Iwaki, May 2022 — Tungaloy has developed a new HS-style chipbreaker for its CBN-tipped insert series to ensure reliable chip breaking and control during hard part turning at elevated parameters.
In hard part turning applications, CBN inserts are predominantly used for finishing processes that require extremely close tolerances of up to RA=0.8a; this translates to low feed rates and light D.O.C. Hardened steel shafts for the emerging continuously-variable transmissions (CVT) system, for one, require even closer tolerances that can only be achieved by grinding, leaving CBN inserts the role in productive semi-finishing processes that requires less stringent surface quality. In this application, effective chip breaking at much higher feed rates and greater D.O.C. are, therefore, wanted with CBN inserts to boost productivity and satisfy required surface quality. With existing HP-style CBN chipbreaker, however, effective chip breaking is a challenge at feed rates exceeding 0.25 millimeters per revolution (.0098 inches per revolution).
To meet this challenge, Tungaloy’s latest technologies have created a new HS-style chipbreaker that features a unique W curve geometry. This geometry ensures superior chip breaking and control at up to 0.3 millimeters per revolution (.0118 ipr) across the D.O.C. range from 0.1 to 0.35 millimeters (.004 to .014 inches), which are the most common cutting depths used in hard part turning operations. Furthermore, the cutting edge is prepared so as to sustain edge-line integrity over an extended period of time and prevent catastrophic failure during machining at an aggressive cutting parameter range.
CBN inserts with new HS-style chipbreaker are available in two CBN grades: BXA10 provides the insert with exceptional wear resistance, allowing it to be applied for continuous to light interrupted machining of hardened steel parts. A versatile CBN grade, BXA20 caters to continuous to interrupted applications at low to medium cutting speeds.