Common Solutions for Tool Sticking on CNC Lathes for Various Materials
Tool sticking on CNC lathes refers to the phenomenon where the cutting tool adheres to the workpiece material during machining. This results in material buildup on the tool surface, affecting both the quality and efficiency of the machining process. To address this issue, it is essential to understand the properties of the materials and the causes of the phenomenon to provide suitable solutions.
1. Aluminum and Its Alloys
Aluminum and its alloys are materials based on aluminum, enhanced by adding other metallic elements to improve their physical and mechanical properties.
Pure Aluminum: Exhibits high ductility and low hardness.
Aluminum-Magnesium Alloy: Magnesium's melting point is similar to that of aluminum, but it has higher ductility.
Aluminum-Zinc Alloy: Zinc's melting point is approximately 419°C, which is lower than aluminum's.
Aluminum-Silicon Alloy: Silicon exists in the form of hard and brittle silicon particles that tend to break off during cutting.
The melting point of aluminum and its alloys is relatively low (about 660°C). During machining, the contact area may reach temperatures of up to 400°C. While this is below the melting point, it is sufficient to cause tool sticking. Aluminum alloys exhibit high ductility (elongation rate of 10%-30%) and plasticity. During cutting, this can lead to the formation of built-up edges, increasing the risk of tool sticking.
Effective Countermeasures：
Tool Material: Use carbide tools.
Tool Coating: Prefer tools with diamond coatings or titanium nitride (TiN) coatings.
Cutting Parameters: Set cutting speeds between 100-300 meters per minute and feed rates of 0.2-0.5 millimeters per tooth.
Coolant Selection: Use high-efficiency coolants specifically designed for aluminum alloy machining.
Cutting Oil Selection: Choose cutting oils that contain sulfur, chlorine, or phosphorus.
Tool Geometry: Control the edge radius to 0.01-0.02 millimeters, with slight edge honing, and the edge hone radius should be around 0.02-0.03 millimeters.
Technical Recommendations: Inspect the tool sharpness every 30-60 minutes of cutting and prefer high-speed machining.
Coolant Injection: Use high-pressure coolant injection to ensure the coolant fully covers the cutting area.
2. Copper and Its Alloys
Copper and its alloys are materials based on copper, enhanced by adding other metallic elements to improve their physical and mechanical properties.
Pure Copper: Exhibits extremely high ductility and relatively low hardness.
Brass (Copper-Zinc Alloy): Zinc has a melting point of approximately 419°C, making it prone to softening and adhering to the tool during cutting.
Bronze (Copper-Tin Alloy): Possesses high wear resistance but is also prone to tool sticking at high cutting temperatures.
Aluminum Bronze: A copper alloy containing aluminum, which has high hardness but tends to generate high temperatures during cutting, leading to tool sticking.
Copper and its alloys have relatively low melting points (copper melts at about 1085°C). During cutting, the contact area between the tool and the workpiece can reach temperatures of 300-600°C, which, while lower than the melting point, is sufficient to cause tool sticking. Copper alloys have high ductility and plasticity, which can lead to the formation of built-up edges during cutting, further increasing the risk of tool sticking.
Effective Countermeasures：
Tool Material: Use carbide tools, such as WC-Co carbide with a grain size of 0.4-0.6 micrometers.
Tool Coating: Choose tools with titanium aluminum nitride (TiAlN) coatings or silicon nitride (SiN) coatings to enhance heat resistance and reduce adhesion.
Cutting Parameters: Set cutting speeds between 50-200 meters per minute and feed rates of 0.1-0.3 millimeters per tooth.
Coolant Selection: Use high-efficiency coolants suitable for copper alloy machining, such as Castrol Syntilo 9954 or Blaser Blasocut BC25.
Cutting Oil Selection: Choose cutting oils containing sulfur and chlorine, such as Castrol Alusol R or Quaker RIMOLINE 70.
Tool Geometry: Control the edge radius to 0.02-0.03 millimeters, with slight edge honing, and the edge hone radius should be around 0.03-0.04 millimeters.
