Milling Machines

The exhaust fan suitable for your milling machine.

The most important characteristics of the milling process are the high precision and the good surface finish of the end product; a good milling machine can produce pieces with tolerances lower than one micron and a mirror surface.
The main working parameters of the milling are the cutting speed, to ensure the cutter speed rotation and smooth entry of the workpiece.
Since the milling works by subtraction, it is necessary that this can be inscribed in the starting piece from which the stock allowance will be removed.

The processing is carried out using tools, called cutters, mounted on machine tools such as milling or boring machines. Milling, unlike other simpler processes, requires the rotation of the tool and the translation of the piece: the cutting edges of the cutter, rotating, remove metal from the piece when it is in interference with the cutter due to the translation of the bench on which the piece is anchored.

The working cycle normally involves a first roughing out phase, in which the removal is done as quickly and therefore as economically as possible, leaving a sufficient stock allowance for the subsequent finishing phase in which the last excess parts are removed to reach the dimensions expected and obtain a smoother surface.

The finishing, consisting of a limited metal removal, allows to respect  the tolerances of the dimensions and the degree of surfaces roughness.

The main advantage of  milling machines is to have very few limits of shapes achievable. With a single work program you can perform several complex operations including drilling, grinding, boring, cutting, rounding…

Milling machines are structurally very solid machines, because they must absorb the considerable vibrations generated by the motorized head without rocking or shaking. During hard metal working or with very high speeds (reaching tens of thousands of revolutions per minute), coolant liquids are used to optimize the cooling of the tip and to reduce the efforts.

The coolant also has the function of retaining the powders and chips to make them flow out in a controlled way, avoiding they increase the consumption of the milling cutters or affect the cutting edge.

These coolants produce oil mists.

These are important informations must be taken seriously into consideration whenever you are going to purchase a mist collector for your machine tool.

Depending on the type of production and working processes required, it is presumed that particular types of pollutants will arise during  milling machine working and consequently a suitable exhaust fan must be suggested.

For example, with metal working with emulsified oil, the oil mists generated are caused by the sum of these factors:

• – evaporation/combustion of coolant and consequent formation of industrial fumes, oil mists and aerosols.
• – oil atomization caused by the high number of spindle/cutter revolutions and by the use of high pruessure pmps of coolant in the machine tool.

The resultant of these two elements physically breaks down the fluids into particles, micro-powders and micro-mists so thin as to make them volatile.

Production needs deriving from the type of processing or from the type of material processed impose a dry processing, without lubrication-refrigeration.

When dry powders reach minimum dimensions become volatile and during processing/cleaning they remain in suspension in air.

We need underlining that in dry mechanical processings, powders and dusts are not the only pollutant; industrial fumes and aerosols also derive from the evaporation/combustion of protective grease/spray residues and coolant oils, remain on the surface of the workpiece throughout production chain.

The problem of oil mists-dusts-fumes if not held in mechanical workshops.

The volatility of polluting particles such as industrial fumes, oily mists and aerosols, whether solid or liquid, entails and creates various problems for metalworking companies, operators and machine tools.

First of all, they negatively affect the health of the air and the health and hygiene conditions of the operators, in particular at the respiratory level, since the particles smaller than 0.3 microns can reach the pulmonary alveoli, compromising the respiratory tract.
Not only that, in contact with the epidermis, they create skin irritations, dermatitis and redness.

From the standpoint of production, micro-dust and oil mists pollution in the workshop considerably reduces the productivity and in particular the efficiency of the machine tools, since the stratification of pollutants invalidates the precision and tolerance of the measuring instruments, with the onerous consequence of having to increase maintenance on the most delicate components.

Dusts, oil mists and aerosols not filtered and purified, make the floor slippery, dirty the surfaces of the machine tools and the walls of the shed, on which they settle.

Without forgetting any possible fines deriving from current regulations, which impose a concentration limit for oil mists in the workplace.
Italian TLV limit 5 mg / m3
more restrictive ACGIH limit 0.5 mg / m3