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The growth of the electric vehicle industry is tremendous, and precision grinding is faced with an unprecedented test. Hardened steel alloys commonly need to be manufactured for EV motor shafts. They also must be ground to a tight tolerance with a high rate of stock removal while still leaving the workpieces with superior surface finishes. The standard practice for grinding hardened steel has been aluminum oxide wheels, but because of the EV market's increasing need for reduced cost, increased productivity and longer life, aluminum oxide wheels are rapidly being replaced with diamond CBN wheels. Zhengzhou Ruizuan Diamond Tool Co., Ltd has emerged at the forefront of this innovation, developing the latest in CBN grinding solutions for the production of EV motor shafts.
Superior Hardness and Wear Resistance
For years, aluminum oxide (Al₂O₃) served the grinding industry well, however, its hardness, approximately 2,000-2,500 HV, simply cannot compete with modern hardened steel alloys utilized in EV motor shafts which frequently reach over 55 HRC. Aluminum oxide wheels wear out fast during EV motor shaft grinding, leading to higher grinding forces, elevated temperatures and frequent dressings.
Cubic boron nitride (CBN), a material second only to diamond in hardness, with a range of about 4,500-5,000 HV, can maintain its sharpness longer. In fact, diamond CBN wheels from Zhengzhou Ruizuan can maintain sharp edges even while working on EV motor shaft materials, leading to drastically increased wheel life and reduced machine down-time during wheel changes-critical for high volume EV production lines looking to optimize throughput and lower overall part costs.
Lower Grinding Temperatures and No Surface Damage
Grinding temperatures should always be minimized to prevent burns, heat treating of the workpiece, micro cracking, and other surface damage that could affect EV motor shaft fatigue life. While aluminum oxide wheels produce high heat due to their dull edges which create friction, CBN wheels act as very good thermal conductors and the cutting action, which produces a shallow, narrow chip, is cooler. This drastically reduces work piece temperature. Since EV motor shaft parts operate at very high rotational speeds and load, eliminating thermal surface damage is extremely important.
Tighter Dimensional Tolerances and Better Surface Finishes
As EV motor shafts must be made to an accuracy of several microns to ensure bearing fit and vibration free rotation, dimensional accuracy must be controlled to prevent a large wheel diameter drift during grinding. While this could cause issues with the accuracy of aluminum oxide wheels due to wear, diamond CBN wheels have long wheel life to maintain form and achieve extremely high accuracy from one part to the next. Furthermore, CBN can often provide excellent surface finishes directly, eliminating any subsequent finishing processes.
Higher Grinding Efficiency and Lower Total Cost
Aluminum oxide wheels appear cheaper up front, but when considering all factors that affect your costs, the CBN wheel is actually more cost effective for grinding EV motor shafts. They remove material faster, require less dressing, produce a much finer surface finish and last considerably longer. One CBN wheel can effectively grind thousands of EV motor shafts before a wheel change is necessary-at least ten to twenty times longer than a standard aluminum oxide wheel. This significantly reduces work piece downtime, part cost and wasted material.
Summary
As the EV industry continues to grow, the standards of grinding need to be met. With their superior hardness and wear resistance, thermal conductivity, overall accuracy, and cost-effectiveness, diamond CBN wheels from Zhengzhou Ruizuan are the clear choice over aluminum oxide wheels for grinding EV motor shafts. Since 2014, Ruizuan has provided high-quality custom CBN grinding solutions supported by CE, SGS, TUV and ISO 9001 certification. Whether you are grinding EV motor shafts, other high precision hard steel parts, or transmission components, please contact Ruizuan today to see how our diamond CBN wheels can help your business!