I read tooling and machine tool model brochures for a living. Interesting as that might sound to gear-heads, it’s probably not as fun as reviewing books for the New York Times. But every so often I do see something new or different that piques my interest. In fact, the pace of innovation in new machine tool and tooling design, construction, function and features has picked up in recent years. For instance, hybrid machines that merge different styles of metalworking are routinely being introduced to the marketplace. And machines like 3D printers that add instead of remove metal are opening whole new markets and encouraging process engineers to think in different ways about manufacturing their products. Change, or as they say, variety “is the spice of life.” And for us manufacturing types, we’re no different. New technology can be exciting!
Over many years of reading specs, I’ve noticed a growing number of machining center model brochures listing a spindle style option known as BIG-PLUS®. There are several spindle taper styles, such as CAT, BT, HSK, to mention three of the most popular. BIG-PLUS® is not new. It’s been around for a while. But why, I wondered, are more and more machine tool builders offering it on their machining centers? In some ways, the answer is more surprising than discovering an all-new machine concept in the last catalog under a pile of conventional 3-axis 40 x 20 VMC brochures.
A spindle is a spindle is a spindle, isn’t it? Sure, one might have a slightly different taper or pull stud length or thread. But the real difference, I thought, was in the gearing or bearing configuration or draw and clamping force and temperature control or coolant-thru capability, right? Well, yes. But what’s really cool and interesting and exciting, and maybe even more so than some all-new design, is a spindle system with reinvented technology. This is what BIG-PLUS® is–a better mousetrap that truly enhances an already good design.
Sure, the substantial BT and Caterpillar V-flange tooling–with full cylindrical surface contact between the tool taper OD and the spindle taper ID, slid one inside the other and drawn together–is an elegant, simple, solid design. So why mess with it? In a word, high-speed. BT and CAT taper tooling systems were developed 40 years ago, long before ten-, twenty-, or thirty-thousand-plus spindle rpms were on the radar. Despite the considerable rigidity of the BT and CAT taper systems, tools need even more spindle support as rpms increase. And that’s what BIG-PLUS® dual contact design is about. As rpm increases, all metals expand. Left unsupported in the axial direction, tool growth is exacerbated and the slightest radial force will introduce runout error that can make a difference. So, as tooling grades evolve, spindle speeds increase, more shops need dual contact (taper and flange) tool support to take advantage of rpm efficiencies without sacrificing finished part accuracy. Oh yeah, and tolerances aren’t getting any looser, either. Everything metalworking is going faster, tighter tolerance, automated and all at lower cost.
But shops have hundreds of thousands of dollars invested in CAT and BT V-flange tooling. And most of it is perfectly suitable for heavy-duty, lower speed operations. A dual contact tooling system is great and even necessary for some of the work, but how can shops justify switching to a new machine spindle configuration to accommodate a new tooling system? No company can easily write off large inventories of tooling.
This is the surprising part. Remember I said that a growing number of machine builders are offering BIG-PLUS®? That’s because spindle speeds are increasing, tolerances are tighter, and BIG-PLUS® addresses these changes while enabling a shops existing CAT or BT V-flange tooling to be used in BIG-PLUS® spindles. Better yet, BIG-PLUS® tooling can be used in every CAT or BT spindle in their shop, too. It provides total interchangeability and expands a shops range of high performance operations capability, all without extra cost (above and beyond the cost of your next new machine tool).
New machines are always being purchased because technology evolves, spindle speeds increase, shops expand. Most machine tool builders know that their machines will be more productive if they’re ordered with a BIG-PLUS® spindle because it provides the best of both worlds without extra cost. And THAT’S why I see more and more machine brochures featuring the BIG-PLUS® spindle option.
I love new technology. But I appreciate good technology made better, even more. I learned more about the BIG-PLUS® dual contact spindle and tooling system online by watching a “Breakfast & Learn” video presentation. I followed that up with two more videos showing actual performance differences using both tool holder types on the same machine with the same conditions, below.