Safety Codes and Friction in Mechanical Systems

Engineering Safety Codes and Standards

Nowadays, the first concern of any engineer is safety. This concern has led to the introduction of worldwide codes and standards for the manufacture and maintenance of machines. Engineers began to understand the science behind the behavior of metals and other materials. The steam engine was one of the first machines which aroused interest in safety standards.

The steam engine works on a very simple scientific principle: when you heat water in a vessel, the molecules expand until, at a certain temperature, the liquid turns into a gas. The American Society of Mechanical Engineers (ASME) produced the Boiler Safety Code. Since then, the ASME has produced codes in all areas of mechanical engineering, including safety standards for:

• Cranes and industrial ladders
• Elevators and machinery shafts
• Liquid fuels
• Incinerators for hazardous medical waste

Principles of Friction in Engineering

Friction occurs when two objects are in contact and one object is moved past the other; a force is created which resists the movement of the objects. Although the effect that friction has on an engineering system depends on the nature of the materials that are in contact, certain facts are known to be consistent for all materials.

Engineers must bear in mind several principles of friction:

• Friction can be reduced by lubrication and by good design.
• The smoother the surfaces, the lower the friction.
• Friction is a force that opposes movement between two objects.

If friction is not taken into account by engineers, the results are both costly and damaging. Either greater friction is caused by worn parts, requiring more power to overcome it, or good contact is lost between the surfaces, causing machine failure.

Methods to Reduce Friction

In order to reduce friction, the surfaces that are in contact need to be made smoother. In addition to machining, this can be done in two ways:

1. Lubrication: A lubricant can be added to reduce the coefficient of friction and so minimize wear and heat.
2. Design: The components can be designed so that the friction is minimal.