Long-term production experiments and the challenges Shanghai Kamaishu faced in after-sales service led to significant vibration issues in high-speed centrifuges. Vibration is a key performance indicator for centrifuges, and effective vibration control is essential. Typically, two main approaches are used: active and passive vibration damping. Active vibration control involves designing the centrifuge's operating speed to avoid the critical speed of the rotating system—most lab high-speed centrifuges are designed with a critical speed much lower than their working speed. Additionally, dynamic balancing during rotor manufacturing is crucial. Passive damping, on the other hand, isolates vibrations from the frame and foundation using various types of dampers.
In most high-speed centrifuge designs, both active and passive vibration control methods are combined. Three primary areas are typically considered for vibration reduction: (1) the main shaft bearing housing is designed as a flexible damping type, (2) a flexible connection exists between the main shaft and the motor, and (3) the entire drive system is flexibly coupled to the frame. Rubber dampers are commonly used and can meet the requirements of high-speed centrifuges. However, the hardness of the rubber affects the system’s critical speed—if the rubber is too soft, it may not provide sufficient damping and could easily fail.
Beyond these three components, an elastic joint can be placed between the rotor and the main shaft. For example, the US Solva company’s RC-z high-speed refrigerated centrifuge uses a layer of silicone rubber between the main shaft and rotor, further reducing vibration. In addition to vibration isolation, these measures also help lower the critical speed of the rotating system, ensuring the operating speed remains well away from it. This explains why some high-speed centrifuges have thick, short spindles that still operate above the critical speed, maintaining a flexible system overall.
There are generally two types of shafts used in laboratory high-speed centrifuges. One is slender and highly flexible, allowing self-alignment, while the other is shorter and stiffer, with minimal bending deflection. Even with a rigid shaft, the presence of damping elements ensures the operating speed stays above the critical speed, making the system flexible. Although both are flexible, the difference lies in how they self-align: a slender flexible shaft bends to allow the rotor to rotate around its center of mass, while a more rigid shaft relies on relative displacement within the rotating system for automatic centering.
Based on this, Shanghai Kamaishu believes that a slender shaft should be made of spring steel, while a shorter, thicker shaft is more practical. The main shafts of centrifuges like the US J2-3, East Germany VACZ5, and Hitachi 20PR-52D fall into the first category—slender and flexible. In contrast, the high-speed centrifuges from the Shanghai Biochemical Institute and Beijing Biophysical Institute use thicker, shorter shafts with greater rigidity. The diameter and length of the spindle depend mainly on the power required by the rotating system and the design of the instrument.
Once the spindle is determined, the flexibility of the rotating system can be adjusted through vibration dampers. Therefore, labeling a spindle as rigid or flexible may not be meaningful. Whether a system is flexible depends not only on the shaft’s flexibility but also on the damping devices and their installation. Strictly speaking, in high-speed centrifuges, the terms "flexible shaft" and "rigid shaft" might not be accurate, and it’s more appropriate to refer to the system as a flexible rotating system.
Conditioner, also known as moisturizer, is usually used in pairs with shampoo. After shampooing hair, evenly apply the right amount of conditioner on the hair, gently rub for about one minute, and then rinse with water. Therefore, it is also known as rinse conditioner, which belongs to hair cosmetics.
Hair can be divided into two types from the appearance of transparent type and emulsion type, emulsion type products are more common in the market.
Shampoo uses anionic and nonionic surfactants as the main raw materials to provide deconsoiling and foaming, while the main raw materials of conditioner are cationic surfactants. Shampoo your hair and then apply a conditioner, which neutralizes the anionic molecules that remain on the surface of your hair, forming a monomolecular membrane that keeps tangled hair compliant and easy to comb.
The healthy surface layer of hair consists of a complete set of hair scales and natural secreted oil to form the protective film of hair. Excessive washing, ironing, and sun exposure will destroy this natural protective film, resulting in the loss of water in the cortex, and make the hair dry and lose elasticity and softness. Only if you use conditioner regularly, can you form a protective layer of hair for a long time and protect your hair from damage.
Under normal circumstances, washing your hair after sun exposure should wait for your scalp and hair to cool down naturally before you begin
Hair Conditioner,Fine Hair Conditioner,Deep Conditioner,Best Conditioner
DONGGUAN VOLES COMMODITY CO., LTD , https://www.volesvip.com