Types of chips used in metal cutting

Introduction

Metal cutting is crucial in industries like automotive, aerospace, manufacturing, and construction, with chip formation being a key aspect. Knowledge of chip types is essential for efficient machining and optimal results. This blog will explore chip types in metal cutting and their importance in various applications.

Illustration titled “Types of Chip” showing four diagrams: Continuous, Discontinuous, Continuous with Built-up Edge, and Serrated. Each features a tool interacting with a material to create chips.

Types of Chip Formation

Various types of chips, which are formed in various cutting conditions and type of machining, can be categorized as follow:

Continuous chip
Discontinuous chip
Continuous chip with built-up edge
Serrated chip

1.Continuous Chip

Continuous chips—also known as ribbon or long chips—are formed when the cutting tool maintains uninterrupted contact with the workpiece. These chips are commonly produced during the machining of ductile materials such as aluminum and copper. Characterized by their smooth, uniform thickness and extended length, continuous chips are often desirable, as they indicate stable cutting conditions and contribute to superior surface finishes. However, proper chip control is necessary to prevent issues such as entanglement or damage to the workpiece and tooling.

Continuous chip, as shown in Figure 1, is formed due to

Machining of ductile materials
Small undercut thickness
High cutting speed
Large rake angle of the tool
Suitable cutting fluids

Diagram of a cutting process showing a tool removing a chip from a workpiece. Arrows point to the tool and the curled chip being formed.

Figure 1

2.Discontinuous Chip

Segmented chips—also known as discontinuous or broken chips—are produced when the cutting action is intermittent or when the material fractures due to its inherent brittleness. Commonly observed during the machining of materials such as cast iron, bronze, and certain hard alloys, these chips appear as short, fragmented segments. Although they can complicate chip handling and disposal, segmented chips offer notable benefits: they help reduce heat accumulation at the cutting zone, lower cutting forces, and minimize tool wear. These factors contribute to a more stable, efficient, and controlled machining process.

Discontinuous chip, as shown in Figure 2, is formed due to

Machining of brittle work materials
Low cutting speed
Small rake angle
Large uncut chip thickness

Cross-sectional diagram of a cutting process shows a tool removing chips from a material surface. Arrows label "Chip" and "Tool" on the diagram.

Figure 2

3.Continuous Chip with Built-up (BUP) Edge

Continuous chip with built-up edge is not an actual chip, but a result of metal cutting affecting chip formation. It occurs when workpiece material sticks to the cutting tool, impacting surface finish. Proper management is essential for cutting efficiency and workpiece accuracy.

Continuous chip with built-up edge, as shown in Figure 3, is formed due to

Large friction or stronger adhesion between chips and tool face
Low rake angle
Large uncut chip thickness

Technical diagram showing a tool cutting material, labeled "Tool" and "Chip." The tool creates a chip as it moves through the material.

Figure 3

4.Serrated Chip

Serrated chips, also called saw-toothed chips, have a zigzag pattern on their edges. They are commonly seen in materials of different hardness or during intermittent cutting. Controlling serrated chips can be difficult, resulting in issues like bad surface finish and higher tool wear. Knowing the factors that cause serrated chips is crucial for improving machining settings.

Serrated Chip, as shown in Figure 4, is formed due to

High temperature at contact surface between cutting tool and workpiece

Diagram illustrating chip formation in metal cutting, showing a cutting tool interacting with material. Arrows denote high and low shear strain zones.

Figure 4

Conclusion

In the metal cutting industry, the morphology of chips produced offers critical information about the efficiency and stability of the machining process. Key factors such as workpiece material, cutting conditions, and tool geometry significantly influence chip formation. A thorough understanding of various chip types is essential for optimizing machining parameters, improving surface finish, extending tool life, and ensuring overall process efficiency.