A Comprehensive Guide to Metalworking Techniques and Machinery

Metalworking has been shaping the way we live for millennia. Entire historical periods, including the Iron and Bronze Ages, have been named by the predominant metals and techniques used in shaping them into items as diverse as tools, weapons and jewellery. Primeval techniques like hammering gave way to forging and steam power in transforming the dormant Middle Ages into the Industrial Revolution and pushing innovation and new technologies. 
This period also marked the transition from intensive manual labour to machine-based manufacturing and the evolution of modern fabrication techniques such as CNC machining and plasma cutting. Many of us don’t realise just how important metalworking is and the scale of multiple processes that have shaped society, past and present. 

Common Metalworking Techniques

There are many metalworking processes, but they can be grouped into four categories: cutting, joining, casting, and forming. 

Metal Cutting Processes 

These divide billet or sheet metal by removing small amounts one cut at a time to get the material into the desired shape. Cutting metals can be done with metalworking machinery that uses force, friction, heat or electricity. Common techniques include: 

Milling  

High-speed rotary cutting spindles and tool attachments remove material from the workpiece by slowly advancing cutting tools. The purpose is stock material removal, reducing thickness, shaping pieces to desired specifications, achieving specialty cuts (slots, holes, grooves, drilled holes) and improving surface finishes. 
Common machines are end, face and thread mills and CNC milling machines, seen in complex aerospace and aviation parts, producing tooling dies, moulds and prototypes in general and specialised manufacturing, gears and levers in other production equipment and automotive components, including engine blocks, transmission cases and suspension parts. 

Turning 

Turning is a machining process that rotates a workpiece in one or multiple axes, while a cutting tool removes in a linear motion to remove material and produce round or cylindrical objects. The operation is performed on a lathe or turning machine, producing items with a high surface finish and parts and components with high tolerances. Different turning techniques (grooving, facing, knurling, reaming) produce everyday items ranging from bolts, screws, nuts and other fasteners to complex parts like turbine shafts, rotors and generators. 

Grinding 

Handheld tools and stationary equipment use grinding wheels, discs, or sanding belts with varying abrasiveness in cutting, grinding, and sanding tasks. All remove minimal amounts of material, with the primary goal of eliminating irregularities or impurities such as rust or weld slag. Using precision grinding wheels helps improve control and consistency, especially when working on detailed finishing tasks. Die and angle grinders are the main handheld tools used with metals, while larger and more powerful stationary belt sanders and linishers are seen in bigger operations.

Drilling 

Belt and gear-driven pedestal drills, radial arm, turret, and mil drills are used for drilling holes in varying thicknesses and in different depths. The machines also offer versatility, with reaming (high-precision holes with clean surface finishes), boring (enlarging holes), and countersinking to accommodate fasteners also possible. The equipment is one of the basic pieces of metalworking machinery, seen in smaller fabrication shops to larger production facilities dealing with high turnout. 

Sawing 

Band and cold saws can cut through ferrous and non-ferrous metal sheets in varying thicknesses. And in straight or angled cuts. The process is efficient, fast and versatile with a variety of common shapes used in metal rods, tubes and extrusions. Clean and accurate cuts are achieved at high rates and eliminate common issues such burrs, sparking and discolouration, without generating a lot of heat or friction. 
Other cutting processes are threading, or inserting internal or external threads in parts like fasteners and plumbing; filing for clean surface finishes, and planer machines in getting flat surfaces and creating slots. Advanced cutting processes include laser cutting, which uses narrow beams of concentrated heat to get extremely precise cuts, and waterjet cutting, where high water pressure cuts metals of almost any thickness. The two processes are fast, and efficient and produce exceptionally clean cuts in specialist fields. 

Joining Processes 

Welding, soldering and brazing are the three most common joining processes. All are based around heat, either created by gasses or electrical current and with or without the use of filler materials such as electrodes. Welding has evolved to include dozens of forms besides the more common MIG, TIG and stick welding techniques and fuses two or more metal pieces in areas like construction, manufacturing and general repairs.
Soldering uses lower temperatures and filler materials placed between the metals, It is a common joining technique in electronics, plumbing and the manufacture of jewellery. Brazing further lowers temperatures, and melts only the filler material. The process is common in plumbing, joining metals of uneven thickness, and specialist industries like HVAC and solar systems. 

Metal Forming 

Forming encompasses a large set of metalworking processes to deform and shape metals into the desired object or shape. This is done by applying force. Forming can be categorised into bulk forming, severe deformation, and sheet forming, or forming metals with a large surface area but smaller relative volume. 
Common bulk forming methods include rolling or feeding metal slabs or plates through two or more rollers to produce thinner metal sheets; forging – or compressing metals between two dies containing the end shape; extrusion – compressing or pushing the workpiece into the die so the metal assumes the form of the die; and wire or rod drawing – when metals are pushed through smaller holes to create wires or rods. 
Sheet metal forming is the process carried out on thinner metal sheets, strips or coils using punches and dies. Methods here include bending (press brakes, pipe benders), deep drawing -pushing a rounded punch into the sheet when creating uniform bends; and shearing or cutting the sheet to the desired sizes (guillotines)

Casting 

Casting is one of the oldest types of metal fabrication and involves pouring molten metal into a cavity or mould in the intended shape. The process is low-cost, requires minimal tooling (therefore fast) and offers the flexibility for complex shapes and parts. What’s more, cast items have high tensile strength and decent surface finishes. 
Items produced this way include engine blocks, alloy wheels and carburettors (among dozens of others) in the automotive industry; hospital beds, stethoscopes and pacemakers in medicine; pulleys, brackets and hydraulic system parts in the aerospace industry and vats, valves and filters in industrial machinery. More popular methods are sand, die and shell casting. 

Most Common Metalworking Machines

• Lathes – one of the most versatile metalworking machines, lathes are used in cutting, drilling, boring, turning, threading, and facing when fitted with the right tooling. 
• Mills – another all-rounder used in face and edge milling, as well as cutting, drilling and forming metals to the desired shapes. 
• Drilling machines – a common feature in almost every fabrication shop, drill presses, bench drills and radial drilling machines can drill holes in a range of metals, and to desired depths with a selection of bits and tooling. 
• Saws – band and circular saws shape and cut metal pieces such as pipes, sheets and rods to the desired lengths. 
• Planers – planers have stationary tooling and mobile planes to cut and shape workpieces. They’re also good at surface finishing, cutting slots and grooves, and cutting at an angle. 
• Guillotines – these are shearing pieces used in cutting, smoothing and shaping metal sheets. 

Newer additions are metalworking machines with computer numerical control (CNC) with increased automation, higher precision, higher production rates and scalability and the ability to produce complex parts at speed. These are now becoming common even in smaller workshops, alongside machines that were once reserved for larger operations, such as plasma, laser and waterjet cutters.