Engineering Leaving Certificate Textbook

PVC is versatile, inexpensive, easily worked, and tough.

Calendering involves feeding heated softened polymer through rollers that gradually flatten it into sheets.

Foaming agents added to polystyrene enhance its toughness and flexibility.

<p>Compression moulding is mainly used for moulding rubber products and is crucial in car tyre manufacturing.</p> Signup and view all the answers

<p>Thermoplastics may lack the necessary heat resistance required for high-speed applications.</p> Signup and view all the answers

<p>The presence of chromium in stainless steel forms a protective oxide layer that prevents corrosion.</p> Signup and view all the answers

<p>Tool steel is known for its hardness and ability to withstand high temperatures during machining.</p> Signup and view all the answers

<p>Extrusion moulding continuously shapes materials, while injection moulding involves injecting material into a closed mould.</p> Signup and view all the answers

<p>Atmospheric pressure forces the plastic against the mould in vacuum forming.</p> Signup and view all the answers

<p>The extrusion process mixes the polymer and forces it through a die, resulting in continuous lengths with a uniform cross-section.</p> Signup and view all the answers

<p>The cavity mould in injection moulding is crucial for producing finite and fixed shape products.</p> Signup and view all the answers

<p>Common products include pens and phone covers.</p> Signup and view all the answers

<p>The screw mixes the polymer pellets and forces them through the barrel.</p> Signup and view all the answers

<p>Talc and similar powders prevent the plastic from sticking to the mould.</p> Signup and view all the answers

<p>Extrusion moulding is most suitable for thermoplastics.</p> Signup and view all the answers

<p>Heaters in the barrel help melt the polymer pellets for injection.</p> Signup and view all the answers

<p>To push a fixed quantity of polymer into the closed mould.</p> Signup and view all the answers

<p>Rotational moulding involves placing granulated polymer in a split mould that is rotated, while injection moulding uses a hydraulic ram to inject polymer into a closed mould.</p> Signup and view all the answers

<p>Spherical hollow objects like balls, kayaks, and storage containers.</p> Signup and view all the answers

<p>Ejector pins help to remove the finished product from the mould after it has set.</p> Signup and view all the answers

<p>It allows the product to set while the mould remains closed.</p> Signup and view all the answers

<p>Because it requires minimal manual intervention and is primarily supervised by operators.</p> Signup and view all the answers

<p>Granulated polymers are used to produce the hollow objects.</p> Signup and view all the answers

<p>The design must allow for even spreading of the polymer around the inner mould wall.</p> Signup and view all the answers

<p>They are permanently joined, creating a strong bond.</p> Signup and view all the answers

<p>Industries that manufacture plastic products like furniture, toys, and electronics.</p> Signup and view all the answers