Metal Properties and Industrial Processing Techniques

General Properties of Metals

• Electrical and thermal conductivity: Excellent conductors of heat and electricity.
• Resistance: Resistant to stress and efforts.
• Mechanical properties: High toughness, ductility, and malleability.
• Physical state: Solid at room temperature (except for mercury).
• Economic factors: Generally economical and heavy.
• Magnetism: Some exhibit magnetic properties.
• Melting point: High fusion temperatures.

Classification of Metals

Most metals are not used in their pure form but as alloys. They are classified into ferrous and non-ferrous metals.

Ferrous Metals and Alloys

• Soft Iron: Considered pure iron; it is silver in color but oxidizes easily and can crack internally.
• Steel: Ductile and malleable; it oxidizes easily but can be forged and welded well. Hardness and tenacity increase with carbon content.
• Cast Iron: Less ductile and malleable than steel but harder. It melts at lower temperatures and has poor weldability.

Non-Ferrous Metals

• Copper: Reddish color, excellent thermal and electrical conductor, corrosion-resistant, easily welded, and very ductile/malleable.
• Tin: Bluish-white and brilliant; a soft metal.
• Zinc: White color, highly resistant to corrosion and oxidation.
• Aluminum: Brilliant white, light, non-toxic, corrosion-resistant, and relatively soft.
• Magnesium: The lightest metal, expensive, and reacts violently with oxygen in a liquid state.
• Titanium: Very expensive, tough, corrosion-resistant, high mechanical resistance, and biocompatible.

Common Metal Alloys

• Brass (Copper + Zinc): Yellow, very malleable and ductile; has twice the traction resistance of pure metals.
• Bronze (Copper + Tin): Yellow, more resistant to traction than brass, corrosion-resistant, and highly fluid when molten.
• Aluminum + Copper + Magnesium: More resistant to stress than pure aluminum.
• Magnesium + Aluminum: Improves the mechanical qualities of magnesium.
• Titanium + Aluminum: Makes the use of aluminum cheaper in specific applications.

Tools for Metalworking

• Measure and Mark: Metallic ruler, steel scriber (tip to trace), and bow compass.
• Hold and Bend: Soft hammer, bench vise, and pliers.
• Cut: Metal scissors, metal saw, pliers, and specialized saws.
• Drill: Drill bits and chisels.
• Deburring and Polishing: Steel wool, metallic scourers, and files.

Manufacturing and Shaping Processes

• Deep Drawing (Embooticio): Sheet metal is placed over a matrix and deformed by the action of a punch under high pressure.
• Punching: Consists of cutting sheet metal with precision using a sharp-edged punch moved by a press.
• Spot Welding: Joining metal plates by creating a cord of welded points along the joint area.
• Drilling (Trepan): Using vertical drills to create holes in metal profiles.
• Sectioning (Trossejament): Involves cutting metal profiles using a running disk.
• Milling and Turning: Removing material from a solid piece using specialized tooling to carve the desired shape.
• Computer-Aided Manufacturing: Integration of computers into the manufacturing process.

Metal Extraction and Environmental Impact

Obtaining Metals

• Smelting: Using high-temperature furnaces to produce steel and other cast metals.
• Electrolysis: Separating metal using electrical power; used for copper, magnesium, titanium, and zinc.

Environmental Impact

The lifecycle of metals involves mining, the metallurgical industry, and waste management, which includes recycling, collection, and reuse.