Measuring and holding work to the thousandth of an inch was commonplace long ago when the micrometer was invented. With the improvement of machine shop methods as time passed and the invention of the vernier and the extremely precise gauge blocks used today, it was possible to measure and work to a ten-thousandth of an inch. Further improvements in precision blocks, the development of the comparator, and the invention of electrical and optical methods of measuring have made it reasonable to demand even finer precision. Another example is the mirror-like surface finishes required on some parts. A surface finish of five tenths (0.5) of a micro-inch is often called for. A micro-inch is one millionth of an inch (0.000001 inch).
It is this painstaking care and accuracy that have made possible the success of our mass production methods. Our automobiles are assembled from thousands of parts which must go together at once and fit without handwork or delay as they flow on the assembly lines. Each separate part must, therefore, be made by the thousands and all exactly alike. Every camshaft and every fender that goes into a particular model of engine or car must be the exact duplicate of every other camshaft or every other fender of its type.
To make this possible, each step of manufacturing must be closely controlled. This is done by the use of specially designed automatic machines, dies, jigs, fixtures, and gauges. In addition, to ensure that all shapes and measurements are in accord with specifications, such measuring instruments as gauges either mechanical or electrical-comparators, precision blocks, optical flats, surface plates, and sine bars are used.
If the product is to be held to these fine limits of accuracy, the tools and dies used for producing and measuring the pieces must be held to even finer limits. The degree to which this is accomplished determines the success of the final assembled product, whether it be an automobile, a machine tool, a pair of roller skates, a jet plane, a machine gun, or any other of the products that distinguish our machine age. Machinists such as tool and die makers produce these tools, and it is readily understandable why it takes many years of experience to produce the topnotch tool.
At this point it may be worthwhile to emphasize that it is not only superlative manipulative skills that distinguish these mechanics. They are also highly skilled in the related technology of the machine shop. The most intricate and complex drawing or blueprint keeps no secrets from them. They are well versed in shop mathematics such as trigonometry and have a thorough understanding of the basic sciences underlying shop practices. They are also skilled in the heat treatment of metals. All this and more are necessary abilities for a topnotch tool and die maker and are the reasons why, in the training of the aspiring machinist, the related technical subjects are all emphasized.
However, not all beginners are going to become tool and die makers. Some must be content with other stations in the trade. All-around machinists, just short of the top bracket, are still highly skilled and versatile mechanics who have spent at least five or six years acquiring their skills. They may be employed at turning out intricate and accurate metal parts or some parts of lesser accuracy. If they have the drive and ambition, they might get an opportunity to become toolmakers.
Because of the specialized training and talents of toolmakers, there usually is a shortage of them. To compensate for this shortage, many large shops employ machine tool specialists to make the separate parts going into a jig, fixture, die, or tool. These parts are then assembled into complete units by specialized bench hands or assemblers. Many large production shops devote entire floors to particular types of machines. One may have scores of lathes of all types run by lathe operators; another may have similar banks of milling machines, turret lathes, grinding machines, or planers and shapers, all operated by specialists. The machinists operating all these machines are usually adept at one particular type and are capable of keeping up with production schedules. They may be producing the parts going into a machine tool or an automatic machine.
These specialized machine tool operators need four to five years of experience to be fully productive. Their narrow scope of work may prevent them from acquiring the necessary experience to reach the top all-around skills unless they can go from job to job, each time operating a different machine or perfecting a different shop technique. However, there are many who are content to be good lathe hands or milling machine operators, especially since these jobs pay well.
The big mass production manufacturing plants, such as the automobile plants, also employ machine operators, but these people are in a different category entirely. Usually they operate machines that are automatic in their cycle of work and, once set up, only require the operator to feed them and take out the finished pieces. Such workers need not be skilled machinists and can usually be trained within a short period of time.
The people who set up and check these machines for the operators, however, are usually skilled, even though they may be narrowly specialized. They may be operators who have spent some years with the machines and have acquired a thorough knowledge of them.
In the case of the automatic screw machines, which turn out small cylindrical parts, they may be machinists who have specialized and learned how to make and set the necessary cams and adjust the cutting tools. Here too, this narrowing of experiences will work against this set-up machinist's reaching top skill status, unless he or she gets around from shop to shop and from machine to machine. Again, many are content with this step since it is an interesting job and often pays well.
We have mentioned that one of the fundamentals of mass production is the necessity for constantly checking shapes and sizes against specifications. This is done by inspectors who are well versed in the use of measuring instruments. Inspection may consist of running the parts through an automatic checking device or gauge in which case it is just a routine job and can be done by people with very little training. The inspector roams the shop and checks the products as they come from the machine. Since this requires training, some companies prefer machinists for this work. Again, it may mean using all the intricate measuring tools, such as verniers, comparators, precision blocks, sine bars, optical flats, and others. This type of inspection is usually done by a machinist who has had at least five years' experience as a mechanic or by a machinist apprentice who has decided to specialize as an inspector. In large plants, he or she may rise to chief inspector, a very responsible job. In recent years, this job of checking products has become a scientific operation known as quality control with a statistical approach; it offers attractive opportunities to mechanics with mathematical aptitude.
It may be helpful at this point to recapitulate.
- As a beginning machinist, you have before you numerous avenues to a good livelihood. If you have had a firm basic training and wish to become an all-around machinist and then a toolmaker, you must expect to put in about ten years of varied experience. If you have had the benefit of a four-year apprenticeship, you can arrive at top brackets within another four or five years.
- You should, however, try to avoid pitfalls of narrow specialization in any one field. There is a great deal of auxiliary information to be acquired, such as blueprint reading, drawing, mathematics, and science, much of which can be gotten in evening and correspondence school as well as on the job. As a toolmaker, you may make gauges, jigs, and fixtures, or you can make dies and tools for such specialties as jewelry and watch cases. With this background, any topnotch job in the shop is within your grasp. If you have the necessary leadership traits, you can become a supervisor and eventually reach higher managerial posts such as master mechanic, superintendent, and work manager.
- Jobs like these can lead to executive levels. But to get started in management, the machinist must have a varied background of some years in most phases of machine shop operations as well as leadership qualities.
- However, not everyone can become a toolmaker. If you wish, you may become a highly skilled machine tool operator such as a lathe hand within four to five years. Here, too, you can rise to supervisory status if you possess the necessary traits and training background. Or you can turn to inspection, which now offers good opportunities to a mechanic with about five years of varied experience. If you like the production shops, with four to five years of experience you can become a set-up person on screw machines, turret lathes, milling machines, and so on. This position may also lead to managerial posts.
- Another opportunity for diversification and advancement for the machinist has emerged in the development of the computerized numerical control technique as applied to the operation of machine tools. This has been mentioned in previous pages. The skilled machinist can take advantage of this.
- A small but growing number of machinists have made the change from wearing a blue collar on the shop floor to a white collar in the upstairs office.
- People with programming experience but no machining experience find it difficult to formulate programs for making parts the simplest and most efficient way. A former machinist said that his firsthand knowledge of machining was very valuable. He could see the operation in his mind as he transferred the specifications of a blueprint onto a program sheet from which a tape would be keypunched.
Our world is being changed by scientists who are creating new forms of energy and power. Yet have you ever thought how futile all these ideas would be if they were not translated into actualities by the engineers and mechanics? Even after the technicians have taken the scientists' formulas and designed machinery and equipment, the machinery still must be made by mechanics who can take the plans and actually bring them to life. In this the machinist has played a leading role. Every atomic energy laboratory or plant has connected to it a large machine shop where toolmakers and machine specialists are kept busy turning out the equipment that makes the scientists' mathematics come to life.