Environmental health Machine safety

Legislation relating to machinery safety has evolved quickly over recent years. From the general requirement to 'securely fence all dangerous parts of machinery' (eg Factories Act 1961), there are now a number of more extensive duties and responsibilities specified as follows:

The latter two lay down much more specifically the areas of machine safety that employers should be addressing

Safety issues

The general principles of machinery safety can be placed in a hierarchy as follows:

  • Identification of hazard(s)
  • Elimination or reduction of hazard(s) by design
  • Use of safeguards
  • Use of safe working practices

Machinery hazards

Mechanical
  • From the movement of machinery parts (ie rotary, sliding or reciprocating)
  • Entanglement or catching (eg hair, clothing, jewellery)
  • Friction and abrasion
  • Cutting
  • Shearing
  • Stabbing and puncture
  • Impact
  • Crushing
  • Drawing in
  • Compressed air/high pressure fluid

Non-mechanical
  • Access problems (eg obstructions/projections)
  • Handling and lifting
  • Electrical
  • Chemical
  • Fire and explosion
  • Noise and vibration
  • Temperature
  • Radiation

Miscellaneous related safety considerations include:

  • Suitability of controls (including start, stop and emergency stop controls)
  • Type and effectiveness of braking systems
  • Feeding devices
  • Work holding devices
  • Lubrication
  • Stability
  • Lighting
  • Safety colours
  • Symbols and access

The British Standard (BS5304) 'Safety of Machinery' provides ergonomic data that establishes safe reach distances for use with guards. 
 
The selection of safeguards will be influenced by whether access to the danger area is required during normal operation:

  • If not, fixed enclosing guard, if so, can use interlocking guard 
  • If not, fixed distance guard, if so, can use automatic guard
  • If not, interlocking guard, if so, trip device, adjustable guard, self-adjusting guard, two-hand control device or hold-to-run control (only if the above cannot be used)

Guard design list
  • Fixed guard - no moving parts, robust, tools needed to remove, preferably captive fastenings, eg fixed enclosing guard or fixed distance guard
  • Interlocking guard - movable part(s), movement is interconnected with the power/control system so that until the guard is closed the power is interrupted OR guard stops locked closed until risk of injury has passed, may be of mechanical, electrical, hydraulic or pneumatic type, need to minimise risk of 'fail to danger' and mustn't be readily overridden
  • Automatic guard - moved into position automatically by the machine, physically removes from the danger area any part of a person exposed to danger
  • Adjustable guard (eg woodworking machines) - may be fixed or movable but the adjustment remains fixed during operation, need regular maintenance of the fixing arrangements
  • Self-adjusting guard - may be fixed or movable and adjusts to accommodate the passage of the material
  • False table - where power-operated feed table carries material to the operating point of the machine

Safe working practices (in addition to the provision of efficient and effective guarding) should include:

  • Ensuring safe access
  • A good standard of housekeeping
  • Provision/display of suitable warning notices
  • Procedures for emergency isolation and dissipation
  • Adequate degree of supervision (which generally increases with risk, up to written procedures and permit to-work systems)
  • Adequate information, instruction and training for operators and supervisors
  • Effective maintenance (and keeping of records) by competent persons. Safe working procedures for maintenance and cleaning are required. This will include effective isolation or locking off, not just switching off)
  • Enhancing machine safety by ensuring good lighting/temperature control/ventilation