Shop Management Part 9

d = time dumping and turning.

e = time returning 100 feet with empty barrow.

f = time dropping barrow and starting to shovel.

p = time loosening one cubic yard with the pick.

P = percentage of a day required to rest and necessary delays.

L = load of a barrow in cubic feet.

B = time per cubic yard picking, loading, and wheeling any given kind of earth to any given distance when the wheeler loads his own barrow.

[Transcriber's note -- formula and Tables omitted]

This general formula for barrow work can be simplified by choosing average values for the constants, and subst.i.tuting numerals for the letters now representing them. Subst.i.tuting the average values from the note sheet on Fig. 2 (page 151), our formula becomes: [Transcriber's note -- formula omitted]

In cla.s.ses of work where the percentage of rest varies with the different elements of an operation it is most convenient to correct all of the elementary times by the proper percentages before combining them.

Sometimes after having constructed a general formula, it may be solved by setting down the subst.i.tute numerical values in a vertical column for direct addition.

Table 3 (page 164) gives the times for throwing earth to different distances and different heights. It will be seen that for each special material the time for filling shovel remains the same regardless of the distance to which it is thrown. Each kind of material requires a different time for filling the shovel. The time throwing one shovelful, on the other hand, varies with the length of throw, but for any given distance it is the same for all of the earths. If the earth is of such a nature that it sticks to the shovel, this relation does not hold. For the elements of shoveling we have therefore:

s = time filling shovel and straightening up ready to throw.

t = time throwing one shovelful.

w = time walking one foot with loaded shovel.

w1 = time returning one foot with empty shovel.

L = load of a shovel in cubic feet.

P = percentage of a day required for rest and necessary delays.

T = time for shoveling one cubic yard.

Our formula, then, for handling any earth after it is loosened, is: [Transcriber's note -- omitted]

Where the material is simply thrown without walking, the formula becomes:

If weights are used instead of volumes: [Transcriber's note -- omitted]

The writer has found the printed form shown on the insert, Fig. 5 (opposite page 166), useful in studying unit times in a certain cla.s.s of the hand work done in a machine shop. This blank is fastened to a thin board held in the left hand and resting on the left arm of the observer.

A stop watch is inserted in a small compartment attached to the back of the board at a point a little above its center, the face of the watch being seen from the front of the board through a small flap cut partly loose from the observation blank. While the watch is operated by the fingers of the left hand, the right hand of the operator is at all times free to enter the time observations on the blank. A pencil sketch of the work to be observed is made in the blank s.p.a.ce on the upper left-hand portion of the sheet. In using this blank, of course, all attempt at secrecy is abandoned.

The mistake usually made by beginners is that of failing to note in sufficient detail the various conditions surrounding the job. It is not at first appreciated that the whole work of the time observer is useless if there is any doubt as to even one of these conditions. Such items, for instance, as the name of the man or men on the work, the number of helpers, and exact description of all of the implements used, even those which seem unimportant, such, for instance, as the diameter and length of bolts and the style of clamps used, the weight of the piece upon which work is being done, etc.

It is also desirable that, as soon as practicable after taking a few complete sets of time observations, the operator should be given the opportunity of working up one or two sets at least by summing up the unit times and allowing the proper per cent of rest, etc., and putting them into practical use, either by comparing his results with the actual time of a job which is known to be done in fast time, or by setting a time which a workman is to live up to.

The actual practical trial of the time student's work is most useful, both in teaching him the necessity of carefully noting the minutest details, and on the other hand convincing him of the practicability of the whole method, and in encouraging him in future work.

In making time observations, absolutely nothing should be left to the memory of the student. Every item, even those which appear self-evident, should be accurately recorded. The writer, and the a.s.sistant who immediately followed him, both made the mistake of not putting the results of much of their time study into use soon enough, so that many times observations which extended over a period of months were thrown away, in most instances because of failure to note some apparently unimportant detail.

It may be needless to state that when the results of time observations are first worked up, it will take far more time to pick out and add up the proper unit times, and allow the proper percentages of rest, etc., than it originally did for the workman to do the job. This fact need not disturb the operator, however. It will be evident that the slow time made at the start is due to his lack of experience, and he must take it for granted that later many short-cuts can be found, and that a man with an average memory will be able with practice to carry all of the important time units in his head.

