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How can machining remove material to create a finished part?

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electron hole: movement — materials science Movement of an electron hole in a crystal lattice.

In materials science, machining is a removal process used to achieve a desired shape by eliminating portions of a workpiece. This is accomplished through two primary categories of methods:1

Mechanical Removal

Most traditional machining involves forcing a cutting tool against a workpiece. Because the tool must be harder than the material being shaped, it removes excess material in the form of chips. This process requires a cutting device, a mechanism to hold and position the workpiece, and typically a lubricant or cutting oil to manage friction and heat. Common equipment includes lathes, milling machines, drilling machines, and grinders.123

Nonmechanical Removal

For materials that are difficult to machine or require extreme precision, nonmechanical processes are used:21
* Chemical milling: Uses chemical solutions to etch away material.1
* Electrochemical machining: Employs electrical current to dissolve material in a controlled manner, essentially reversing the plating process.1
* Electrical discharge machining: Uses high-energy sparks or electrical discharges to erode or cut the material.1
* Laser machining: Utilizes an intense beam of light to cut through metallic or refractory materials.1