A new range of gear honing rings using specially fused abrasives, said to last virtually twice as long as similar consumables on the market, has been introduced by Tyrolit. Called MIRA, the products are available in the U.K. through the company's Crick subsidiary in Northamptonshire. Not only do the rings last longer, allowing production machines to complete more gears before the tool needs changing, but cycle times are also reduced as infeed rates can be increased. Both factors combine to raise honing productivity by up to 30 percent, without the need for capital investment in new machine tools.
In any case, even if new machinery could be justified, there are currently long delays associated with delivery as the world emerges from recession. Demand from the automotive industry for quieter vehicle transmissions to satisfy more and more discerning customers means that tooth geometry and surface quality must constantly be improved. In the manual transmission of a luxury car, up to 70 percent of the gear wheels undergo honing on the flanks. Finish-honing of large volumes of gears in their hardened state is therefore called for and it is this trend that prompted Tyrolit to develop new abrasive specifications for its MIRA rings.
John Willis, managing director of the manufacturer's U.K. operation, commented, "In the last few years, automotive primes and their global supply chains have faced their greatest challenge for a generation due to massive swings in demand for their products. Weak sales have given way to a need for enormous increases in output as the market for automotive products has returned with a vengeance. The trouble is that production capacity cannot simply be switched on and off."
He said that other challenges come from external influences that are difficult if not impossible to control, such as higher raw material costs, combined with ever increasing pressures from customers to reduce costs and at the same time improve quality. Tyrolit's MIRA hard machining consumables for internal and external honing of gear teeth is one technological solution. The firm has long been active in the manufacture and supply of diamond and conventional abrasives for grinding gears, splines, sprockets, worms and shafts.
Tyrolit has a dedicated manufacturing plant in Neuenrade, Germany, where honing rings for hard finishing of gears as well as diamond dressing gears and masters are produced. Such rings traditionally employ abrasive grains in a relatively weak resin bond, making dressing and profile-holding problematic. Especially when a lot of stock is to be removed, low radial infeeds and long honing times result.
Three categories of Tyrolit's patented MIRA honing rings offer a clear improvement in this area. Resin-bonded rings use aluminium oxides embedded in an epoxy matrix. Compound rings use a novel construction involving vitrified conglomerates embedded in a resin matrix, resulting in suitable grain retention and stock removal combined with the good damping characteristics of epoxy. The third MIRA honing product group comprises vitrified rings for high performance gear honing, capable of stock removal rates as high as 0.1 mm per flank.
Tyrolit also produces profiled dressing worms for the continuous generation of involute gear forms and together with the development of new, low cost diamond dressing tools for this application, customers now have a wider choice of consumables and the opportunity to reduce costs. Complementary products include electroplated and vitrified CBN grinding wheels for shaft grinding.