A Detailed Explanation of Metal Cutting Methods: Principles, Types, and Key Factors

 

Metal cutting is one of the core technologies in modern manufacturing. By precisely removing excess material from the workpiece, parts with high precision and surface quality can be obtained. This article will systematically analyze the basic principles, common process types, key influencing factors, and application fields of metal cutting.

 

Basic Principles of Metal Cutting

The essence of metal cutting is to cause the material to undergo shear - sliding deformation and form chips through the relative motion between the tool and the workpiece. During the cutting process, the tool cuts into the surface of the workpiece at a specific speed and peels off the material through extrusion and friction. The following parameters need to be precisely controlled in this process:

1. Cutting speed: The relative motion speed between the tool and the workpiece, which directly affects the machining efficiency and tool life.

2. Feed rate: The moving distance of the workpiece per revolution or per stroke of the tool, which determines the surface roughness of the machined part.

3. Cutting depth: The thickness of the workpiece cut by the tool in a single pass, which affects the material removal rate and the magnitude of the cutting force.

 

Main Types of Metal Cutting Processes

1. Turning

Turning uses a lathe to rotate the workpiece, and the turning tool feeds axially or radially to machine cylindrical, conical, and other rotary parts. It is characterized by high efficiency and wide applicability, especially suitable for the mass production of shaft - type and disc - type parts.

2. Milling

Milling uses the rotational motion of a multi - edged milling cutter combined with the workpiece feed to machine planes, grooves, and complex three - dimensional curved surfaces. Compared with turning, milling can achieve more flexible machining paths and is commonly used in mold manufacturing and precision part machining.

3. Drilling

Drilling uses a drill bit to machine round holes in the workpiece and is a basic process for hole machining. High - speed steel or cemented carbide drill bits can meet different precision requirements, and through - holes, blind holes, and deep holes can all be achieved by drilling.

4. Grinding

Grinding uses grinding tools such as grinding wheels to perform micro - cutting on the workpiece surface, which can achieve a dimensional accuracy of IT6 or higher and a surface roughness of Ra 0.4μm or lower. It is commonly used for the high - precision forming of difficult - to - machine materials such as hardened steel and ceramics.

 

Three Key Factors Affecting Machining Quality

1. Selection of Tool Materials

 - High - speed steel: With a heat resistance of up to 600°C, it is suitable for medium - and low - speed cutting and the manufacture of complex tools.

 - Cemented carbide: With a hardness as high as HRA89 - 93, it is suitable for high - speed cutting and the machining of materials such as cast iron and stainless steel.

 - Ceramic tools: With a heat resistance exceeding 1200°C, they are specially used for the finishing of hardened steel and nickel - based alloys.

2. Characteristics of Workpiece Materials

The cutting performance of different materials varies significantly:

 - For non - ferrous metals such as aluminum alloys, tools with large rake angles should be selected to prevent built - up edges.

 - For stainless steel machining, high - cobalt cemented carbide should be used in combination with coolant.

 - For hardened steel cutting, the cutting temperature should be controlled to prevent burning of the workpiece surface.

3. Optimal Use of Cutting Fluids

Cutting fluids can reduce the temperature in the cutting zone by 30% - 50%, reduce tool wear, and improve the surface quality. The following can be selected according to the machining requirements:

 - Emulsions (general - purpose cooling and lubrication)

 - Extreme - pressure cutting oils (heavy - duty machining)

 - Synthetic fluids (precision grinding)

 

Typical Industry Application Scenarios

1. Automobile manufacturing: Key processes such as engine block milling, crankshaft turning, and gear grinding all rely on metal cutting technology.

2. Aerospace: Five - axis milling of titanium alloy structural parts and precision grinding of turbine blades achieve micron - level accuracy of parts.

3. Mold processing: Complex cavity molds are manufactured through the combination of high - speed milling and electrical discharge machining.

4. Energy equipment: The turning of large - scale turbine shafts and the precision boring of nuclear power valves ensure the reliability of major equipment.

 

Technological Development Trends

With the advancement of intelligent manufacturing, metal cutting is developing in the following directions:

 - High - speed cutting: The spindle speed exceeds 50,000 rpm, and the cutting speed of aluminum alloys can reach 7,500 m/min.

 - Dry cutting: Machining without coolant is achieved through coating technology and tool structure innovation.

 - Intelligent monitoring: Force/thermal sensors are integrated to optimize cutting parameters in real - time and improve machining stability.

Mastering the core principles and key points of metal cutting technology can not only effectively improve the quality of part machining but also reduce manufacturing costs by more than 30% through process optimization. For manufacturing enterprises, continuously following up on cutting tool innovation and parameter optimization strategies will be the key to maintaining market competitiveness.