Metal Forming Sheet Metalworking

1. Metal FormingSheet Metalworking Introduction

2. Material: Sheet Metal • Typical parts • Enclosures • Boxes • Brackets • Mounting Structures • Frames • Made from thin sheet-metal (low carbon steel) • 1/16 in to 1/4 in • above ¼ in, a sheet metal is referred as a plate.

3. Processing: Sheet Metal • Typically done at room temperature (cold working) • If thick sheet metal, warm working may be used to assist with deformation • Tools used for bending are generally called presses • Stamping press – typical machine tool used • punch and die (tooling) • In mass production, long strips or coils are used

4. Operations: Sheet Metal • Cutting • Shearing • Blanking • Punching • Other • Cutoff and Parting • Slotting, Perforating and Notching • Trimming, Shaving and Fine Blanking • Bending • V-bending and Edge Bending • Flanging, Hemming, Seaming and Curling • Drawing

5. Bending • Neutral axis (compression and stretching of the material is achieved inside and outside of the neutral axis respectively) • Plastic/permanent deformation • There is little or no change in thickness

6. Analysis • Bend Allowance • If the bend radius is small relative to the stock, the metal tends to stretch during bending. • It is important to estimate the amount of stretching (in order to achieve accurate dimension). Ab=2 * pi * (Alpha/360) * ( R + Kba * t) Where Alpha is the bend angle, R is the bend radius, t is the thickness, Kba is a factor to estimate stretching. Kba = 0.33 if R < 2t and Kba = 0.5 if R ≥ 2t

7. Springback • Overbending • Bottoming