The performance and stability of screw compressors are 80% dependent on the main unit’s head, namely the screw compressor head.
Let me briefly introduce screw compressor heads and their evolution in China:
Compressor heads fall into two main categories: standard-version heads and custom-version heads. Standard-version heads are manufactured by specialised compressor head producers, such as Germany’s GHH, Löddring, AERIEN, Italy’s TMC, Shanghai’s Hanbell and Baoshi, and America’s Gordon-Danell.
Although numerous factories in China claim to manufacture air compressors, they lack the capability to independently produce this core component. Most small and medium-sized factories source their heads from standardised models.
Proprietary heads, conversely, are those developed and manufactured in-house by air compressor manufacturers. These are protected by patents and involve significant technical barriers to entry. Examples include brands such as Atlas Copco, Ingersoll Rand, Sullair, Kaishan, Fusheng, and ZEGA.
Swiss compressor heads are imported products for Chinese air compressor manufacturers and are subject to a 33% import duty. Previously, to compete for the Chinese and global markets while reducing costs, global brands relocated their compressor head production bases to China. Among them was Atlas Copco, the top air compressor brand. Over a decade ago, when acquiring LIUTech, it relocated LIUTech’s compressor head production line to Belgium to demonstrate that its heads were imported, with finished heads then shipped back to China. Now, to adapt to the fierce domestic market competition and reduce import tax costs, the relocated compressor head production line has been transported back to China and installed at the Atlas Copco headquarters factory in Wuxi. Ingersoll Rand’s compressor heads are manufactured by Aertec in Shanghai, while Sullair’s compressor heads are fully imported, processed by the East India Company. Specialised domestic cylinder head manufacturers include Shanghai’s Baosi and Hanzong, which have achieved considerable scale. Earlier entrants include Ningbo Xinda, Wuxi Xiyap, and Nanjing Compressor Factory. Recent additions encompass Shanghai Skelo, Wuxi Wuyang Saide, and Yantai’s Binglun.
The heads of single-screw compressors are entirely manufactured domestically in China, with both the technology and place of origin being Chinese. No other country produces single-screw air compressors; they are a distinctive feature of China. The debate over whether the main unit is imported merely highlights the production location. In reality, the bewildering array of heads incorporates technology from other nations, utilising their processing equipment, with only the production site situated within China. In previous years, no Chinese company truly mastered the core head development technology. However, in recent years, domestic Chinese technology has advanced by leaps and bounds. Companies have gradually begun developing their own heads, significantly reducing production costs. These heads are now being launched one by one, growing and expanding.
The quality of the screw compressor head determines the stability of the air compressor, while the head’s lifespan is dictated by its bearings. The longevity of the head hinges on the interplay between the male rotor’s rotational speed and the load borne by the bearings. Within a certain range, lower rotational speeds reduce the likelihood of bearing overheating and overload, thereby extending bearing life. Globally, all compressor head bearings are manufactured by Sweden’s SKF. Consequently, the remaining competitive edge lies in the control of the male and female rotor speeds within the compressor head. A select few large manufacturers possess sufficient R&D personnel and funding to develop screw compressor heads, conducting extensive testing under diverse operating conditions to refine performance through iterative adjustments. Furthermore, they utilise well-established brands for components, paying meticulous attention to details such as vibration damping, heat dissipation, noise reduction, and energy efficiency. This holistic approach enhances the compressor’s overall performance, durability, and stability.
Indeed, the barrier between small and large manufacturers extends beyond technology to encompass integrity. Sometimes, the stability and reliability of a large manufacturer’s compressor stems not from exceptional technology, but from avoiding cost-cutting measures. Choosing a compressor increasingly boils down to whether corners have been cut: lower prices often mean fewer components and reduced durability. This presents users with an internal dilemma: ‘Do I opt for temporary savings and short-term reliability, or embrace a long-term approach with slightly higher upfront costs?’
