Part 4

Suitable warning signs should be placed on cranes that are undergoing repairs, and buffers or rail stops should be clamped to the crane rails a few yards in front of the disabled crane when others are operated on the same runway. If practicable, a suitable floor area directly underneath the disabled crane should be roped off or inclosed in some other way, to prevent accidents that might be caused by tools or other objects falling from the crane. Similar precautions should be taken when men are at work on the runways, and red flags or other warning devices should be placed at both ends of the section undergoing repairs.

Chains and Hooks.

Chains and hooks should be carefully inspected at regular intervals, and they should also be annealed from time to time by competent workmen who thoroughly understand the art of annealing, and who know how to secure the results that are desired. Particular care should be taken with hooks in this respect, because a hook, when properly annealed, should gradually yield or straighten if subjected to a serious overload, and thus give warning of danger; whereas if it is not properly annealed, and therefore hard, it is likely to snap off suddenly, without warning. Chains and hooks should be inspected with care immediately after annealing, because they are then cleaner than at other times, and hence any existing defects or flaws in them may be detected with greater certainty. All chains and hooks should be numbered, and a careful record should be kept of the inspections and annealings. Hoisting chains are particularly liable to failure through fatigue or over-strain, on account of the severe treatment to which they are frequently subjected; and they should therefore be examined minutely, and link by link, to detect insecure welds and slight cracks or other defects. Chain slings should never be crossed or twisted when placed around loads, and every chain that is to be used as a sling should be made of the highest quality of wrought iron. All chains should be oiled frequently, to prevent rusting.

Forged hooks, or laminated hooks made of steel plates securely riveted together, should be used in preference to those made of cast steel. Hooks are sometimes subjected to severe abuse by workmen who try to force them into position by striking them with heavy iron bars or other implements. This is a dangerous practice, and should be strictly prohibited.

Wire-Rope Slings.

Well-made wire-rope slings give better service than chain slings, because they are stronger, weight for weight, and also because deterioration is usually indicated by broken strands that are readily discoverable by an experienced and qualified inspector. Wire-rope slings are pliable, and may be adapted to almost every use. They should be kept in good condition, and to prevent rusting and unnecessary wear from friction they should be treated with oil or with a good cable lubricant prepared specially for the purpose. Wire-rope for slings used in handling molten metal or hot castings should have a soft iron-wire core, because a hemp core is quite likely to be destroyed by the heat.

Slings in General.

A sling should never be allowed to rest directly against the sharp corners of a heavy flask, casting, or other similar object, but should be protected by wooden corner-pieces, or by pads of burlap or other soft material.

Every sling, whether composed of a chain or a rope, should be long enough not only to surround the load it has to support, but also to leave a considerable space between the sling and the upper surface of the load. The oblique parts of the sling, which lie above the load and join it to the hook (or to the point where the suspension first becomes vertical) should never be so flat as to make an angle of less than 45 degrees with the ground. This precaution is highly important, but it is often overlooked or neglected, because the men do not realize that the stress on the ends of a sling is greater, the flatter (or more nearly horizontal) they lie. When the ends are inclined at an angle of 45 degrees, the stress upon each of them is about 41 per cent. greater than it would be if the ends were vertical; and if the sling is so short that it barely goes around the load and has but little slack, the stress upon it may be very great indeed.

We strongly advise that all slings, when not in actual use, be kept under lock and key and placed in charge of some responsible person who knows their condition and is competent to select safe and appropriate slings for every occasion. They may be stored in the tool room or supply room, for example, and be in charge of a qualified foreman.

Hoisting Apparatus in General.

Hoisting apparatus of every kind should be inspected frequently and thoroughly, and all parts that are defective in any way should be promptly repaired or replaced. The man charged with the operation of the apparatus should not attempt to make repairs or adjustments, however, unless the foundry is a small one, where this constitutes a part of his recognized duty. Under all other circumstances he should immediately report to the foreman or repairman, in order that the job may receive attention in the proper way. If the defect is serious enough to constitute a possible source of danger, the apparatus should not be operated until the necessary repairs or adjustments have been made.

Tumbling Barrels.

Tumbling barrels (or “rattlers”) for cleaning rough castings are of two general types, respectively known as wet and dry. There are numerous mechanical hazards in connection with both types, and with dry tumbling barrels considerable danger to health may be caused by the dust created by them unless suitable preventive measures are adopted.

