Related Glossary Terms
- cutting speed
Tangential velocity on the surface of the tool or workpiece at the cutting interface. The formula for cutting speed (sfm) is tool diameter 5 0.26 5 spindle speed (rpm). The formula for feed per tooth (fpt) is table feed (ipm)/number of flutes/spindle speed (rpm). The formula for spindle speed (rpm) is cutting speed (sfm) 5 3.82/tool diameter. The formula for table feed (ipm) is feed per tooth (ftp) 5 number of tool flutes 5 spindle speed (rpm).
- high-speed steels ( HSS)
high-speed steels ( HSS)
Available in two major types: tungsten high-speed steels (designated by letter T having tungsten as the principal alloying element) and molybdenum high-speed steels (designated by letter M having molybdenum as the principal alloying element). The type T high-speed steels containing cobalt have higher wear resistance and greater red (hot) hardness, withstanding cutting temperature up to 1,100º F (590º C). The type T steels are used to fabricate metalcutting tools (milling cutters, drills, reamers and taps), woodworking tools, various types of punches and dies, ball and roller bearings. The type M steels are used for cutting tools and various types of dies.
Steel strapping is effective for bundling materials, but poses a number of problems for a machine shop. Its sharp edges make it something of a workplace hazard, while its long, ungainly shape makes storage and disposal difficult. It's also made of mid-carbon steel, so even though throwing the strapping in the dumpster is the easiest way to handle it, possible profits from recycling are dumped as well.
When Michael Rudnicki, president of Thunder Bay, Ontario-based machine shop Rudnicki Industrial Inc., built a machine in the late 1990s to help a friend's shop dispose of ungainly steel strapping by cutting it into pieces, he considered the machine to be a fill-in until a permanent solution could be found. Today, that original machine is back at Rudnicki's shop as memorabilia, while newer versions of the company's Strap Eater strapping recycling machine have been shipped as far away as Australia and Europe, as well as throughout North America.
"I've built a number of them since that first machine and have been constantly modifying the design," he said. "I've reduced the size and weight to the point that they can be shipped by UPS or other carriers without hiring a trucking company."
The current generation of Strap Eaters measure 13" x 24" x 14" and weigh 148 lbs. The 0.5-hp machine rests on a 45-gal. drum and strapping is fed into the machine's three-blade system, which turns most steel and plastic strapping into pieces 4" (102mm) in length before dropping them into the drum.
"Some similar machines exist," Rudnicki said, "but most of them use a two-blade system and are very slow. I actually had a friend who bought a machine to supplement his shop's existing strap cutter, and he came back to me and said, 'No one wanted your so-called competitor's machine because it's so slow — can you do anything to speed it up?' I said no, but it told me I was doing something right."
Rudnicki explained that a two-blade system uses one blade to hold strapping in place while a rotating cutter shears the material, whereas the Strap Eater uses two HSS cutting blades, in addition to the holding blade, which reduces vibration and increases cutting speed.
Sales of the Strap Eater constitute about 5 percent of the shop's total business, Rudnicki said, but he expects that percentage to grow.
"I can sometimes find potential customers just by spotting steel strapping sticking out of garbage cans, waiting for the garbage man to grab it," he said. "When I tell them they can recycle it, make money and increase shop safety, sometimes they're surprised a piece of equipment like this even exists. One of my clients takes a 45-gal. drum of scrap steel to the recycling yard every week, so it's become quite a lucrative investment for them."
— E. Jones Thorne