 and 20 feet) are fed into the material handling system via a large powered table that runs on tracks laid into the floor. Once this manual intervention is complete, the laser processes the larger sheets just as it does the smaller ones, loading the sheet and then removing the nest skeleton and finished parts automatically.
“To have a tower storage system for 20-ft sheets would not have been cost effective, while this combination of fully automatic and semiautomatic methods is extremely productive,” Mills says.
The massive weight of the steel, concentrated in vertical stacks, required Heil to reinforce the concrete floor on which the laser was installed. And the 5,000-sq-ft footprint of the system dictated that some of the support columns be relocated and reinforced.
Heil had to pour a five-foot concrete pad beneath the storage towers. The pad had to be isolated from the rest of the floor with a half-inch-thick cushion in order to maintain proper operation of the laser.
Special power supply
The laser also required a special, clean electrical supply and exceptionally pure laser and assist gases, as well as a clean, dry air supply. It's the preparation in services and attention to detail that ensures the investment will pay and that the machine can deliver to its true potential, according to Mills.
Heil ordered the laser cell in June 2001 and began the civil engineering for the project over the Thanksgiving break. Much of the construction work took place during the Christmas break to minimize the amount of time that normal production would be affected. Prior to that time, Mills and Mike Atwell, manufacturing engineering manager from the Heil Phoenix facility, had traveled to Bystronic headquarters in Switzerland to test the machine and accept it.
The equipment arrived in January (all eight trailer loads of it), and Heil began producing parts with it in early March.
“The project had to go right because we were launching a new product with it, which was designed with our new fabrication equipment in mind,” Mills says.
The laser cell was designed as a modular system that could be installed in Fort Payne and Phoenix simultaneously.
“The cells have the potential to be installed elsewhere,” Mills says. Heil, a Dover company, also manufactures dump bodies in multiple locations.
The twin machines, located 1,750 miles apart, produce the same parts to the same standards, making it possible to manufacture identical products. They represent Heil's first laser purchase.
“We studied our needs, then went to the market to see what was available,” Mills says. “We had a lot of questions to answer. What type of resonator should the laser have? What type of material handling system do we need? What about the software? How many units of this type does the manufacturer have in operation? How will the manufacturer train our technicians?”
One of Heil's sister companies manufactures resonators. Kevin Laughlin from PRC Laser provided valuable input for the shopping process.
The laser and other advanced machine tools in the Heil plants work best when they are networked together. To accomplish that task, Heil ties the equipment together with a fiber optic network.
“We have product engineers, manufacturing engineers, and research and development engineers,” Mills says. “All of our engineers and equipment are connected via fiber optics.”
The network allows the plants also to communicate with Heil Environmental in Chattanooga, Tennessee, some 70 miles from Fort Payne.
Three years ago, the company began using Pro E as its engineering software. Each of the three engineering staffs use the same package, simplifying communication between staffs.
Getting into shape
In order to maximize the value of the laser-cut parts, Heil also acquired new CNC press brakes from Pullmax, a manufacturer based in Sweden. The two press brakes (a 14-ft, 350-ton model and a 700-ton, 24-ft brake) replace 30-year-old machines that were new when the Fort Payne plant first opened.
The 24-ft model enables Heil to reduce seams, all with +/- 1° accuracy and with automatic compensation for variations in the material.
Included is a six-axis back gauge, variable lower die, and real-time angle measurement, which, like the other machine tools in the plant, can be programmed offline. These machine codes are stored on engineering networked servers to allow the programs to be downloaded as production requires them.
The Pullmax brakes are a vital element to the entire process. Heil needed the most reliable, accurate, and consistent press brakes available to complement the quality components from the laser.
Heil installed the same machines in the Phoenix plant.
A team of robots
It was the potential benefits of robotic welding that started the automation upgrade at Heil Environmental. After lengthy research, the company chose a robot produced by CLOOS Robotic Welding, the Schaumburg, Illinois, representative for Carl Cloos Schweisstechnik GmbH of Germany.
“One of the things we liked about Cloos was the fact that they were a welding company long before they began producing robots,” Mills says. “That was a key for us. As we started this new automation project, we kept asking, ‘Who is going to be our partner?’ We were looking for someone who could offer us a complete package without having to go through a local integrator. It has turned out to be a good choice. Our first robot has been running two shifts every day for the past four years.”
It also was important to buy from someone who would train Heil personnel to operate, maintain, and repair the systems.
“We have to be self-sufficient,” Mills says. “That includes all of our equipment — not just robots. Fort Payne is not a location that factory service personnel can get to quickly. We can't afford to wait two days for a technician to fly in. We have to do all of the work ourselves.”
Heil purchased its first welding robot in October 1998 to weld the tailgate and front arms of front loaders. The second one the company acquired welds subframes and body sides.
“Because the process is identical each time, our heat input is consistent, and the weld paths are identical,” Mills says. “With the weld parameters constant, we don't have any distortion. That's critical for the subframe, because it is the foundation of the unit. If it isn't right, everything else is off.”
