Above: Finished parts from Cole Manufacuring Corp., ready to be sent to the customer for assembly.

Obtaining a sleek exterior requires both technique and grit

November 2013 - As the holiday season approaches, stores and shops prepare with enticing floor and price displays, luring in potential sales. Functional display holders among the rows of clothing items must have a smooth surface and serve as an aid to shoppers, not a distraction. To achieve the desired finish, Cole Manufacturing Corp. needed to upgrade how it grinds its parts before applying paint.

“We needed a way to deburr and smooth parts out in a uniform manner,” says Nic Cole, purchasing manager and production supervisor for the West Bend, Wis.-based metal fabrication shop. The company works with hot-rolled pickled and oiled steel and some stainless in sizes from 20 gauge to 1⁄2 in. The company recently installed a new Mitsubishi laser and runs two CNC press brakes, two robotic welders, MIG and TIG hand welders, various punch presses, and has a fully equipped tool room for building dies and fixtures.

Cole Manufacturing fabricates display holders seen in major department stores such as Kohl’s and stamps out various parts for exercise and lawn and garden equipment. It also forms and fabricates parts for table bases seen in McDonald’s, and laser cuts and finishes signage for fast food chains.

In search of a better grinding method, Cole Manufacturing found a flyer from Norwalk, Conn.-based CS Unitec Inc. with information about the PTX Eco Smart electric linear and Multi-Max stationary multipurpose grinding systems. “Previously, we used 4.5 in. grinding wheels and orbital sanders and they weren’t doing the best job,” Cole says.  

“We saw the PTX and Multi-Max surface finish during a demonstration and it looked like something right up our alley,” Cole says.

After contacting CS Unitec, Cole Manufacturing was referred to Abrasive & Fastening Solutions Inc., Yorkville, Ill. “We were able to take some of our parts and try them out on the machine,” Cole says. Operators tried the PTX on some customer parts and found they were able to remove blemishes from the surface with relative ease.

“I believe the process they were using required four steps to take raw material to finished product,” says Guy LaPore, sales manager at Abrasive & Fastening Solutions. “Our system was able to reduce that to two steps using the advanced grain combinations and CS Unitec abrasive sleeves and refined finishing drums they have available.”

Cole Manufacturing knew there were better ways to finish parts before purchasing the grinders from CS Unitec, but didn’t have enough specialized work to justify the required capital investment. “But during the last two years, we’ve received a lot of consistent display work,” Cole says. “Back in the day, we received a metal part, stamped and formed it out and the job was done. Now the parts we make are carefully scrutinized, so it’s important to pay attention to the details and aesthetics. We knew we had to get a machine like this for the type of work we were doing.”

Consistent finish

Time was of the essence as the company had just secured a large order for steel rectangular display holders. “We needed something pretty quickly and it had to be smarter to work with than what we were doing,” he says. After taking some time to figure out which grit to use on the parts, Cole says operators were able to get to work. 

The PTX grinder is a 15 amp handheld tool that grinds and polishes to achieve a flat surface for open or closed pipe constructions. It grinds from coarse to very fine finishes and burnishes to a high-gloss finish. Its hollow core system allows operators to change out abrasives without tools, as there are no screws to remove. Operators need only slide the wheels and accessories onto the finned, rigid rubber shaft which secure themselves automatically when the machine turns on.

Cole Manufacturing found the PTX grinder helped with hard-to-reach areas and custom-built a holder for its parts for easy use. “Rather than put down the piece we were grinding, we found it was easiest to build a holder so we could use two hands with the finisher,” Cole says. 

The Multi-Max uses two shaft mountings with grinding discs with 5⁄8 in.-11 UNC or 7⁄8 in. mounting and abrasive grinding wheels for longitudinal surface finishers. It uses a fix hook and loop system, which has a flexible backing pad, allowing a disc to be changed in seconds without tools. For plain and fine grinding it has a transparent hinged grinding guard and roller support for more accurate work. The adjustable support rail has a safety hood for grinding discs up to 7 in. The drive motor can be used with a flexible shaft, allowing the Multi-Max to take on 1⁄8 in. or 1⁄4 in. shaft abrasives with an adapter for polishing rings up to 6 in. diameter, and grind narrow and awkward spots.

Switching to CS Unitec’s grinders has proved to be a worthwhile investment as parts are smooth and uniform. “There are no start and stop marks, no scratches or big divots,” Cole says. “You can get a smooth finish across the board without wearing down the metal too much in any one area.”

Cole Manufacturing uses a clear, nearly chrome paint color, leaving no chance of disguising any flaws. “With CS Unitec’s grinders, you get almost a mirror finish,” Cole says. “Not only do these grinders help cut back on reworking material and getting things uniform, we’ve also been able to help move production along.”

Prior to owning the PTX and Multi-Max grinders, Cole Manufacturing found it spent a lot of time reworking material. “You’d get parts back from the paint department and would immediately see defects and have to get the parts stripped down again and reground to try and make them uniform,” Cole says. 

An interchangeable finish

Both the PTX and Multi-Max grinders use the same abrasives. The cost of accessories can add up and CS Unitec’s grinders remove the need to double up on certain accessories. “So you get the same finish with both machines,” says Brad Hummel, sales representative, CS Unitec. “There’s a lot of different bench grinders out there, but it’s not typical to find machines that incorporate the same accessories as their handheld units, enabling you to match the work you’re doing on one piece to another.”

CS Unitec has fleece, interleaf and grinding sleeves in various grits. “You could be using 80 grit but how that grit is applied depends a lot on the material, its density, firmness—like a nonwoven material with the abrasive blended with it (impregnated fleece),” Hummel explains. 

Hummel recommends customers save time by getting a lower number finish from steel suppliers and grinding it themselves. “The most popular finish is No. 4—instead, bring it in at No. 2 or No. 3 finish,” Hummel says. “Steel suppliers have much bigger equipment on a conveyor and are finishing on that so unless you’re using the same abrasives and equipment, it can be a lot more difficult and labor intensive to try and match their finish versus bringing the material in at a lower number and finishing it yourself.”

For some applications, Cole Manufacturing has found the belts last longer and take more material off in one pass using a heavier grit instead of using a lighter grit, Cole says. 

“Cole Manufacturing uses our tools for very specific parts,” Hummel says. “I’ve been selling this tool to customers using it for everything from removing rust off regular tubing to the marine and food service industry, where customers use the grinders to get a mirror finish on stainless steel.”

Since purchasing the PTX and Multi-Max grinders, Cole Manufacturing is able to offer customers different finishes. “We can make the material better looking and suggest to customers that we can finish surfaces to add an effect to a part,” Cole says. “We can use the grinders to remove rust on metal and clean it up. We can use them throughout the plant for various things, even just maintenance.” FFJ