Metal processes

Press forming process

Forming method - used for automotive parts, appliance components

How it works:

1. Metal is rolled out and straightened

2. Metal is cut to required blank size

3. The blank metal is clamped over the die and held in the correct position using the back gauge

4. A hydraulically operated punch is then pushed into the sheet metal

5. Once the desired shape is formed the punch is retracted and the sheet component is ejected

Press forming advantages & disadvantages

Advantages

• Good for high-volume production

• Precise and consistent results

• Can be used with many types of metals

• Metal sheets can be easily shaped into 3D forms

Disadvantages

• Requires expensive moulds

• Not suitable for very complex shapes

• Limited to thin materials

Spinning

Forming method - used for bowls, cones, saucepans

How it works:

1. A metal disk is mounted on a spindle and rotated at high speed

2. A tool is applied to the spinning disk to shape it into a hollow form

3. The formed piece is then removed from the spindle

Spinning advantages & disadvantages

Advantages

• Can create symmetrical shapes easily

• Good surface finish

• Suitable for producing lightweight parts

Disadvantages

• Limited to round and symmetrical shapes

• Not suitable for very thick materials

• Can be slow for large batches

Cupping process

Forming method - used for drink cans, containers, automotive parts

How it works:

1. A flat sheet of metal is placed into a die

2. A punch presses down on the metal, forming it into a cup shape

3. The finished cup is removed from the die

Cupping advantages & disadvantages

Advantages

• Can form deep shapes from thin materials

• High precision and minimal waste

Disadvantages

• Requires specialised equipment

• Can be slow for large quantities

Deep drawing process

Forming method - used for automotive body parts, kitchen sinks, gas tanks & screwdrivers

How it works:

1. A metal sheet is placed in a die with a punch

2. The punch draws the sheet into the die, forming a deep, hollow part

3. The formed part is then removed and finished

Deep drawing advantages & disadvantages

Advantages

• Great for high-volume production of deep parts

• Produces parts with high dimensional accuracy

• Creates tough and hard products

Disadvantages

• Requires expensive dies and tooling

• Material thinning can occur

Wrought iron forging

Forming method - used for tooling, automotive components, decorative fencing

How it works:

1. An iron bar is heated to a high temperature and placed in a die

2. A hammer or press is used to shape the metal by applying force

3. The shaped metal is allowed to cool and is then finished

Wrought iron forging advantages & disadvantages

Advantages

• Produces strong, durable parts

• Suitable for high-performance applications

• Can create complex shapes

Disadvantages

• Requires high-energy input

• Limited to high-strength metals

Drop forging

Forming method - used for automotive parts, hand tools, railway components

How it works:

1. Metal is heated and placed in a die

2. A hammer is dropped onto the metal to shape it

3. The part is then cooled and removed

Drop forging advantages & disadvantages

Advantages

• Produces strong, tough parts

• Cost-effective for large quantities

Disadvantages

• Expensive dies

• Limited to simple shapes

Bending

Forming method - used for brackets, structural supports, metal furniture

How it works:

1. A metal sheet or bar is placed in a die or between rollers

2. A force is applied to bend the metal into the desired shape

3. The bent part is then removed and finished

Advantages

• Fast and cost-effective for many parts

• Can be used with a wide variety of materials

Disadvantages

• Limited to simpler shapes

• Can cause material fatigue

advantages & disadvantages

Rolling

Forming method - used for steel sheets, pipes, structural beams

How it works:

1. Metal is passed between two rotating rolls to reduce its thickness

2. The rolls can be adjusted to create the desired thickness

3. The metal is then finished and cut into sheets, plates, or coils

Advantages

• Can produce large quantities of uniform products

• Suitable for many metals

Disadvantages

• Limited to certain thicknesses

• Requires specialized equipment

advantages & disadvantages

Sand casting

Forming method - used for engine blocks, garden furniture, caterpillar tracks

How it works:

1. Make a mould in the sand using to half moulds (cope and drag) making sure the corners are rounded/tapered

2. Fix the cope and drag together with nuts and bolts

3. Pour molten metal into case

4. Let it cool and remove mould

5. Apply finishes

Advantages

• Inexpensive

• Complex shapes can be produced

• Large components can be produced

Disadvantages

• Sand moulds can only be used once

• Surface finish not always good

• Labour intensive

• Slow production rate

advantages & disadvantages

Die casting

Forming method - used for taps, model cars

How it works:

