A machine tool is a device used in workshops and factories to shape solid objects either by the systematic removal of material from a larger block—a process called machining—or by drawing or pressing a sheet of flexible material into shape in a machine press. Traditional machine tools use implements to remove material by mechanical means, while some modern machines use electrical discharges, electrochemistry, lasers, or ultrasound to remove material without direct mechanical contact with the workpiece.
Lathe development
A lathe is a machine tool that produces helical, or cylindrically symmetrical, pieces, such as bolts, drive shafts, locomotive wheels, and pulleys. A lathe spins workpieces between two rotating grips aligned on a common axis; its cutting tool tracks along the workpiece from end to end, altering its distance from the central axis according to the intended profile of the finished piece.
The lathe is the most widely used and the oldest of all machine tools—a lathe was depicted in an Egyptian tomb painting of around 300 B.C.E. Early lathes were used to produce wooden objects such as spindles and chair legs. One method of driving these early lathes was to wrap a cord around the workpiece and pull first on one end of the cord and then on the other, producing a back-and-forth turning motion. While one person operated the spindle in this way, another used hand tools to shape the workpiece. In the 15th century, treadle-operated lathes replaced cord driven machines. Using a principle similar to that of the spinning wheel, such machines turned the workpiece continuously in one direction.
By the 18th century, soft metals were being worked in the lathe using hand tools. Around 1770, a French engineer, Jacques de Vaucanson, designed an iron-framed lathe with adjustable head- and tailstocks to support workpieces of various sizes and a brass carriage that ran on iron guides to support the cutting tools.
By the end of the 18th century, the need for precision-manufactured components for steam engines and textile machinery was stimulating rapid advances in lathe designs. Important contributors to these advances were a British engineer, Henry Maudslay, and a U.S. inventor David Wilkinson, both of whom in 1797 designed power lathes whose cutting tools moved along the workpiece at a rate proportional to its turning speed. This feature made it possible to carve perfectly helical screw threads into shafts.
In 1821, Thomas Blanchard, a U.S. engineer, invented a lathe whose cutting tool followed a template as it moved along the workpiece. This improvement enabled identical—and therefore interchangeable—components to be produced with relative ease. The ease of use of lathes increased further with the introduction of the turret lathe in the mid-19th century. Turret lathes have several cutting tools, each of a shape appropriate for a given cut. The tools are set around the edge of a circular mount and selected by rotating the tool mount to present the chosen tool to the workpiece. The mount is then locked in position.
With the development of the turret, the lathe had effectively arrived at its modern form. Subsequent developments increased the precision of cutting and the degree of automation.
