Are Cutting Tools Leading or Following?
To remain in the forefront requires an ongoing awareness, appreciation and knowledge of the tooling essential to the creation of the future.
Early NC machines mimicked the way manually operated equipment worked, and programs were written around standard tooling. As software and machine configurations progressed, tooling materials, coatings and geometries evolved to accommodate more complex and challenging parts. CAD design systems and a changing business climate has caused a significant realignment of the manufacturing base, resulting in the adoption of new and radically different tools and methods.
Free-machining materials and tighter tolerance parts led many of the high-volume commodity units to be off-shored or automated. Consequently, machine shops were faced with shorter runs of highly complex parts in exotic materials. This facilitated the move to multi-operation machines capable of running unattended and completing all machining in a single setup. Ancillary processes, including bar feeding, part loading and inspection, have likewise been fully or partially automated. Nowhere have these changes had a bigger impact than in Swiss-type machining.
Originally designed to machine watch components, the widely held perception was that Swiss machines made small-diameter parts from barstock. Today’s multi-axis machines, however, are putting new demands on the tools, workholding and software they use and the companies that make them. The latest multi-purpose machines use many of the design features found in traditional Swiss-type lathes, but can machine larger parts. Cutting tools are designed to keep pace with modern machine capabilities and, in many cases, innovation in tooling is now a factor in machine design and vice versa. A perfect example is thread milling.
Thread milling has become increasingly popular for the ability to run unattended, achieve better chip and burr control, require lower torque and power, and provide predictable tool life. Thread milling can also eliminate second operations and produces an improved and more accurate result. Manufacturers have been frustrated for years by the inherent weaknesses of tapping. Small taps wore quickly and often broke, resulting in lost time and scrapped parts. Thread milling generated improved profiles, finishes, efficiencies and longer tool life. Further, thread milling is ideal for live tool stations on lathes that have speed, but are not always that rigid. With thread milling, the tool and machine complement each other. To take it one step further, by using a rotary axis, some machines can give a standard thread mill the additional helical clearance required to cut a two-start thread.
Other round tools have also been dramatically improved to meet the increasing complexities of modern parts. Micro drills down to 1-mm diameter are available with coolant-through capabilities for better performance and longer tool life. Traditional gun drills have been replaced by more traditional drills capable of drilling 30 or more diameters. From an efficiency and performance standpoint, some of the most interesting advances have occurred with the development of two- and three-function tools that assist in the consolidation of tool stations and offer programming flexibility. Mill, thread mill and chamfer combination tools produce a better result and really improve machine usage.
Indexable tools have been radically improved through nanotechnology, both in the substrates and coatings. Nanocomposite coatings are 25 percent harder and more heat resistant than a typical AlTiN multilayer coating. Recent advances in the coating area have made it possible for shops that machine newer, non-traditional materials to access custom compounded formulas to meet their individual needs.
The increase in automated systems has created demand for indexable tools engineered with chip formers that eliminate tending during machining operations, as well as new and unique geometries. The traditional three-cornered shape has been joined by polygon and other configurations. To cope with thermal considerations, chip evacuation, and extended life, high-pressure coolant holders are available for even smaller Swiss line tooling.
It has been said that manufacturing advanced components has moved from a process business to a knowledge business. In modern manufacturing, it is also an extension of the mind and its capability for creativity.