The Difference Between Ball Screw And Trapezoidal Screw

- Aug 10, 2020-

The difference between ball screw and trapezoidal screw

There are some differences in the applications of ball screws and trapezoidal screws. The application system of the original equipment manufacturer often needs the "right" product, and the lead screw is often the right choice. Lead screw products are easy to adjust to specific applications to achieve the expected performance while keeping costs to a minimum. In some cases, life testing is required in the design phase, but for original equipment manufacturers, carrying out such additional work in the early stage can help reduce product costs. Ball screws can run continuously, withstand much higher loads, and reach faster speeds. The increased cost is worthwhile. For the end user, the ball screw has good predictability, so it is the best choice to ensure rapid integration and reliability. For example, factory automation systems rely heavily on ball screw technology. Of course, there are many original equipment manufacturer applications that also require ball screws, such as the machine tool industry. For original equipment manufacturers, it is performance and cost that determine technology, not predictability.


The main difference between a ball screw and a trapezoidal screw is the way the load is carried between the moving surfaces. Ball screws use recirculating ball bearings to minimize friction and improve efficiency, while trapezoidal screws use the low coefficient of friction between sliding surfaces. Therefore, the trapezoidal screw generally does not reach the efficiency of the ball screw (about 90%). A simple analysis of the tribological mechanism (study of wear and friction) can find that the predictability of sliding friction must be lower than that of the transmission using recirculating ball technology. The fatigue life equation (such as L10 life) is very reliable in its applicable range.


In summary, because of the difference in predictive performance and life expectancy between ball screws and trapezoidal screws, their application fields are also fundamentally different. Although the ball screw has various advantages (load, stiffness, efficiency, load cycle, predictability), its cost is higher. Although they are cost-effective compared with other translational linear motion solutions, the design of ball screws is more complicated, requiring hardened precision bearing surfaces and a ball circulation device. The size of the lead screw is small, the design is very flexible, the noise is small under the correct use, the corrosion resistance is good, and the self-locking function can be configured to meet the needs of vertical applications. They play an important role in many application areas, of course they also have some limitations.