No system of time study can be looked upon as a success unless it enables the time observer, after a reasonable amount of study, to predict with accuracy how long it should take a good man to do almost any job in the particular trade, or branch of a trade, to which the time student has been devoting himself. It is true that hardly any two jobs in a given trade are exactly the same and that if a time student were to follow the old method of studying and recording the whole time required to do the various jobs which came under his observation, without dividing them into their elements, he would make comparatively small progress in a lifetime, and at best would become a skilful guesser. It is, however, equally true that all of the work done in a given trade can be divided into a comparatively small number of elements or units, and that with proper implements arid methods it is comparatively easy for a skilled observer to determine the time required by a good man to do any one of these elementary units.

Having carefully recorded the time for each of these elements, it is a simple matter to divide each job into its elementary units, and by adding their times together, to arrive accurately at the total time for the job. The elements of the art which at first appear most difficult to investigate are the percentages which should be allowed, under different conditions, for rest and for accidental or unavoidable delays. These elements can, however, be studied with about the same accuracy as the others.

Perhaps the greatest difficulty rests upon the fact that no two men work at exactly the same speed. The writer has found it best to take his time observations on first-cla.s.s men only, when they can be found; and these men should be timed when working at their best. Having obtained the best time of a first-cla.s.s man, it is a simple matter to determine the percentage which an average man will fall short of this maximum.

It is a good plan to pay a first-cla.s.s man an extra price while his work is being timed. When work men once understand that the time study is being made to enable them to earn higher wages, the writer has found them quite ready to help instead of hindering him in his work. The division of a given job into its proper elementary units, before beginning the time study, calls for considerable skill and good judgment. If the job to be observed is one which will be repeated over and over again, or if it is one of a series of similar jobs which form an important part of the standard work of an establishment, or of the trade which is being studied, then it is best to divide the job into elements which are rudimentary. In some cases this subdivision should be carried to a point which seems at first glance almost absurd.

For example, in the case of the study of the art of shoveling earths, referred to in Table 3, page 164, it will be seen that handling a shovelful of dirt is subdivided into, s = "Time filling shovel and straightening up ready to throw," and t = "Time throwing one shovelful."

The first impression is that this minute subdivision of the work into elements, neither of which takes more than five or six seconds to perform, is little short of preposterous; yet if a rapid and thorough time study of the art of shoveling is to be made, this subdivision simplifies the work, and makes time study quicker and more thorough.

The reasons for this are twofold:

First. In the art of shoveling dirt, for instance, the study of fifty or sixty small elements, like those referred to above, will enable one to fix the exact time for many thousands of complete jobs of shoveling, const.i.tuting a very considerable proportion of the entire art.

Second. The study of single small elements is simpler, quicker, and more certain to be successful than that of a large number of elements combined. The greater the length of time involved in a single item of time study, the greater will be the likelihood of interruptions or accidents, which will render the results obtained by the observer questionable or even useless.

There is a considerable part of the work of most establishments that is not what may be called standard work, namely, that which is repeated many times. Such jobs as this can be divided for time study into groups, each of which contains several rudimentary elements. A division of this sort will be seen by referring to the data entered on face of note sheet, Fig. 2 (page 151).

In this case, instead of observing, first, the "time to fill a shovel,"

and then the time to "throw it into a wheelbarrow," etc., a number of these more rudimentary operations are grouped into the single operation of

a = "Time filling a wheelbarrow with any material."

This group of operations is thus studied as a whole.

Another ill.u.s.tration of the degree of subdivision which is desirable will be found by referring to the inserts, Fig. 5 (opposite page 166).

Where a general study is being made of the time required to do all kinds of hand work connected with and using machine tools, the items printed in detail should be timed singly.

When some special job, not to be repeated many times, is to be studied, then several elementary items can be grouped together and studied as a whole, in such groups for example as:

(a) Getting job ready to set.

(b) Setting work.

(c) Setting tool.

(d) Extra hand work.

(e) Removing work.