Materials, tools and processes Extension material for Level 1 Design and Visual Communication Study Guide ISBN 978-1-877459-02-3, Page 153 Tools Tools are used to work materials to improve their appearance, change their function or change their properties. Although each trade has traditionally had its own tools designed the material they are used with: Marking out, measuring and testing tools e.g. rulers, tapes, gauges, callipers, squares, knives, centre punch, sliding bevel. Driving tools e.g. screwdrivers, hammers, spanners, pliers, drills. Shaping of materials can be achieved by removing parts (wasting), deforming and changing the nature by casting or moulding, and by adding parts. Ways of working materials Wasting Machines used are circular saws, band saws, thicknessers, planers, routers, drills, milling machines, lathes, and disc, belt and orbital sanders. Deformation Wood Wood can be bent over formers or moulds. Sometimes the wood is steam-heated beforehand to make it pliable. Formers used to produce a salad server
2 Materials, tools and processes Thermoplastics Thermoplastics are plastics which soften when heated (so that they may be bent into different shapes) and become stiff and solid again when cooled. This process can be repeated again and again. Thermoplastics may be heated in an oven to 160 170 C and then pressed over a mould. Strip heaters are used to heat a line on acrylic so that the acrylic can be bent along the line. Strip heater Acrylic book holder being formed over wood former after strip heating is called blow moulding. Blow moulding equipment and article In vacuum forming Vacuum forming Vacuum forming box with heater and plastic in place
Materials, tools and processes 3 resin (together they form Fibreglass), can be shaped over or inside moulds. Injection moulding Fibreglass laid up over mould Thermoplastic granules are heated and forced through a die in a process known as extrusion (this is how plastic tubing is made). into a mould, which, after setting, is opened Plastic sheet and upholstery materials are produced by heated rollers squeezing softened plastic into a continuous sheet that can then be laminated onto a backing sheet. Metals Metals are deformed by forging, cold forming, spinning, beating and pressing. To forge mild and tool steel, it is heated to 1 200 C in a forge, picked up with tongs and hammered on an anvil. A variety of areas, twists and holes. Forging Small sections of mild steel can be forced into pegs in a plate. This is called cold forming. Cold forming jig
4 Materials, tools and processes Sheet steel is bent using folding bars that are held securely in a vice, and then pressure is applied. Bending Disc of aluminium about to be spun into a bowl Aluminium and stainless steel in thin sections may be spun. A thin disc of the material is mounted on a lathe and the tool presses it against a former as it rotates. This procedure is often used to produce kitchenware. Car bodies are pressed out of thin metal sandwiched between a male and female mould. Pressing metal Copper and brass can be beaten into hollow shapes after annealing (the process of making metals softer and easier to work). The metal is heated, kept at that temperature for a period of time (this is called soaking) and then cooled.
Materials, tools and processes 5 To make shallow dishes, concentric rings are marked out on the metal and it is hit repeatedly with a bossing mallet on a sandbag. Beating copper on a sandbag Sheet metal forms are made by cutting out a surface development, which is folded and soldered. Moulds and casts Molten metal or thermosetting plastic resins may be cast into moulds to harden. A pattern is used to make a hollow in sand, the pattern is removed and the molten material is poured into the hollowed sand. Casting Lost wax casting the cuttlebone, a top is made with holes for metal to enter and air to escape and then molten pewter or silver are introduced. Fabrication methods Materials are fabricated by fastening them together using a range of fasteners, glues and The common fasteners screws, nails, staples, nuts and bolts are described later.
