3.1 Processes,techniques and specialist tools

Question 1

What influences the properties of metals such as hardness or ductility?

Answer 1

The grain structure of metals

Metals are made up of millions of tiny metal grains.

Question 2

What is the process of altering metal properties through controlled heating and cooling called?

Answer 2

Heat treatment

Heat treatment affects properties like hardness and ductility.

Question 3

What is the effect of hardening medium and high carbon steels?

Answer 3

Increases hardness and brittleness

Hardening involves heating, holding at a temperature, and quenching.

Question 4

What process reduces excess hardness and brittleness in hardened metals?

Answer 4

Tempering

Tempering increases toughness and ductility.

Question 5

At what temperature is metal heated during the tempering process?

Answer 5

Below the critical point

The exact temperature determines the amount of hardness removed.

Question 6

What does case hardening do to steels with less than 0.4 percent carbon content?

Answer 6

Hardens the surface while retaining inner core properties

It improves surface hardness and resistance to surface indentation.

Question 7

What is the first step in the case hardening process?

Answer 7

Carburising

Carburising changes the chemical composition of the surface to absorb more carbon.

Question 8

What is the role of the ceramic box in the carburising process?

Answer 8

Holds carbon for diffusion into low carbon steel

The box is heated to about 930-950°C.

Question 9

What happens to the depth of the carbon layer during carburising?

Answer 9

It increases with longer exposure time

The carbon atoms diffuse into the material’s structure.

Question 10

What temperature is the product heated to after carburising?

Answer 10

About 760°C

This is followed by quenching to seal the hard surface case.

Question 11

What is the purpose of quenching in the case hardening process?

Answer 11

To fast cool the metal and seal the hard surface case

Quenching does not affect the inner core properties.

Question 12

What is annealing?

Answer 12

The heating and slow cooling of work-hardened metal to make it easier to work, less brittle and more ductile.

Annealing is a crucial process in metallurgy to improve the workability of metals.

Question 13

What is the purpose of normalising in metallurgy?

Answer 13

To give low carbon steels a uniform, fine-grained structure, making the metal more ductile with increased toughness.

Normalising is often carried out after the metal has been hot worked into a shape.

Question 14

What are the steps involved in the normalising process?

Answer 14

1. Heating to about the same temperature as for hardening.
2. Quick quenching.
3. Left to cool.

This process enhances the toughness of the metal.

Question 15

Define an alloy.

Answer 15

A metal made of two or more metals or combining two or more elements, one of which must be a metal.

Alloys typically exhibit enhanced properties compared to the original metals.

Question 16

What is the process for producing alloys?

Answer 16

The metals are melted together in specific quantities and poured into bars or ingots.

Alloys can be produced in a furnace or in a casting process.

Question 17

What is the four-colour printing process used in flexography and offset lithography?

Answer 17

Cyan, magenta, yellow, and key (black) (CMYK).

These colours are printed in various quantities to achieve the desired print colour.

Question 18

What is offset lithography?

Answer 18

A versatile printing process capable of producing one colour to multiple colours using different roller machines.

It can handle complex printing tasks including varnishing and duplex printing.

Question 19

What types of products is offset lithography used for?

Answer 19

Books, documents, magazines, posters, and packaging.

It is suitable for medium and long print runs.

Question 20

List the advantages of offset lithography.

Answer 20

• Consistently high-image quality.
• Higher volume print runs of 1000 or more.
• Long life of printing plates.

These advantages make offset lithography popular for large-scale printing.

Question 21

What are the disadvantages of offset lithography?

Answer 21

Expensive setup and running cost for small quantities.

This can make it less viable for small print jobs.

Question 22

What type of inks does Flexography use?

Answer 22

Fast drying water-based inks

Flexography is known for its quick drying capabilities, making it suitable for various applications.

Question 23

How is ink transferred in the Flexography process?

Answer 23

Ink is transferred to the roller then to the material via pressure from the printing roller

This method allows for efficient and effective printing on different materials.

Question 24

What is a key characteristic of the Screen Printing process?

Answer 24

The screen has open areas for the ink to pass through

Each color requires a different screen, which is a defining feature of this technique.

Question 25

What type of printing process is Gravure?

Answer 25

Rotary printing process ## Footnote Gravure involves engraving or etching images onto a rolling cylinder for printing.

Question 26

Name three uses of Gravure printing.

Answer 26

* Newspapers * Comics * Catalogues ## Footnote Gravure is widely used for high-volume printing applications.

Question 27

What is a common use of Screen Printing?

Answer 27

Small print runs of items such as posters, display boards, and textile t-shirts ## Footnote This method is favored for its versatility in producing unique designs.

Question 28

What are two advantages of Flexography?

Answer 28

* High print speed * Suited for long runs ## Footnote These advantages make Flexography a popular choice for large-scale printing projects.

Question 29

What is a disadvantage of Flexography?

Answer 29

The cost of the printing plates is relatively high ## Footnote However, the plates can last for millions of print runs.

Question 30

What is a key advantage of Screen Printing?

Answer 30

Minimal setup costs due to the use of basic screens and printing inks ## Footnote This makes it accessible for small businesses and custom projects.

Question 31

What is a disadvantage of Screen Printing?

Answer 31

A slow process with a reasonably high cost per product ## Footnote This can limit its use for larger production runs.

Question 32

List two advantages of Gravure printing.

Answer 32

* Excellent print quality * High printing speed ## Footnote Gravure is often used for high-volume production due to these benefits.

Question 33

What is a disadvantage of Gravure printing?

Answer 33

Expensive setup costs for making the cylinders ## Footnote This can be a barrier for smaller projects or businesses.

Question 34

Fill in the blank: Gravure is used for high volume printing such as _______.

Answer 34

[packaging, gift wrapping, wallpaper] ## Footnote These applications benefit from the efficiency of the Gravure process.

Question 35

True or False: Screen Printing can be used for CMYK printing.

Answer 35

False ## Footnote While it can print in multiple colors, it is not as efficient for CMYK as other processes.

Question 36

What is a disadvantage of Fine text lettering in Screen Printing?

Answer 36

Not as sharp as other processes ## Footnote This can affect the quality of designs requiring fine detail.

Question 37

What are the five types of metal casting?

Answer 37

Sand Investment Gravity die Pressure die Plaster if paris

Question 38

What are the advantages and disadvantages of sand casting metal?

Answer 38

X labour intensive X not high quality finish / good for one off production / good for small batch production

Question 39

What is the process of investment casting

Answer 39

Wax patterns are used which melt on contact with the molten metal to give high quality, intricate shapes

Question 40

what metals does gravity die metal casting use?

Answer 40

Metals with lower melting points like aluminium or aluminium alloys

Question 41

What batch size is a pressure die useful for?

Answer 41

Large