General Technical Terms

Upset (mechanical)

Upset: A Bulge in the Metal for Strength and Threads

In the world of manufacturing, the term "upset" refers to a deliberate enlargement of a metal workpiece, often achieved by forging or rolling. This enlargement, which can occur internally or externally, creates a bulge in the material, resulting in increased strength and diameter.

Internal Upset:

Internal upset, as the name suggests, takes place within the workpiece. Imagine a cylindrical bar of metal. By applying pressure to its ends, we can cause the metal to flow inwards, increasing the diameter of the central portion while reducing the diameter of the ends. This technique is commonly used to create threaded portions within the workpiece, providing a stronger and more secure hold for fasteners.

External Upset:

External upset involves increasing the diameter of the workpiece at a specific location on its outer surface. This can be achieved through various methods like cold heading or forging, where the metal is hammered or pressed to expand at the desired point. External upset is often used to:

  • Create a head for a bolt or screw, providing a larger surface area for the wrench or screwdriver to grip.
  • Form a flange on a shaft or tube, which can be used for attachment or sealing purposes.
  • Strengthen a section of the workpiece, making it more resistant to bending or breaking.

Benefits of Upset:

  • Increased Strength: The localized bulge created by upset increases the cross-sectional area of the material, leading to a significant improvement in its strength.
  • Improved Thread Formation: Upset is crucial for producing strong and accurate threads. The increased diameter at the threaded portion provides a wider engagement area for the fastener, resulting in a more secure connection.
  • Versatility: Upset can be used to create a variety of shapes and features on metal workpieces, making it a versatile technique in manufacturing.

Examples of Upset in Application:

  • Screws and Bolts: Upset is used to create the head and threaded portion of fasteners, ensuring a secure and reliable connection.
  • Shafts and Tubes: Upset is utilized to create flanges, shoulders, or other features on shafts and tubes for mounting or joining components.
  • Rivets: Upset is employed to form the head of a rivet, securing it firmly to the joined materials.
  • Machinery Components: Upset is a crucial process in manufacturing various mechanical components, including gears, sprockets, and other precision parts.

In summary, upset is a fundamental process in manufacturing, enabling the creation of stronger and more complex metal workpieces. By strategically increasing the diameter of the workpiece at specific locations, upset enhances its strength, allows for thread formation, and creates versatile features for a wide range of applications.


Test Your Knowledge

Upset Quiz:

Instructions: Choose the best answer for each question.

1. What is "upset" in manufacturing?

a) A type of metal alloy. b) A deliberate enlargement of a metal workpiece. c) A manufacturing defect. d) A specific type of welding process.

Answer

b) A deliberate enlargement of a metal workpiece.

2. How does internal upset affect a workpiece?

a) Increases its overall length. b) Creates a head at one end. c) Increases the diameter of the central portion. d) Reduces the diameter of the central portion.

Answer

c) Increases the diameter of the central portion.

3. What is a common application of internal upset?

a) Forming a flange. b) Creating a head for a bolt. c) Producing threaded portions. d) Strengthening a shaft.

Answer

c) Producing threaded portions.

4. What is NOT a benefit of using upset in manufacturing?

a) Increased strength. b) Improved thread formation. c) Reduced material cost. d) Versatility in creating various shapes.

Answer

c) Reduced material cost.

5. Which of these is NOT a common example of upset in application?

a) Screws and bolts. b) Shafts and tubes. c) Rivets. d) Plastic molding.

Answer

d) Plastic molding.

Upset Exercise:

Task: Imagine you need to create a custom bolt with a threaded section and a hexagonal head. Explain how the process of upset would be involved in creating this bolt, highlighting both internal and external upset techniques.

Exercise Correction

To create a custom bolt with a threaded section and a hexagonal head, the process of upset would be crucial. Here's how it would work:

1. **Internal Upset for Threading:** A cylindrical bar of metal would be subjected to internal upset. Pressure applied to the ends of the bar would cause the metal to flow inwards, increasing the diameter of the central portion. This would create the threaded section of the bolt, providing a stronger and more secure hold for the nut.

2. **External Upset for Head Formation:** After the threaded section is formed, external upset would be applied to one end of the bolt. This could be done through cold heading or forging, where the metal is hammered or pressed to expand at the desired point. This would create the hexagonal head of the bolt, providing a larger surface area for a wrench to grip.

Therefore, both internal and external upset techniques are essential in creating a custom bolt with the desired features. The internal upset forms the strong threaded section, while the external upset creates the hexagonal head for easy and secure tightening.


Books

  • "Metal Forming: Processes, Analysis, and Applications" by George E. Dieter (Covers the fundamentals of metal forming processes, including upset forging)
  • "Forging Handbook" by the Forging Industry Association (Provides detailed information on forging practices, including upsetting)
  • "Machinery's Handbook" by Erik Oberg and Franklin D. Jones (A comprehensive reference on various manufacturing processes, including upset forming)

Articles

  • "Upsetting: A Versatile Metal Forming Process" by The American Society for Metals (ASMT) (A detailed overview of upsetting with different applications)
  • "Cold Heading: A Cold Forming Process" by The Precision Metalforming Association (PMPA) (Discusses cold heading, a type of upsetting for making fasteners)
  • "The Use of Upsetting in the Manufacture of Bolts and Screws" by The Institute of Mechanical Engineers (A specific application of upsetting in fastener production)

Online Resources

  • "Upsetting" on Wikipedia (Provides a concise definition and examples of upsetting)
  • "Upset Forging" on The Engineering ToolBox (Offers a basic explanation of upsetting with relevant calculations)
  • "Cold Heading" on Industrial Automation (An online resource dedicated to cold heading, a common upset process)

Search Tips

  • "Upsetting metal forming"
  • "Cold heading process"
  • "Forging upset"
  • "Upset applications"
  • "Upset thread formation"

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