1. Create and lubricate the mould

2. Once mould has been created, molten metal is shot under high pressure into the die

3. When the die is full, the pressure is maintained until the metal has solidified

4. The mould is then removed and finishes are applied

Advantages

• High rate of production

• Good surface finish

• Economical

• Precise parts can be made

Disadvantages

• High set-up costs

• Long lead time

• Limited sizes

• Must be large scale demand for it to be economical

advantages & disadvantages

Investment casting

Forming method - used for turbine blades, gears, machine parts

How it works:

1. Cold wax mould made of desired shape

2. Wax mould attached to sprue before being dipped into liquid ceramic/stucco

3. Then heated to remove wax and set ceramic

4. Molten metal is then poured into the cermaic mould and allowed to set

5. Ceramic shell is then broken off revealing product

Advantages

• High quality surface finish

• High dimensional accuracy

• Very complex parts can be made

• Any metal can be cast

• No parting lines from mould

Disadvantages

• Only small castings can be made

• Expensive

• Labour intensive

• Time consuming to create wax mould - slow production rate

advantages & disadvantages

Low temperature casting (pewter)

Forming method - used for jewelry, small decorative items, figurines

How it works:

1. Prepare a mould using sand or a permanent material

2. Heat pewter alloy to a low temperature (typically around 230°C)

3. Pour the molten pewter into the mould

4. Allow the metal to cool and solidify

5. Remove the casting and apply finishing touches

Advantages

• Low melting point allows for easy handling

• Good for small, intricate designs

• Low cost and fast production

Disadvantages

• Limited to low strength applications

• Not suitable for large-scale production

• Pewter can be brittle

advantages & disadvantages

Key differences between MIG and TIG welding

• MIG welding uses a consumable electrode wire, while TIG welding uses a non-consumable tungsten electrode and manual filler addition.

• MIG welding is faster and easier for beginners, while TIG welding provides more control and precision but is slower.

• MIG welding is better suited for thicker materials and faster production, while TIG welding is ideal for thinner materials and more detailed work.

• TIG welding offers cleaner welds with no spatter, whereas MIG welding can produce more spatter.

Metal inert gas (MIG) welding

Joining method (permanent) - used for cars, bike frames, metal barriers

How it works:

1. Used to weld thin metals

2. MIG welding uses an electric arc to create heat

3. Carbon dioxide/argon is used to form a flux shield to protect the weld area from oxidation

4. Then an electrode wire (of the same material) is melted to fill the gap for the weld

Advantages

• Easier than oxy-acetylene welding

• Quicker than most welds

• Very strong joint

Disadvantages

• Poor aesthetics

• Can accidently melt through the metal if not careful

advantages & disadvantages

Tungsten inert gas (TIG) welding

Joining method (permanent) - used for aerospace, stainless steel welding, pipe welding, artistic metalwork

How it works:

1. Used to weld thin to medium thickness metals, often for high-precision work

2. TIG welding uses a non-consumable tungsten electrode to create heat for the weld

3. An inert gas (argon or helium) is used to protect the weld area from oxidation

4. The filler material (if needed) is manually fed into the weld pool

5. The welder controls the heat and filler material to ensure a clean and precise weld

Advantages

• Produces high-quality, clean, and precise welds

• No spatter as no filler rod is required (when welding thin metals)

• Can weld a wide range of materials (steel, aluminum, titanium)

• Great for intricate and detailed work

Disadvantages

• Slower than MIG welding

• Requires more skill and precision from the welder

• Higher equipment and operational costs

• Not as suitable for welding thick metals compared to MIG

advantages & disadvantages

Spot welding

Joining method (permanent) - used for automotive industries, electronics, household appliances, metal sheet fabrication

How it works:

