All About Machinery Lubricants

What are Lubricants?

Lubricants lessen friction between material surfaces. A thin layer is applied to parts that are in direct contact with each other. This allows them to glide past each other unhindered, which in turn minimises heat generation and wear, meaning machines can be operated reliably, reducing downtime and maintenance costs. They also provide better power transmission, cooling, vibration damping, and they seal and protect against corrosion.

Further advantages of lubricants:

• Decreased friction in motors

• Controlled friction in drives

• Protection against oxidation

• Prevention of counter-threads seizing

• Remove dirt and other contaminants

• Reduce the impact high temperatures have on viscosity

• Noise reduction

• Machinery lasts longer

Requirements for Lubricants

Lubricants don't just have to lubricate well. They are subject to mechanical influences (e.g. pressure and shear stresses) and thermal effects. They must also withstand chemical interactions with other substances on surfaces and in the air and they should not succumb to ageing processes.

Types of Lubricant

Different lubricants vary in their nature:

• Solid lubricants (e.g. graphite)

• Semi-solid lubricants (greases or pastes)

• Liquid lubricants (oils and cooling lubricants)

• Gaseous lubricants (air)

In industrial environments and heavy-duty plants, mainly mineral or synthetic lubricants, greases, and synthetic oils are used.

Oil has a particularly high creeping and wetting capacity. It flows even into the smallest gaps and dissipates heat well. However, oiling limits bearing speed and reduces cooling capacity. Lubricating oils are used at high speeds and temperatures.

Grease seals against impurities such as moisture and foreign bodies and stays at the lubrication point. Industrial greases also offer better start/stop performance than machine oil. Preferred areas of implementation are roller and plain bearings, spindles, fittings, seals, guides, as well as chain drives and gears.

Pastes have a higher content of solid lubricants than greases. They are characterised by good separating, lubrication, and anti-rust qualities, even at high temperatures, under extreme pressure and in contact with aggressive media. Lubricating pastes are suitable for screw connections as well as for pressing pins, bolts, and gears.

Which Lubricant is Suitable for What?

In addition to multi-purpose lubricants, many types with specific properties are commercially available for a wide variety of tasks. Some examples are:

• Anti-corrosion: water-resistant and dirt-repellent with a molybdenum base

• Wire cables: dehydrating oil-based lubricant spray especially for use on wet ropes or cables

• Electronics: colourless silicone oil for lubricating, insulating, and protecting sensitive electronic components

• Chain links and chain drives: for use at high temperatures, also available for food-grade applications

• Wood: clear, PFTE based lubricant; also for cardboard, paper and textiles

• Hydraulic systems: temperature-resistant and food-safe lubricant for air compressors and hydraulic equipment

• Pneumatic tools: FPS lubricating spray for dry, non-greasy surfaces

• Hinges: there are several options for hinges, including non-toxic and biodegradable lubricants made from rapeseed oil

• Locks: grease-free, odourless, and antistatic graphite dry lubricant powder and other lubricants for locks usually come in a tube for precise administration

• Valves: metal-free and vapour-resistant high-performance lubricants with graphite/calcium fluoride formula are suitable for valves

Approval Conditions for Lubricants in Food Processing

In cases where lubricants may have incidental food contact, food-grade grease must be used. The National Sanitation Foundation (NSF) determines which types are allowed for which purposes. The USDA also approves lubricants for the food industry. Products with an NSF-H1 certificate or USDA-H1 approval are often of the same grade. Since 2006, the ISO 21469 standard has uniformly regulated food-grade lubricants. According to the EC Directive, these regulations also apply to the production of animal feed.

Lubricants with NSF approval must be tasteless, odourless, and safe. The use of appropriate raw materials affects all components from underlying and base oils to additives and active ingredients to thickeners. They must be free of heavy metals such as zinc and barium and must not contain any organometallic EP additives (e.g. zinc or a molybdenum base). Even approved additives such as sulphur and phosphorus are often limited in their quantity.

If there is any chance of lubricants having incidental contact with food during manufacturing, only NSF-H1-certified products must be used.

Important: Even if these H1 lubricants are considered to be safe, food contamination must be ruled out at all times.

NSF Certifications for Lubricants

NSF H1: For all applications where incidental food contact is a possibility.

NSF H2: Must not come into contact with food. Suitable for all applications where there is no food contact. Free of toxic components.

NSF H3: Soluble lubricants, for example, to prevent corrosion on hooks or knives; must be wiped off before use. Must not come into contact with food.

NSF 3H: Anti-caking agents for production lines with direct or continuous contact with food. Avoid use where food packaging is made, or where food can stick to grills, baking pans or knives.

Food-Grade Base Oils

Base oils are the basis of every lubricant. The four types of food-grade oil approved for food processing are characterised by various advantages and disadvantages:

Lubricant Standards

The standards for lubricants can be categorised as follows. Some regulate designations and others dictate minimum requirements. In addition, there is a comprehensive set of rules on the permissible test and test procedures.

Examples:

• DIN 51503 Minimum requirements for refrigeration oils

• DIN 51517 Minimum requirements for lubricating oils

• DIN 51520 Minimum requirements for cooling lubricants

• DIN 51524 Minimum requirements for hydraulic oils

Properties of Lubricants

Physical key figures describe the most important properties of lubricants and help you find the right lubricant. Which lubricant is suitable for which task depends on the material and processing steps as well as the tool surface and processing speed.

Temperature also plays an important role.

• The density of a lubricant depends on pressure and temperature. The higher the density, the greater the possible performance losses

• Viscosity: The flow properties determine the creep capacity of the lubricant. They help measure the thickness of the oil layer between two surfaces. The viscosity index describes how the viscosity changes as a function of temperature

• The aniline point indicates the lowest temperature at which the aniline and oil of the lubricant still form a mixture. Aniline serves as an additive of lubricants in the production of fuels. It is of particular importance when used in motors

• The dropping point indicates the temperature for the transition from semi-solid to a liquid state. This is important for processes with high temperature effects

• The setting point indicates the lowest temperature at which lubricant still flows. This is particularly important for cold-intensive processes

• The flash point indicates the temperature value at which a flame is immediately formed by contact with an ignition source. The focal point is slightly higher; a persistent fire can be triggered at this temperature. The temperature at which a flame is produced even without an external ignition source is called the ignition point

• The neutralising capacity indicates how much potassium hydroxide is needed to balance free acids in the oil. It is crucial for the ageing of lubricants

Popular Manufacturers & Brands

Well-known lubricant manufacturers include Ambersil, CRC, Rocol, RS PRO, SKF, and WD-40. In addition to these brands, we also stock lubricants and greases from Klüber, which are characterised by their resistance to oxidation and aggressive chemicals.