Shifting Gear to Electric

Growth of electric vehicles accelerates trend of smaller, more lightweight and efficient auto parts

Chunhui Xu  |  OSG Shanghai

Interest for electric vehicles (EVs) has surged significantly in the past couple of decades. In addition to lower long-term costs and the reduction of ecological footprint, many car buyers are drawn to the latest cutting-edge technology of EVs, which have greatly contributed to their rising popularity. With increasing market demand, a new wave of electric cars is expected to be released from major automakers around the globe. The promotion of EVs, however, is nothing short of challenge. Battery life, repair and replacement costs of EVs are enough to put off many potential buyers. Moreover, the resale value of EVs, hybrids, plug-in hybrids are significantly less than traditional automobiles on the market, which also heavily influences buyer’s choice. Last but not least, charging stations are few in number in comparison to gas stations, making EVs an unrealistic choice for many. In order to aggressively promote cleaner and more energy efficiency transportation, government incentives are essential.


Energy Vehicles in China

In China, the world’s largest automotive market, the government is mandating more new energy vehicles to help reduce the severity of air pollution. Battery electric cars, plug-in hybrids and fuel-cell cars all fall within the category of new energy vehicles. China is one of the world’s top sellers of environment-friendly vehicles since 2015. According to government plan, China aims to have at least one in every five cars sold in the country to be a new energy vehicle by 2025. To reach its target, Chinese policymakers are requiring automakers’ sales of battery electric or plug-in hybrid to constitute approximately 8 percent of their total sales in the country by 2018, and plans to gradually increase the ratio as time goes by. Furthermore, in order to accelerate growth in the sector, the Chinese government will continue to encourage research and development, and invest in necessary infrastructures, such as charging stations and charging piles.

Energy Efficient Scroll Compressor

China’s increasing demand for new energy vehicles has become one of the driving forces behind the development of greater efficiency auto parts. The scroll compressor is among one of the components. A scroll compressor is a device used for compressing air. It is commonly used as an automobile supercharger and as a vacuum pump. The latest models of scroll compressors are designed with lighter weight and fast speed capability to reduce engine load for maximum efficiency. They are also engineered to operate smoothly to reduce noise and vibration. Made primarily of aluminum, a scroll compressor is composed of an orbiting scroll and fixed scroll, which serve as a compression unit. Each of the scroll has end plates and wrapped scroll blades, and a unit that drives the orbiting scroll through the crankshaft. The orbiting scroll and fixed scroll are key components for the process of gas compression. In order for them to interact harmoniously, very tight tolerances is required, where the depth of tooth, the wall thickness and tooth type vortex line should be identical in size.


Tailored Application Solutions

OSG not only supplies powerful standard cutting tools for manufacturing, but also provides tailored application solutions to help clients facilitate better processing with higher efficiency and longer durability based on their specific needs. For many years, OSG has offered its cutting tool expertise and application solutions for scroll compressor manufacturers.

In addition to standard tooling, OSG also offers tailored application solutions to help clients facilitate better processing with higher efficiency and longer durability based on their specific needs.

Achieving Stability and Superior Surface Finish with Custom Tooling

OSG was recently approached by a manufacturer of orbiting scroll in China (whose name cannot be disclosed due to confidentiality reasons). The material of the workpiece is aluminum alloy (DL4032). The customer was seeking cutting tool solutions to further improve the stability of the machining process as well as the surface finish of their orbital scroll and fixed scroll. The workpiece has a height of 12.9 mm and a thickness of 3 mm. High accuracy is required for the part, with a permissible tolerance of +/- 0.01, depth parallelism of 0.02, perpendicularity of 0.02, roughness within Ra 0.8, and R-angle of 5.25 mm. The customer was using a Japanese brand machining center and a high-precision thermal expansion shank (HSKA50) for the processing.

The customer had requested for a 6-flute, 10 mm dia. end mill, and asked the OSG engineering team to customize the rest of the tool specifications. Based on past experience, the diameter of the finishing machine tool accounts for approximately 70 percent of the minimum of R-angle. After a careful evaluation of the application, OSG proposed a custom tool with a cutting length of 15 mm, overall length of 70 mm, clamp length of 42 mm, and with coolant holes for internal coolant capability.

The parameter of the cutting condition was set at a cutting speed of 250 m/min, a feed per tooth of 0.0125 mm, an axial depth of cut of 0.05 mm, and a radial depth of cut of 0.05 mm. Using 10 percent coolant, with the customized end mill’s coolant holes, the cooling effect was evident. Tested repeatedly, the custom end mill was able to demonstrate consistent performance and a superior surface finish between Ra 0.5 and Ra 0.6 that surpassed the customer’s expectation and required tolerances.

The automotive industry has been evolving rapidly in recent years through new discovery of materials, technologies, and the rising concern to conserve energy. To accommodate more complex machining, custom tooling can offer an additional solution to manufactures seeking maximum result. OSG will continue to use its experience, technical expertise and creativity to help manufacturers develop compact, lightweight and highly efficient products to contribute to the growth of energy vehicles and a more environmentally friendly transportation system.