Metalworking Coolant Selection
Choosing the Right Metalworking Fluid
Proper metalworking fluid selection is essential to successful machining. For example, some lubricants and corrosion inhibitors are targeted specifically to work with certain metals, so choosing a metalworking fluid designed for aluminum might give poor performance if it is used strictly for ferrous metals. Metals that corrode easily will require an oil-based product and some hard-water situations call for specific metalworking fluids. Choosing the wrong metalworking fluid can be a costly mistake on many fronts, so start off right by choosing the appropriate metalworking fluid for the job. Most fluid manufacturers have a team dedicated to helping companies in their product selection process. There are three major classes of metalworking fluids and they each carry their own inherent advantages and disadvantages. All metalworking fluids will lubricate, cool the metal, carry off chips and provide rust protection for the work piece and the machine. However, the huge number of available ingredients makes it possible to create an infinite number of variations.
Water-Soluble Oils
Water-soluble oils are the workhorses of the metalworking industry. They are most commonly used for CNC machining of ferrous metals but can be used in a wide variety of applications. They leave behind an oily layer on the parts and machines, which acts as a rust preventative. When the coolant is used properly, it is very uncommon to have rust problems. The disadvantage of the water-soluble oils is that they will emulsify tramp oil (hydraulic oil, spindle oil, etc.) until the tramp oil becomes part of the coolant. This weakens the emulsion stability of the metalworking fluid and can eventually cause the coolant to separate.
Synthetic Metalworking Fluids
Synthetic metalworking fluids lend themselves well to grinding and light-duty machining. Synthetics work great for grinding because they allow for swift settling of the small fines created during grinding. Grinding fluids should be cleaner than machining fluids because they cover a larger work area and can splash more than a machining operation. Whereas water-soluble oils will absorb tramp oils, synthetics typically will reject the oils – allowing them to be skimmed from the surface of the metalworking fluid. In some applications, this feature allows synthetics greater longevity in the sump. Many synthetics work well for machining all metals and some of the newer and more expensive synthetics can approach the tool life of water-soluble oils. The disadvantage of synthetics is that some components such as lubricants and rust preventives can be used up before the rest of the metalworking fluid.
Semi-Synthetic Metalworking Fluids
Semi-synthetic fluids are a good compromise between the water-soluble oils and synthetics – they are hybrid products of both water-soluble oils and synthetics. Therefore, they carry both the advantages and disadvantages of both groups. Semi-synthetics are less likely to cause rust than synthetics, will still provide rust protection because of their oil content and will emulsify tramp oils. Semi-synthetics are suited ideally for machining and grinding of cast iron.
Manufacturers will formulate different grades of products, so that there are products available for all types of machining operations. Each category of coolant can have low- to high-grade products. Typically, the higher the price of the product, the better performance it will give. Just because a metalworking fluid is lower in price does not mean that the customer will save money in the long run, because tool life can be affected greatly by metalworking fluids. To get the most out of your metalworking fluid, select the right metalworking fluid to begin with, then adhere to a good sump maintenance program.
This entry was posted on August 20, 2008 at 6:07 pm and is filed under Rustlick. You can subscribe via RSS 2.0 feed to this post's comments.
Tags: coolant, lubricants, metalworking fluids, semi-synthetic, synthetic, water-soluble
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