Finishes in Metal & Wood & Production Systems PDF

Finishes in Metal & Wood & Production systems  In order to protect most woods and metals from the environment and to improve their durability it is necessary to apply a finish. Finishes are coats of material which act as a barrier to the elements and will greatly extend the longev...

Finishes in Metal & Wood & Production systems  In order to protect most woods and metals from the environment and to improve their durability it is necessary to apply a finish. Finishes are coats of material which act as a barrier to the elements and will greatly extend the longevity of a product. An added advantage is that it often improves the look of a material. Finishes are often applied in successive coats and have varying drying times between coats. Finishes can be applied manually by brush or by automated methods as required. Finishes for Description Wood Paint Paint comes in any colour you could require and is available in a variety of textures. It can be applied by brush or spay. A base coat or primer layer is usually applied followed by one or more top coats. The base coat or primer layer may be a specialist paint which differs in colour and texture to the top coats. The purpose of this layer is to seal the timber and improve the adhesion of the top coats. ‫ ورنيش‬Tough clear finish which is available in a variety of textures Varnish and allows you to see the natural grain of the timer. It is applied in successive coats by brush or spray.  Transparent coloured varnish which allows you to see the natural grain of the timer. Stain It is available in a wide variety of colours and textures but ‫ صبغة‬is usually used to make pine look like a more expensive timber like oak or mahogany. It is applied in successive coats by brush or spray. ‫طارد‬ Moisture repelling finish for exterior timber. It is available in ‫الحشرات‬ green, brown and dark brown and is recognised easily by its Creosote distinctive smell. It is applied in successive coats by brush or spray. Steam Moisture repelling anti fungal chemicals that penetrate into Treating the surface of the wood and are applied by placing the timber in an atmosphere of steam. Natural Natural oils that are applied to interior timbers to help Oils protect from moisture. ‫ قشرة‬A thin layer of natural timber or coloured and patterned Veneer plastic sheet that is used to cover a less attractive piece of wood like chipboard or MDF.  Finishes Description for Metal Paint comes in any colour you could require and is available in a variety of textures. Paint It can be applied by brush or spay. A base coat or primer layer is usually applied followed by one or more top coats. The base coat or primer layer may be a specialist paint which differs in colour and texture to the top coats. The purpose of this layer is to improve the adhesion of the top coats. Large products like car bodies can also be sprayed by robotic arms or dipped in paint to ensure even coverage. ‫ورنيش‬ Tough clear finish which is available in a variety of textures Lacquer and allows you to see the natural colour of the metal. It is applied in successive coats by brush or spray and generally used for precious or semi precious metals to stop them from tarnishing. ‫عدم اللمعان‬  A thick coat of plastic that is applied by heating the metal Dip Coating part and then dipping it into plastic. The plastic is ‘fluidised’ by blowing air though it in a ‘fluidiser.’ This allows the metal to be dipped into the plastic as if it were a liquid. Mild steel is dipped in a solution containing zinc. An electric Galvanising current is applied which causes the zinc to stick evenly to the surface on the mild steel and protect it from moisture. It doesn’t look particularly good and is often painted over. Modern cars are often galvanised to improve their expected life. A protective film that is created on Aluminium by placing it in an Anodizing aluminium solution an passing an electric current through it. This forces the surface to oxidise which makes it tougher and more resistant to further oxidisation. Dies can be added to colour the anodized layer.  A Lateral Approach to Finishes Manufacturers are increasingly replacing metallic parts of traditional products with plastics or composite materials because they require no finish and are easier to form. Car bumpers, wing mirrors and bicycle frames are now commonly made from plastic or composite materials as they do not rust like mild steel and require no expensive finish to be applied. This also removes maintenance costs of repainting when they are chipped. Production Systems  Different production systems are employed by companies depending on the volume of production and complexity of the product that they are manufacturing. The manufacturing processes and type of labour that is employed is determined by the volume of a product that has to be produced and the materials which it is made from. System Description Labour Products This will involve Very highly skilled, Ships, the production of experienced and bridges, One Off Production a single product specialised designers, oil rigs, which will be engineers and tradesmen large unique and cost a who are constantly buildings, lot of money due developing professionally artwork, to the high cost of will not come cheaply. But some design and use of the work undertaken will jewellery time consuming be of a high quality and and traditional or problems encountered will furniture. complex be overcome easily due to manufacturing the level of education and methods. experience of the labour involved.  Putting exact figures of what volume Batch production Furniture constitutes batch production is difficult. relies heavily on , musical It is better to think of batch as being a skilled labour that instrume limited number of a particular product can perform a nts, which will be produced to meet a variety of jewellery particular order. Companies involved in specialised tasks , boats, Batch Production batch production will typically produce a and adapt quickly to aircraft, variety of similar products to order new jobs in order to houses. which can be tailored or personalised to produce new meet the clients specification. products, meet Batch production relies heavily on the demand for a use of programmable automated particular part or machinery, jigs and templates to speed cover for absent up production and eliminate time workmates. consuming repetition during Constant training is manufacture. The same jigs and causes expensive templates are often used for multiple ‘down time’ for products. manufacturers.  