What function does the tailstock serve in the CNC machining process?
Whether a tailstock is required when using a CNC lathe to machine a workpiece depends on the length of the piece. Short-length pieces can be machined without a tailstock. However, for accurately machining long, slender pieces such as a rifle barrel without distortion or chatter, a tailstock is essential to the CNC machining process.
What Is a Tailstock?
Positioned opposite the headstock on a CNC lathe machine, tailstocks serve to secure and support the free end of a workpiece during machining. They ensure that the longitudinal rotary axis of the workpiece remains stable and precisely parallel to the lathe bed.
Tailstocks can be adjusted along the bed ways to accommodate workpieces of varying lengths. Once locked in position, the tool is mounted and precisely positioned using a lead screw.
In addition to securing workpieces in place, tailstocks are utilized for drilling out the centers of workpieces. A cutting tool, such as a drill, tap, or reamer, housed within the tailstock, is employed to create a hole with precise depth, shape, and diameter. However, unlike the process of hole-making with a drill press or milling machine, the tool within the tailstock remains stationary while the workpiece rotates.
When is the Use of a Tailstock Necessary in the CNC Machining Process? Tailstocks are not indispensable for every machining task. So, when should they be employed? Tailstocks become imperative when machining long, slender pieces, but they also offer utility for shorter workpieces.
Most manufacturers recommend the use of a tailstock to support any workpiece exceeding a length-to-diameter (LTD) ratio of 3:1. The higher the LTD ratio, the greater the risk of flaws in the final product.
For instance, a workpiece with an LTD ratio of 2:1, such as a piece that is 2 inches long and 1 inch in diameter, might be machined without requiring a tailstock. However, a tailstock can aid in preventing such pieces from dislodging by securely holding them in place during machining. When LTD ratios surpass 3:1, a tailstock becomes essential to ensure the quality of the finished product.
Alignment and Rigidity Are Crucial for Proper Operation A tailstock must be meticulously maintained to ensure accurate alignment with the headstock. Misalignment of the tailstock can lead to issues such as tapering and chatter (surface marks caused by inadequate fixation of the workpiece by the tailstock). The rigidity of the tailstock, and its capability to firmly hold a workpiece on center, significantly impacts the quality of the end product. Tapering, inaccuracies, and other distortions can occur when the tailstock is not properly secured.
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Common Queries Regarding Tailstocks
What is the function of tailstock?
Tailstocks are employed to provide support to elongated components on a lathe or rotary table.
Is a tailstock indispensable when employing a CNC lathe for workpiece machining?
The necessity of a tailstock hinges on the length of the workpiece. For short-length workpieces, operating without a tailstock is feasible. Nonetheless, for elongated, slender workpieces — like a rifle barrel — a tailstock is essential to ensure precise machining devoid of distortion or chatter. Learn more
What is the procedure for verifying tailstock alignment?
The tailstock's center is initially aligned with the spindle's center if it comes pre-aligned from the factory. When the tailstock is introduced to a rotary table, its center height is matched with that of the rotary table. To verify alignment, one would perform an indicator sweep of the tailstock quill. Indicators can be affixed to either the lathe spindle or the rotary table faceplate. While tailstocks can be adjusted laterally, if the center height is inaccurate, shims may need to be added if it is low or material may need to be removed if it is high.
What variations exist among tailstocks?
Tailstocks come in various types, including manual, hydraulic, and pneumatic variations, as well as those equipped with built-in live centers. Additionally, for rotary tables, heavy-duty tailstocks resemble another rotary table, designed to support heavy parts.
What are the typical types of centers utilized in tailstocks?
Two common types of centers used in tailstocks are dead centers, which remain stationary and are primarily employed in manual machine tools or rotary table tailstocks, and live centers, equipped with bearings, which are frequently utilized in CNC machines and applications requiring higher RPMs.
