Custom TRS 3-flute drill enhances productivity, tool life and achieves stable quality of inclined exit holes without burrs in connecting rod application
The connecting rod is an important automobile engine component that links the piston to the crankshaft to transmit power. Working together with the crank, the connecting rod transforms the linear up and down motion of the piston into the rotational movement of the crankshaft. Connecting rods are engineered to withstand dynamic stresses from combustion and piston movement. In mass-produced automotive engines, connecting rods are commonly made of steel.
The small end of the connecting rod is connected to the piston by a piston pin. The big end of the connecting rod is connected to the crankpin to provide a pivot point on the crankshaft. In recent years, due to advances in technology, the geometry of the exit threaded holes of the big end of connecting rods has evolved to become more inclined. With an inclined exit surface, hole quality consistency, tool life and machining efficiency can be greatly affected during drilling.
Left: Photograph of a connecting rod made of material 46MnVS5 (equivalent to forged alloy steel) with a hardness of 296-340 HB (32 to 36 HRC).
Right: The custom TRS-HO 3-flute drill exhibits minimal wear after drilling 2,000 workpieces.
Recently, a large connecting rod processing company located in northern China, whose name cannot be disclosed due to confidentiality reasons, was seeking for an improved drilling solution for its connecting rod production. Established in 2004, this company is a leading manufacturer of connecting rods in the industry in terms of both manufacturing technology and product quality. Currently, this company employs more than 700 staff in its 33,000-square-meter production facility and has nine global connecting rod production lines with an estimated annual production capacity of 6.8 million pieces.
This manufacturer’s connecting rods are made of material 46MnVS5 (equivalent to forged alloy steel) with a hardness of 296-340 HB (32 to 36 HRC). Two through holes at a depth of 23 mm are required to be drilled in each workpiece. The customer was originally using a competitor 7.01 mm diameter 2-flute coolant-through carbide drill that averaged 700 workpieces in terms of tool life. The customer came in contact with OSG through a distributor for processing improvement. After a throughout evaluation of the cutting condition and requirements, OSG recommended the TRS-HO high-feed 3-flute carbide drill for the application. The WD1 coated TRS-HO coolant-through carbide drill is engineered for high efficiency processing of steels and cast irons with drilling feed exceeding 1,000 mm/min. The TRS-HO drill earned the nickname “Mega Muscle Drill” due to its extreme performance. To further maximize performance and achieve stable hole quality without burrs, OSG Shanghai made multiple modifications to the drill geometry such as the point angle and relief angle, as well as replacing the original WD1 coating with one of OSG’s latest EgiAs coating at its Songjiang Factory.
A standard TRS-HO high-feed 3-flute carbide drill. The WD1 coated TRS-HO coolant-through carbide drill is engineered for high efficiency processing of steels and cast irons with drilling feed exceeding 1,000 mm/min. Nicknamed as the Mega Muscle Drill due to its extreme performance.
The competitor 7.01 mm diameter 2-flute drill was used at a cutting speed of 88 m/min (4,000 min-1), a feed rate of 500 mm/min (0.125 mm/rev) and completed 1,400 holes (700 workpieces) in terms of tool life. OSG’s customized 7.01 mm diameter TRS-HO-S-GDL 3-flute coolant-through carbide drill, on the other hand, can be used at a cutting speed of 75 m/min (3,400 min-1), a feed rate of 1,000 mm/min (0.294 mm/rev) and completed 4,000 holes (2,000 workpieces) in terms of tool life. The parts were machined using a vertical machining center with water-soluble coolant. The customized TRS-HO-S-GDL 3-flute drill is able to double machining efficiency and achieve nearly three times the tool life versus the competitor tool.
The stability of 3-flute drills is better than that of 2-flute drills because 3-flute drills have one additional supporting pillar than 2-flute drills. With 2-flute drills’ two pillar design, balance tends to collapse due to unstable center of gravity, making 2-flute drills prone to chattering that affects hole quality. The TRS drill’s sharp edge geometry further reduces cutting resistance and effectively suppresses the occurrence of burrs. In addition, the TRS drill’s wide chip pocket configuration allows trouble-free chip evacuation even at high speeds and feeds. With the addition of OSG’s original EgiAs coating, superior wear resistance and long tool life can be achieved.
Image of chips generated by the custom TRS-HO 3-flute coolant-through carbide drill. The chips are short and compact, which are the keys to trouble-free chip evacuation.
By employing the customized TRS 3-flute drill, this manufacturer is able to significantly reduce production costs and effectively increase machining efficiency. In addition, OSG offers regrinding and recoating services, which enable the client to further reduce tooling costs.