When EddyTech Systems Inc., Middleburg Heights, Ohio, began marketing its state-of-the-art digital eddy-current inspection system, the EddyChek 5, it did not want to offer customers a mere quick fix for finding product defects.
Rather, the company strove to provide a product that would be a valuable tool for companies to help eliminate problems before they occur.
"Although the equipment can identify faults and sort out defective product to prevent it from reaching the customer, that’s not its main purpose," says Richard Fisher, president of EddyTech. "The important thing is to be able to analyze what’s going on and hopefully make changes in your process upstream so you avoid those defects downstream.
"The overall intent is to actually improve the process so you don’t get defects to begin with."
The EddyChek 5 electronics unit forms the heart of the eddy-current inspection system, says Fisher. It enables a company to connect a multitude of inspection probes and coils and inspect a wide variety of products.
"This is primarily used for in-line production testing," says Fisher. "We can test products as small as a 0.004-inch-diameter filament wire or as large as 40-inch-diameter tubing. Eddy-current systems can also function at speeds as slow as TIG-welded tube mills that typically run at line speeds of a few inches per minute all the way up to hot-rod material moving at a blistering pace of 23,000 feet per minute, which is over 250 miles per hour."
EddyTech also has rotating probe systems that can be used on bars to detect surface defects as small as 50 microns.
"The EddyChek 5 electronics unit is completely sealed from the elements, lined internally with stainless steel for heat dissipation and probably not much larger than a tabletop microwave oven," says Fisher. "The sensors that connect to the unit, though, can be very tiny--from what we call pencil probes--all the way up to large magnetizing heads with encircling coils that can be enormous and weigh several hundred pounds. It all depends on what’s being tested. So the applications are fairly wide."
One of the most common applications for the EddyChek 5 is the inspection of seam welds in seam-welded tubing.
"When they make tubing, they start with flat strip material, run that through a mill, form it into a tube shape and then weld the seam on the fly as it passes through an induction welder," says Fisher. "Our equipment is located pretty closely after that process so that as the tube is passing underneath our inspection coil, we can examine the heat-affected zone to see if there are any pinhole defects or other faults in the weld. We can then give an early warning to the operator that he has a problem."
Additionally, the EddyChek 5 marks defects, which allows end users to cut out flaws or segregate faulty tubes after they have been cut to length.
About 85 percent of companies with an EddyChek 5 use it to inspect welded tube. Some companies rely on the system to perform other inspection tasks, such as butt-weld detection in steel strip, wire or rod.
"With some products, you can’t see the butt-weld. In copper wire, for example, the butt-weld may be covered by a vinyl jacket coating," says Fisher. "But by running it through one of our encircling coils, it’s pretty easy to find, even at high speeds."
Double-wall brake-line tubing is another big application for the EddyChek 5, where it is used to detect voids in the bonding between the two brazed layers. Additionally, it can be used with customized mechanical handling systems for component inspection.
In terms of material, the EddyChek 5 can handle a wide range of metals. Carbon steel is the most common, but others include stainless steel, copper, brass, aluminum and titanium, Fisher says.
Put into practice
A majority of EddyChek 5 customers are manufacturers of semifinished products. This is the case for GL Precision Tube Inc., Aurora, Ill.
The company produces carbon steel round, square and rectangular tubes mainly for the transportation and furniture industries. In regard to the latter, it also produces different styles of furniture tubing, including pear-shaped and flat oval.
GL Precision Tube opened in January 2008, and two months later, it purchased an EddyChek 5, says Gilbert Markus, plant manager.
"What prompted the purchase was our customer requirements and better process controls," he says. "We have a lot of transportation customers, which includes motorcycles, ATVs and the auto industry. They flat-out won’t buy tube unless you’re eddy-current testing. It’s one of their requirements.
"Plus, we’re all looking for better process and fewer rejects, and this is a tool that helps you achieve that. Part of our ISO format is to constantly try to improve, and this is one of the things that you need to have if you really want to improve."
GL Precision Tube uses its EddyChek 5 on every product it manufactures, even if a customer does not require eddy-current testing. Markus describes it as added insurance in these cases.
He also says the company has had a positive experience with EddyTech on a macro level, in terms of customer support and training, and on a micro level, with the EddyChek 5 itself.
"It expanded our customer base, it allows us to produce a quality tube and it helps us find problems before they become major problems," says Markus. "It also gives us a higher degree of weld integrity."
This is a high priority for GL Precision Tube, which is why the company does a great deal of destructive testing.
"We crush it, we punch it, we expand it, we bend it," says Markus. "And naturally, if you did this to every tube you run, you wouldn’t have any tube going out the door. So in between tests, [the EddyChek 5] gives us the confidence that we’re still running with a good weld." MM