In metalworking processes, lubricants play a pivotal role. The point of contact between the tool and the workpiece, they act to ensure smooth working, heat regulation and a safeguard against damage to either the tool or the material. Depending on your requirements, it is necessary to find the most appropriate kind of metalworking fluid to use. Let’s take a look at what these different kinds are, and what they are made of.
General properties of metalworking fluids
Metalworking fluids are designed with key properties such as high heat-absorbing capacity, allowing them to efficiently cool tools and workpieces during machining. They also have a high flash point to ensure safety at elevated temperatures, and are non-corrosive to protect metal surfaces. Additionally, these fluids offer excellent lubrication properties and remain odourless and stable over time for comfortable and prolonged use.
Types and uses of metalworking fluids
At its most basic, metalworking fluids are composed of different fluids in different amounts. Primarily made of oil and water, there are also performance additives that aid the work of the lubricants.
Depending on the purpose for which the fluid is prepared, the varying degrees of oil and water have varying advantages and disadvantages. For example, a greater amount of water is excellent for cooling but not great in lubricating, while mineral oils are the opposite. There are four basic types of metalworking fluids, which can be categorised as the following:
- Straight oils or Mineral Oils
These are typically petroleum-based oils that are used for drilling, tapping, milling and turning. They also have extreme pressure additives to enhance the performance, which makes them ideal for slower operations where a highly effective lubricant is required. Straight oils are used as received without any mixing, and are also useful in preventing corrosion of any kind.
- Soluble oils
They are also known as emulsifiable fluids and often contain around 30-50% oil along with various additives. The concentrated fluid is mixed with water before use. Mostly, solubles are used in large-scale operations as they provide both excellent lubrication and cooling. Due to the mixing, solubles often appear milky-white, and are some of the most common of the metalworking fluids.
- Synthetic fluids
These fluids are primarily composed of water which have numerous additives in order to enhance performance. Some may require further dilution with water, and are mainly used in areas of work that require fast cooling, such as high-speed processes where heat cannot remain for too long. A higher concentration of additives allows them to last longer. These appear clear and provide very low foaming, which is considered to be a positive characteristic.
- Semi-synthetic fluids
Comprising approximately 35% oil, these fluids are a combination of oils and synthetic fluids as well as water. The concentrate is further diluted to create the finished fluid. Semi-synthetic fluids have a translucent appearance. Despite being difficult to formulate, these fluids are becoming increasingly popular for their optimal balance of lubrication and cooling properties, along with their clean and efficient performance.
What kind of metalworking fluid you choose depends on multiple factors, such as type of workpiece material, the operating speed, the type of operation, the machine tool, the fluid maintenance demands, etc. Using the appropriate metalworking fluid results in optimal processing, longer tool life and better maintenance.
