Horn Cutting Tools Ltd, Ringwood has introduced the Horn System DR range of high productivity high precision insert based modular reamers, developed for rapid sizing of blind and through hole diameters from 11.9 mm to 100.6 mm.  The reamers are produced under licence from the Swiss based boring and reaming specialist Urma AG, with whom Horn has a long standing relationship.  System DR has been developed for use with steels, castings, non-ferrous materials and plastics.

Mike Green, general manager of Horn Cutting Tools, comments. “This is a very impressive range of tooling which complements our existing ranges of milling and boring tooling extremely well.  It exhibits the established Horn virtues of combining very high performance with excellent tool life.”

The system has been available for some time in its home market and has demonstrated significant time and cost advantages.  Cycle time improvements of ten or eleven times are not uncommon along with capability to deal effectively with different material types with no loss of performance using a single cutting grade.

A prominent feature of DR reamers is the use of a very narrow section high rigidity ring-type cutting element, produced using either micrograin carbide (coated and uncoated) or cermet. A noticeable aspect of the inserts’ design is the uneven spacing of the cutting teeth; this has been found to prevent the onset of vibration and guarantees the required high standard of bore finish and accuracy.

By contrast with more conventional reamer designs, the cutting element is only 4.3 mm thick; though this may seem a little on the thin side testing has shown that most reamer wear occurs within 2 mm of the leading edge whilst guidance is normally satisfactory with 4 mm total thickness.  The thin section also has benefits in terms of reduced friction and chip evacuation, as well as allowing tighter manufacturing tolerances to be maintained.  For applications that nevertheless require additional guidance the DR system includes holders equipped with guide pads
Attachment of the cutting element to the tool holder uses HSK-style mating tapers for positioning repeatability within 0.004 mm.  Ample face-to-face contact and multiple screw clamping ensure maximum system rigidity and the very high repeatability makes for rapid insert exchange.

Depending on the application, different cutting element geometries are available.  For through-hole applications a left helical fluted cutter is recommended whilst blind hole applications are served by straight fluted cutters.  All are available in a wide range of carbide or cermet grades.
A comprehensive range of holders and system adaptors is available.  Holders for diameters from 11.9 mm to 35.6 mm are available in two different lengths for aspect ratios of 3-4 x and 6-8 x hole diameter. In the case of longer length holders the option of either steel or carbide shank material is available.  All are equipped for through-tool coolant supply; holders for through hole applications have coolant nozzles immediately behind the cutting element whilst blind hole applications are served by a coolant jet passing through the nose of the cutter/holder assembly.
Diameters from 35.601 mm to 100.6 mm are catered for by a modular shank/insert holder system which offers integrated run-out adjustment capability to maximize accuracy.

As well as the DR holders, adaptors are available to allow existing proprietary exchangeable head reaming holder systems to use the DR reamer technology.  This offers a cost-effective upgrade path as most of the performance advantages of DR are maintained.
By its nature, Horn System DR lends itself to customized tooling applications.  These range from cutting elements for particular bore diameters to special cutter geometries and development of specialized toolholders for applications such as line boring or multi-diameter reaming.

Mr Green concluded. “Having DR available will certainly expand our capability to provide high performance solutions for existing and new customers. It’s a very exciting take on an area of tool development that hasn’t seen major innovation for quite a while.”