When purchasing the machineries or equipments, it should meet safety requirements. The first requirement is that the machine should be constructed in such a way that it is not necessary to add extra protection.
Some of the safety requirements includes
The machine should be safe in such a way that the operator will not be injured even if his/her attention should wander or he/she should make a sudden, reflexive movement.
All protection/guards, maintenance instructions and safety instructions should be included.
Guards or covers that can be opened while the machine is in operation must have switches or devices which cut off the electrical supply.
When the machine is installed, care must be taken to ensure that all the guards are properly fixed and used. Certain machines will require special safety devices. Examples are press machines, cutters, shapers, etc. which require hand operations in the dangerous area.
Risks connected with machine work
Machines with ingoing nip points
Machines with ingoing nip points includes rollers in a rolling mill, mangles and other similar machines, cog-wheels, chains and sprockets, bolts or bands and band cylinders, conveyor belts and so on. A particular hazard area is the ingoing nip points or “bites” where one surface rotates close to another.
All nip points need protection. Never think just a warning sign is sufficient .The best method of preventing accidents when working with such machines is to guard the nip points of the machine. If the guard cannot be complete, a supplemental protective guard must be put around the actual nip zone to prevent any direct contact with inrunning rolls or similar hazards.
Risks connected with drilling machines include contact with the drilling spindle and the drilling surface. One common cause of accidents is getting the shirt sleeve caught in the spinning bore.
Hair, loose fitting clothes etc. can easily catch in rotating machines and cause serious injuries. For example, drilling machines can be fined with adjustable shields that prevent clothes etc. from fastening.
This risk can be reduced by wearing arm covers, special arm guards or short sleeve shirts. People with long hair should use hairnets. This precaution applies to work with all machines with revolving parts.
Machines for cutting and slicing
Cutting and slicing machines or tools occupy a major place in all workplaces and this category of machines includes grinding wheels blades for slicing or cutting, guillotines, band-driven saws circular saws milling blocks and planing machines.
The safety requirements for grinding machines and grinding wheels are very high. A grinding machine should have a guard against the wheel breaking up during work, a splinter guard and a suitable adjustable balance plate. Always use some sort of eye guard, i.e. a partition of safety glass and safety goggles while working on a grinding machine.
Grinding machines are very common in metal work. The most common types of accidents connected with grinding are eye-injuries usually caused by flying dust particles or splinters flying from the grinding wheel. Accidents can also happen when the grinding wheel breaks while in use.
Therefore, as the precautionary rule, every stationary and manual grinding machine should have local ventilation. If there is no ventilation system, the worker should use a breathing apparatus.
The best way of avoiding eye-injuries is to use eye protection. For a grinding machine the safety guard should consist of an easily adjustable partition of non splinter glass mounted on the machine guard itself and a pair of approved safety goggles.
If you lose your sight it can never be replaced. Always use protective glasses when cufting and grinding. Emery grinding machines must be equipped with spark shields. Protective glasses must also be available close to the machine.
Emery grinding and cutting disks can explode. They must be regularly checked. Replace cracked or worn disks. In addition, make sure that the disk is made to suit the speed of the machine’s revolutions. The protective shield must never be removed.
A permanently fixed (stationary) grinding machine, i.e. a grinding bench should have a firm balancing plate attached to it. It should be easily adjustable and fixed in a position not more than 2 mm from the grinding wheel, slightly under the horizontal central line position of the wheel. The gap between the balancing plate and the wheel should be checked at regular intervals. If the gap is too large the object being ground can get stuck between the grinding disc and the balancing plate. There is then a major risk that the wheel can be smashed. This can be fatal to the operator. To avoid this danger the wheel should be carefully suspended between two equally large flanges. The diameter of the flanges should not be less than 1/3 of the diameter of the grinding wheel. The best thing is to have the flanges with a diameter equal to one half of the diameter of the grinding wheel.
In order to reduce the risk of injury by the smashing of a grinding wheel, there should be a splinter guard of steel or cast metal. A splinter guard also helps to prevent the unintentional touching of the wheel.
Careful servicing of machines is most important from the point of view of job safety. Never check or carry out repairs on a machine while it is operating. Even if the machine has stopped there is always a risk that it can suddenly start up again or be switched on by someone unaware of the fact that the machine is being repaired or serviced. Accidents of this kind are unfortunately all too common.
In order to avoid accidents of this kind, put warning signs over the starting motor and switch. A sign reading “Danger, work in progress, do not touch the switch” can quite easily fall off or accidentally be removed. The best measure is to lock off the starting switch or starting motor and to remove the fuses.
Safety design preventing accidental starting
Many injuries occur during inspection, repairs or maintenance on machinery because the machines are accidentally started. This type of work should not begin before the machine has stopped and a safety tag and lock had been put in place to prevent accidental starting.
Handles, buttons and pedals on the machine which are used to perform dangerous operations should be so designed and positioned that they cannot be accidentally activated. Stop buttons on the other hand should be easily accessible and coloured red.
Safety devices on machinery
The provision of guards for some machines, does not effectively prevent contact with dangerous parts. These include different types of presses and cutters, and machines with rubber rollers. Some of the following safety devices are used to prevent injuries when using these types of machines.
Two-hand operation :
Both hands must be used at the same time to start the machine and keep it running.
Light beams (photoelectric cell devices):
A series of light beams in front of the danger zone (if a hand breaks the beams, the machine automatically stops operating).
A guard which must be in the correct position to protect the operator before the machine can start.
The machine stops when someone or something enters the danger-zone.
Dead man’s hand:
A handle which must be held in order to perform hazardous operations with the machine. When the Tools and equipment handle is released the machine shuts off.