In the metalworking industry, equipment, accessories and other products in preparation for painting, welding or other operations generally require pre-cleaning of metal mechanical surfaces such as grinding and polishing to remove oil, rust or oxide layers that may cover the surface, or other metals that are plated, and covered with cast sand, organic or biological materials.

Grinding and polishing using mechanical cleaning may use sandblasting, grinding wheel sanding, sandpaper or abrasive belt sanding and other types of equipment. Regardless of the type of equipment used for sanding and polishing, dust generation is inevitable and in order to capture these large and heavy particles, the suction air velocity is usually very high and the collection hood should be placed directly in front of the dust raising point. In practice, it is often desirable to use a suction hood to cover as large an area as possible, but if the material being handled contains toxicity, a fully sealed hood may be required, and the operator will need to wear a respirator, together with local extraction.

1. Grinding and polishing equipment.

Grinding is the removal of metal surfaces with a hard substance. General grinding wheels and grinding stones are made of hard abrasive materials with sticky pressure. Commonly used materials such as aluminum oxide and silicon carbide can be sticky pressed on fiberboard, paper or cloth for manual polishing. Just as diamond grains can be used as abrasives.

Typical applications: sandpaper grinding, drum grinding, belt grinding, grinding machines, horizontal double spindle disc grinding machines, vertical spindle disc grinding machines, jack grinding machines, portable grinding machines, small diameter grinding machines, surface grinding machines, oscillating grinding machines, grinding benches, grinding tables.

Grinding and polishing dust characteristics.

The dust in the grinding process contains coating materials, metal particles, grinding wheel abrasives, and wheel binders. The dust is abrasive, cohesive, and can be flammable and explosive. Regardless of the type of grinding and polishing equipment used and the type of dust generated, a suction hood capable of collecting the dust needs to be installed as close as possible to the point of operation, and care needs to be taken that explosive dust collection and metallic dust with sparks are not used together in a dust collection system.

2. Grinding and polishing

The purpose of polishing is to make the rough surface smooth. However, there may be different finish requirements for each part, while processing separately. Polishing and grinding can be divided into three categories: sanding treatment, preliminary polishing and final polishing that brings out the luster of the material.

Sanding: produces a satin, brushed or highly polished metal surface. The sanding process first polishes the surface of the workpiece and then gives it a softer and duller appearance with a brushed finish. It contains a compound of abrasive, mixed gum or grease.

Preliminary polishing: removes traces of previous processes to give a smoother surface. The workpiece is moved with moderate to intense pressure towards the grinding wheel.

Final polishing: finely adjusts the surface and brings out the shine. The workpiece is moved with light to moderate pressure in the direction of the grinding wheel.

Polishing: Not a precision process. It is only used to remove metal surface fines and bring out a shiny surface. The friction generates high temperatures that soften the surface of the workpiece. Polishing is usually done in several stages, followed by polishing and grinding.

Typical applications: manual grinding and polishing, polishing lathes, backstand roller polishing machines, linear automatic polishing, circular automatic polishing and metal polishing belts.

The capture, transport and storage of polishing dust particles are the simpler parts of filtration management and either bag or cartridge dust collectors are suitable for use. Either type of dust collector faces the same problem of fibrous dust that may reside in the piping, on the cartridge, on the cross section or on any opening, causing a bond to form between flange and flange. If left uncleaned for a long time, it will clog the piping and filters of the dust collector, so it is crucial to maintain the equipment and clean the ash drums, drawers, dust collection boxes, etc. regularly.