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Shaping techniques, Marking,cutting and finishing techniques:, Joining,…
Shaping techniques
Wire drawing
A wire is pulled through a hole that has the required dimensions. A rotating drum is used to pull it through the hole to increase its length while reducing its diameter.
Uses: Metal strings and wires.
Punching
This is a cold forging process: a sheet of metal is hit with a punch to make the required shape in a mould.
Uses: Hollow pieces, such as bearings, from flat pieces.
Rolling
The unprocessed metal is passed through a series of rollers that compress it, reduce its thickness and increase its length. It's usually done when the metal is hot.
Uses: Sheets, plates, bars ...
Extrusion
The heated metal is pushed through a hole by a piston, using compression.
Uses: Bars, tubes and other shapes.
Press forging
The heated metal is placed between two dies, one fixed and the other mobile. The dies are the shape of the object we want to make. They are pressed together so that the piece takes the shape of the die.
Uses: Car body parts, radiators ...
Casting
Molten metal is poured into a container with a hollow space inside, which is the shape of the object we want to make. The mould can be made from sand, steel or cast iron.
Uses: Engine blocks, fire hydrants, small parts and alloys with low melting points, ornaments, jewellery, sculptures and dental implants.
Forging
The metal piece is shaped by repeated and continuous compression forces using hammers, tongs and anvils.
Manual forging has been replaced by industrial or mechanical forging.
Uses: Railings, bed headboards, horseshoes, keys, tools, nails, screws, rivets, engine pieces ...
Bending
A metal sheet is subjected to force to make a curved shape with a specific curve radius.
Uses: Curved pieces or with angles.
These are techniques used to change the shape of the piece of metal by applying an external force. It can be done when the metal is hot or at room temperature.
Marking,cutting and finishing techniques:
The centre punch is used to mark lines and the scriber to mark points on sheets of metal.
Put the centre punch on the point you want to mark and hit the other end of the scriber hard once with a hammer.
Use the scriber to mark straight lines on the metal. You can also use dividers to draw lines, circles and arcs, and to transfer measurements.
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Cutting:
Cutting
Used to cut soft, flexible, thin sheets of metal. It can cut in straight, angled or curved lines.
guillonete
Used to cut thin sheets of metal.
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POWER TOOLS FOR CLEANING
Sander
The motor moves the sandpaper, which is made from abrasive material, backwards and forwards rapidly. Sanding is quick and even.
Grinder
This tool removes material to perfect surfaces.
It is very precise and can remove as little as a hundreth of a milimeter of material.
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Finishing
Grinding. A grinder is used to refine surfaces to precise, accurate dimensions and to remove any imperfections. We can use it on flat pieces or cylinders.
Lapping. A lapping machine has a vertical handle and abrasive discs. This is usually used for finishing openings and conical surfaces, and is very accurate.
Polishing. This technique produces a shine, using a polishing wheel with revolving, abrasive wheels or strips.
Buffing. This technique also produces a shine. A mechanical buffing wheel is used with a steel disc or roll, which can be abrasive.
Coating. This technique is used to protect the metal. The metal is coated in plastic or other metals, e.g. zinc, silver, gold, nickel or chrome. This technique is called galvanisation. Paints, varnishes and enamels can also be used.
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