High-Performance Drilling in 42CrMo4 Alloy Steel

Next generation AD solid carbide drill boosts 1.4 times tool life in expansion sleeve production

Yukai Zhang  |  OSG Shanghai

Containing chromium, molybdenum and manganese, ISO grade 42CrMo4 alloy steel is one of the most commonly machined materials in manufacturing. 42CrMo4 is equivalent to 4140 in the SAE steel grades system, SCM440 in the JIS standard, and 42CrMo4 in the DIN standard. Due to its toughness, high fatigue strength, and abrasion and impact resistance characteristics, 42CrMo4 is a highly versatile material widely used across numerous industries. With an average hardness of 22 to 26 HRC, 42CrMo4 alloy steel is incorporated in a vast number of transmission components, such as crankshafts, gears, steering knuckles, shaft components and slewing bearings.

A manufacturer of belt pulleys, gears, sprockets, couplings and other machine tool parts located in Sichuan, southwestern China, whose name cannot be disclosed due to confidentiality reasons, recently consulted with OSG regarding the production of their expansion sleeve production made mostly of 42CrMo4 alloy steel.

Established in 2003, this manufacturer employs over 1,000 staff in its 200,000-square-meter production facility. This client is an existing user of OSG’s A-POT M6 and M8 spiral point taps from the A-Tap series. Great successes with the A-POT taps have given this user the confident in OSG to further persuade cost savings in its expansion sleeve production used for precision mechanical transmission. The client has been producing this part since the founding of the company. It manufactures approximately 400 parts daily, with an estimate annual production volume of 100,000 pieces.

Each of the expansion sleeve requires the drilling of five through-holes with a diameter of 5.2 mm and an effective depth of 10 mm. The application uses a vertical machining center with external water-soluble cutting fluid. A BT40 ER holder is employed to secure the drill, and the part is clamped with a pneumatic three-jaw chuck. The processing depth of the drill is 12.8 mm. 

Expansion sleeves made mostly of 42CrMo4 alloy steel. Each expansion sleeve requires the drilling of five through-holes with a diameter of 5.2 mm and an effective depth of 10 mm.

This client was previously using a competitor drill running at a cutting speed of Vc 67 m/min and a feed rate of 0.15 mm per revolution. The average tool life was 1,000 parts per tool, which is equivalent to 5,000 holes. After a detail evaluation of the application, OSG recommended the AD-2D 5.2 mm diameter solid carbide drill to further enhance performance.

The application uses a vertical machining center with external water-soluble cutting fluid. A BT40 ER holder is employed to secure the drill, and the part is clamped with a pneumatic three-jaw chuck.

The AD is a part of OSG’s versatile next generation high performance carbide drill series. The AD drill’s special point design allows it to dramatically inhibit margin wear when machining carbon steel and cast iron. Smooth chip evacuation capability further allows low thrust and disturbance-free machining torque, making this series highly adaptable to a variety of machining environments. With the addition of OSG’s original EgiAs coating, high wear resistance can be achieved to further prolong tool life.

The AD is a part of OSG’s versatile next generation high performance carbide drill series. Standard stock is available in 2xD length and 4xD length with diameters ranging from 2 to 20 mm.

OSG provided two AD-2D 5.2 mm diameter drills for the initial cutting trial. Under identical cutting condition as the competitor tool, the final tool life of the AD drill was 1,400 parts, which is equivalent to a total of 7,000 holes and 1.4 times the tool life versus the opponent.

As illustrated in figure 1, the chips generated by the AD are compact and consistent in shape versus the competitor’s elongated chips. The AD solid carbide drill does not only demonstrate superior cutting capability, but also exceptional cutting chip management. With a production volume of 100,000 partsannually, small changes can add up to big results.

Figure 1. Chips generated by the AD are compact and consistent in shape versus the competitor’s elongated chips. The AD solid carbide drill does not only demonstrate superior cutting capability, but also exceptional cutting chip management.

For more information on OSG’s next generation high performance AD carbide drill series