Robot welders help keep Case line moving
By BOB SAAR
for The Hawk Eye
The salt of the earth in America is right here in the form of the Iowa farmer. It stands to reason, then, that the heart of farming machinery manufacturing is also in Iowa.
That is indeed the case in the form of the Case company, a world leader in backhoe manufacturing technology.
It used to be that when a farmer wanted to dig a hole, he attached a backhoe implement -- a big metal shovel -- to his tractor and dug away. That changed in 1957, when Case Co. created the modern standalone backhoe based on a design by Burlington engineer Elton Long.
It's a tractor with a permanently mounted backhoe, but its simplicity created a new industry.
While Long's backhoe does little more than dig holes and lift dirt -- it doesn't pull agricultural implements like a standard tractor, but it dug the man's grave at Aspen Grove cemetery -- the Case model has been copied by the big boys ever since it was introduced.
Case representative Doug Brooks said that Case's competitors include companies like Caterpillar and John Deere in America and JCB in Europe.
"The good news here is that competition forces product improvement," Brooks said.
Smaller European companies in the market are trying to sell in the United States, too. They include Owen-Kay and Fiat-Allis. Kubota is building a nice little 10-foot model, but it's a toy compared to what Case puts out.
"We could sell you anything from a 580-M, which is a 14-foot backhoe, to a 590-Super M which is a 16-foot backhoe," Brooks said. Case makes four models of backhoes and two models of landscaper -- a tractor with a box scraper instead of a backhoe. They also produce an all-terrain forklift.
The world has modernized quite a bit since Long's days and robots are a common feature of today's manufacturing facility. When Brooks started at the Burlington plant in 1989, it was dominated by welding, machining and first operations fabrication. Then in 1992, the company decided to take out all the FOF but kept welding and machining.
By 2002, Case wanted to get out of welding, too, so it outsourced the process to outside suppliers. From then until late in 2006, Case had no welding operation, but found they had issues with suppliers -- delivery, quality, pricing. The company wanted to get back into welding its own parts. At the end of 2006, it put in three robotic welding stations and started welding backhoe loader arms and chassis assembles.
The chassis is the tractor mainframe and everything bolts to it: the transmission, engine, loader arm and the backhoe.
"If you want to be successful in industry you have to build something better, and you have to build it at less cost," Brooks said.
The modern approach to assembly line production is to use programmable robots for mundane, repetitive tasks such as welding. Case welding robots are made in Germany by Cloos, the inventors and leaders in tandem wire welding technology.
With tandem wire welding, two wires -- a leading wire and a trailing wire -- feed the torch at one time. The leading wire burns the joint between two pieces of metal and the trailing wire fills it. This doubles the welding speed of single-wire robotics.
Humans are slower than a single-wire robot.
Case still is shaking out the bugs in its robotic welding stations only because the installations are so new, and Case relies on both the manufacturer and independent specialists for field support.
"Cloos supports us with our issues, and Jim also supports us," Brooks said of Jim Berge, a robotics specialist from Louisiana. "They help us dial in the program, and then we have Jim come in and really finetune it"
Berge, former general manager for North American operations of Cloos and now president of Berge Robotics, has spent the last 22 years in the robotic welding industry.
"Jim is more than just a programmer," Brooks said. "Jim's an expert in every part of it: the processing, making sure parts are correct coming in to the robot, everything. Cloos has many companies to support, so Jim helps us improve our process just for us."
Berge was at the Burlington plant recently to tweak a tandem wire welding station.
"Several of the companies I work with don't want their competitors to know that they're using robots," he said. "I don't know why. Maybe it's because they worry that once a competitor finds out, then they'll also buy a robot and therefore be more competitive. Case Corporation wants everybody to know that they're improving their product quality."
Berge explained the tandem welding process, which was originally developed by Cloos.
Single wire welding has to do everything all at once: heat the metal, burn the metal, fill the metal. The key to tandem welding is two wires. One follows the other in the weld joint -- that's the junction of two pieces of metal. The first wire burns the steel, providing penetration so that the second wire, which follows the path of the first, can fill that joint with molten metal.
"This isn't just laying metal on top of the joint like a Band-Aid," Berge said. "It's burning into the joint, melting the stock so that the second wire can 'glue' the two pieces together with molten steel."
The molten puddle has to penetrate the base metal, not just lie on top of it, a mistake called cold-lapping. Cold joints break apart easily because they have no strength.
"A primary criteria of any kind of welding is the penetration into the base metal, and one of the common failure modes is lack of penetration," Berge said.
The welding robots can change parameters on the fly.
"We can change from a slower, wider weave to an increased travel speed and weave frequency while narrowing the weave to produce a smaller, faster weld," Berge said.
The speed of welding is determined by how fast metal can be put into a weld puddle, and both wires in the tandem system feed into the weld puddle. The leading wire can run at up to 700 inches per minute, while the trailing wire can work up to 500 inches per minute.
"We're feeding somewhere between 1,000 and 1,200 inches of wire per minute into the weld puddle," Berge said.
The offset in speeds is because the lead wire uses more wire per second to burn the metal than the trailing wire uses per second to fill the joint, and so the wires travel at the same physical speed but use different amounts of wire per time period.
The wire comes in 1,000 pound spools, which must be changed once every week or two.
Case presently has eight robots online.
"We have one robot that's a little smaller in its reach capabilities," Brooks said. "The other seven are similar, but the cell layouts are different."
Single-station cells have a robot that welds on one fixture for one system only. A two-station cell has a robot and a human. The human operator does manual tasks to prepare the chassis for the robot to weld. When the robot is done, the operator uses an overhead lifting device to move the completed chassis to a conveyor that moves them to the postweld station for final assembly.
Backhoe chassis are welded in this manner -- the robot welds in its station while the human operator is in the other station doing manual welds, loading and unloading assemblies and parts, and so on.
"You can always tell a manual weld because it's not quite as consistent and usually not as straight," Berge said.
"We try to keep the operator busy doing manual welding and still be able to get done in time for the robot to come over and finish," Brooks said.
The ratio of work done is about two to one; robot welders are about twice as fast as humans.
"There's very little manual welding any more," Brooks said, using the loader arm assembly as an example. More than 90 percent of the welding is done by robots.
And a 100 percent of Iowa farming is still done by farmers -- not robots.
