Metal Deformation Flashcards
What is Metal Deformation
Manufacturing processes in which plastic deformation is used to permanently alter the geometry of a material
What are the Desirable Material Properties of Materials Undergoing Metal Deformation
Low Yield Strength
High Ductility
Friction
Strain Rate - Rate of Deformation of a material
Rolling: Thickness is reduced by compressive forces exerted by opposing rolls
Forging: Material is compressed between two dies
Extrusion: Material is pushed through a die opening by compressive forces.
Drawing: Material is pulled through a die opening by tensile forces.
In the following Formula Explain what Each Component represents
Explain the benefits to hot and cold forging
Explain the Difference between Impact and Press Forging
Cold- Increased Strength of product from strain hardening
Hot- Increased Ductility of the Work metal from a Reduction in strength.
Impact: Uses a Forge Hammer to apply an impact force
Press: Applies a Gradual force.
a) Open Die Forging : Material compressed between two flat dies, allows lateral flow
b) Impression Die Forging: Die Contains cavity that is pressed onto the workpart
c) Flashless Forging: Material compressed whilst being restrained in a die. No Excess Flash.
What are the Most Common Processes in Metalworking
Bending - Deforming sheet around a straight axis
Drawing - Deforming the sheet into convex and concave shapes
Cutting - Shearing the Sheets into Smaller geometries
What are the Following Processes
Explain Bending
Deforming sheet around a straight axis
Area Inside Neutral Plane is Compressed
Area Outside Neutral Plane is Stretched
Explain the Following Processes
Explain the Components of this Formula
How do you make sure you’re part is the correct geometry after bending
Bending Allowance + Desired Length = Amount Fed into Machine
What is Springback?
Why does it Occur?
Increase in radius of bent part, & increase in acute angle between the sheet ,after die is removed
When pressure is removed, Elastic Energy remains in bent part, causing it to partially recover toward its original geometry.
Explain the Components of this Formula
Explain the Process
Deep Drawing
Sheet placed over cavity, Punch pushes metal into opening
Explain the Process
Explain the Processes
A ) Blanking - part(Blank) is cut from a metal sheet(Stock)
B) Punching - Some material(slug) is cut from the part
How do you calculate the True Stress of a material
What is the Difference Between Engineering Stress and True Stress
How Do you Convert between Engineering Stress and True Stress
Engineering Stress Assumes a Constant Cross-Sectional Area
True Stress Accounts for changes in force and cross sectional area
What is flow Stress
What is the Average Flow Stress
What are the Advantages and Disadvantages of cold-forming metal deformation
Better Accuracy
Better Surface Finish
No Heating
Grain Flow is in a more desirable Direction
Higher forces Required
More Power Required
Ductility and Strain Hardening Limit amount of Deformation possible
What is the difference between Warm and Hot Working in metal deformation
What are the Advantages and Disadvantages of Warm-working metal deformation
Warm is performed below recrystallization temperature, and hot is performed above (above 0.5 Tm)
Lower Forces and Power Required then cold forming
More compiled Geometries then cold forming
Reduced need for Annealing (Heat Treatment)
Heating is required
What is the difference between Warm and Hot Working in metal deformation
What are the Advantages and Disadvantages of Hot-working metal deformation
Warm is performed below recrystallization temperature, and hot is performed above (above 0.5 Tm)
Much more compiled Geometries then cold forming & Warm-Working
Lower Forces and Power Required then cold forming & Warm-Working
All sections of sheet post-deformation have near-equal strength
Lower Accuracy
Heating is Required
Surface Oxidation (Poor Surface Finish)
What is Strain Rate
During Hot working how does a metal behave?
Metal Behaves like a perfectly Plastic Material (Strain hardening exponent =0)
Flow Stress Becomes constant
