The 5 most common defects of power presses

Power Presses are unforgiving machines. When in operation, they store a large amount of energy ready for the next operation.

To prevent coming in to contact with stored energy, there are safety systems which are incorporated into the design. When operated with these appropriate controls in place they will continue working safely for many years. When these safety systems are interrupted or bypassed there is the potential risk of workplace injuries, such as amputations of fingers, hands, and potentially even arms.

Overtime, all items of workplace equipment start to deteriorate and potentially become unsafe. Any such situation can have several consequences, from loss of production, to injury to the operator or others in the vicinity.

Anyone who operates power presses should refer to the HSE’s guidance documentation HSG236 which, if followed, will identify the measures to be taken to comply with part IV of Provision and Use of Work Equipment Regulations 1998 (PUWER). HSG236 is divided into two parts: Part 1 deals with good practice in the maintenance of power presses and Part 2 is aimed at the thorough inspection and tests that are to be carried out by the engineer surveyor.

Thurra’s experienced engineers have extensive practical and theoretical knowledge as well as experience to detect defects or weaknesses. Armed with such data they can determine how far these defects or weaknesses will affect the safe operation of the power press.

Thurra’s engineers will make their assessment independently and impartially. With only one aim, and that is to ensure the continued safe operation of the power press.

5 of the most common defects associated with power presses are:

1. Protective guards. On numerous occasions we have found guards to be defective due to the operational demands put on the press or that the guards are disabled to increase production. Such a protective guard is a pullback safety bar, which is set up to prevent the operators hand coming into deliberate or accidental contact with the moving parts of the press.

Damage / disabled guarding increases the risk of the operator coming into direct contact with the power press when it is operating. In such circumstances there is the real danger of the operator becoming entangled in the moving parts of the power press and being subject to severe injury. This is often to such an extent that the only course of action is amputation. Thurra’s engineers at every inspection check, test and measure all guarding to ensure that the operator does not come into contact with the press during its movement.

2. Broken foot shroud. Foot shrouds are fitted to prevent the accidental operation of the press. The operation of the press has to follow a sequence of actions which will ensure that the press will only operate when all the safety measures are in place. The operator must carry out a deliberate action to allow the press to operate in a safe manner.

The integrity of the foot shroud is assessed at every inspection by Thurra’s engineers. Any deterioration in the foot shroud is communicated to the site representative, highlighting the potential hazard that exists. This is carried out before leaving site and is also recorded on the inspection report.

3. Cracked Pitman Screw / Pitman Cup. The pitman screw is the part which connects the ram and crankshaft and is subject to constant impact during operation. If the pitman screw was to fail it would present a significant loss of production and may also cause damage to other components.

Thurra’s engineers conduct non-destructive testing of the pitman screw. This identifies defects that can’t normally be seen by the naked eye. If any concerns are indicated, they are then discussed with the site representative and the service engineer. Early identification of a cracked pitman screw can save a far more costly breakdown and avoid the loss of production.

4. Cracks in the clutch key / keyway. The clutch key withstands a significant amount of dynamic stress when in operation and is therefore prone to wear and potential cracking of not only the key / keyway but other connecting components. At the thorough examination, the clutch key / keyway and the other connecting components are subject to inspection by both visual and non-destructive testing by Magnetic Particle Inspection.

As with the Pitman screw, Thurra’s engineers conduct extensive non-destructive testing of the clutch key and keyway. If necessary, an early indication of the repair action required is provided, therefore preventing any non-promulgated loss of production. All areas of concern are communicated to the site representative and service engineer prior to leaving site.

5. General housekeeping, hydraulic leaks, damaged / poorly fitted cable glands. By maintaining a high standard of general maintenance, the condition and operating environment can be improved. Oil leaks create a risk of slipping to the operator and people in the local area. There is also a fire risk, especially if there is an ignition source nearby. Poorly fitted electrical cables with incorrectly fitted cable glands could be that ignition source. Any slip, trip or fire have the devastating consequence of injuring personnel and potential destruction of very expensive machinery.

At every examination, Thurra engineers look at all areas of housekeeping and before leaving site we report all our observations to the site representative.


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