Industrial oils

Classification of industrial oils according to viscosity (ISO 3448 – 75)

Oils for hydraulic systems

Oils for hydraulic systems

ISO classification of oils for hydraulic systems

Hydraulic fluids with rapid biodegradation have a water hazard class of 0, while conventional hydraulic oils have a water hazard class of 2. They have the following designations:

• HEPG - Hydraulic fluids based on polyglycol. Application temperature from -30 to 90°C.
• HETG - Hydraulic fluids based on vegetable oils (rapeseed oil and triglycerides). The application temperature of these oils is from -20 to 70°C.
• HEES – Hydraulic fluids based on synthetic ester. Application temperature from -30 to 90°C.
• HEPR – Hydraulic fluids based on polyalphaolefins or related hydrocarbons. Application temperature from -50 to 80°C.

Highly flammable hydraulic fluids

Highly flammable hydraulic fluids are used in those hydraulic systems that operate near flammable sources where there is a risk of fire, such as foundries, ironworks, cement factories, glass factories and mines. According to ISO 6743-4 or DIN 51502, the following division was performed:

HFAE – Oil-in-water emulsion with more than 80% water. Used for power transmission up to 300 bar. It is most often used for supporting beams of underground mines.

HFAS – Synthetic aqueous solution with more than 80% water. It is used for hydrostatic drives up to 160 bar and temperatures from 5 to 55°C.

HFB – Water-in-oil emulsion with 60% mineral oil. It is used in mining at temperatures from 5 to 60°C.

HFC – A solution of water and polymers with more than 35% water. It is used for hydrostatic plants in industry and mining at temperatures from -20 to 60°C.

HFDR – Synthetic flame-retardant fluid without water, based on phosphoric acid ester. They are environmentally friendly. They are used for industrial hydraulics as well as for lubrication and reduction of turbines. Application temperatures from -20 to 150 ° C, and in hydrostatic systems from 10 to 70°C.

HFDU – Synthetic flame-retardant fluid without water, based on carboxylic acid. It is used for hydrostatic drives and industrial hydraulic systems at temperatures from -35 to 90°C.

Quality specifications of hydraulic fluids

Oil quality specifications for gears

Oils for air compressors

Compressors are devices for compressing air or gases. In practice, rotary (centrifugal, screw) and reciprocating compressors are most common. Lubricant and lubrication requirements depend not only on the type of compressor, but also on the type of medium to be compressed. For example, air and gas compressors are similar in construction, but the main difference is in terms of the effect of oil on the media.

Criteria for selection of oil for air compressors according to DIN 51 506

Selection of oil for compressors

Oils and liquids for metal processing

Oils and liquids for metal processing belong to cooling and lubricating agents (SHP) whose basic tasks are: cooling, lubrication, rinsing of sawdust and corrosion protection. Due to the large number of products, which are applied in very different processing operations on materials of different quality, it is difficult to choose the criteria according to which the classification and standardization of SHP would be performed.

According to the ISO standard, it was divided into two categories:

• ISO–L–MH – non-emulsifying oils for metalworking (pure cutting oils)
• ISO–L–MA – emulsion and water-soluble metalworking fluids

Classification of metalworking agents

Classification of metalworking agents according to the area of application

Note: ● – main application ○ – possible application

Classification of non-emulsifying cutting oils according to their nature and properties

Classification of emulsion and water-soluble fluids according to their nature and properties

Non-emulsifying oils for metalworking - pure cutting oils

Non-emulsifying oils for metal processing require extremely good lubrication, withstanding high pressures as well as a flawless appearance of the treated surface. Non-emulsifying cutting oils for metal processing are divided according to the corrosive effect on copper into: inactive and active

Inactive cutting oils are produced on the basis of mineral oil raffinates in several grades. They contain, in addition to oxidation and corrosion inhibitors, appropriate additives in an inactive form based on sulfur, phosphorus and chlorine, which do not have a corrosive effect on non-ferrous metals and their alloys. These oils can be used to lubricate the machine itself and to fill the hydraulic systems of the same machine, as recommended by the machine tool manufacturer. That is why they got the name - three-purpose oils.

