Metalworking oils, sometimes referred to as metalworking fluids, is an umbrella term for an extensive selection of different lubricants designed to assist in metalworking processes. The oils are engineered to perform specific roles such as cooling, cleaning and lubricating while processes like machining, grinding, cutting, and milling occur.
High-quality metalworking oils are vital to machining as they are designed to reduce the heat and friction generated between a workpiece and the cutting tool effectively. This can mitigate multiple side effects of machining, like burning and smoking. However, metalworking oils do far more than act as coolants. When applied correctly, they can also refine the quality of the workpiece in production by continuously ridding the work area and cutting tool of chips, fines and swarfs, which are different sized shards of metal removed during metalworking processes.
The wider benefits of oils in metalworking extend beyond the cooling, cleaning, and lubricating they carry out. They are also of key importance for their protective properties, which safeguard equipment from short-term and long-term damage. This can lead to stoppages in productivity and a loss of investment when machinery can no longer function.
Here, we’ll take a deeper look at the critical roles that metalworking oils execute and explore some of the different oil types deployed in detail.
Understanding the five jobs of a metalworking oil
As mentioned, metalworking oil is a multi-purpose solution designed to facilitate different metalworking process. Below we’ll examine five areas metalworking oil must assist with.
Reduce friction
A core function of every metalworking oil is to effective decrease friction at the tooling area where metal-on-metal contact is inevitable. Reducing friction levels has several operational gains. These include lower energy consumption to create the parts and far less drag on metal, which creates a more consistent flow of metal arriving through the machine’s forming die. Lower friction also decreases the number of unwanted particles within the punch area, and commonly results in much less debris build-up clogging and cluttering up key work areas.
Protect
A key job of metalworking oils is to efficiently separate the workpiece and the machine tool. Oils with optimum viscosity can create a protective film that can block contact in between them and safeguard the tooling. The reason this film is so important is because tooling costs are substantial. Fortunately, a high-quality metalworking lubricant has the power to cover its own cost while extending tool providing excellent economy.
Clean
Metalworking oils must also promote cleanliness during all metalworking processes and facilitate in always creating as well as maintaining a clean operating environment. However, metalworking oils used must never be difficult to remove from a newly formed part. They must also be able to prevent a build-up of any unwanted deposits. Health and safety regulations also insist that they are completely compatible with and cleaner or degreaser deployed.
Cool
While this isn’t recognised as their key attribute, metalworking oils can also serve a coolant. It is a given that in most types of metalworking operations, extreme heat is a critical element present. When required, specific types of metalworking oils are designed to deliver cooling properties to key work areas, reducing operating temperatures to keep machines working within acceptable parameters without risk of damage or danger to health and safety.
Corrosion control
Metalworking oils must also work to keep any corrosive forces present under control. As well as inhibiting corrosion, a metalworking oil must also work to defend the main body of the machine, as well as its key components like the guides, slides and punch, against potential damage inflicted by wear particles.
These critical functions of metalworking oils are the cornerstone of their importance during a wide variety of processes.
What are the different types of oils used in metalworking?
The metalworking industry is fiercely competitive and as a result, the machinery involved typically operates at extreme work rates and loads and under intense conditions. To ensure machines run effective, several different oil types are used to aid equipment and processes. Below are some of the most used metalworking oils today and the crucial roles they play.
Cutting oils
These metalworking oils are frequently used to protect equipment by cooling and lubricating cutting tool edges. When processes involve working with softer metals, cutting oils are especially important as more heat is generated. Water-based cutting oils are sometimes selected for their cooling qualities, and oils are enhanced with additives that improve lubrication or the wear protection they provide.
Removing heat is a primary function of cutting oils. The oils cool down the tool as well as the workpiece. In cutting process, the oil passes over both areas and heat is extracted via conduction. To decrease thermal stress and metal expansion, removal of excess heat is vital. The ability of a cutting oil to maintain a consistent temperature can mitigate thermal distortion producing work of higher quality.
