The Technique of FURNITURE MAKING

TYPES OF METAL Ferrous metals

Composed mainly of iron with small additions of other metals or substances, e. g. wrought iron, cast iron, mild steel and carbon steel.

Wrought iron

Iron with traces of silicate.

Properties: malleable, can be shaped or bent cold or hot, readily sawn, chiselled, filed, drilled, brazed and soldered. Rusts in exposed conditions—protect with paint, preserve indoors by waxing.

Uses: decorative work such as screens and gates.

Cast iron

Iron with small amounts of carbon, silicon, sulphur etc.

Properties: brittle, but with a very hard skin; breaks if struck hard or dropped. Can be sawn, filed or drilled, but not easily brazed or welded, rusts slowly if exposed to air—protect with paint, preferably bitumen.

Uses: cylinder blocks, piston rings, vice/vise bodies, fire backs, manhole covers.

Mild steel

Iron with up to 0.3 per cent carbon.

Properties: easy metal to work—bends, files, saws and drills well; can be soldered, brazed or welded. Rusts easily—protect with paint or indoors with clear lacquer.

Uses: general-purpose metal used in bar, rods, sheet, rolled section and angle form; nuts, bolts, screws, tubing; furniture construction.

Stainless steel

Steel with chromium and nickel. Approximately 18 to 8 per cent.

Properties: resists corrosion, although this property can be destroyed by overheating.

Tough and difficult to work; can be soldered and brazed.

Uses: cutlery, furniture frames.

Tool and alloy steel

Composition varied by addition of different elements.

Properties: harder than mild steel—difficult to file and cut. Can be soldered and brazed and hardened, to produce a strong cutting edge. Rusts easily—protect with oil or grease; paint non-cutting parts.

Uses: saws, chisels, plane irons, scissors, knives, hammer heads, springs.

Non-ferrous metals

These contain little or no iron, e. g. aluminium, copper, lead, zinc, tin.

Aluminium

Pure metal.

Properties: lightweight and corrosion-resistant; can be bent, formed, filed or sawn easily, but soldered only with special materials. Polishes to a high finish and needs no protection indoors.

Uses: kitchen utensils, furniture and fittings.

Copper

Pure metal.

Properties: can be bent and shaped easily, but may work-harden and need annealing if worked repeatedly: saws, files, solders and brazes easily. Polishes well, although colour darkens on exposure to air—protect with clear lacquer.

Uses: hot water pipes, electrical parts and decorative work.

Lead Pure metal.

Properties: heavy, soft and malleable; cuts and works easily cold; can be soft soldered. High resistance to corrosion by weather.

Uses: plumbing, flashings, container linings, weighting objects.

Pure metal.

Properties: fairly hard and brittle—has a 'grain' and bends more easily in one direction than another; bends better if immersed in boiling water first; can be soft soldered.

Uses: substitute for lead in flashings and linings. Perforated zinc for air vents etc.; plating.

Tin

Pure metal.

Properties: very soft and malleable; with high resistance to corrosion.

Uses: a base for alloys and a coating for mild steel; rarely used in pure state.

Alloys

Combination of two or more metals and other substances. Divided into two sub-classes: ferrous alloys (e. g. special steels such as nickel steel, tungsten steel, chromium steel) and non ferrous alloys (e. g. brass, bronze, duralumin, pewter).

Bronze

Copper with tin.

Properties: very resistant to corrosion: can be filed, sawn, bent, chiselled, soldered, brazed or welded.

Uses: pump units, marine fittings, gears and bearings.

Duralumin

Aluminium with copper and other metals.

Properties: nearly as strong as mild steel, but one-third its weight. Bends, folds and works well cold, but may need annealing; cannot be soldered by normal methods; paint for exterior use.

Uses: where high strength and light weight is important—shelving systems, chair legs, pulleys, bolts, rivets, claddings.

Copper with zinc.

Properties: sheet brass is soft and ductile—it shapes and bends easily, but work hardens and needs annealing for repeated working. Brass strip can be filed, sawn, drilled, bent and soldered easily; treat decorative work in the same way as copper.

Uses: cabinet hardware, screws, decorative work.