Technical Recommendations: Inspect tool sharpness every 20-40 minutes of cutting and resharpen as needed; use high-efficiency cutting techniques wherever possible.
Coolant Injection: Use high-pressure coolant injection to ensure the coolant fully covers the cutting area, reducing cutting temperatures and friction.
3. Stainless Steel
Stainless steel is a steel alloy containing chromium (typically at least 10.5%), which provides excellent corrosion resistance and mechanical properties.
Austenitic Stainless Steel: Exhibits high toughness and high ductility, with a strong tendency for work hardening.
Martensitic Stainless Steel: Low thermal conductivity leads to difficulty dissipating heat during cutting, causing temperature rise in the tool-workpiece contact area, which easily results in tool sticking.
Duplex Stainless Steel: Combines characteristics of austenitic and ferritic stainless steels, offering high strength and good corrosion resistance.
Stainless steel's high strength and toughness, coupled with low thermal conductivity, result in high temperatures (300-600°C) in the tool-workpiece contact area during cutting, leading to material adhesion to the tool. Work Hardening Tendency: Stainless steel's strong tendency for work hardening during cutting increases the difficulty of machining, exacerbating tool sticking issues.
Effective Countermeasures
Tool Material: Use high-hardness, wear-resistant carbide tools.
Tool Coating: Select tools with titanium aluminum nitride (TiAlN) or titanium silicon nitride (TiSiN) coatings to enhance heat resistance and reduce adhesion.
Cutting Parameters: Set cutting speeds between 50-150 meters per minute and feed rates of 0.05-0.2 millimeters per tooth, maintaining moderate cutting speeds and feed rates to reduce heat buildup and work hardening.
Coolant Selection: Use high-efficiency coolants suitable for stainless steel machining.
Cutting Oil Selection: Choose cutting oils containing sulfur and chlorine.
Tool Geometry: Control the edge radius to 0.01-0.02 millimeters, ensuring sharp tools to reduce cutting resistance. Maintain smooth cutting edges to minimize material adhesion.
Technical Recommendations: Inspect tool sharpness every 20-40 minutes of cutting, keeping tools sharp; utilize high-speed cutting techniques wherever possible.
Coolant Injection: Use high-pressure coolant injection to ensure the coolant fully covers the cutting area, reducing cutting temperature and friction.
4. Mild Steel
Mild steel refers to steel with a low carbon content (usually less than 0.25%) that possesses good toughness and ductility.
Low Carbon Steel (e.g., AISI 1018): Has low carbon content with high ductility and toughness.
Soft Low-Alloy Steel: Contains small amounts of alloying elements, offering slightly increased strength but still prone to tool sticking.
Mild steel’s high ductility and low hardness make it prone to plastic deformation during machining, leading to material adhesion to the tool. During cutting, mild steel tends to form built-up edges, which increase friction and temperature, exacerbating tool sticking.
Effective Countermeasures
Tool Material: Use high-speed steel (HSS) or carbide tools to ensure good wear resistance.
Tool Coating: Select tools with titanium nitride (TiN) or aluminum titanium nitride (AlTiN) coatings to enhance wear resistance and reduce adhesion.
Cutting Parameters: Set cutting speeds between 80-150 meters per minute and feed rates of 0.1-0.3 millimeters per tooth, maintaining moderate cutting speeds and feed rates to minimize heat buildup.
Coolant Selection: Use high-efficiency coolants suitable for mild steel machining.
Cutting Oil Selection: Choose cutting oils containing sulfur and chlorine.
Tool Geometry: Control the edge radius to 0.01-0.02 millimeters, ensuring sharp tools to reduce cutting resistance. Maintain smooth cutting edges to minimize material adhesion.
Technical Recommendations: Inspect tool sharpness every 20-40 minutes of cutting to keep tools sharp; utilize high-speed cutting techniques whenever possible.
Coolant Injection: Use high-pressure coolant injection to ensure the coolant fully covers the cutting area, reducing cutting temperature and friction.
