6 Common Machining Methods

Machining processes vary depending on the material and product requirements; the traditional methods commonly referred to are turning, milling, drilling, planing, and grinding. With advances in mechanical science and technology, additional machining techniques have emerged, including electroplating, wire EDM, casting, forging, and powder metallurgy. Today, we’ve compiled six common machining methods for you:

1. Turning. Turning primarily involves the workpiece’s rotation, with a cutting tool shaping the workpiece into the desired form. When the tool moves parallel to the axis of rotation, internal and external cylindrical surfaces can be produced. Conical surfaces are formed when the tool follows an inclined path intersecting the axis. Rotational surfaces are created on profiling lathes or CNC lathes by controlling the tool’s feed along a curved trajectory. Another type of rotational surface is generated using a form‑cutting tool with horizontal feed. In addition, threaded surfaces, end faces, and eccentric shafts can also be machined by turning.

2. Milling. Milling relies primarily on the rotation of the cutting tool and can be categorized into horizontal milling and vertical milling. In horizontal milling, the machined surface is produced by the cutting edges on the cylindrical surface of the milling cutter, whereas in vertical milling, it is formed by the end cutting edges. To achieve higher cutting speeds and improve productivity, the spindle speed of the milling cutter can be increased. However, the intermittent engagement and disengagement of the cutter teeth generate impact forces, leading to vibrations during the cutting process and thereby limiting improvements in surface finish.

3. Planing. Planing primarily involves the reciprocating linear motion of the cutting tool to remove material from the workpiece, resulting in relatively low cutting speeds and consequently lower productivity. However, planing offers more stable machining accuracy and surface finish compared to milling.

4. Grinding. Grinding primarily involves machining workpieces using grinding wheels and abrasive tools, with the wheel’s rotation driving the process. During grinding, the abrasive grains on the wheel perform three main functions: cutting, carving, and sliding. As the grains become progressively dull due to their sharpness, the cutting efficiency declines and the cutting forces increase. Consequently, after a certain period of grinding, the wheel must be dressed using a diamond dresser.

5. Gear Tooth Surface Machining. Gear tooth surface machining is a relatively new manufacturing process, which can be broadly classified into two main categories: form‑cutting and generating methods. The form‑cutting method is typically performed on conventional milling machines, using form‑shaping cutters and requiring two basic motions: the rotational motion of the cutter and a linear feed motion. Common machine tools used for generating gear tooth surfaces include hobbing machines and shaping machines.

6. Machining of complex surfaces. For the machining of intricate curved surfaces, CNC machine tools prove indispensable. Three-dimensional surface cutting is typically performed using contour milling, CNC milling, or specialized machining techniques. Contour milling relies on a master model as the shaping tool; the ball‑nose cutter maintains constant contact with the master surface under a specified pressure. The motion of the cutter is converted into an electrical signal, which in turn modulates the three‑axis movement of the milling machine, thereby defining the tool’s trajectory along the curved surface. While most cutters employ ball‑nose end mills with a radius matching that of the contouring tool, the advent of CNC technology has introduced more efficient methods for machining curved surfaces.

When selecting a machining process, it is essential to consider a wide range of factors and choose the most appropriate method to ensure the precision and quality of the finished product. With the continuous advancement of science and technology, machining techniques have become increasingly diverse. In addition to the several common methods described in this article, numerous other processing approaches are available.