Nature of the Work
Machinists use lathes, milling machines, grinders, and other types of machine tools to produce precision metal parts. Although they may produce large quantities of one part, precision machinists often produce small batches of one-of-a-kind items. They use their knowledge of the working properties of metals and their skill with machine tools to plan and carry out the operations needed to make machined products that meet precise specifications. The parts that machinists make range from bolts to automobile pistons.
Machinists first review electronic or written blueprints or specifications for a job before they machine a part. Next, they calculate where to cut or bore into a piece of steel, aluminum, titanium, plastic, silicon, or any other material that they are shaping into a product or tool. They determine how fast to feed the work piece into the machine and how much material to remove. They then select tools and materials for the job, plan the sequence of cutting and finishing operations, and mark the work piece to show where they are to make cuts.
After this layout work is completed, machinists perform the necessary machining operations. They position the work piece on the drill press, lathe, milling machine, or other type of machine, set the controls, and make the cuts. During the machining process, they must constantly monitor the feed rate and speed of the machine. Machinists also ensure that the work piece is lubricated and cooled properly because the machining of metal products generates a significant amount of heat.
Some machinists, often called production machinists, may produce large quantities of one part, especially parts requiring the use of complex operations and great precision. Many modern machine tools are computer numerically controlled (CNC). CNC machines, following a computer program, control the cutting tool speed, change dull tools, and perform all necessary cuts to create a part. Frequently, machinists work with computer control programmers to determine how the automated equipment will cut a part. The machinist determines the cutting path, speed of the cut and the feed rate, and the programmer converts path, speed, and feed information into a set of instructions for the CNC machine tool. Many machinists must be able to use both manual and computer-controlled machinery in their job.
Because most machinists train in CNC programming, they may write basic programs themselves and often modify programs in response to problems encountered during test runs. Modifications, called offsets, not only fix problems, but they also improve efficiency by reducing manufacturing time and tool wear.