The Preparation of Plantation Rubber Part 17

It has been remarked in the chapter dealing with crepe preparation that much depends upon the condition of the coagulum. There is no necessity, or desirability, for having a standard higher than 2 lbs. dry rubber per gallon, and it has been argued that it would be better to select a standard of 1-1/2 lbs. The tougher the coagulum, the more the power required, and the slower the rate of output of the leading machines.

In ordering machines for crepe-making, only large rolls should be considered--_e.g._, rolls having a diameter of 12 inches to 18 inches and from 15 inches to 18 inches face.

ROLLS RUNNING HOT OR "FREE."--If the rolls are found to become hot, work on that machine should be stopped, and an examination made, otherwise there is the possibility of the crepe becoming sticky and "tacky" when dry.

Although comparatively cold water may be flowing upon the rubber and the rolls, little alleviation may be noticed, inasmuch as the source of heat lies generally at the bearing ends of the rolls. This may be tested by placing the hand on the top of the "standard" of the machine. The development of the heat may be due to lack of lubrication, worn bearings, or sometimes faulty setting-up of the machines.

Allusion has been made to the necessity for avoiding the running "free" of rolls--_i.e._, in the absence of rubber. The grinding of the rolls, when working close together, produces a fine powder, which causes a more or less p.r.o.nounced deposit on pale crepe. When the rolls have been in action for some time and become slightly worn, this deposit may be confined only to the edges of the rubber.

SHEETING MACHINES.--The foregoing paragraphs have dealt entirely with machines for crepe preparation. Concerning machines for use in sheet-making, the ground has been mainly covered in Chapter IX.

Where both crepe and sheet are made, it is permissible and advantageous to use the heavy smooth rolls for the rolling of the sheets, and it is only necessary to instal one or two light machines for placing a pattern on the rubber.

Where a heavy battery does not exist, light machines with smooth rolls may be employed satisfactorily. Even engine-power is not necessary for the preparation of excellent sheets, but the output is limited where hand-power only is employed. Estates are known on which upwards of 1,000 lbs of sheet rubber are made daily with hand-power machinery in one station. Beyond this figure, it is deemed advisable to instal a small engine, say of 7-9 horse-power. This is ample to drive a battery of three smooth-roll machines and two markers, and yet have sufficient reserve to actuate a small pump for the water supply.

LUBRICATION OF MACHINES.--It must always appear to those inexperienced in engineering matters that existing methods for lubricating rubber machinery are distinctly crude, when one considers the delicacy of the material to be prepared. Many existing machines are still lubricated with oil, which has to be administered in generous quant.i.ties. Generally, such machines have been so designed that the excess of oil may find an easy pa.s.sage into the tray which receives the rubber. If not, it drops just outside the tray to the floor, and is washed away in great gouts. Even where grease-cap lubricators are fitted it is common to find that the excess can often be transferred from the bearings to the trays and so to the rubber. One would have expected from the attention which is being given to machinery for rubber estates that some improvement in lubrication methods would have been devised.

It is probable, however, that a great deal of the disabilities attaching to present methods of lubrication might be obviated if closer attention were given to the actual operation of the lubricators. Coolies should not be allowed to handle them, and the responsibility should be placed upon a foreman or the engine-driver.

TRAYS.--The most unsuitable and damage-causing part of the vast majority of machines, without doubt, is the tray. On nearly all machines the tray is wider than the effective portion of the rolls, so that any excess of lubricant may drop into it. On others, not only is the tray wider than the rolls, but its edge either is in contact with the shaft of a roll or just a small distance away. The edge of the tray is thus favourably situated for acting as a "wipe," and the lubricant is transferred to the inside of the tray. Considering that the effective portion of rolls is about two-thirds of their length, it must be unnecessary to have trays wider than the length of the rolls. For the preparation of fine crepe trays are quite superfluous, and their place can be taken by a narrow piece of board if required. If the bed of the machines has been covered with glazed tiles, even a piece of board is not necessary. Where trays have been removed from the fine-crepe rolls on a number of estates, a marked decrease in the number of spoiled pieces of rubber has resulted.

It must be recorded that the foregoing paragraph appeared in our 1913 publication. After a lapse of over seven years, the remarks remain as true as when originally written. One of us is continually meeting with cases in which the defects are plainly attributable to the cause indicated above, and the fault often lies with the management of estates. On most machines the trays are not fixtures, and could be removed if desired.

