Special Die Forgings

While the ordinary forged piece is seldom suited for use in accurate machine construction without previous machining, several firms are now producing special die forged machine parts of an accuracy in dimensions and perfection of finish that leaves little to be desired.

Heat Treatment

Under this head comes the modern method of giving to many machine parts such as spindles, shafts, gears, cones, clutches, and many others, a special heating and cooling treatment. The production performances of our modern machines are in many cases made possible only because the constructor has learned that certain steel parts when heated and cooled in a predetermined scientific manner are given an added strength to resist wear or breakage.

Ball Bearings

The use in machines of specialized ball bearings has gained rapidly in recent years. While in the case of machine tools their use has been more largely confined to such machines as drillers, their certain use is everywhere self-evident.

Bearing Alloys

Where accuracy of bearing and closeness of fitting is especially desirable, the older type of plain bearing is believed by many machine construction engineers to be the better. To ensure the proper wearing qualities under the varying conditions of service, it has become desirable that the several bearing alloys be carefully studied and their characteristics tabulated.

Bearing Lubrication

Correct proportions of bearing surface to the load, a suitable bearing alloy, and assured bearing lubrication are sought. In studying bearing lubrication, all these must be considered.

Jigs and Fixtures

Where strict interchangeability of parts is essential, special work-holding and tool-locating devices are indispensable if a low manufacturing cost is to be attained. These are known as jigs and fixtures.

Time Study

The nearer to a minimum cost a machine can be constructed while maintaining a proper commercial standard, the greater are the chances that the business will be successful. It is, therefore, among other things, extremely important that the lowest possible labor cost shall be ascertained. In modern efficiency work, an exhaustive time study is made of each operation performed in the shop until definite time figures are obtained and recorded in the manager's office.

Motion Study

This term is used to designate that particular line of investigation which has for its objective the elimination of all unnecessary movements in performing a given piece of work. Investigation has shown that an untrained workman when performing even the simplest of operations may, and usually does, make many entirely useless movements to get his results.

Overheads

Under this name are classed all those expenses of manufacture which cannot be as directly charged to production as can labor cost and the cost of materials. They include such items as heat, power, light, insurance, depreciation, taxes, office help, executives, beside others, and are known as the shop burden.

Selling Costs

The cost of selling the manufactured machines may or may not be charged to their cost under the head of "overheads". In any case it must be at least approximated if not exactly known and, of course, charged along with the previous items to the production costs.

Production Machines

The brief review of modern machine methods given in the preceding pages indicate the trend of the developments being made by the progressive construction engineers. The modern machine constructor makes use of the work of scientists whenever it touches his line of production, and in fact is ever reaching out and searching the world for new production ideas. In the following section will be briefly described and illustrated a few of the more modern special or specialized machine tools used in machine manufacturing.