MACHINING

Turning is the process of using lathes to remove material from the outer diameter of a rotating workpiece. Lathe machining mainly uses turning tools to turn the rotating workpiece. Lathes are mainly used to process shafts, discs, sleeves and other workpieces with revolving surfaces, and are the most widely used type of machine tool in machinery manufacturing and repair factories.

Turning is the most basic and common cutting method and plays a very important role in production. Turning is suitable for machining revolving surfaces. Most workpieces with revolving surfaces can be processed by turning methods, such as inner and outer cylindrical surfaces, inner and outer conical surfaces, end faces, grooves, threads, and rotary forming surfaces. The tools used are mainly turning tools.

Among all kinds of metal cutting machine tools, lathes are the most widely used, accounting for about 50% of the total number of machine tools. The lathe can not only turn the workpiece with turning tools, but also use drills, reamers, taps and knurling tools for drilling, reaming, tapping and knurling. According to different process characteristics, layout forms and structural characteristics, lathes can be divided into horizontal lathes, floor lathes, vertical lathes, turret lathes and copy lathes, most of which are horizontal lathes

Advantages and Shortcomings of Turning

Advantages

• The surface roughness is smaller than that of milling and grinding.
• The surface of the thread after rolling can improve the strength and hardness due to cold work hardening.
• CNC lathe thread turning has a high utilization rate of materials.
• Productivity is doubled compared to cutting Growth, and easy to automate.
• The rolling die life is very long.

Shortcomings

• The hardness of the workpiece material for rolling threads does not exceed HRC40.
• The dimensional accuracy of the blank is high.
• The precision and hardness of the rolling die are also high, and it is difficult to manufacture the die.
• It is not suitable for rolling threads with asymmetric tooth shape.

Milling is a common metal cold processing method. Different from turning, the milling is performed with a machine in which the cutters rotate to remove the material from the workpiece present in the direction of the angle with the tool axis.

Milling refers to the use of rotating multi-blade tools to cut workpieces and is a highly efficient machining method. When working, the tool rotates and the workpiece moves, and the workpiece can also be fixed, but at this time, the rotating tool must also move. Milling machines include horizontal milling machines or vertical milling machines, as well as large gantry milling machines. These machine tools can be ordinary machine tools or CNC machine tools.

Grinding is one of the most widely used cutting methods. Compared with other cutting methods, such as turning, milling, the characteristics of grinding include:

1. The grinding speed is very high, up to 30m ~ 50m per second.
2. The grinding temperature is high, up to 1000”C ~ 1500oC.
3. The grinding process lasts for a very short time, only about one ten thousandth of a second.
4. Grinding can obtain high machining accuracy and small surface roughness value.
5. Grinding can not only process soft materials, such as Unquenched steel, cast iron and non-ferrous metals, etc., and can also process quenched steel and other hard materials that cannot be machined by tools, such as porcelain parts, cemented carbide, etc.
6. The cutting depth during grinding is very small, and in one stroke The metal layer that can be removed is very thin.