Complex products with many Semi or low skilled workers Vehicles, Line Production separate parts are often assembled are trained to perform one or household on a production line where workers two tasks on the line and will electrical often work shifts around the goods, add one part or sub assembly to the clock so that production bicycles, product at a time as it moves along doesn’t have to stop. computers, on a conveyor. Some parts along the Production lines are usually clothing, line can also be performed by set up in countries where footwear. automated or robotic machinery. labour is very cheap. Mass production involves the manufacture Cheap low skilled labour is Electronic of tens of thousands to millions of a used to keep machines filled goods, toys, Mass production product using expensive equipment. It with material and provide plastic relies on an ‘economy of scale’ where the janitorial work in the factory wares, initial high cost of machinery and tooling is round the clock. mobile offset by the sheer volume of products A small group of technicians phones, which will be sold. Despite the high set up will look after equipment and kitchens costs the volume of production means that service it as necessary. accessories. the price per part is very cheap. Mass production also relies on designing products that will use cheap and quick assembly techniques to keep costs low. CAD Computer Aided Design. Products are Highly educated and Used during designed in 2D and 3D on computers skilled labour which the design where parts can be checked for requires constant process. assembly and changes can be made training in order to quickly and easily if needed. stay up to date. It is possible to communicate designs over large distances by email. The cost of hardware, software and constant upgrading are high. CAM Computer Aided Manufacture. Cheap low skilled Furniture, Computer controlled machinery that labour will work mechanical can quickly and accurately produce shifts around the parts, parts which have been designed on clock to put pre cut prosthetics, CAD. material into technical Computer controlled machinery does machinery and components for not eat, does not sleep and will not clean out cuttings. machinery. stop for a break or to go home to sleep. It operates 24/7 and is 100% accurate every single time. CIM Computer Integrated Manufacture. A computer keeps track of the volume of materials and separate parts waiting assembly so that there is little wastage as no extra materials are bought in and extra parts will not be produced other than those needed to fulfil an order. Any breakdowns in machinery or lack of particular components will also be flagged by the computer so that they can be addressed quickly. Computer Numeric Controlled Low skilled labour work Component CNC machinery is reprogrammable and can shifts around the clock parts for perform many different tasks which will to keep the machinery furniture and always be 100% accurate. running. mechanical CNC machinery works 24/7 and is very High skilled individuals devices. Ideal fast. are responsible for for batch Every part produced will be identical. programming the production. It is also versatile as one machine can machinery to produce be programmed to produce lots of parts that are accurate different parts. and correct.  Glossary of terms - Mechanised or computerised. Automated - Device which allows the same Jig process to be repeated easily and quickly without repeating time consuming work such as measuring. - Pre determined shape which can be Template drawn round to avoid time consuming marking out. - The time spend while employees are Down Time undertaking training. This is expensive because training costs money, employees are being paid and no work is being produced.  Assembly Methods in Plastic When manufacturing components for products made of plastic careful consideration is always given during the design process to limiting the number of parts wherever possible. The less individual parts there are to assemble the faster and cheaper the manufacture of the whole product will be. Once the number of parts has been limited to what is absolutely necessary the easiest or most appropriate assembly method will be employed. This choice will be determined by the functionality of the product (does it need to be disassembled to change the batteries or bulbs), the strength requirements of the product (is it likely to be dropped, does it need to support weight) or simply by cost. Assembly Description Advantages Disadvantages Method Small clips on the inside of Very fast Cannot be taken casings that fasten together assembly apart without Self when they are assembled. (cheaper). breaking the casing. fastening Often used to hold remote No additional Not very clips controls and mobile phones components strong/durable. together. needed like Can also be used to good effect screws or glue. with battery compartment covers. Screw Screw threads moulded into Can be Requires a high components so that they can be disassembled. degree of accuracy threads screwed together and Cheap as there in manufacture. unscrewed to allow access. are no additional Not possible with Used in bottles and torches. processes or some processes. components.  