Company Puts Lens-Grinding Know-How Into Shaft Grinder

After several months of publicity before the International Manufacturing Technology Show, France-based industrial giant Fives officially unveiled its Landis Twin Turret (LTT) grinding machine at the trade fair in Chicago earlier this month.

Jointly manufactured in the United Kingdom and the United States by Fives' Landis business unit, the LTT grinder is engineered for production of shaft-type parts. The company is targeting the aerospace, medical, and automotive markets. Likely automotive applications are transmissions, gears, camshafts, and fuel injection components.

The LTT shaft-type parts grinder uses machine design features developed for extremely accurate lens grinding. The LTT shaft-type parts grinder uses machine design features developed for extremely accurate lens grinding.

At IMTS, Steve Thiry, managing director of Fives Landis Ltd., which is based in Keighley, West Yorkshire, England, walked through the key features of the grinder, saying the machine is among the most accurate on the market, with tolerances in the microns.

The design of the LTT grinder is based on a twin turret optical grinder that Landis makes in the UK for grinding high-precision lenses, and which operates at "nano-level accuracy" -- down to 29 nanometers -- according to Thiry. (One nanometer is equivalent to 0.001 micron.) Among its applications, the machine has made lenses for the Hubble Space Telescope. "It achieves a level of accuracy in the contour and shape of lenses that has not been seen before," Thiry noted.

The optical grinder derives much of its accuracy from its construction. Landis builds the grinder on a granite base for thermal and environmental stability, and it has eliminated most metal from the rest of the structure. The optical grinder also uses air bearings to eliminate metal-on-metal contact and thus the potential for wear, which could affect accuracy.

Landis applied much of this optical grinder's design to the LTT machine. The LTT's base is granite, as is the one on the twin turret optical grinder. The base and associated components are manufactured in the UK and then shipped to Fives Landis Corp., in Hagerstown, Md., for construction of the grinding system and other components.

The machine's two rotary hydrostatic turrets have integral servomotors along with X-axis hydrostatic ways with linear motor in-feeds. The use of hydrostatic components, of course, means there is no metal-on-metal contact, which reduces wear and maintenance, improves reliability, and helps maintain accuracy.

There are also no ball screws, gears, V- or flat-guide ways, or linear rails in the assembly. These have been replaced with linear and radial servomotors for all motions to eliminate backlash, as well as with rigid hydrostatic spindle bearings.

The LTT grinder operates up to seven radial axes and one linear axis. The machine achieves a swing range of 180 mm (7.08 in) and a maximum workpiece length of 400 mm (15.7 in), while operating a CBN (cubic boron nitride) grinding wheel at the maximum 350 mm (13.7 in) diameter and 40 mm (1.57 in) width, and at speeds to 120 meters per second (4,724 in/s).

The LTT grinds a range of shaft-type shapes and forms, and performs multiple operations on parts in a single fixture. These include outer- and inner-diameter grinding, processing of diameters and faces, and precision tapering and contours. The contours can be done in eccentric and concentric patterns and traverse configurations

The LTT uses a Landis 6400 CNC control, an open-architecture system.

The grinder is said to provide ergonomic operation and easy integration with automated systems. The load and access height is 1,125 mm (44.3 in), which the company says is within the comfort zone of operators and ideal for integration of loading and unloading robots.

Importantly, the LTT grinder is compact, taking up relatively little floor space in a shop, although Landis hasn't released size numbers yet.

Cutting Tool Sales Dip in July

The IMTS show is expected to boost sales of machinery and components in the fourth quarter, as suppliers fill orders placed at the show. Prior to the event, however, business in some product areas dropped slightly, which observers say is typical in show years given that attendees often delay purchases until after IMTS.

Such was the case in July with U.S. cutting tool demand. Sales were down 1.1 percent from June, to $170 million, according to figures released Sept. 10 in the Cutting Tool Market Report (CTMR), which is produced by the U.S. Cutting Tool Institute and the Association For Manufacturing Technology, the organizer of IMTS. Sales in July, though, were up 1.5 percent from the same period in 2013.

Whatever the reason for the drop, the July decline in cutting-tool sales is another sign of uneven performance in consumption this year. As reported on Aug. 20, month-to-month sales in 2014 rose in January, March, April, and June, but declines were seen in February, May, and now July.

Total cutting tool sales through July as reported by the CTMR were $1.18 billion, which means they are on track this year to roughly equal 2013 sales of $2.03 billion. IMTS, however, could push this year's results past 2013 sales with strong results in September and the fourth quarter.

As always, stay tuned.

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