Finding Faster Deburring

While attending a trade show in the fall of 2000, a research and development employee at Upchurch Scientific (Oak Harbor, Washington) saw a magnetic deburring and polishing machine. It was well known throughout Upchurch that manual deburring was very labor intensive, so he took note of it.

Upchurch is a manufacturer of precision fittings for high-pressure liquid chromatography and other scientific instrumentation. Liquid chromatography is the study of fluids to determine the components that make up the fluid. According to Shannon Braun, head of the finishing department, the company's president often uses an example to describe the accuracy of HPLC systems. "He says, ‘If you spit into an Olympic-size swimming pool while chewing gum, an HPLC system could be used to analyze a sample of that water and tell you what brand of gum it was.'"

The majority of Upchurch's fittings are destined for instruments used by pharmaceutical, biotechnology, and chemical companies, as well as university and government research laboratories.

At the time of the trade show, Upchurch employees deburred using a microscope, small knives, simple files, or pick and brushes. The process was quite labor-intensive. Many parts required several minutes of deburring each, plus inspection time to ensure all areas had been deburred. Repetitive stress injuries were mounting.

Ms. Braun also faced space constraints if she continued with the manual deburring operation. Four people were doing the deburring during the day. "I had a full complement of people filling our work area, and I didn't have room to add anyone else," she says.

After speaking to her coworker about the sPINner magnetic deburring and polishing machine from Techniks that he had seen, Ms. Braun decided to call the manufacturer.

She spoke with Greg Webb in Indianapolis. He is vice president of the Earth-Chain division for Techniks, and he urged Ms. Braun to send some sample parts to him for testing.

"Within a week, he sent those samples back to us, and I passed them through the QA (quality assurance) department," she says. "They were amazed at the polished finish and the complete burr removal.

"When the parts came back, they were burr free. QA thought the process was terrific. One of the gentlemen actually said he would do a little dance on the tabletop if we got this piece of equipment in. I haven't held him to that, though," Ms. Braun quickly adds.

From Techniks' perspective, the Upchurch application seemed to be a perfect fit.

"Upchurch had all of the elements that we really look for: parts that were very small; a manual process, which I knew was very labor intensive; and the parts themselves really didn't have heavy burrs, " Mr. Webb says. "I knew if you had the right type of media, you were going to be able to get into those areas and clean it up. Once you had all those factors, it was just a winner."

Upchurch didn't hesitate. The company purchased the EHD 766 model with its two 13 by 13 double tanks. When the R & D person first saw the machine at the show, it was October 2000. By November 1, Ms. Braun was writing a purchase order. "This was the first time we had seen this type of instrument, and we went after it," Ms. Braun says. "Plus, it was well within the budget that I was looking to keep."

"We moved so quickly," Ms. Braun continues, "because we recognized that the quality of the parts coming out of the magnetic grinder was more consistent than can be achieved with manual processes. The polished surface is also something we haven't been able to achieve before. We now give all the parts the same surface finish. They are shinier. And the thread, when it engages with its mating part, has no resistance at all."

The sPINner has changed everything for Upchurch. The parts are in the machine for 45-minute cycles, and a deburring job that was taking 4 hours to manually perform is now being accomplished in 1 1/2 hours. Moreover, when the parts are in the machine, it can run unattended until the deburring is complete. After that stage, employees eyeball the part to remove pins and make sure that no heavy burrs remain.

The keys to the sPINner are the small stainless steel media that do the polishing and deburring. The media are special stainless steel pins that range in size from 0.008 inch in diameter to 0.060 inch in diameter and from 0.040 inch to 0.200 inch long and are held to tight tolerances so the media do not vary in size like conventional rock media. The stainless steel pins are hardened to 30 Rockwell C scale for long use. The media should last 3 to 5 years, depending on usage.

The size of the media allow them to get into places such as small cross holes and small slots that conventional media cannot. As an example, when rock media are used, the rocks sometimes get stuck into the hole or slot, thus creating more of an issue than the original problem.

A magnetic disk below the well of the machine rotates and excites the media. The disk has powerful permanent magnets in it. The magnets are arranged on the disk in a circular pattern that changes the polarity constantly from North to South Pole as the disk rotates. The constant changing of the polarity of the magnets makes the small steel pins jump up and down and spin all around the bucket in a circular pattern. This action of the steel pins spinning in a bucket creates an abrasive and polishing effect on the part, thus deburring and polishing it.

Another benefit of the sPINner to Upchurch has been its cleaning prowess. Parts come out of the solution clean of oil. Before, Upchurch would perform two cleans on all parts—once after they left the machine shop and then a second time after the deburring operation. Now, only one cleaning is necessary, which saves labor and cleaning fluid costs.

Ms. Braun reports that morale in the finishing department has improved with the advancement in deburring technology. "The group has always set goals for themselves, so every time they'd see a part come up, they would see how long it took them to do it last time, and they were always challenging themselves to do it faster," she says. "So when they were seeing that the parts were taking even less time with the grinder, there was an excitement there, and that hasn't gone away. They still think it's great that they're spending less time on a part."