Active cutting oils are produced on the basis of mineral oil raffinates also in several grades. They are used in the processing of steel and its alloys, where they give good results due to their pronounced activity. In addition to oxidation and corrosion inhibitors, they contain appropriate additives based on sulfur, phosphorus and chlorine in active form, which react chemically at lower temperatures and adversely affect non-ferrous metals.

Emulsion and water-soluble metalworking agents

Water-soluble coolants and lubricants are usually more complicated in composition than non-emulsion oils for metal processing, because the presence of water brings additional problems such as: stability of emulsions, corrosion behavior, action of microorganisms, etc. Emulsion and water-soluble agents are used in metal processing where in relation to lubrication, primary cooling and sawdust rinsing.

The basic division is made according to the content of mineral oil, ie synthetic components in the following way:

• products with more than 60% mineral oil,
• products with less than 60% mineral oil,
• products based on synthetic raw materials (without mineral oil) and
• products based on soluble inorganic and organic salts and alcohols (without mineral oil)

Products with more than 60% mineral oil give a milky white emulsion (known as 'bohr oil' - drilling oils) when mixed with water. In addition to mineral oil, it contains emulsifiers, bactericides, and may also contain EP additives. Their properties largely depend on the composition of the water, and they are used in concentrations of 3 to 10%.

Products with less than 60% mineral oil in use are most often called semi-synthetic liquids, and differ from the first group in the lower content of mineral oil (usually 30-60%) and higher emulsifier content. Emulsifiers are usually synthetic bases, which is why they are called semi-synthetic products. As emulsifiers are usually a good substrate and food for the development of microorganisms, biostable synthetic emulsifiers have been developed that prevent the development of microorganisms. In this way, semi-synthetic biostable products stable to microbiological degradation have been developed, which enables long-term use without the need for the addition of bactericides. EP additives can also be added and they can be used for difficult processing operations. They look transparent. They are mostly used in concentrations of 3 to 5%.

Products based on synthetic raw materials do not contain mineral oil. These are organic and inorganic chemical compounds, with added additives to reduce the surface tension of water, corrosion inhibitors, and, if necessary, EP additives. They are transparent in appearance and have a very long-lasting use. They have a number of advantages in terms of increasing the cooling and lubricating effect so that the quality of the treated surface is high.

Emulsion preparation

Of great importance to the stability of the emulsion is the way they are prepared. Therefore, the following should be observed when preparing the emulsion:

• you should always add concentrate to the water - never water to the concentrate,
• mix vigorously during topping up, and add the concentrate in a thin uniform stream,
• the concentrate must be at room temperature before mixing, and if it is a longer storage of the concentrate, it must be pre-mixed,
• test the emulsion mixing water and, if necessary, soften, filter, remove microorganisms or increase its hardness (if it is below 5°C or 1 mmol/l),
• adhere to the recommended oil / water ratio and avoid mixing different concentrates,
• do not mix the emulsion in the tank of the machine,
• containers and tanks in which the emulsion is mixed must be clean and should be disinfected from time to time,
• the emulsion should be prepared immediately before use and the concentration examined.

Oils and liquids for metal processing

Recommendations for the selection of coolants and lubricants

When choosing coolants and lubricants, the optimal choice should be sought taking into account all necessary factors such as: types and shape of tools, condition of tools used, conditions of machine tool, specific conditions of machining mode (cutting speed, cutting depth, sawdust cross section, quality of the treated surface), etc.

Pure cutting oils are mainly used in production operations where the primary lubrication is, ie in which the cutting process is performed with relatively low cutting speeds with the appearance of high cutting resistances.

Oil emulsions are used in production operations where the primary cooling is, ie in which the cutting process is performed at high cutting speeds with the appearance of relatively low cutting resistances.

Synthetic solutions are an alternative to oil emulsions, and due to their exceptional properties, they are increasingly used in all types of processing.

Oils for heat treatment of metals

Tempering oil must meet the basic requirements:

• to remove heat from the workpiece at a sufficient speed,
• to cool more slowly in the lower temperature range, to prevent distortions and cracks,
• that it is not corrosive,
• that it is thermally stable, etc.