Metal working consists of a wide spectrum of operations. To describe each and every production process in detail would be beyond the scope of this paper. In view of this, we are attempting to give a brief overview of the important metal working operations and understand the hazards associated with the same and the risk management measures to be adopted.

Process Description

The various processes involving metal working can be classified into following groups :

Processes that do not involve cutting of metals : eg., forgings, rolling, pressing, straightening, bending, punching.

Processes that involve cutting, machining (chip removal) : eg., sawing, milling, drilling, turning, spark erosion, grinding

Processes carried out at high temperatures (Hot working) : Abrasive cutting, flame cutting, turning, welding, soldering.

Surface Treatment : Electrochemical Processes : electroplating, anodizing, chromium plating ; Painting: immersion, spray, powder painting with subsequent drying Coating: application of metal surfaces: e.g., galvanizing.

Changing material properties : Carburizing, nitriding, hardening, tempering.

Plastic injection moulding/extruding

Manufacture/Assembly Works

Loss Exposure

During the cutting and grinding processes of metalworking the abrasion of these discs produces small particles of abrasive (corundum) and adhesive. These are poor thermal conductors and can hardly absorb any heat, so that the grinding energy is completely transferred to the metal, which is a much better conductor. Oxidizing metal fragments are also torn off from the workpiece. These have been heated up so much – not least by the contact pressure – that they burn in the air and thereby attain very high spark temperatures. The amount of thermal energy not only ensues from the work process itself, therefore, but also increases along the flight path of the particles on account of their combustion. These high-energy particles are capable of making dust and solids glow and smoulder. They also have the property of bridging over distances of up to 10 m without losing their inflammability.