Just the Right Tools for the Job

Roughing tiny parts in big machines calls for just the right tools. End mill size and construction are as integral to the manufacturing process as the toolpaths and precision machine operation used to create these components. Tony Johnson knows this and that’s why his customers trust him – and partner Amir Rashidi – with their high-precision jobs.

Co-owner and President of United Machine & Metal Fabrication, Johnson started UMMF in 1993 in his father’s garage with one small lathe and one small milling machine. After outgrowing the garage shop, he realized he needed a sales team and some help with the direction of the shop. Enter Rashidi, who contacted Johnson regarding machined parts for a fabricating shop in which he worked. The two eventually became partners and built their current facility in Newton, North Carolina.

The company houses a combination of two 5-axis machining centers—one multitasking, the other a turning milling center—three EDM machines, six lathes, eight CNC vertical machining centers, one horizontal machining center, one CNC horizontal boring mill, five manual mills, four manual lathes, and a collection of grinding, welding, and other finishing machines for close tolerance machining and metal fabrication of parts ranging from very large to very, very small.

“With smaller parts, it’s all about choosing the right tools,” Johnson said. For tiny parts for production clamping fixtures found on robots on automotive factory floors, and for the production of nail guns, he entrusts Mischon Rashidi, who graduated from University of North Carolina Charlotte with a degree in Mechanical Engineering, to machine the small precision parts using 3-axis routines and Mastercam.

“For starters, using the software’s toolpaths, especially the Dynamic Milling and Peel Mill toolpaths, helps the machinist select the optimal machining strategy to cut the parts faster, more efficiently, and more accurately,” said Johnson. “And that means increased productivity. “Before, we used to get one or two parts per tool. With Dynamic Milling and Peel Mill, we get 12 parts per tool. And these aren’t cheap tools. On top of that, we get the time savings – not just the cycle time, but also the time saved in changing out the tools. It all rolls up to be quite a lot.”

The Peel Mill toolpaths use the full flute length of the cutter, literally peeling away the material layer by layer with constant climb milling motion via trichoidal-type motion with accelerated back-feed moves when the tool is disengaged. The machinist has the option of defining the width of the cut. Dynamic Milling toolpaths are similar in that they use the entire flute length of the cutter, which remains constantly engaged with the material, minimizing stepovers and air cuts. Tool breakage is dramatically reduced if not eliminated. All of these highspeed toolpaths can be verified using the software’s Verify and Backplot functions.

Rashidi shares CNC programming duties with Tony Johnson’s son, Alex Johnson, who holds a bachelor’s degree in electrical engineering from Liberty University in Lynchburg, Virginia. Both second-generation programmers are integral to the growth of the company, helping the elder Johnson and Rashidi in their efforts to continually push their machines and people to manufacture smarter and take on more challenging jobs.

You can read an article featuring United Machine & Metal Fabrication in Manufacturing Engineering magazine here: Shop Pushes Boundaries, Software for Dynamic Success.

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