There are two methods that are commonly employed for removing the dust from dry tumbling barrels. One of these consists in attaching an exhaust system directly to the machine, and the other consists in inclosing the barrel in a dust-proof compartment from which the dust may be exhausted. The first method, as a rule, is practicable only in connection with tumbling barrels that are of special design, and are provided with the necessary attachments for connecting with exhaust fans. In nearly all other cases dust-proof inclosures must be built, and it is practicable to secure satisfactory results in this way when the system is properly arranged. The compartments should be made as tight as possible, and should be constructed of sheet metal or well-seasoned lumber. The doors may be arranged to fold, or to slide upward or sidewise; or they may be hinged to open in any way that is most convenient. In some cases rolling steel shutters are used. Doors that rise vertically should be suitably counterweighted so that they will not drop upon the workmen, and the counterweights should be inclosed. In addition to the counterweights we recommend the use of catches or fastenings for holding up the doors.

When tumbling barrels (either wet or dry) are not located in compartments, substantial double railings, at least 42 inches high, should be placed about them, with a clearance of not less than 15 inches nor more than 20 inches. (When railings are placed more than 20 inches away, workmen are likely to crawl inside of them to do any necessary work, and they are then in greater danger than they would be in if no railings were present; whereas if railings are omitted altogether, the workmen are likely to be struck or to have their clothing caught by small objects that may work through perforated or loosely-fitting covers, or by the projecting cover-fastenings.) The railings should be provided with gates so arranged that opening the gates will automatically throw the driving belts or clutches into the off position, and will prevent the machines from being started until the gates are closed. Driving belts should be guarded to a height of at least 6 feet above the floor, and all exposed gears should be completely inclosed. Chain hoists should be provided for lifting heavy covers, and suitable brakes or locking devices should be installed to prevent any movement of the machines while they are being loaded or unloaded. Securing the barrels in position by means of bars or props is a mere makeshift method, and is manifestly unsafe.

Sand Mixers and Sifters.

Sand mixers are of two general types, one of which simply mixes the materials, while the other not only mixes but also grinds them. The mixer consists of a horizontal semi-cylindrical vessel in which the sand is placed and the mixing is done by revolving blades. The top of the cylinder should be covered by a substantial grating composed of 3/8-inch round stock suitably reinforced to insure rigidity, and provided with free-swinging discharging doors. All gears should be inclosed by substantial guards, and the driving belt should be protected to a height of at least 6 feet above the floor. A well-designed belt-shifter should be provided, and should be so arranged that it may be locked to prevent creeping of the belt.

The combination mixer and grinder is similar to the revolving dry-pan used in the manufacture of bricks, and it may be driven either from underneath or from overhead. In either case the driving gears and all other exposed gears should be suitably inclosed, and the driving belt should be protected and be fitted with a belt-shifter, as described above in connection with the sand mixer. The revolving pan should be completely surrounded by a substantial guard of heavy, reinforced wire netting extending to a height well above the hubs of the grinding wheels. An opening should be left in one side of the guard, and at this point a sheet-metal feeding hopper should be securely riveted on. A drag or other suitable mechanical device should be provided to force the sand out through the discharging door, and the use of hand shovels for removing the sand from the pan while it is in motion should be prohibited.

Pipe or angle-iron railings 42 inches high should be installed at the sides of rotating sand sifters, at a distance of at least 15 inches, and not more than 20 inches, from them. Belt-shifters should be provided, and the belts should be guarded to a height of at least 6 feet above the floor.

When sand mixers and sifters are driven by electric motors every precaution should be taken to prevent electric shocks and burns. See that all live wires and other parts are thoroughly insulated, and guard all dangerous rotating parts. Inclosed switches should be used, and they should be located in convenient and easily accessible positions; fuses of the inclosed type should also be used.

Automatic Molding Machines.

The gears on both sides of these machines should be entirely inclosed by substantial guards of sheet metal, expanded metal, or close-mesh woven wire. The connecting rods should be similarly guarded, the inclosures in the latter case to extend as high as possible without interfering with the adjustment. Whether the machines are driven by belts or by electric motors, such precautions should be taken with regard to belt-shifters, belt-guards, and electrical safeguards as have been recommended above in connection with sand mixers.

Chipping Department.

Many serious eye injuries occur in the chipping department, and practically all of these may be prevented by requiring the general use of suitably-designed eye-protectors or goggles. Eye-protectors for cupola men and others engaged in handling molten metal have been described in a previous paragraph, and those to be used by chippers should be similar. Cheap, flimsy eye-protectors should not be used. It is economy to buy substantial goggles at a higher price, not only because they afford better protection, but also because they are more durable.