ARRANGEMENT OF MACHINES.--In considering the future arrangement of machines, the first care should be to see that machines and windows are to be found together.[16] Of all the factory operations, rolling of rubber should be given the maximum light. At the same time it would not be advisable always to choose a southern aspect, unless outside shades were supplied. The best position for setting up machines, therefore, is along a wall having a number of windows. This is extremely convenient also from the view of power transmission, and gives the maximum free floor s.p.a.ce to the factory. In setting up machines, foresight must be displayed, otherwise one may find, when future extensions are made, that the extra machines may obstruct an entry or exit.

[16] Windows imply the existence of walls. Such is the conventional design of factories. It may be pointed out that walls are not necessary. The roof may be supported on pillars between which expanded metal of large size may be placed. This fulfils all requirements and gives the maximum of light and air. Many new factories have been erected to such a design.

For the actual erection of machines, no labour should be accepted without European supervision. At present there are machines which are practically useless owing to faulty workmans.h.i.+p, and on many machines bearings run hot for no apparent or explicable reason. Whether the fault lies with the turning of the rolls or the setting of the machine cannot be decided; but at any rate too much care cannot be expended on the supervision of setting up machines.

There is no reason why everything in a factory should not be made as easy to clean as possible. For this desirable condition all machines should have the beds faced with tiles. A word of caution should be given against using marble slabs under the machines, as they would be eroded in time by the slight amount of acid washed out of the rubber. There would be no such objection against the use of white glazed tiles, if they are well set.

ACCESS TO BACK OF MACHINE.--In a few factories it has been noticed that the drainage of water from the machines runs to the front of them. This means that the coolies are put to unnecessary inconvenience and discomfort, and they often suffer from sore feet. All water should drain to the back of the machines. The necessity for seeing that these drains are kept clear might then induce those in charge to examine the back of the machines. It is often the case that, while the front of the rolls and tray are kept clean, little attempt is made to cleanse those parts which are not visible or accessible from the front. There should be no need to point out that any labour expended in such "front-window" work is rendered useless by the contamination from acc.u.mulations of old rubber and grease at the back of the machines. In the course of visiting factories one of us has many times seen great surprise exhibited by the manager or a.s.sistants on being shown the state of affairs at the back of the machines. There should have been no occasion for such surprise, for the back of the machines is quite as accessible to them as to the visitor.

In conclusion it might be said that the manager needing advice as to the best machines cannot go far wrong in purchasing any of the better-known makes, such as Shaw's, Bridge's, Robinson's, Bertram's, Walker's, Carter's, Iddon's, etc. This list does not include local manufacturers such as the "United Engineers." It must not be imagined that their machines are not recommended. As a matter of fact, their machines compare well with those made at Home. It would be well to judge in the final decision upon--

1. Cost.

2. The experience of those already using the machines.

3. Simplicity of parts.

4. Lubrication system.

5. Mode of adjusting rolls.

6. Fitting of trays.

ENGINES.--It is not intended here to discuss particular makes of engines, or even to attempt to lay down definite statements with regard to the type of engine. Without a full knowledge of local circ.u.mstances, it is not possible to recommend whether the engine shall be oil-driven, gas-driven, or steam-driven.

a.s.suming a copious supply of very cheap timber, there could be no objection to the employment of a steam-engine; but for most estates such a choice is out of the question.

Again, in deciding between oil and gas, local economic factors must be considered. Suction-gas plants are now made, in which a wonderful variety of refuse can be consumed in the production of gas, whereas ordinarily estates are restricted to the use of either charcoal or anthracite coal.

Both oil and gas driven engines are eminently suitable for the purpose of a rubber factory, and the results obtained on different estates with either are often discussed in favour of one or the other. The selection ultimately narrows itself down to one of cost of running, in which availability of supplies becomes an essential feature.

POWER.--No matter what type is selected, there should be made an ample allowance for margin of power. The general experience of estates has been that when the first portion of the estate comes into bearing, there is a desire to avoid great outlay, which should really have been secured in the original capital. The result has been that as later the estate expands, the original power unit is found to be inadequate, and a larger engine has to be purchased. In a short while the original engine is found to be unsuitable even as a "stand-by," inasmuch as it is incapable of doing more than a portion of the work required. This means eventually that another large engine is required. Had sufficient margin of power been allowed originally, only two engines would have been bought, as against the three indicated above. Without going into finer details, it is usual to allow a rate of 10 horse-power per heavy machine used for crepe preparation. In actual practice, when a battery is working under full load, the power demanded is about 6 horse-power per machine. Thus a 50 horse-power engine running six machines and a sc.r.a.p-washer is really running with only a small margin of power, and if large pieces of hard coagulum are placed in the washer or the macerator there may be a sudden stoppage. a.s.suming an average estate commences with only three machines for crepe-making, on an expanding programme, allowance of power should be made for six machines and a sc.r.a.p-washer, if the purchase of larger power units is to be avoided later.