6 Materials, tools and processes Wooden articles are constructed in four ways. planks, e.g. cupboards. Carcase construction Stool frame construction, e.g. table, chair. Stool frame construction Flat frame construction, e.g. window frames. Large timber structures are often held together with nail plates made of steel. Some of these are nailed on and others have protrusions, which are hydraulically pressed into the timber. The effect of using nail plates is to spread the load. Flat frame construction Slab construction, e.g. furniture. Sheets of Slab construction
Materials, tools and processes 7 Joints Butt joints are quick and simple but are not very strong. They can be strengthened by corrugated fasteners, wooden blocks or metal angle brackets. Butt joint Mitre joints no end grain is visible. They are not very strong, so they are sometimes strengthened by veneer keys. Mitre joint with veneer key Halving joints can be used for corners, for strengthened by dowels or screws. Halving joint Dowels are small rods that are inserted in Dowels
8 Materials, tools and processes Mortise and tenon joints are the strongest tenon. Mortise and tenon Bridle joints are strong and are often used in outdoor constructions such as carports and pergolas. Bridle joint Box pin joints give a large gluing area but are not as strong Box pin joints Dovetail pulled apart in one direction and are often used for drawer construction. Dovetail halving joint
Materials, tools and processes 9 carcase constructions like bookcases. Housing joint There are many variations on the above more attractive. to be able to be taken apart for moving and reassembling later. These are called. Fasteners Common fasteners are screws, nails, staples, and nuts and bolts. Wood screws have a variety of heads and slots. Countersunk screws sit with the surface, Coach screws are heavy duty, with square heads designed to be turned by a spanner. Countersunk, round-head and coach screws There are three common types of slots straight, Phillips and Pozidriv hence different screwdrivers are needed. Screw slots straight, Phillips and Pozidriv
10 Materials, tools and processes Nails are named for the shapes of their heads and the functions they perform. Nails for general use are brads and have small heads, which can be punched below the surface with a nail punch; Special nails that have springheads are used for securing corrugated iron and preventing leaks. Staples are used to secure wire. Corrugated fasteners are hammered or pressed in across joints. Staple Corrugated fastener There are specialised fasteners for securing wood or metal to concrete, called masonry anchors Masonry anchor Nail plates made of metal with holes for the nails are commonly used for roof trusses. Nail plate Nail plate Metal plate on joint nailed in place
Materials, tools and processes 11 Nut and bolt drilled through both pieces of metal, the metals are aligned and the rivet is placed in the Rivet and rivet in place Sheet metal lap joint Sheet metal grooved joint Tensol cement. Structure Many of the qualities mentioned depend on the structure groups of structures: Frame structures, e.g. bridges and roof frames. Shell structures, e.g. containers, tubes, pipes, spheres and polygons. Frame structure Shell structures
12 Materials, tools and processes Natural structures abound Leaf Snail shell Spider's web Forces act on structures. Tension is a pulling force, compression is a squashing force. Bending compresses one side of a beam while stretching the other side. The top surface of the beam is in tension and the bottom surface is in compression. Beam in tension and compression Torsion is a twisting force and shear is a cutting force. Torsion Shear
Materials, tools and processes 13 each other. A system in equilibrium To resist forces, designers support structures in different ways, e.g. a beam on edge is RSJ and a hollow square section are all light but strong. Various beam sections piece of paper, but fold it lengthwise. Compare the load each will support.
14 Materials, tools and processes Columns and cantilevers cantilevers as braced to resist bending. under tension ladder legs; and reinforcing rod can be run along the bottom edge of a beam. To resist compression, triangulation is used. Corrugated cardboard packaging material is made even stronger with a sheet of card on either side of the corrugations to prevent them from distorting under pressure.
Materials, tools and processes 15 Ribbing is frequently used to strengthen products. Ribbed plastic containers The edges of metal shelves are frequently bent into a stronger section for rigidity, as are the steps on metal stepladders. Bookcase shelf Doors are strengthened using a structure similar to a honeycomb, which is light yet when sandwiched between two sheets is very strong. Door structure Fibreglass yachts use the principle of foam them light but strong. Foam sandwich
16 Materials, tools and processes Cupboards and shelves are made rigid by either giving them a solid back or by bracing them. Shelves triangulated by bracing Be aware of all the principles outlined above in your designs.