Out of all the screws you can use in industrial motion control, ball screws lead the way in advantages compared to acme or roller screws. A ball screw can convert rotary motion into linear motion with precision. Here’s a closer look at the top ways ball screws increase efficiency.
Life and Loads
A ball screw can effectively handle a tensile and a compression load. A compression load compresses or squeezes a screw axially, which forces the screw to bow. In contrast, a tensile load can stretch a screw axially. Typically, a compression load is more problematic, and a tensile load can cause a screw to lengthen and crack.
Screws are designed for thrust loads and linear axial thrust motions. An overturning of any kind or a side load can drastically reduce the life of a screw by nearly 90 percent.
When creating custom ball screws, the engineer must consider critical speed and buckling. Determining the screw’s load direction and the mounting required assists the screw selection process. When selecting a fixed bearing mount, review the proper mount length necessary for the final assembly.
Critical speed is known as the speed that stimulates the natural frequency of a screw. The critical speed will vary with diameter, length, speed, and end fixity. Two other factors that play a role are the straightness of the shaft and alignment in assembly.
One of the top ways ball screws increase efficiency is through accuracy. Considering the different processes for creating a ball screw, there are a few options for evaluating accuracy.
A rotating die deforms a metal bar to generate a spiral pattern. This method is highly cost-effective but can produce screws with less accuracy.
A grinding wheel will cut through the threads of a screw and turn it into a case-hard material, resulting in higher accuracy levels than rolled screws. For applications like aerospace, ground screws are preferred.