On Manufacturing/March 2016

Portable Coordinate Measuring Machine

Hexagon Manufacturing Intelligence has introduced a new portable coordinate measuring machine (PCMM), the ROMER Absolute Arm 77 Series. This series comes in models ranging in measuring range from 2.5 m to 4.5 m.  And the key of this new series is the level of accuracy provided by the arms. For example, there’s the smallest, the 7725, which has the 2.5-m range.  It provides a probing point repeatability of 0.017 mm and a probing point volumetric accuracy of ±0.026 mm. Then, the largest, the 7745, with a 4.5-m range, offers a probing point repeatability of 0.060 mm and a probing point volumetric accuracy of ±0.174 mm.

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These PCMMs are available in six- and seven-axis configurations and can be equipped with laser scanners as well as touch probes. The units offer acoustic and haptic operator feedback so they can be readily used on noisy shop floors. A 3,000-N magnetic standard base allows the arm to be located in various places and positions.  hexagonmetrology.us 

High-Speed Spindle

When it comes to spindles, there are high-speed types and then really high-speed spindles. Like the RBX12 produced by BIG Daishowa Seiki, an air-powered spindle for micromachining applications that provides a variable rotational speed between 100,000 and 120,000 rpm.

The spindle can be used on existing machining centers as it is driven by air supplied through a stop block, although air from the machine spindle can be used. The machining center spindle doesn’t rotate, just the RBX12, so there is no issue with wear of the machining center.

The spindle features ceramic ball bearings and an ultra-precise collet system: the AA-grade Mega Micro Collet guarantees 1-micron runout at the collet nose and 0.102-mm collapsibility assures highly concentric clamping of the micro-tool shank. What’s more, thermal displacement in the Z-axis is held constant at <0.001 mm. 

All of this contributes to the ability to perform ultra-thin wall cutting. The RBX12 is available with BCV40, BBT30/40 and HSK-A63/F63/E32 interfaces, and models not requiring a stop block have an extremely small body diameter of Ø32 mm. bigkaiser.com

Hard Scudding for Gear Production

A few years back, scudding was introduced for gear production. It is performed by making several small enveloping cuts. It can be done without the need for an undercut or groove for clearance; the lead of the gear can be manipulated via axial motions (crown/taper). This process is found to be five to 10 times faster than gear shaping. It is being deployed for the production of internal, external, helical and spur gears, as well as for splines.

But while conventional scudding is good for green, or soft, gears, according to German Machine Tools of America (GTMA), there is a process that can be used for re-machining hardened gears with a tooth-to-tooth composite error and total composite error in the AGMA 12, DIN 5 range and a surface finish better than 1.5 Ra.

It’s called “hard scudding.” It can be performed on machines like the Profilator machines from GTMA member company Profilator with solid carbide tools. Hard scudding of an automotive ring gear can be performed in from 25 to 30 seconds, as compared with 40 to 50 seconds for scudding. The process is said to be cost-effective compared with conventional grind-and-hone operations. gmtamerica.com