CHAPTER XIV

_FACTORIES_

GENERAL CONSTRUCTION.--On the question of general construction there is little to be said, except that buildings are now being properly designed in more permanent form than were some of the earlier buildings. On the whole there is little fault to be found with factories in general, except in so far as the output has outgrown the accommodation.

Most factories are now erected in iron, but there are a few which are built of bricks. It should be premised that a factory in which rubber is to be prepared should be as light and airy as possible. In this respect quite a number of the older factories are lacking, and they seem to have been designed to exclude as much air and light as possible. Under these circ.u.mstances, the building is always dark, there is always an air of dampness, dirt may acc.u.mulate, and there is usually a bad smell. Rubber prepared under these conditions is always liable to be below the high standard which should be attained, and the general tone of the factory is depressing.

PLENTY OF LIGHT.--The old idea that light must be excluded is now known to be erroneous; so that in designing a factory, provision should be made for ample light and air. It should not be forgotten that in tropical climates, iron buildings may become uncomfortably hot, as most of our older factories are. Usually it will be found that the ventilation is imperfect. There is a lack of window s.p.a.ce, and the roof is imperfectly ventilated. The ridge of the roof should be opened up by means of a "jack-roof," so that the warm air rising naturally may escape at the highest point of the building. These are defects which should be remedied in old buildings.

As a rule no rubber remains in the factory at night-time, except in the form of coagulum, the loss of any of which would be noted with ease. The conventional idea of enclosing the factory with walls of galvanised sheeting, wood, or brick, is not strictly necessary. In modern buildings these walls are replaced by large-mesh expanded metal, thus making the machine-room perfectly light and plentifully ventilated. Under such conditions, dirt cannot acc.u.mulate unseen, and the general tone of the work is raised.

THE FLOOR.--The floor should be of thick concrete, and have a good surface layer of cement. Preparations are now advertised for which claims are made that their employment renders the surface of such floors waterproof and dustproof. If these claims can be substantiated when the use is applied to the floors of rubber factories, the employment of a preparation of this nature should result in a considerable saving of expense and trouble.

Preferably the floor should not be flat, but should slope slightly from the longitudinal middle of the building to the sides on either hand. If the floor is level it usually results in acc.u.mulation of water, the cement breaks in patches, and the factory always appears to be dirty.

POSITION OF MACHINES.--All machines should be arranged adjacent to and parallel with one of the long sides of the building, and should be raised about 6 inches above the floor, so that water may escape easily. Tanks for the reception of latex, sc.r.a.p rubber, etc., should be placed along the opposite wall to the machines, and the intermediate length of the building should be entirely free from fixtures. It was not uncommon in older factories to find the engine situated in the middle of the floor, so that what with the s.p.a.ce occupied by the engine, and the s.p.a.ce rendered unavailable by the belt-drive, the real accommodation of the factory was sadly diminished. In no modern factory should the engines be brought into the main room. They should always be accommodated in a special compartment, situated outside the wall, along the inside of which machines are placed.

In this way considerable floor s.p.a.ce is left available, and the machines may be worked by direct drive. Not only so; but if a suction-gas plant is worked, there can then be no excuse for particles of coal or charcoal dust being found in the factory.

POSITION OF ENGINES.--It scarcely need be pointed out that if the engines are placed outside the wall which is opposite the machines, a long belt-drive would be necessitated, and that the presence of the belt would prevent the use of end doors. It is presumed in these arguments that two engines are to be installed. One can hardly imagine a modern factory in full working being equipped with only one engine, which might possibly have an excess of power necessary to drive all the machines. In the case of breakdown, which sometimes happens in the best supervised factories, it would be small consolation to know that this excess of power was present theoretically.

