STOCK MATERIALS

INTRODUCTION

• The material out of which stampings are made is known as STOCK MATERIALS.

• Stampings can be made from metallic or non metallic materials.

• Metallic materials include ferrous and non ferrous metals.

• Ferrous metals :

• Hot rolled steels
• Cold rolled steels
• Stainless steels
• Spring steels etc.

• Non ferrous metal :

• Copper
• Brass
• Bronze
• Aluminum
• Tin
• Zinc etc.

Non metallic materials :

• Plastic
• Rubber
• Wood
• Cloth
• Paper etc.

STOCK STRIP.

• Stock strips are fed into the tool.

• They are advanced through the required advance distance at each press stroke for a series of repetitive operations.

 

FERROUS METALS:

UNIT STOCK

• Stock materials which are fed individually into the tool for processing are called unit stock.

PIECE PART

• A piece part is a product of a tool.

• It may be a complete product in itself one component of a product.

Hot rolled steel sheets:

• They are used for manufacturing where scaling and discolouration are not objectionable.

• The surfaces are painted after operation (if required). 

Pickled and oiled sheets:

• Immersing hot rolled sheets in acid solutions results in smooth clean scale free surface.

• Oiling protects the surface against rusting.

• Pickled and oiled sheets are used in the manufacture of parts for household appliances, automobile parts. toys etc.

• The sheets can take long lasting painting due to the absence of scales.

Medium carbon steels.

• These are hot rolled carbon steels having 0.4 to 0.5% carbon.

• They are hard, tough and resistant to abrasion.

COLD ROLLED SHEETS

• They have a smooth deoxidized finish.

• This provides excellent base for paint lacquer or enamel  coating.

• The thickness of the sheet is uniform.

• They are available in six grades of hardness.

HARD.

• Hard sheets and strips cannot bend in either direction of the grain without cracks or fracture.

• Such sheets are used for producing flat blanks that require resistance to bending and wear.

THREE QUARTER HARD.

• Three quarter hard strips can be bend to an angle 60" from flat only  across the grain.

HALF HARD.

• Half hard steel strips can be bent to 90° across the grain.

QUARTER HARD.

• This can be bent over flat (180°) across the grain and to a sharp right angle along the grain.

SOFT.

• Soft grades of steel can be bent over flat (180°) both across and along the grain direction.

DEAD SOFT.

• This grade of steel is used for severe forming and drawing operations.

DEEP DRAWING STEEL SHEETS.

• They are cold rolled low carbon steels.

• They are thoroughly annealed, deoxidized and oiled.

• Deep drawing steel sheets are used for difficult drawing, spinning and forming operations.

SILICON STEEL.

• Silicon steel is used for electrical laminations.

STAINLESS STEEL.

• They are used where corrosion resistance is a requirement.

NON FERROUS METALS.

• Copper and its alloys are widely used as a stock material.

• They are good conductors of heat, electricity and also are highly non - corrosive.

Copper alloys include:

• Beryllium copper
• Red brass
• Low brass
• Cartridge brass
• Yellow brass
• Muntz metal
• Phosphorus bronze.

OTHER NON FERROUS METALS USED ARE:

1. Aluminium and Aluminium alloys.
2. Magnesium and Magnesium alloys

RARE METALS.

• Rare metals like zirconium, tantalum, vanadium, tungsten and molybdenum and their alloys are used in press working.

PRECIOUS METALS.

• Precious alloy like that of gold, silver, platinum etc are used for manufacturing laboratory equipment and for electrical industry.

CLAD METALS.

• It consists of a core of one metal and a covering layer of dissimilar metal

PREPARATION OF STOCK.

• In steel mills the metal is formed into large sheets by rolling.

• The sheets are cut into strips in a shearing machine.

• Slitting machines are also used to cut the sheets.