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COST OF GOOD VERSUS POOR LUBRICATION.
There is one other point to be discussed, and that is, the cost of obtaining a reduction in friction and the value resulting to the buyer.
From the records of many years' work it is found that the money value of a ten per cent. reduction of the total horse power of a manufacturing plant will more than equal the cost of lubricants for one year. In individual cases it is easy to obtain a record of the total cost of coal for power (coal being the only item effected of which it is convenient and possible to keep a yearly or monthly record), the total horse power, and the cost for oil for one year. It is then possible to determine whether a reduction of a certain amount of power will be of value.
The actual cost for good lubricants need not exceed fifteen per cent. more per year than the cost of the cheapest and poorest. In many cases the cost per year has been reduced by from five to twenty per cent., while the price per gallon of the new oil has been sometimes three times greater.
If the engine were overloaded to such an extent that it need be replaced by a larger one, or a motor installed and current purchased, then any reduction that could be made which would keep the old engine in service should be credited with the entire cost of the proposed installation, interest on the investment and any amount saved by not shutting down the plant for the alteration.
PRACTICAL EFFECTS OF CHANGES IN LUBRICATION.
In countries where reductions in power through lubrication have been accepted at their full value, it is customary for owners to investigate the frictional losses in their plants before making any change in their driving power.
In Germany a manufacturer intended to install a thirty horse power electric motor in order to operate additional machinery which had been purchased, his steam engine having already reached its maximum power. A change was made in lubricants with the result that over fifty horse power was saved, which allowed
the new machinery to be operated by the original engine without the expense of purchasing an additional motor. At the same time the cost of lubrication with the new oils was fifteen per cent. below the yearly cost of the lower priced and poorer lubricants. (Test No. 10.) COMPARATIVE POWER RECORDS
TEXTILE MILL FORMER OILS
MASSACHUSETTS - U.S.A.
SPINNING 5546 1.H.P.
SPINNING 55446 1.H.P.
LOAD - SAVINGSAVING. SPINNING 481 2.9 6.4 CARD ROOM 14-8 207
22.8 WEAVING 1704 26
1707 SHAFTING 1907
In a department in a cotton mill in England it would have been necessary to put in either a larger engine or an electric motor as the load was being greatly increased. By the substitution of better oils the extra load has been put on the original engine, which runs slightly over normal speed, thus showing there is a reserve power which did not previously exist.
In England the steam engine in a joiner's shop was to have been removed on account of its being too small for the work and electrical motors installed to drive the plant. A change in lubricants, which brought about a reduction of over one fifth of the total load, so relieved the engine that it was amply large enough for the work and the extra expense for the motor was not necessary. (Test No. 20.)
In America in a cotton mill driven by water turbines, power was saved by a change of lubricants which allowed the speed of the mill to be increased by two per cent. with the same amount of water. At another water power mill it was found that by changing their lubricants, a 150 horse power engine used as an auxiliary, was not necessary as the wheels were quite sufficient with the reduced total load.
In America there have been numerous cases where the engines have not been large enough to drive the entire plant, especially in the morning when the load was heavy, yet by changing the lubricants and saving a percentage of the frictional loss the load was so reduced that the engines were quite large enough for the work.
In a mill in Finland, motors had been installed to drive certain machines, and upon 'starting, these motors were found to be too small for the work. Changes were made in the lubrication of the machines to be driven by the motors, which resulted in saving nearly one sixth of the total horse power, when the motors carried the load easily.
In Switzerland in a mill operated by water power, during the season of the year when the water is low and the
great value, the greatest care is taken to reduce the frictional item of the mill to the lowest point by the use of suitable lubricants. The same care however is not exercised during the period when an excessive quantity of water is to be had.
In Russia, even where the price of the necessary lubricants for securing frictional reductions is from 10 to 20 times more than the cost of local oils, the results from their use is found to justify the extra expense.
In India it has been found possible to operate machines and plants at higher speed, giving a greater production at less cost for power and with absolutely no stoppages from heated bearings, simply by taking advantage of the greater possibilities of friction-reducing lubricants.
The foregoing instances are the practical observations made by the shop and mill managers during the progress and at the
conclusion of tests for lubrication efficiency. The frictional loss reductions were being more carefully recorded by a comparative power test. A full description of the methods used for proving and determining the value of saving friction, with the summary of results obtained in the various countries and upon the various kinds of plants will, it is hoped, largely add to the knowledge on the subject.
DESCRIPTION OF VARIOUS KINDS OF PLANTS OPERATED UPON.
The plants upon which the tests in this paper were made are average plants in the following lines of business:
Cotton Spinning Mills.
Paper Mills. The plants are in America, England, Germany, Russia, Japan, and India.
The average mill for each class of textile in all countries consists of about the same proportion of machines of various types. While these are closely related as far as their mechanical operation is concerned, the frictional surfaces depend to a considerable extent upon features introduced by the different manufacturers. Some mills of course will have extra machines for the purpose of simplifying the various operations or for making some specialty. The mills for each class of work in each country present individual characteristics that give additional interest to the comparative results of power tests secured by using the same system of observation.
The plants for spinning the vegetable and animal fibres are quite different. The machinery in regard to weight, or what would impress the investigator as fineness, would put silk mills first, cotton second, worsted third and woolen fourth. Flax, jute and linen mills contain very much heavier machinery than the other spinning mills and the mills are so very different from cotton and woolen mills that they require quite different treatment in regard to lubrication.
In making comparative efficiency tests it would be reasonable to expect to be able to secure better data from a mill containing light machinery owing to the variables in the power being smaller. The results however seem to show that with care and expertness even the variables do not require to be greatly considered.
SELECTION OF PLANTS FOR TESTS. A large and well organized staff of salesmen is constantly endeavoring to secure plants where lubricating oils, which are specially manufactured to reduce friction, can be introduced. Whenever a mill director shows an interest in the subject and desires an opinion in regard to the frictional losses in his plants, a specially trained inspecting engineer makes a careful report upon all the frictional characteristics of the plant. The chief testing expert then compares this information with the records of plants already tested upon, tempering his opinion with his own knowledge of local influences and conditions, and an estimate of a certain percentage of reduction in the total power is given the management. The matter is then decided upon the basis of whether the reduction in power would be of sufficient value to the mill to make the proposed tests.
PLAN AND SCOPE OF TESTS.
The purpose of the tests is to prove that a reduction in power is secured by placing more suitable oils in use, and it is therefore necessary to secure an absolute average horse power of the plant under ordinary working conditions with the old oil and to have the records so complete that a duplicate power test can be made at some future time under absolutely the same conditions.