HOW MANY STOREYS.--There can be no doubt that, taking all things into consideration, the best type of factory is that consisting only of one floor. The factory should be quite separate from all other buildings, and if attempts are made to conserve ground s.p.a.ce by putting a drying-room over the factory, much trouble will ensue, especially if pale crepes are to be made. In the first place, the factory is made very much darker, and hence more difficult to keep clean; secondly, the ventilation of the factory is seriously interfered with; and thirdly, it is manifestly prejudicing the drying of rubber to place it directly over a room which is always more or less awash with water. At night such a building would reek with a moisture-laden atmosphere, and little drying could be expected to take place in that interval. From actual experience it has been shown that rubber hung to dry in such a room, situated over a damp factory, is very liable to attacks of "spot" diseases, since the presence of perpetual moisture is favourable to the development of these diseases. If a double-storey building has to be worked, it will be readily seen that no first-grade rubber should be allowed to dry in it. The accommodation over the factory may be restricted to the purpose of receiving lower grade rubber which is not so liable to "spot" diseases, and possibly does not take so long to dry as first-grade rubbers of equal thickness. It is evident, therefore, that the erection of double-storey factories is false economy, as separate drying-houses have to be built eventually. This conclusion does not apply with the same force to factories worked in conjunction with smoke-houses for preparing sheet rubber, but, nevertheless, such a factory should not have another floor above the work-room.

VERANDAHS.--One of the worst features in many factories is the necessity for coolies to bring latex into the factory. As already mentioned, the floors of factories are usually running with water (or should be), and it can be imagined that the pa.s.sage to and fro of scores of coolies must bring in a great quant.i.ty of dirt. Not only so; the very presence of the coolies is a hindrance to the efficient working of the factory, and considerable floor-s.p.a.ce and time are wasted.

This feature in factory working is all the more annoying because the necessity for it could so easily be obviated. All that is necessary is the erection of a wide, open verandah outside the wall of the factory. Here all latex could be received and strained, sc.r.a.p-rubbers could be received and pa.s.sed through an opening into tanks placed in convenient position. Water could be laid on in this verandah so that coolies might wash their buckets, and the whole verandah might be enclosed only with expanded metal so as to avoid interference with the lighting of the factory. In this way it would be quite unnecessary for any field coolie to enter the factory proper, and this would facilitate cleanliness. Such an arrangement has been discussed by the writers many times during the last few years, but the number of estates which have made such provision is still in the minority, and the same slipshod and dirt-making procession of coolies continues to walk through the factories, and the same piles of bark-shavings and sc.r.a.p-rubber continue to acc.u.mulate and ferment in a few instances.

An indication of types of verandahs is given in Chapters VII. and IX. These are not intended to be representative of a universal design, but may be suggestive in the planning of others according to local conditions.

SITUATION OF TANKS.--It will be noted that these verandahs are raised from the ground-level to a height of about 3 feet in order that latex may be gravitated, with a slight fall, into the coagulating tanks which are within the factory. There exists a real necessity for this practice, inasmuch as otherwise to obtain gravitation of latex (which is quicker and cheaper than handling) the coagulating tanks would have to be either placed on the floor or sunk beneath the level. The risk of contamination of latex or coagulum under such circ.u.mstances would be appreciable. Apart from this, it is advisable to have the coagulating tanks raised to a height of between 2 and 3 feet, to secure the advantage of ease of working in the processes of coagulation and the handling of coagulum--a not inconsiderable factor.

In some modern designs it is proposed to place the coagulating tanks in a separate building. This would seem to be an unnecessary refinement in a new building, if observance is given to the suggestions made in previous paragraphs.

DESIGNS AND "LAY-OUT."--In a previous publication[17] comment was made upon grievous errors in designs prepared by those inexperienced in the requirements of the tropics. There is little ground now for complaint, and local engineering firms are fully capable of advising upon, and constructing, suitable buildings.

[17] "Preparation of Plantation Rubber," Morgan, 1913.

In considering the first installation of a factory and equipment one always has to weigh the question of prime cost against the probability of future expansion of crop. If it should be decided at first merely to cater for contemporary requirements, the fullest consideration should be given in discussing design of building and lay-out of machinery to the practicability of later extension. The site should be large enough for the eventual group of buildings, the building should be easily capable of extension with the least cost, and the same forethought should govern the lay-out of the machinery.

DRAINS.--Lastly, there is the question of drains. Generally speaking, all factories are well provided with drains, and the only difficulty is that of getting an adequate fall for efficient drainage. But there is a certain amount of laxity exhibited in the matter of providing sieves in drains. To anyone acquainted with factory working, it must be apparent that quite a lot of small pieces of rubber are washed into the drains. This rubber should be collected at intervals during the day; but in many instances that collected is only a fraction of what escapes. Wherever possible the drainings of a factory should be carried as far as is practicable from the buildings by means of cement drains. Too often these are short, and lead into earthen drains. Even if no pieces of rubber are present, the serum from the coagulum is subject to decomposition, the effluvium from which is objectionable.