Using brains rather than brawn brings work home
April 19, 2013
When Oddello Industries, a supplier of fabricated assemblies to OEMs in a variety of markets, was invited to bid on a contract for a high-end adjustable mattress foundation, it searched for a piercing machine and a cutting machine that could handle the tubular portion of the project. It combined the two machines into a single integrated unit that processes more than 15 miles of tube per day.
What do you do when one of your big, influential customers asks you to make an assembly from several stampings and tubular components? If this is a chance to bring work back to the U.S., you throw quite a few resources at the project to make it happen. This is what happened at Oddello Industries, Morristown, Tenn., when one of its customers asked the company to build an adjustable mattress foundation.
Oddello’s experience in developing automated systems was a chief advantage and helped it win the contract.
A contract manufacturer on steroids, Oddello works with sheet metal, tube and pipe, composites, and medium-density fiberboard (MDF) on a bigscale. It makes components and assemblies for many markets, mainly nontradition-al furniture, automotive, and truck and trailer. It’s a fabricator on a big scale, similar to that of a Tier 1 supplier in the automobile industry. The company is staffed with a deep pool of engineering expertise and often builds its own machines and material handling equipment when the need arises. This capability lets the staff start with a blank sheet of paper, developing processes first, then buying or, when necessary, designing and building the equipment.
“We build equipment to suit the process,” said Chief Operating Officer Tom Roberts, who oversees the company’s manufacturing and operations. “We don’t adapt processes to suit the available equipment.”
Oddello doesn’t manufacture run-of-the-mill products. It simply isn’t suited to low-end commodity items. It concentrates at the high end of the market, and the proposal suited its niche: A sturdy, adjustable mattress foundation, made from several lengths of tubing and a handful of stamped parts. The tubular portion of this project was specified as 1-in. square tubing in two wall thicknesses—11 and 16 gauge—made into 38 unique parts, or stock-keeping units (SKUs). These would be combined with a handful of stampings made from coil thicknesses from 0.060 to 0.180 in.
The scope of the project meant that, to make these mattress foundations efficiently, Oddello would have to rely on the speed and repeatability of automated machines and systems. The tubes would be cut on an automated machine and the units would be welded robotically. To make the welding process flow smoothly and quickly, the tube would need square, burr-free cuts.
Oh, one more thing. The tubes would need several holes pierced in them, and the customer required a hole location tolerance of ±0.010 in. If that sounds like a tall order, Oddello’s team came up with a process that would make it even more challenging. It would start by piercing all of the necessary holes along every 28-ft. length of raw material. This was an unusual start, according to Roberts.
“Nobody pierces 28-ft. lengths,” he said.
Cutting first, the conventional approach, had a logistical drawback, Roberts explained.
“One option was to cut them to length, and then take this multitude of different part lengths and put them
into some kind of a process to pierce holes in them, which would require an enormous number of setups, and automating this would be incredibly costly,” Roberts said.
The second option, piercing first, was technically more challenging, which resulted in no small amount of skepticism from some of the equipment vendors Oddello consulted.
“Everyone told us we were nuts for trying to do it this way,” Roberts said. “That’s why we did it.”
To make the tube fabrication system work accurately and quickly enough to be efficient, Oddello’s engineering team had to achieve several critical goals:
Two critical technologies were PLCs for programmability and servo drives for accuracy.
“Usually this sort of piercing is a repetitive pattern, like a Unistrut®,” Roberts said, referring to the metal framing hardware that has a row of holes or slots in a single size with regular spacing. “Ours is anything but repetitive,” he said. Oddello needed a programmable piercing machine capable of holding a tight hole location accuracy over a 28-ft. length of tube.
The Oddello staff developed a
process that uses two machines: a piercer manufactured by Criterion Machinery and a cutoff machine made by Haven Mfg. Corp.
“When a full-length tube feeds into the piercer, we drive the tube against a hard stop,” Roberts said. “A sensor determines that the tube is present, a clamp secures the tube, the hard stop retracts, and the servo moves into position and grabs the tube,” he explained.
The machine uses four press heads to make holes of four unique diameters. An elevator-transfer system designed and built by Oddello moves the tube into the shear machine’s bundle loader. To keep the tolerances as tight as possible, the shear machine uses a process similar to that of the piercer—the end of the tube is driven against a hard stop, then the machine does a registration cut, removing about 0.75 in. of material. It uses a hitch-feed system with a closed-loop servo drive to control the cutting head and a rock-solid clamping system to keep the tube stationary.
After cutting the tube to the specified length, which varies from 6 to 66 in., the machine uses a series of nine gates with kickers to sort them into the appropriate bins. Further downstream, an operator fixtures the stampings and tubular components, and after a vision system verifies that all the components are present, a robot does the welding. The operator inspects the welds visually, then hangs the assembly on a hook, and a monorail system takes it through a wash-and-rinse cycle, through a dip tank for coating, and into a curing oven..
Programming the machines was quite a challenge. Of the 38 SKUs, Oddello gets a maximum of nine SKUs from each 28-ft. stick of tube, so it had to develop several cut layouts to produce all of the parts. Once that was done,
Oddello relied on assistance from the two machine vendors to coordinate the two machines’ actions.
When changing from one part run to another, Oddello’s staff changes the program in the Criterion machine, which feeds that information to the Haven machine. Although this cooperation made changeovers essentially seamless, the commissioning process did reveal a few wrinkles that needed to be ironed out. Oddello’s staff realized that a few subtle adjustments—timers and a few other bells and whistles—would enhance the system’s functionality.
“Haven’s programmer was quick to answer a phone call or an e-mail, and he’d send us the software update immediately, and we’d download it and get back to business,” Roberts said.
The result of merging the hardware and massaging the software is a single pierce-and-cut system that feeds 10 robotic welders.
“The system processes about 2,400 lengths of the 16-ga. tubes every day, and 400 of the 11-ga. tubes,” Roberts said, for a total of 78,400 ft., or nearly 15 miles, of tube.
Despite the large number of hits the system makes every day, the cut quality meets Oddello’s needs and doesn’t vary.
“The dies that hold the tube in the Haven machine are custom-fit to our tubes, and they hold the blades absolutely square. We have no issue with squareness whatsoever,” Roberts said. Of course the blades wear, but the gauge changes necessitate die changes. The changeovers from one gauge to another occur before burrs develop.
And despite the high throughput, the system holds tight tolerances. It starts with the Criterion machine, which holds a hole location tolerance of ±0.005 in. The Haven machine doesn’t add much to that.
“On the Haven machine, we typically see overall length tolerances of ±0.001 to ±0.0015 in.,” Roberts said. “We never see any variance more than 0.003 in.”
The result is an assembly that meets the customer’s dimensional requirements.
“The hole location tolerance from the tube end is ±0.010 in.,” Roberts said. “The accuracy of both machines makes this possible.”