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Assignment No.04

“Developing a manufacturing strategy for sheet metal operation in automation

industry”

ROOHUL AMIN

REG NO: A1EWT-216005

SUBJECT: “PRODUCTION AUTOMATION”

PROGRAMM: B.TECH (Mech) 4 YEAR (WEEKEND)

SEMESTER: SUMMER 2016

PIMSAT KARACHI

Submitted by:

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Metal Sheet

Introduction

Sheet metal is simply metal formed into thin and flat pieces. It is one of the fundamental forms used in metalworking, and can be cut and bent into a variety of different shapes. Countless everyday objects are constructed of the material. Thicknesses can vary significantly, although extremely thin thicknesses are considered foil or leaf, and pieces thicker than 6 mm (0.25 in) are considered plate.

Sheet metal processing

The raw material for sheet metal manufacturing processes is the output of the rolling process. Typically, sheets of metal are sold as flat, rectangular sheets of standard size. If the sheets are thin and very long, they may be in the form of rolls. Therefore the first step in any sheet metal process is to cut the correct shape and sized ‘blank’ from larger sheet.

Thickness of sheet metal = 0.4 mm to 6 mmThickness of plate stock > 6 mm

Operations usually performed as cold working

Sheet Metal forming processes

Introduction

The sheet metal industry has focused on the automation of punching, shearing, nesting processes and bending operation for sheet metal parts. The representation of a sheet metal part should provide sufficient information to make a complete production plan. As a first step, the design must be unambiguous; it should represent one and exactly one part, in either flat pattern or final shape. Secondly, the design must be complete so all the information required to recognize a correct part is present, such as tolerances. Finally, additional information helps identify aspects of the design such as known features. While this last item is not necessary, it can make an extremely difficult planning task relatively easy. We have identified several important features for bending process. These features are later used to help prepare the process plans.

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Two approaches have been developed to identify features in a design:

a. Feature recognition: - The feature recognition approach searches the geometric description of a part for known patterns and then labels the geometry subsets with a feature name.

b. Design-with-features: - The design with-features approach allows the designer to directly label the geometry. This has been used in various ways.

Sheet metal processes involve plane stress loadings and lower forces than bulk forming. Almost all sheet metal forming is considered to be secondary processing. The main categories of sheet metal forming are

a. Shearingb. Bendingc. Drawing

Shearing

Shearing is a sheet metal cutting operation along a straight line between two cut-ting edges by means of a power shear.

Blanking and punching

Blanking and punching is similar sheet metal cutting operations that involve cutting the sheet metal along a closed outline. If the part that is cut out is the desired product, the operation is called blanking and the product is called blank. If the remaining stock is the desired part, the operation is called punching. Both operations are illustrated on the example of producing a washer.

Bending

Bending is defined as the straining of the sheet metal around a straight edge. Sheet metal bending operations involve placing sheet metal on a die up against a back gage to precisely locate the part. At this time, the machine is commanded to close the gap between the punch and die until the part is bent into the V-space of the die (see Fig. 1). In air-bending the part is not forced into the bottom of the V but rather is left in the air. This process causes less wear on the machine and tools than a bottoming (or coining) operation. When the part is taken out of the machine, the bend partially “springs back” by a small, but unknown amount which is usually determined by experiments

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Types of Sheet metal Bending1. V-bending - performed with a V-shaped die2. Edge bending - performed with a wiping die

Drawing

Drawing is a sheet-metal operation to make hollow-shaped parts from a sheet blank. Sheet metal forming to make cup-shaped, box-shaped, or other complex-curved, hollow-shaped parts. Sheet metal blank is positioned over die cavity and then punch pushes metal into opening

Products: beverage cans, ammunition shells, automobile body panels

Tools and Accessories required for sheet metal processing

Marking and measuring tools

a. Steel Rule: It is used to set out dimensions.b. Try Square: Try square is used for making and testing angles of 90degreec. Scriber : It used to scribe or mark lines on metal work pieces.d. Divider : This is used for marking circles, arcs, laying out

perpendicular lines, bisecting lines, etc.

Cutting Tools

a. Straight snip - They have straight jaws and used for straight line cutting.b. Curved snip - They have curved blades for making circular cuts.

Striking Tools

Mallet - It is wooden-headed hammer of round or rectangular cross section. The striking face is made flat to the work. A mallet is used to give light blows to the Sheet metal in bending and finishing.

Sheet and plate metal parts for consumer and industrial products such as

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Applications of sheet metal

1. Roofing

2. Ducting

3. Vehicles body buildings like 3 wheelers, 4 wheelers, ships, aircrafts etc.

4. Furniture: House hold articles and Railway equipment

Sheet and Plate Metal Products

1. Automobiles and trucks 2. Airplanes 3. Railway cars and locomotives 4. Farm and construction equipment 5. Small and large appliances 6. Office furniture 7. Computers and office equipment

Advantages of Sheet Metal Parts

1. High strength

2. Good dimensional accuracy

3. Good surface finish

4. Relatively low cost

5. For large quantities, economical mass production operations are available