Lecture 3: Shaping Flashcards
What happens during hot deformation?
Hot deformation involves deforming materials at temperatures close to their melting points (70-80%), which reduces the force required but uses a lot of energy and lead to recrystallization for improved structure.
What is warm deformation and its benefits?
Warm deformation occurs at 30-40% of the melting temperature of the material. It reduces the force needed for deformation without causing recrystallization, striking a balance between energy use and material strength.
Describe cold deformation and its effects.
In cold deformation, materials are deformed at or near room temperature, leading to work hardening as the existing crystal structures are compressed and twisted without heat softening.
Compare continuous and discrete shaping processes.
Continuous processes (e.g., rolling, extrusion) are ongoing as long as material is supplied. Discrete processes (e.g., forging, sheet-metal forming) create individual pieces one at a time.
Explain the 5 characteristics of Forging
1.Shaping by applying compressive forces.
2.High equipment and labor costs.
3.Achieves high strength/toughness materials.
4.Allows for complex shapes and production of small to large products.
5.Usually done in batches.
Cold forging :(3)
-Good surface finish and
accuracy
- Crystal deformation
- A lot of force needed
Hot forging (3):
- Lower forces required
- Worse surface finish
and accuracy. - Strengthening
Differentiate between Open-Die Forging (2) and Closed-Die Forging (3):
Open-Die Forging:
1.Limited shapes, small quantities, mostly hot forging.
2.Leaves parting line and flash.
Closed-Die Forging:
1.Used for complex shapes and larger quantities.
2.Mold more expensive due to die shape information.
3.Leaves parting line and flash but molds hardly ever completely close.
Heading =
= changing the shape in a number of steps, each step gets
closer to the shape we want.
Coining =
= a process with high accuracy and surface finish. We do not have any
flash in coining.
What are the key 4 characteristics of the Extrusion process (hot and cold):
1.Uses machines.
2.Moderate-to-high die and equipment cost, low-to-moderate labor cost.
3.Involves enormous forces to push material through die.
4.Hot extrusion has low ductility and heat requirements, used for batches; cold extrusion has high ductility and is often combined with forging, individual production
What are the 3 primary features of products produced through Extrusion?
1.Product geometry: long lengths, constant cross-section, discrete products.
2.Made in batches or semi-continuous processes.
What challenges arise in extrusion when attempting to create sharp corners and work with very strong materials?
1.Very sharp corners and unbalanced voids are difficult to achieve.
2.Extrusion with extremely strong materials, like steel, is not feasible due to the inability of dies to withstand the high forces involved.
What are the 2similarities and 3 differences between Drawing and Extrusion processes?
Similarities:
1.Both have low-to-moderate equipment and labor costs.
2.Low-to-moderate operator skills required.
Differences:
1.Drawing: Material pulled out of the die.
2.Extrusion: Material pushed through the die.
3.Drawing works only with cold material and results in increased strength.
Describe the product geometry and process nature of Drawing.
Product geometry: Long rods and wires with different cross-sections.
Process is continuous.