[Illustration: FIG. 14. MOLDING MACHINE OPERATED BY COMPRESSED AIR.]

In addition to the eye-protectors, shields of canvas or other suitable material, mounted on substantial frames, should be provided, wherever needed, to protect near-by workmen from flying chips.

Chippers should not be permitted to work with battered or otherwise defective tools. Broken hammers and sledges should be discarded, and cold-chisels and other implements should be dressed when they become burred or mushroomed.

Grinding Wheels.

Emery wheels and wheels of other abrasive materials are used in grinding castings, and these sometimes burst and cause serious injuries to the operators. All grinding wheels should be fitted with safety collars or flanges, and, where practicable, should be inclosed by substantial metal hoods connected to exhaust fans for removing the dust. Stationary grinding machines should be mounted on solid foundations to prevent vibration, and their bearings should be ample in size and be kept well lubricated and properly adjusted. It is important that grinders wear goggles, to protect their eyes from flying dust and sparks.

Further details with regard to the design, care, and operation of grinding wheels will be found in a booklet, entitled “_Grinding Wheels_”, published by the Engineering and Inspection Division of THE TRAVELERS INSURANCE COMPANY.

Compressed Air.

Compressed air is commonly used in foundries for operating air hoists, blow guns, spraying devices, pneumatic hammers and chisels, sand-blasts, molding machines, and sand-blast tumbling barrels. Serious accidents are often the result of the improper use of compressed air, and workmen should never be allowed to play pranks with it, but should use it only for the purposes for which it is provided. In particular, a sand-blast should never be turned upon a person, because it might easily destroy his eyesight or cause other serious injuries.

The introduction of compressed air into the human body causes great distention of the intestines, accompanied by agonizing pain; and the victim usually dies after a short period of intense suffering. Every man about the foundry should therefore make it his special business to see that no attempt is made to use the air lines for perpetrating so-called “practical jokes”.

[Illustration: FIG. 15. A SPECIAL CHAMBER FOR SAND-BLASTING.

(Strong air suction, through the exhaust hoods shown in the upper part of the picture, will remove a large quantity of the dust that is created, but it would be better if the ducts were placed in the floor, with gratings over them, or in the side walls. The helmet which the operator is wearing is of a type commonly used in work of this kind. As explained in the text, no entirely satisfactory helmet has yet been devised.)]

Sand-blasting.

Sand-blasting may be done in the open air if eye-protectors and respirators are worn and other suitable precautions are taken, but it is far better to provide a dust-proof chamber for this work. The operator of the sand-blast should then wear an appropriate helmet, to effectively protect his lungs and eyes from the dust. The form of apparatus used should be adapted to the work to be done, and to the conditions that must be met. Considered from the point of view of the dust hazard alone, the ideal arrangement appears to consist in a helmet well ventilated by means of a hose supplying an adequate flow of dust-free air. The hose may be run from the compressed-air tank to the upper part of the helmet, and it should be provided with a regulating valve located where it may be easily controlled by the man who is to be supplied. The air current should be so adjusted that it will not only afford sufficient oxygen to serve for respiration, but also prevent dust from rising into the helmet through openings in the lower part of it. In practice, however, it is frequently found that the plan here outlined is highly objectionable to the men, and in fact they often refuse to wear apparatus of this type, claiming that the cool air passing down the neck soon causes them to catch cold. Baffles and various other distributing devices to regulate the flow of the air within the helmet have been tried, but no ideal and wholly satisfactory solution of the difficulty has yet been worked out, so far as we are aware. In the opinion of certain foundry experts, an ordinary helmet with a respirator attached, or used in conjunction with a separate respirator, constitutes the best device for the protection of the sand-blaster, when all phases of the problem are considered.

Each compartment used for sand-blasting should be provided with an exhaust system capable of removing the dust in a satisfactory manner.

[Illustration:

_Courtesy of the Western Electric News._

FIG. 16. CABINETS FOR SAND-BLASTING SMALL CASTINGS.

(The castings are placed in the cabinets and are held and turned about by the operators, who watch the progress of the work through glass panels. The dust is carried off through the exhaust ducts.)]

Illumination.

The average foundry is poorly lighted, and many accidents may be attributed directly to this condition. There are many problems to be considered in providing proper and adequate light for foundries, and as the conditions that have to be met vary a great deal, it is impossible to make any general recommendations that will be applicable in all cases.