Cutting oils were specifically engineered for use in metalworking. Oils are applied within the machining zone to effectively reduce friction levels in between the chip, tool and workpiece. However, oils can also be used as a rust preventative and to clean work areas by flushing out chips and other unwanted debris. Loose chips are most common when high cutting speeds are in use.
The operational and cost benefits of cutting oils is that they create a stable workplace and extend the lifespan of the tool’s cutting tip by properly lubricating its working edge, reducing the chance of tip welding.
Grinding oils
These oils are used to enhance metalworking processes. They are designed to stop metal debris from accumulating on the surfaces of the machine’s grinding wheels. However, grinding oils also have both anti-corrosion and cooling benefits. Grinding oils are available for use on cylindrical, centreless and creep feed industrial grinders. However, selecting the correct oil always depends on the metallurgy of the parts being ground, hardness and composition of the grinding wheel used, total material removed, and the finished parts surface finish requirements among other factors.
Water soluble oils, as well as solution synthetics, are often used in grinding operations. Usually, water soluble oils have a concentration range from around 5% to 15%. Semi-synthetic solutions contain mineral oil, at a lower percentage in comparison to water soluble oils. They provide excellent bio-stability, lubricity and are clean to use.
Choosing the correct grinding oil for an operation is critical and after the oil is inside the machine it’s equally important to apply it properly. The grinding wheel ferries the oil around and inside the arc of the cut. As a result, the oil must be added to the outside of the grinding wheel just before the point at which it enters the cut’s arc.
Release oils
Release oils, also referred to as mould oils, are lubricants utilised in metalworking operations to prevent materials sticking to moulds and dies during production processes. These oils are applied to the mould’s surface prior to introducing metal into the mould’s cavity. The core purpose of release oils is to make it a cleaner and easier task to release a finished product from a mould, while simultaneously maintaining the mould’s integrity
Rolling oils
These lubricants are designed to be applied during metal rolling processes, and provide a smoother finish on completed products. They facilitate a reduction in thickness of a wide variety of metals when required, including aluminium, copper, and alloys of steel. Oils are typically organic in formulation and applied either straight or mixed with water, like an emulsion.
Heat Transfer Oils
Heat transfer oils are formulated to convey thermal energy away from the work zone during processes. Effective heat transfer can have multiple benefits to operations. It can reduce heat-related damage to the overall machine as well as the tooling. However, it can also help maintain correct temperature levels of the workpiece ensuring it does not become distorted or damaged.
Quenching oils
These built-for-purpose oils are often employed in steel working. They are designed to change the structure of metal as it starts to cool. Oil is often used to support quenching activities because it can transfer heat rapidly while not causing the metal to distort substantially. Water-based quenchants can cool even faster, but often result in distortion and cracking of materials.
Oils are also very flexible. Their temperature, viscosity, and other properties are adjustable with different additives designed for various purposes. As Quenching oils are versatile and can be controlled, they can be used to streamline metalworking operation.
Quenching oil has two key functions. First, it hardens the component via control of heat transfer during the quenching process. Second, it enhances the wetting of the part to minimise undesirable conditions that could cause cracking and distortions. There are multiple types of oil employed in quenching, but the two most commonly classes are hot oils, and fast oils.
Hot oils are deployed at high temperatures ensuring that the surface and core temperatures of a part don’t vary during quenching. This lowers the risk of cracking and distortion. Quenching with hot oils can take longer but provides more uniform cooling throughout the part’s cross-section. As implied by their name, fast oils cool parts quickly. Specially formulated, they reduce the length of the vapour stage while extending the boiling stage length.
Operational advantages of metalworking oils
Finally, while oil plays a critical role in supporting metalworking processes helping machines perform effectively and parts produced provide higher quality finishes, they are also critical to the success of every metalworking operation. By enhancing processes and protecting equipment from harm, plants can access seamless productivity with minimised maintenance and operational downtime. Oils also safeguard the onsite equipment which typically represents a significant investment. As a result, these cutting-edge oils designed to serve a wide variety of requirements will always be a critical element of any metalworking facility.
