Numerical Control (NC) Machine Operator
One of the most important recent developments in machining practices has been the successful automation of machine tools by a system known as numerical control. Using electronic circuitry and controls, it is now possible to program a series of machining operations, punch or otherwise prepare a tape, feed it through these controls, and cause a machine, such as a lathe, mill, or drill press, to automatically machine a part and duplicate this for as many pieces as required. All that needs to be done is to position this part and the machine will do the rest.
As a result, there has arisen a need for operators who can set up programs from blueprints, punch or otherwise prepare the tape, feed it into the controls, position the piece to be machined, set the machine in motion, make the necessary adjustments, oversee the operations, measure or otherwise check the results, and, in general, be responsible for the machine, the controls, and the production. Numerical control operators can be trained to specialize in just one system or machine, and need no particular skill as machinists, or they can add these specialized skills to their training background to make them more valuable to their employers.
Depending, therefore, on this aspect, the pay scales of numerical control machine operators may vary from $8.00 to $9.50 per hour. Some of the very best might make up to $15.00 per hour.
Computer Numerical Control (CNC) Machine Operator
The job of a CNC machine operator is very much like that of an NC machine operator. This person has to know everything the NC machine operator does as well as have some knowledge of computers. The CNC machine tool has no paper or magnetic tape. It is controlled by commands transmitted by the computer, which the CNC machine operator has entered through the computer keyboard. In some instances a large mainframe computer is used, but more commonly a smaller mini or microcomputer is used.
Electrical Discharge Machine (EDM) Operator
This person is responsible for the set up and operation of the electrical discharge machine. On a conventional EDM, the operator generally machines the electrodes used in the machining operation. Knowledge of basic physics, math, and metallurgy is essential. The most recent development in electric discharge machining is the use of a wire rather than an electrode for ultra precise cutting. A wire EDM operator must plot the path of the wire. Wages vary from $9.00 to $11.00 an hour. Some EDM operators make as much as $20.00 an hour.
Engine Lathe Hand Or Operator
You might have seen a wood turning lathe. The engine lathe works on the same principle the part to be finished is rotated or turned against it except that it is a much more powerful and complicated machine than the simple speed lathe. It needs the power because it is used for turning all kinds of metallic parts into circular shapes. It is more complicated because the tools used for working on the metal can be adjusted to many angles and can be fed automatically into or across the work. In addition, many jobs other than straight turning can be done. These may be the cutting of all kinds of screw threads, taper and angular turning, boring holes, and other internal work. Engine lathes vary from small ones mounted on benches to the immense machines used for turning sixteen inch gun barrels or ships' propeller shafts. All kinds of castings can be handled as well as the finest of precision jobs, such as boring the holes in jig plates and dies.
Engine lathe operators must be able to operate all standard types and sizes of lathes. They must first set up the machine, which means that they must be able to read and interpret the blueprint of the particular part they are to machine; mount the part in the lathe so that it is securely held, either on centers, on a faceplate, in a chuck, or in a collet; select and set the speed with which the lathe will turn the part to be machined; select the tool that will do the work; adjust and clamp it in the proper place and at the proper angle in the tool rest; and select and set the speed with which the tool will be fed longitudinally across the turning work, or into and across the work, or at an angle, whichever is needed. They then turn the work and shape it in accordance with the blueprint, measuring with the proper instruments, such as calipers, micrometers, and steel scales. They may also use indicators to true up holes and to perform similar tasks. In addition, they make special purpose set ups for grinding, boring, and other operations.
Lathe operators should be able to grind tool bits or ends to the proper shape for turning whatever metal they are to be used on, such as the various kinds of steel, aluminum, cast iron, and bronze. They should be able to work to very fine measurements, often being held to dimensions that must not vary from specifications by more than one thousandth of an inch or perhaps even finer.
Engine lathe hands may be graded as first class the top grade second class, and third class. Graduates of vocational and technical high schools and adult trade courses and machinist apprentices may become lathe operators, which usually is an interesting and varied occupation.
Lathe operators may become tool room or production specialists or may rise to become set up persons, supervisors, and the like. The lathe operator has a good opportunity to become an all around machinist, as this machine is the fundamental one in the shop.
Milling Machine Hand Or Operator
The milling machine differs from the lathe in that the work is held stationary on a table that moves past a rotating tool turned by a horizontal spindle, very much like a food slicer, where the food is clamped to a table that is moved past a rotating knife. Milling machines are of several types, such as the universal mill, in which the table can be adjusted to horizontal angles, and the vertical mill, in which the tool is rotated by a spindle held in a vertical instead of a horizontal plane. They are also made in various sizes from the bench type to the large production machines used in milling cylinder blocks in automobile plants.
The milling machine hand must be able to operate all the standard types and sizes of mills and should be able to set them up. This consists of reading and interpreting the blueprint of the part to be machined and figuring out the necessary sequence of milling operations to be performed; clamping the work to the mill table with clamps and T bolts, by the use of a vise, by holding the part in an indexing head, or by any other feasible method; selecting the cutters necessary to the work; setting and clamping the cutters by using an arbor, a collet, or holder of any type; adjusting the table in relation to the cutters to get the desired machining results; selecting and setting the proper speed at which the cutters should rotate; selecting and setting the proper feed or speed at which the table and work will move horizontally or vertically past the cutter or across it; using proper measuring devices, such as indicators, height gauges, verniers, and micrometers; making the first cuts; and checking results.
The operations may be face milling, slab milling, form milling, straddle milling, or dovetail cutting. In addition, the operator should be able to make the necessary calculations and set the mill for such work as simple indexing (as in spline cutting), compound and differential indexing (for such work as cutting helixes), and jig boring, using the vertical mill with the various stops, graduated dials, indicators, and other devices.
The work is interesting and varied and often provides opportunities for the exercise of a great deal of ingenuity. There may be some heavy lifting, although mechanical lifting devices are usually provided. Graduates of vocational and technical high schools and trainees from adult courses may go in for this specialty, which may lead either to production or tool room work.
Promotion may be to set up person or supervisor, or the specialist may go on to become an all around machinist if he or she has the opportunity to learn the other machines.
