Understanding Chip Types in Metal Cutting: Classification, Causes, and Impact

There is no way to avoid chip generation in metal cutting and machining processes. These chips can come in a variety of shapes and sizes, which leads to their classification. Many factors influence the types of chips produced during the metal cutting process, which I shall discuss more.

The purpose of today’s presentation is to discuss the definition, purpose, and many types of chips used in metal cutting and machining operations. We’ll also learn about the many elements that influence the types of chips produced during the process. You’ll also learn about the benefits and drawbacks of the chips kinds machining procedure.

What are chips?

Chips are materials that have been removed from a workpiece using tools. Shearing produces chips, which are made during machining procedures. The material ahead of a cutting tool installed on a machine is shear and distorted under great pressure as it engages the workpiece. This distorted material tends to fracture and flow over the tool in the form of a chip to relieve its strained state.

Some chips have a commercial purpose. Scrubbing and cleaning household utensils are done with coiled stainless steel chips.

Factors that determine the types of chips to be produced

Below are the factors that determined the types of chips produce during a machining process:

• The material that was used to create the cutting tool
• The tool’s dimensions.
• Materials needed to create the workpiece
• The cutting speed.
• During the cutting process, forces are applied.
• Friction between the tool and the workpiece.
• Temperature, for example, is a cutting environment.

Types of chips

Below are the various types of chips in metal cutting or machining processes:

Discontinuous chips:

These types of chips are small segments that adhere loosely to each other and form a slightly larger length. They are formed when the amount of deformation the chips undergo is limited due to fracture repeatedly. The segments are formed regularly due to the rupture of the metal ahead of the tool.

Discontinuous chip types in ductile materials are produced because the hydrostatic pressure near the cutting edge is tensile or the shear energy reaches a critical level. Although the formation of this chip in brittle materials offers a good finish, increases tool life, and consumes less power. In ductile materials, these chip types may result in poor finish and excessive tool wear. However, smaller chips can be disposed of.

While machining hard and brittle metals like bronze, brass, and cast-iron, discontinuous chips are obtained. Sometimes, cutting of ductile metals at very low feeds with a small rake angle of the cutting tool and high speeds and high friction forces at the chip tool interface also result in the production of these types of chips.

Advantages and disadvantages of discontinuous chips

Advantages:

Below are the benefits of discontinuous chips on brittle materials:

• Increases tool life
• Good surface finish.
• Reduces consumption of power.

Disadvantages:

Below are the limitations of discontinuous chips on ductile materials:

• Poor surface finish.
• Excessive wear and tear of the tool.

Continuous chips:

The pressure on the workpiece rises in a continuous chip formation until the material fails by slipping along the slip plane. Metal chips are created without segments, that is, without fracture, during machining in these sorts of chips. When ductile material is machined at a high cutting speed with minimal friction between the chip and the tool face, it can be produced. It is preferable to use a ductile material such as mild steel.

Advantages of continuous chips

Below are the advantages of continuous chips during the machining process:

• Offers better surface finish to ductile materials.
• Low power consumption.
• Less heat generation is due to minimizing friction between the chip and tool face.
• Less wear and tear, resulting in longer tool life.

Continuous chips with a built-up edge:

When a ductile material is machined with high friction at the chip tool interface, a continuous chip with a built-up edge is formed. These types of chips are similar to the continuous chips but their smoothness is less due to the built-up edge.

The built-up edge is formed when the chip flows in an upward direction and high friction exists between the interface of the chip and tool. This high friction between the tool and chip causes intense heat to be generated at the nose of the tool. The compressed metal adjacent to the tool nose gets welded to it. This compressed metal welded to the nose is what we called a built-up edge.

Continuous chips with built-up edge are attained at excessive feed rate, the small rake angle of the tool, low cutting speed, and lack of coolant, which increases the friction between the chip tool interfaces.

Advantages and disadvantages of continuous chips with built-up edge

Advantages:

• The tool is protected from getting damaged from high friction and temperature generated during the process.
• The tool life is increased.

Disadvantages:

• A rough surface finish is obtained.
• Change in rake angle and cutting forces.

Watch the video below to learn more about the various types of chips in the metal cutting and machining process: 

Conclusion

Chips are materials removed from a workpiece with the aid of a tool. They are reprocessed to serve other purposes. That is all for this article where we’ve explained the various types of chip and their advantages and disadvantages.

I hope you get a lot from this post, if so, kindly share with other students. Thanks for reading, see you next time!