Self Screws are used to hold Can be Expensive Tapping the casings together. disassembled. process as it is Screws The screws pass Very strong. often done through existing holes in Several components manually and one casing and into a can be assembled by needs screws to carefully positioned placing them be purchased. ‘boss’ in another casing. between the casings Visible screw Used in more expensive that are being heads. products like mobile screwed together. phones and MP3 players. Adhesives Surfaces of plastic Very quick and Cannot be components glued cheap. disassembled for together. Can be automated. repairs. Often used for battery Can glue different Requires large casings and to fasten materials together. contact areas to screens onto mobile Quite strong. work effectively. phone casings.  Assembly Methods in Wood Assembly methods for products made from wood will vary greatly depending on whether they are ‘traditionally built’ or more modern ‘flat packed’ products which use knock-down fittings. The table below outlines the differences. Factor Traditionally Built Flat Packed ‫مودرن‬ ‫تقليدي‬ Made from natural timbers Generally made from cheaper Materials which are strong, durable and man made boards which are not look great. as strong. Different veneers are used to improve the looks and give different styles. Made by highly skilled craftsmen Mass produced by automated who use traditional tools, machinery. Manufacture machinery and techniques to Boards are cut to size and all produce ‘one off’ or ‘batches’ of slots and holes are machined unique products. accurately by CNC machinery. Extra holes are often added so that pieces can go more than one way round. Assembly Assembled at the factory or workshop by Assembled at home by the consumer skilled craftsmen using traditional joints which using knock-down fittings and basic tools are very strong and durable. They also look which are often provided. great or cannot be seen at all. Knock-down fittings are not as strong as traditional joints and not very durable. Expensive materials. Cheap materials. Expensive skilled labour for manufacture and Few labour costs – no assembly costs. assembly. Cheap automated manufacture of parts. Time consuming manufacture and assembly. Quick manufacturing time. Costs Transport costs paid by consumer – ‘factory Low transport costs as you can fit lots of to shop’ and ‘shop to home.’ You can’t fit flat boxes in a truck and consumers can many in a truck and you need to pay for take goods home in their car. delivery to get it home from the shop. Will last much longer – may never need replaced. Can be seen as a status symbol by some Seen as a cheaper alternative to consumers. traditional furniture. Market Generally bought by more mature consumers Generally bought by younger consumers for durability as opposed to cheapness. who don’t have as much expendable income.  Use of natural hardwoods is damaging Man made boards are often made to the environment. from recycled materials. Environment Much more durable – will last longer Contributes to ‘throw away society’ – than several flat packet products so people will often throw out flat environmental impact could be lower packed furniture because they want overall. a different style. It can be replaced Can be made from reclaimed timbers. cheaply and can’t be recycled. Very Durable. Cheap (materials, manufacture, Advantages Will look impressive. assembly and transport). Is seen as a status symbol. Will come in a variety of styles. Expensive (materials, manufacture, Not very durable. Disadvantages assembly and transport). High environmental impact as it will Use of hardwoods and increased need replaced quickly and cannot be for transport will have greater recycled. environmental impact.  Assembly Methods in Metal When choosing an assembly method for metal components the decision will often be determined by the nature of the product. Mechanical products need to be disassembled for maintenance (cars, bicycles, washing machines).Some products need to be waterproof or airtight (fire extinguishers, boats, gas pipes).The product may be made from different types of materials (school chairs have metal legs and plastic seats, school tables have metal legs and wooden tops)The cost of the assembly technique should also be taken into consideration. Some techniques can be automated which will make it quick, cheap and accurate. Other techniques need highly skilled labour and take time which will make it very expensive. Assembly Description Advantages Disadvantages Method Welding Used for sheet metals. Very quick. Not particularly strong. Electricity is passed Cheap. Leaves visible ‘spot’ marks. Spot through both sheets of Can be automated. Sheet metal only. metal in one small Good for mass area. production. Welder uses electrical Very strong. Leaves weld line which has to machinery to Waterproof. be removed. Arc Welding effectively melt Airtight. High skilled labour is separate pieces Can be made to expensive. together into one. look ‘seamless’. Takes time. Good for one off Uses gas and other production. expendable materials (cost money). Sheet metals process Strong. Takes time. where a metal pin is Cheap for small Requires skilled labour. Riveting passed through two number runs. Requires access from both holes and then the end Semi permanent – sides. is hammered/punched can be drilled out. Not totally waterproof or into shape to seal the airtight. plates shut. Visible rivet heads.  Sheet metal process. Access is only needed Not very strong. Nuts and Bolts Pop Riveting Pop rivet ‘gun’ is used to from one side. Visible rivet heads. fasten sheets together with Very quick and cheap. a ‘pop rivet’ Good for repairs - Semi permanent. Can be automated. Nuts and/or bolts are used to Can be disassembled. Time consuming. threads) manually assemble Strong. Requires a high degree (Screw mechanical parts which need of accuracy in to be disassembled for manufacture. repairs/maintenance. Requires skilled labour. Holes are drilled/punched in Can be disassembled. Not very strong. Tapping Screws sheets of metal and a screw Quick process. Visible screw heads. Self with a sharp thread holds Cheap process. them together. Can be automated. Surfaces of metal Very quick and cheap. Cannot be components glued together. Can be automated. disassembled for Adhesives Can glue different materials repairs. together. Requires large contact areas to work. Not very strong.