Advantages of vacuum carburizing for automotive parts

Vacuum Carburizing Applications for Automotive Parts

Gas carburizing, a process used in the carburizing heat treatment of automotive parts, is one of the most widely used heat treatment processes for automotive parts due to its excellent treatment quality and low cost. Over the past decade, vacuum carburizing has also gained widespread application in the automotive industry. The combination of low-pressure vacuum carburizing and high-pressure gas quenching technology can meet the high-quality heat treatment requirements of automotive transmission and engine parts.

Vacuum Carburizing Requirements for Automotive Parts

Gears play a central role in automotive transmission systems. Carburized gear steel, a key material for gear manufacturing, directly impacts vehicle power transmission efficiency and reliability. New energy vehicles, both new energy vehicles and commercial vehicles, are facing increasing demands for lightweight and miniaturized transmission systems and gear components. Furthermore, they are subject to increasing compressive loads, placing new demands on gear materials. The speed of gears in pure electric vehicle reducers is 2-3 times higher than that of gasoline-powered vehicles (peak motor speeds currently exceed 20,000 rpm). Traditional carburized steel struggles to meet operating conditions above 6,000 rpm. Therefore, gear manufacturing requires a deep hardened layer depth, requiring extended carburizing time during vacuum heat treatment, resulting in low production efficiency.

Advantages of Vacuum Carburizing for Automotive Parts

Compared to conventional carburizing, the low-pressure vacuum carburizing process is simple to operate, boasts a rapid temperature rise, and is easy to start and stop. It also saves energy and has low gas consumption. Low-pressure vacuum carburizing furnaces are carbon black-free and environmentally friendly. Actual production has proven that the low-pressure vacuum carburizing process significantly reduces production costs compared to conventional carburizing.

Compared to cyclic vacuum carburizing processes, semi-continuous and continuous vacuum carburizing processes can increase production efficiency by approximately 25% and 40%, respectively. Semi-continuous and continuous low-pressure carburizing and high-pressure gas quenching automated production lines will become a key development trend in high-quality carburizing heat treatment equipment for automotive parts. Currently, cyclic low-pressure carburizing and high-pressure gas quenching furnaces and semi-continuous low-pressure carburizing production lines are already in use by automotive companies for heat treatment of heavy-duty commercial vehicle transmission and engine parts, gear sleeves and gears, passenger car engine and automatic transmission parts, and final drive sun gear shafts. For example, high-speed, heavy-load precision automotive gears require a hard and wear-resistant surface while also maintaining excellent core toughness. Compared to traditional carburizing processes, vacuum carburizing offers superior surface purification and activation for gears, a faster carburizing speed, and a carburizing time of approximately one-half to one-third of conventional carburizing. It also eliminates intragranular oxidation, achieves uniform carburization across all parts, achieves high carburizing efficiency (20-30% of the heat is applied to the part, compared to only 6-10% with traditional processes), and is energy-efficient and environmentally friendly. Another example of a challenge in carburizing heat treatment for automotive connecting rods is the small diameter and depth of the small oil holes within the end caps (a few millimeters), and the carburizing requirements are essentially the same as those on the surface. Carburizing within these small holes is particularly challenging, and conventional atmosphere carburizing cannot meet product requirements. To address this issue, vacuum carburizing furnaces are used. After treatment, the carburized layer on the product surface and the small hole surface are nearly identical, meeting the technical requirements for connecting rods.

Vacuum Carburizing Furnace