The second robot was equipped with a tandem-wire welding gun.
“Tandem wire welding allows us to weld more than 2½ times faster than single-wire speeds,” Mills says. “This delivers a huge increase in productivity and gives us even greater control over heat input.”
The third robot Heil purchased combined the best features of the first two. It switches between a single-wire gun and tandem-wire. The robot uses the twin-wire gun when possible and grabs the single-wire gun for those areas where the larger twin-wire gun cannot reach.
Heil acquired its fourth and fifth robots to work in tandem. The smaller of the two welds subassemblies. The larger robot welds these subassemblies into larger components.
A sixth robot, acquired two years ago, is assigned to the manufacturing engineering department for training and testing weld procedures and developing advanced programming techniques. Heil's robots are large, gantry-style installations with cycle times ranging from 30 minutes to more than four hours. With the long integration time required, Heil is able to install only two to three per year.
“We started programming our robots with a teaching pendant, but now we have developed techniques for programming them offline,” Mills says. “With our 3-D software, we can validate procedures without taking our robots out of service. As our robots produce more and more, to take them out of service to upgrade programs due to engineering design improvements or new products becomes a costly proposition. Therefore, it is vital to have offline programming capabilities. This software is also crucial in allowing our product engineers to design for robotic manufacturing from the beginning.”
The company has added other tools in recent years, including:
A Whitney 3700 ATC fabricating center (acquired in 1999). The combination plasma system and hydraulic punch produces parts from material up to 3/4" thick. The automatic tool changer carousels hold 42 or 45 tools respectively. The 3700 ATC offers 40 tons of punching power. It, too, includes a loading mechanism to facilitate material handling.
“This has been so successful that we installed another one in our Tishomingo, Mississippi, dump body plant in the fall of 2000,” Mills says. Heil uses the 3700 ATC to cut small- and medium-size components from 5-ft × 10-ft or smaller sheets of steel where tolerances are not quite as critical as those cut on a laser.
“Under the right circumstances, such as parts that have a lot of holes, the 3700 beats the laser hands down,” Mills says. “And it is a bulletproof machine.”
A 20-ft plate roll (purchased in September 2000). Acquired from Comeq Inc of Baltimore, Maryland, the Roundo plate roll can process half-inch-thick steel.
“This is a specialized piece of equipment, and we had a lengthy wait to get it,” Mills says. “We were able to get a temporary roll from Comeq until ours could be delivered. That's the kind of partnership and support we look for from our equipment suppliers.”
A CNC vertical bandsaw (purchased in 1999). The saw features automatic mitering, auto indexing, and a large throat for batch processing. Heil merged the saw with an existing Marvel model to allow the operator to handle two saws simultaneously.
Automated paint system
Added to the Fort Payne plant this year was an automated paint mixing system for its dual-component epoxy topcoat.
“Our old system relied on human input to mix the paint and hardener,” Smith says. “This new automated mixing system makes sure that the proper amount of hardener is put into the paint to ensure proper curing.”
Fort Payne's location in northern Alabama has moderate temperature swings, sufficient enough to affect the speed at which the paint cures. To accommodate these changes, Heil has developed two distinct paint recipes. One is applied in the summer months, the other during cold conditions.
“There are a lot of variables that affect paint,” Smith says. “Our automated mixing system and our different recipes are intended to give us the best mix for the conditions. The main benefit, however, is the control over the paint recipe parameters. If the paint is not mixing at precisely the right amount, the system will alarm and shut down. This prevents any inferior paint application.”
The paint upgrades also include a manifold system, enabling painters to more quickly switch between colors.
It has been an extended process, but Heil has transformed its 30-year-old refuse collection vehicle plant into an ISO-9001:2000 facility. The equipment has made the operation more productive, more flexible, and allowed it to substantially improve product quality.
“No bones about it, the equipment is expensive,” Smith says. “But we have bought the best available, and we are basing our decisions on life-cycle costs — not just purchase price.”
Management also likes the consistency that the new equipment provides.
“Once a robot is programmed, you no longer have to worry about the changes that occur when people weld,” Smith says. “And the added productivity allows them to do other things.”
Smith points to a 60-70% improvement in productivity when the company changed a manual cell to a robotic welding cell. “We don't even have a robot welding operator. We can tack the pieces together and push a button, and the robot does the rest,” he says. “We took four of the seven people who had been working in that cell and deployed them elsewhere.”
The key for much of the new equipment has been its precision. The tolerance of the Bystronic laser is +/- .002", compared with .005" to .008" for a punch plasma and .012 to .015" for plasma burner.
“The laser is the first step in the fabrication process,” Mills says. “Cuts are perfectly square, and there is no slag to contaminate the weld as the parts move through production. Even in painting — the end of the manufacturing process — the effects of the laser are felt. That is because there is no degradation of the paint around laser-cut edges.”
“Our industry has a history of beating and banging things together,” Smith says. “But why beat steel into place when you can get it to fit right in the first place?”