1. Spot welding uses two copper electrodes to apply pressure and heat to the material

2. The materials to be welded are placed between the electrodes, and an electric current is passed through them

3. The electrical resistance at the interface causes localized heating, forming a weld at the contact point

4. Heat and pressure are maintained for a short period, allowing the metal to fuse at the spot

5. No filler material is used, and the weld is typically small and concentrated at the point of contact

Advantages

• Fast and efficient for high-volume production

• No need for filler material

• Suitable for thin sheet metals

• Produces strong welds in less time compared to other methods

Disadvantages

• Limited to welding thin materials

• Can’t be used on metals with significant thickness

• Welds are localized and can be weak if not properly controlled

• Not ideal for materials that require high aesthetic quality in the weld

advantages & disadvantages

Oxy-acetylene welding

Joining method (permanent) - used for general engineering

How it works:

1. Used to weld low carbon steel

2. The metal is prepared by creating a v shaped joint between to two metals

3. An oxygen and acetylene blow torch then heats the area

4. This creates a melt pool, this melt pool mixed with a steel filler rod creates the welded joint

Advantages

• Weld is as strong as parent metal

• Clean joint - no flux needed

• Portable equipment

• No electricity needed

Disadvantages

• Safety issues (gas equipment etc)

• Poor aesthetic joint

• Large heat effected zone

advantages & disadvantages

Hard soldering

Joining method (permanent) - used for jewellery, ornaments, silverware, model engines

How it works:

1. The two metals being joined is cleaned

2. Then the two materials are held together using a former

3. The metal is then heated up to the same temperature as the melting point of the  solder

4. The solder is then applied to the joint area

Advantages

• Stronger than soft soldering

• Better aesthetics

• Can solder larger objects

Disadvantages

• More skill

• Higher melting point

advantages & disadvantages

Soft soldering

Joining method (permanent) - used for electronics

How it works:

1. The two metals being joined is cleaned

2. Then the two materials are held together using a former

3. The metal is then heated up to the same temperature as the melting point of the solder

4. The solder is then applied to the joint area

Advantages

• Low melting point

• Quick process

• Little skill

Disadvantages

• Weak joint

• Only suitable for small objects

advantages & disadvantages

Brazing

Joining method (permanent) - used for general engineering and bike frames

How it works:

1. The two materials being joined are cleaned before welding

2. Then the two materials are held together using a former

3. Flux is applied to prevent the join area from oxidation

4. A welding torch then heat the join area and a brazing rod is used to fill the joint area

Advantages

• A good general purpose joint

• Cab be undertaken with little training

• Low bond temperature needed

• Can join dissimilar materials

Disadvantages

• Needs flux (if not weak joint)

• Metal must be cleaned before hand (time consuming)

• Not as strong as other welding techniques

advantages & disadvantages

Riveting

Joining method (permanent) - used for aerospace, structural steel, sheet metal work, automotive, construction

How it works:

1. Riveting involves using a rivet (a short metal pin) to join two or more materials together

2. The rivet is placed into a pre-drilled hole and the ends are deformed to hold the materials in place

3. A hammer or machine is used to flatten one end of the rivet (the “tail”) against the surface of the material, creating a strong joint

4. The process may be performed manually or with automatic riveting machines

5. Once the rivet is deformed, it holds the materials tightly together, forming a secure bond

Advantages

• Strong, durable joint

• Can be used on a variety of materials, including metals and plastics

• Simple, reliable method

• Effective for joining thick materials or materials that can’t be easily welded

Disadvantages

• Visually noticeable and may not be suitable for aesthetic purposes

• Can be labor-intensive for high-volume production

• Requires access to both sides of the workpiece for installation

• May not provide as high a strength-to-weight ratio as welding

advantages & disadvantages

Self tapping screws

Joining method (temporary) - used for furniture assembly, machinery, automotive repairs, electronics, construction

How it works:

• These screws have a pointed tip that allows them to cut into the material, creating their own thread for a secure hold without the need for a pre-drilled hole.

Machine screws

Joining method (temporary) - used for furniture assembly, machinery, automotive repairs, electronics, construction

How it works:

• Machine screws are typically used with nuts or threaded holes to fasten components together.

• They are versatile and available in different sizes, providing a strong, secure connection.

Nuts and bolts

Joining method (temporary) - used for furniture assembly, machinery, automotive repairs, electronics, construction

How it works:

• Consist of a bolt (a threaded fastener) and a nut (a threaded component) that are used together to clamp materials securely.

• This method allows for easy disassembly and reassembly, making it ideal for temporary or adjustable connections.

