Upgrading the operation of a CNC turret is an important way of extending machine performance. If it's done right, operators can add fabrication versatility, spindle speed, and torque with little more than the addition of a live tool.
One supplier that recently expanded its range of live tools is Heimatec Inc., of Prospect Heights, Ill. The company, whose parent firm is based in Renchen, Germany, increased the selection and capabilities of its Base Mount Tooling (BMT) line of live tools, which are available in radial and axial versions.
Preben Hansen, president of the U.S. operation, said Heimatec maintains an inventory of around 25,000 live tools in its database that fit virtually every brand of CNC machine on the market, including many from Asian brands with proprietary turret designs.
In an interview at the International Manufacturing Technology Show (IMTS) in Chicago in September, and in a recent follow-up telephone conversation, Hansen and Brian Ostrowski, marketing manager, discussed the key features of Heimatec's BMT line.
One benefit the tooling provides to CNC operators, Hansen and Ostrowski said, is that the components are more rigid than the VDI types that are common in the market. (VDI stands for VereinDeutscherIngenieure, or Society of German Engineers, and refers to uniform shaft openings in the face of a turret whose dimensions have been widely adopted by the industry.) VDI tools have a serrated coupling that is held in place with a mated part inside the turret, which is tightened by an external nut after insertion.
Heimatec's X- and Z-axis BMT tools are used in combination with an inverted spindle and a collet nut. The tool sits deeper in the turret housing and is tightened with four bolts, which increases its rigidity, according to Hansen and Ostrowski. The amount of rigidity varies by application, but Ostrowski estimated that CNC operators get 5 to 10 N-m of extra torque out of Heimatec's BMT tools than VDI versions. More rigidity additionally means improved finishing capabilities and longer tool life, he added.
(BMT, of course, is also an industry acronym for bolt-mounted tooling, which attachesto a turret with bolts and likewise achieves greater rigidity than VDI tools.)
In addition to rigidity and its effect on cutting and tool life, Hansen said the company's BMT models have speed increasers and torque increasers on the drive end of the tooling that are adjustable to CNC machining needs. Both are driven by integrated gear mechanisms positioned between the drive and collet.
The speed increasers convert spindle rpm into higher cutting speeds. They are available in three ratios: 1:2, 1:3, and 1:4. A 1:2 ratio doubles a 6,000-rpm spindle speed to 12,000 rpm; 1:3 increases it to 18,000 rpm; and 1:4 boosts spindle speed to 24,000 rpm.
These increases are automatically generated, along with other machining parameters, by the CNC program.
The torque increaser (or gear reducer) operates in essentially the same way but in reverse. A 6,000-rpm spindle can be programmed to run at 3,000 rpm.
Hansen said the range of machining capabilities possible with the BMT tooling includes hobbing, broaching, drilling, boring, tapping, and threading. The tooling is available with the company's u-tecflexible machining system, which generates high power transmission rates through a polygonal drive and has quick-change capabilities.
Additional features of the BMT line include forward tapered roller bearings within the tools for greater operational precision,high-pressure internal coolant that runs at 2,000 psi, and custom tool design capabilities.
Hansen noted that Heimatec uses a Yasda machining center to cut the BMT tool bodies to the precise tolerances necessary for the internal bearings, gears, drive system, coolant, and other parts. Yasda machining centers are not well known in North America, and they can be expensive, he explained, but they are extremely accurate and, in this case, vital to Heimatec's ability to achieve the tolerances necessary for its live tools.
Ostrowski added that the tolerances of the BMT line are so precise that no "run in" is required for the tools. They can immediately go into production with the initial installation, he said.
Hansen said at IMTS that one of the factors he expects to influence sales of the BMT tools is that shops want to get more operations out of their CNC machines. "We are showing them a variety of ways to approach a workpiece," he said.
Heimatec's BMT tooling comes in two versions: axial (shown here) and radial.