Mega Muscle drill demonstrates ultra efficiency even after regrind
Vis Huang | OSG Shanghai
In the automotive manufacturing sector, components such as engine blocks, cylinder heads and crankshafts are commonly produced from materials like cast iron, alloy steel and aluminum. Due to the mass production nature of the business, reliability and cost efficiency are often the key determinants in the choice of tooling.
In this case study, a cylinder block made of HT250 (equivalent to gray cast iron) with a 180 to 220 hardness was being evaluated. The customer is a major automotive manufacturing company based in Zhengzhou, China, with an annual production capacity of 400,000 units. The material of the cylinder block is brittle with low tensile strength but is easy to cast. The total lot had 380 blocks with each requiring 15 drilled holes. The part was being machined in a Makino horizontal machining center, with a BT50 drill holder using internal and external emulsion 8-percent coolant. The drills used in this part are reconditioned and reused to maximize cost efficiency. This manufacturer was originally using a 2-flute coolant-through carbide drill running at a cutting speed of 100 m/min, 4,680 min-1 revolution, 0.15 mm/rev feed per revolution, a feed rate of 1,700 mm/min, and drilling at a hole depth of 14 mm (blind hole). The manufacturer was looking to further improve efficiency and had decided to switch from 2-flute to 3-flute tooling.
Conventional 3-flute drills are most commonly used in the processing of materials with short cutting chips, such as cast iron and cast aluminum. Because 3-flute drills have a smaller flute size (chip room) than 2-flute drills, they are used less in difficult-to-machine materials like steels. OSG’s TRS “Mega Muscle” drill has been heavily advertised as a 3-flute series with ultra machining efficiency. The Mega Muscle drill is designed with a special shaped flute that breaks steel chips into small, manageable pieces for easy evacuation. This allows for increased feed rates up to 1.5 to 2 times faster than 2-flute drills. More importantly, rotational speed can be decreased, thus decreasing the amount of wear on the drill to prolong tool life. With its special negative cutting edge, the tendency of chipping at the corners on breakout of through-holes can be minimized. Its unique geometry further enhances hole accuracy with less work hardening, which gives secondary operations such as tapping even more tool life.
After putting one of the Mega Muscle drills (TRS-HO-5D dia. 6.8 mm) on the spindle for test, the manufacturer was able to witness this drill’s real potential. Running at a cutting speed of 100 m/min, 4,680 min-1 revolution, 0.25 mm/rev feed per revolution, a feed rate of 1,170 mm/min, the Mega Muscle drill was able to machine a total of 5,600 holes (approximately 109 m of materials) before regrind, compared to 4,800 holes versus the previous 2-flute drill. After tool reconditioning, the Mega Muscle drill was able to achieve 2,800 holes, while the previous 2-flute drill had machined 2,500 holes after reconditioning. The Mega Muscle drill had dominated the test trials due to its stable efficiency.
The 120-degree equal spacing margins of the 3-flute design allows for more predictable, vibration free hole processing, thereby increasing hole quality and tolerance. This stability is consistent throughout the 3-flute drill’s tool life, whereas a 2-flute drill often has drastic changes of hole size and quality. With this 3-flute design, the Mega Muscle drill is capable of achieving hole accuracy twice as precise as a 2-flute drill. From CGI engine blocks to forged steel crankshafts, the Mega Muscle drill can provide high efficiency drilling solutions for the manufacturing of automotive components and applications.
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