Horizontal milling

Wasting process - used for cuttings gears, produce slots, drilling

How it works:

1. Material is clamped into place

2. Cutter is selected and RPM is chosen

3. The material always remains stationary while the machines cutting tool rotates

4. As the cutting moves, it presses against the workpiece and shapes the material

Advantages

• Runs faster than vertical milling

• Very precise

• Can run at a higher capacity than vertical milling

• Durable machine - can do many runs

• No parting lines from mould

Disadvantages

• Not good at doing radial cuts

• Machinery takes up lots of space compared to handheld version

• Uses electrcity/needs to be plugged in

• More expensive machinery than vertical milling

advantages & disadvantages

Vertical milling

Wasting process - used for cutting gears, produce slots, drilling

How it works:

1. Material is clamped into place

2. Cutter is selected and RPM is chosen

3. The material always remains stationary while the machines cutting tool rotates

4. As the cutting moves, it presses against the workpiece and shapes the material

Advantages

• Visibility - can see machine work

• Can be CNC controlled and so automated

• Ease of use

• Very precise

Disadvantages

• Uses electricity/needs to be plugged in

• Expensive to buy machines

advantages & disadvantages

Turning

Wasting process - used for table legs, table lamp, engine parts, handles

How it works:

1. Begin by placing a circular, square or rectangular shaped piece of metal/wood into the lathes drive area

2. The metal/wood piece is typically secured using a pressure pad

3. Once in place, the lathe is activated to rotate and press the mould against the metal/wood piece

4. The rotational force of the lathe then deforms the metal/wood piece to achieve the same shape as the mould

5. When metal/wood spinning is performed by hand, a worker manually presses the mould against metal/wood piece

Advantages

• Complex designs/shapes can be made

• Energy efficient

• Good surface finish

• Can be computer controlled

Disadvantages

• Dangerous pieces can be ejected from machine potentially causing harm

• Some materials are very hard to turn

advantages & disadvantages

Flame cutting

Wasting process - used for cutting steel, pipes, and plates

How it works:

1. Oxygen and fuel gas (acetylene or propane) are used to heat and melt the material.

2. A stream of oxygen is directed at the molten material to blow it away, creating a cut.

3. This process is typically used for cutting thicker materials, especially steel.

Advantages

• Economical for thicker materials

• Good for cutting ferrous metals

• Simple and portable equipment

Disadvantages

• Not suitable for precision cutting

• Produces rough edges

• Requires post-cut cleanup

advantages & disadvantages

Plasma cutting

Wasting process - used for sheet metal, heavy machinery, automotive parts

How it works:

1. Plasma cutting uses a high-temperature plasma jet to cut through electrically conductive materials.

2. Compressed air or other gases are ionised by the electric arc, turning them into plasma which melts and blows away the material.

3. Commonly used for cutting metals like steel, aluminium, and brass.

Advantages

• Fast and efficient cutting process

• Can cut a variety of metals with thicknesses up to 100mm

• Provides a cleaner cut compared to flame cutting

Disadvantages

• Higher initial equipment costs

• Produces slag and requires post-cut clean up

• Not ideal for cutting reflective materials like copper and brass

advantages & disadvantages

Laser cutting

Wasting process - used for cutting thin sheet metal, precision components, aerospace parts

How it works:

1. A high-powered laser beam is directed at the material to melt, burn, or vaporise it.

2. The laser beam is highly focused and can cut with extreme precision.

3. Laser cutting is often used for thin materials and is ideal for intricate and detailed cuts.

Advantages

• Extremely precise cuts

• No tool wear, reducing maintenance costs

• Can cut complex shapes with high accuracy

Disadvantages

• High initial setup cost

• Not suitable for thick metals or materials with high reflectivity

• Can cause material warping from heat generation

advantages & disadvantages

Punching/stamping

Wasting process - used for shape sheet metal into shapes with holes, washers, cogs, tin can pull tabs

How it works:

1. Process is usually done via a CNC

2. The CNC program moves the platen carrying the sheet metal

3. Once the sheet metal is under the stamp the die is punched against the sheet metal

4. The waste material is then recycled and the stamped metal is collected

Advantages

• Economical

• Can be done many times very quickly

• Highly automated

Disadvantages

• Residual cracks appear along the edges

• Hardening along the edges

• Burrs can be created if clearance is excessive

advantages & disadvantages