5. Low Carbon Steel and Carbon Steel
Low carbon steel and carbon steel refer to steels with varying carbon content, offering good strength and toughness.
Low Carbon Steel (e.g., AISI 1018): Carbon content is usually less than 0.25%, with high ductility and toughness.
Medium Carbon Steel (e.g., AISI 1045): Carbon content ranges from 0.25% to 0.60%, prone to forming built-up edges during cutting, leading to tool sticking.
High Carbon Steel (e.g., AISI 1095): Carbon content is typically greater than 0.60%, with high hardness, but cutting at high temperatures can cause tool sticking.
Low carbon steel and carbon steel have high ductility and plasticity, leading to plastic deformation during machining and material adhesion to the tool. Medium and high carbon steels are more prone to forming built-up edges during cutting, increasing friction and temperature, exacerbating tool sticking.
Effective Countermeasures
Tool Material: Use carbide tools, especially fine-grained carbide (grain size 0.2-0.4 micrometers) to improve wear resistance.
Tool Coating: Select tools with titanium nitride (TiN), aluminum titanium nitride (AlTiN), or titanium silicon nitride (TiSiN) coatings to enhance heat resistance and reduce adhesion.
Cutting Parameters: Set cutting speeds between 80-180 meters per minute and feed rates of 0.1-0.25 millimeters per tooth to minimize heat buildup and work hardening.
Coolant Selection: Use high-efficiency coolants suitable for machining low carbon steel and carbon steel.
Cutting Oil Selection: Choose cutting oils with high-pressure additives.
Tool Geometry: Control the edge radius to 0.01-0.03 millimeters, ensuring sharp tools to reduce cutting resistance. Maintain smooth cutting edges to minimize material adhesion.
Technical Recommendations: Inspect tool sharpness every 20-40 minutes of cutting to keep tools sharp. For high carbon steel, use appropriate cutting fluids to lower machining temperature.
Coolant Injection: Use high-pressure coolant injection to ensure the coolant fully covers the cutting area, reducing cutting temperature and friction.
6. Titanium and Its Alloys
Titanium and its alloys are materials based on titanium, combined with other metallic elements to achieve high strength, low density, and excellent corrosion resistance.
Pure Titanium: Low thermal conductivity, high strength, and prone to generating high temperatures during cutting, leading to tool sticking.
Titanium-Aluminum Alloy: High strength and good corrosion resistance, but tends to generate high temperatures and chemical reactions during cutting, causing tool sticking.
Titanium-Molybdenum Alloy: Excellent mechanical properties and heat resistance, but low thermal conductivity, making it prone to tool sticking during cutting.
Titanium and its alloys have low thermal conductivity, causing high temperatures to concentrate in the contact area between the workpiece and the tool, reaching up to 800°C, leading to material softening and adhesion to the tool. Titanium alloys are highly chemically active, especially at high temperatures, and can react with the tool material to form metal compounds, increasing the risk of tool sticking.
Effective Countermeasures
Tool Material: Use ultra-fine grain carbide tools (grain size below 0.5 micrometers) to enhance wear resistance.
Tool Coating: Select tools with aluminum titanium nitride (AlTiN) or titanium silicon nitride (TiSiN) coatings to improve heat resistance and reduce adhesion.
Cutting Parameters: Set cutting speeds between 30-90 meters per minute and feed rates of 0.1-0.3 millimeters per tooth. Maintain low cutting speeds and moderate feed rates to reduce heat buildup.
Coolant Selection: Use high-efficiency coolants suitable for machining titanium alloys.
Cutting Oil Selection: Choose cutting oils with high-pressure additives.
Tool Geometry: Control the edge radius to 0.02-0.04 millimeters, ensuring sharp tools to reduce cutting resistance. Maintain smooth cutting edges to minimize material adhesion.
Technical Recommendations: Inspect tool sharpness every 20-30 minutes of cutting to maintain sharpness. Prefer high-speed cutting techniques where possible.
Coolant Injection: Use high-pressure coolant injection to ensure the coolant fully covers the cutting area, reducing cutting temperature and friction.