The floors, walls, supporting columns, ceilings, and materials in foundries are usually covered with grime and dust which absorb from 95 to 98 per cent. of the light that strikes them, and which give them all the same general tone or color. With no contrasting background it becomes exceedingly difficult, at times, to distinguish objects lying upon the floor, and care should therefore be taken to see that the floor is kept free from tools, materials, and obstacles of every other kind, over which the workmen might stumble. Moreover, if the ventilating system is inadequate to keep the air reasonably clear, the dust, smoke, and gases will not only reduce the intensity of the illumination and thereby invite accidents, but may also affect the health of the working force.

During certain stages of the work,--notably at pouring time,--the men are exposed to a dazzling, blinding radiation from the white-hot, molten metal. Very often, too, lighting units of intense intrinsic brilliance and high candle-power are placed where they shine directly into the eyes of the men. Conditions such as these impair the vision of the worker, thereby reducing his efficiency as a producer, and multiplying the opportunities for accidents.

One of the best artificial lighting sources for foundry work is the Mazda C lamp (500 to 1,000 watt sizes). To determine the proper location of the lamps, and their spacing, suspension heights, and other features (such as the types of reflectors that should be used) it is necessary to understand, as fully as possible, the exact conditions that must be met. Where incandescent lighting units are to be used, wall brackets, fitted with angle reflectors, provide the best means of securing satisfactory illumination at the floor level. Good results may be obtained by installing the brackets on the supporting columns, under the crane runway and below the smoky zone.

Although we have spoken only of artificial light for foundries, it is important to admit the greatest possible amount of natural light. As a usual thing, skylights are of little value on account of the clouds of smoke that often fill the upper part of the building, and therefore practically all the natural light that can be really serviceable must pass through windows in the side walls. For the same reason the effective window area must be considered as only that below a height of approximately twelve feet. It is essential that the windows occupy as much of the wall space as possible, and, where the width of the room is great, prism glass should be used. Prism glass, when properly set, will reflect the light into the room in a nearly horizontal direction. Satisfactory natural illumination can hardly be had without keeping the windows clean; and we also strongly advise whitewashing the walls, ceilings, and supporting columns, applying fresh coats whenever they are needed.

[Illustration:

_Courtesy of American Blower Company._

FIG. 17. GOOD DAYLIGHT CONDITIONS IN A FOUNDRY.

(Observe also the ventilating duct, near the roof, and the downwardly-projecting Y-shaped nozzles connected to it through which the smoke and dust are drawn out of the building.)]

The Foundry Yard.

The fact that orderliness and system promote safety is probably nowhere better exemplified than in a large foundry yard. The maintenance and cost of a foundry yard is small as compared with that of the foundry itself, and it is good economy, therefore, to use the yard as much as practicable for the storing of scrap, sand, flasks, finished product, raw materials, and miscellaneous supplies; but the maximum efficiency and economy cannot be realized unless the yard is kept in a neat and orderly condition. If a yard is just large enough to meet the needs of a foundry, and is not used to its full capacity, it usually follows that the foundry floor space is littered with material that could be stored in the yard more advantageously; and the crowding of the foundry floor increases the number of accidents, many of which might be eliminated if the yard were utilized to better advantage. This is specially true of a foundry where every available foot of floor space is required for production. In this class belongs the “jobbing foundry,” in which work of a miscellaneous nature is done, as distinguished from the “repetition foundry,” in which the work consists mainly in the continuous reproduction of certain standard stock patterns.

The jobbing foundry owes its existence to the fact that many manufacturers who use castings have no room for a foundry, or have too limited a need for castings to warrant the expense of maintaining a foundry of their own. A foundryman who depends largely or wholly upon job contracts to keep his plant in operation usually has to turn out an exceedingly varied assortment of castings, and speed is often an essential factor in the contract. This means that as soon as one job is finished, the flasks and patterns must be removed and a different set substituted. If the yard is not well kept there is little likelihood that there will be ample space in it for the flasks and sand, and if there is not, it may be necessary to use the foundry floor for storage until the new flasks are brought in. The floor is then in a disorderly, crowded state, just when clear space is needed. It is evident that the probability of accident is greatly increased when such conditions prevail.

It is important for the foundry yard to be level and fairly smooth, and it will pay the owner well to put forth every reasonable effort to secure a yard of this kind. Material can be handled and stored with much greater safety and facility, in a level yard, than in one that is sloping or uneven. Foot paths, and passageways for wheelbarrows and trucks, can also be kept in good condition more easily.