Types of Chips Formed During CNC Milling

Creating a smooth and efficient CNC milling process requires a thorough understanding of the different types of chips that can be formed during the machining operation. These chips can have a significant impact on the overall quality of the workpiece, the tool life, and the overall efficiency of the milling process.

Understanding the characteristics of each type of chip, as well as how they are formed, is crucial for optimizing the milling operation and achieving the desired outcome. In this article, we will explore the different types of chips that can be formed during CNC milling, and how they can affect the machining process.

Continuous Chips

Continuous chips are long, continuous curls of material that are formed during the machining process. These chips are typically formed when machining ductile materials such as aluminum, copper, and brass. Continuous chips are formed when the cutting tool shears the material, causing it to deform and flow along the rake face of the tool.

One of the key advantages of continuous chips is that they can help to dissipate heat from the cutting zone, which can help to prolong tool life and improve surface finish. However, continuous chips can also present challenges, such as chip evacuation and the potential for chip entanglement around the cutting tool.

To effectively manage continuous chips during CNC milling, it is important to use cutting tools with the appropriate geometry and chip-breaker designs. Additionally, optimizing cutting parameters such as cutting speed, feed rate, and depth of cut can help to control the formation of continuous chips and improve the overall machining process.

Discontinuous Chips

Discontinuous chips, also known as segmented chips or saw-tooth chips, are broken chips that are formed during the machining of brittle materials such as cast iron and some steels. These chips are characterized by their short, fragmented appearance, and are typically the result of the material fracturing under the cutting forces.

One of the key challenges associated with discontinuous chips is their tendency to produce jagged, uneven surfaces on the workpiece. Additionally, the formation of discontinuous chips can result in increased cutting forces and tool wear, as well as reduced tool life.

To manage the formation of discontinuous chips during CNC milling, it is important to optimize cutting parameters and use cutting tools with the appropriate geometry and edge preparation. Additionally, controlling the cutting forces and minimizing the impact of built-up edge formation can help to improve the overall machining process when working with brittle materials.

Stringy Chips

Stringy chips, also known as bird's nests or rat's nests, are long, string-like chips that are formed during the milling of materials such as stainless steel and some high-temperature alloys. These chips are characterized by their tendency to wrap around the cutting tool, potentially causing chip entanglement and tool breakage.

The formation of stringy chips can be attributed to the material's tendency to exhibit high strain hardening and work hardening characteristics. As the material undergoes plastic deformation, it can form long, continuous strands of material that are difficult to break and evacuate from the cutting zone.

To effectively manage the formation of stringy chips during CNC milling, it is important to use cutting tools with the appropriate geometry and edge preparation. Additionally, optimizing cutting parameters such as cutting speed, feed rate, and depth of cut can help to control the formation of stringy chips and improve chip evacuation from the cutting zone.

Scrappy Chips

Scrappy chips, also known as short chips or chipping chips, are small, broken chips that are formed during the machining of materials such as ceramics and some composites. These chips are characterized by their irregular, fragmented appearance, and are typically the result of the material's resistance to plastic deformation.

One of the key challenges associated with scrappy chips is their tendency to produce poor surface finish and potentially cause built-up edge formation on the cutting tool. Additionally, the formation of scrappy chips can result in increased cutting forces and tool wear, as well as reduced tool life.

To manage the formation of scrappy chips during CNC milling, it is important to use cutting tools with the appropriate geometry and edge preparation. Additionally, optimizing cutting parameters and controlling the cutting forces can help to improve the overall machining process when working with materials that tend to form scrappy chips.

Chunky Chips

Chunky chips, also known as big chips or hogging chips, are large, thick chips that are formed during the machining of materials such as titanium and some high-strength alloys. These chips are characterized by their size and thickness, and are typically the result of the material's resistance to plastic deformation and the high cutting forces involved in the milling process.

One of the key challenges associated with chunky chips is their potential to cause chip evacuation difficulties and tool breakage. Additionally, the formation of chunky chips can result in increased cutting forces and heat generation, as well as reduced tool life.

To effectively manage the formation of chunky chips during CNC milling, it is important to use cutting tools with the appropriate geometry and edge preparation. Additionally, optimizing cutting parameters such as cutting speed, feed rate, and depth of cut can help to control the formation of chunky chips and improve the overall machining process when working with materials that tend to form thick, heavy chips.

In summary, understanding the different types of chips that can be formed during CNC milling is essential for optimizing the machining process and achieving the desired outcome. By recognizing the characteristics of each type of chip, as well as the factors that contribute to their formation, it is possible to effectively manage chip formation and improve the overall efficiency and quality of the milling operation. Whether working with ductile materials that form continuous chips, or brittle materials that produce discontinuous chips, implementing the appropriate cutting tools and cutting parameters is crucial for controlling chip formation and achieving successful machining results.