2862398
Descrição
FlashCards por Niamh Walsh, atualizado more than 1 year ago
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Criado por Niamh Walsh
mais de 9 anos atrás
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| Questão | Responda |
| PROCESSES | Processes covered: - steam bending - laminating - drop iron forging -wrought iron forging - 'lay up' resin techniques - die casting - investment casting - sintering - routing - coating |
| Steam bending A process suitable for most woods, including laminates. The timber is moistened in a steam chest, to the point where the timber is more pliable. The wood is then held in shape around a former until dried, after which it will retain its shape. Uses include jewellery and ribs on boat hulls | |
| Laminating This is the process of layering materials to create a finished product. For example, plywood is formed by layering hardwood veneer at 90˚ to each other and bonding with resin, forming warp-resistant board. Laminate flooring and kitchen work surfaces are formed by layering chipboard/fibreboard with a hardwood veneer and a clear, hard-wearing resin on the top | |
| Drop Iron Forging Used where large numbers of similarly shaped objects are required. It is a refining process. Large forces (the upper half of the mould half drops) on the metal blank force it into the shape of the die. This usually happens with many dies to achieve the products final shape. | |
| 'Lay up' Resin techniques The term used for processes involved with Glass Reinforced Plastic manufacture. A mould is required. | 1. Coat mould with releasing agent 2. Apply gel coat, colour and harden it 3. After coat has cured, apply glass fibre matting 3 times. Ensure all air is driven out and mat is wet 4. Leave for 3hrs+ before removing work from mould - full hardness achieved after curing for 24hrs |
| Die casting The process used to cast metals with low melting points - alloys used are generally zinc or aluminium based. | Gravity die casting: molten metal is poured into mould through runners; gravity ensures metal reaches all of mould Pressure die casting: molten metal is poured into mould, then a hydraulic ram applies pressure - good for more complex shapes High pressure die casting |
| Industrial die casting Usually hot chamber high pressure die casting. More than one die is often used, so complex shapes can be achieved. Uses include door locks and the internal components of electrical sockets | Advantages of die casting - superior finish to that of sand casting - accuracy is good - material tends to be of better quality due to the rapid cooling - suitable for large scale production - low energy costs as alloy melting points are low |
| Investment casting An extremely old process and not commonly used. Suitable for metals with a high melting point. | 1. accurate wax pattern is produced 2. pattern coated in a high temperature ceramic material and left to dry 3. pattern fired in kiln. This causes the wax to melt, leaving just the clay mould 4. molten metal poured into the cavity in the clay 5. when the cast has cooled, the ceramic mould is broken (and destroyed), leaving the cast product |
| Sintering Used for materials which are difficult to process in any other way. | 1. Material is crushed into a powder 2. Powder compacted into a die 3. Compacted shape heated to promote bonding between particles of the material. Manufactures tool tips and hard magnetic products. |
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