November 20, 2014 / best practices, blade failure, Cost Management, LIT, preventative maintenance, productivity, quality, resource allocation
As any maintenance manager can attest, coolants are a critical part of any metal-cutting operation. They save you maintenance time, improve cut quality, and extend tooling life. They also save you money. For example, according to this white paper, low coolant levels on a band saw can lead to premature and uneven wear of band wheels, which typically cost a whopping $1,000 each. By instituting regular coolant checks as part of a preventative maintenance program or daily operator checks, managers can eliminate unnecessary tooling costs, as well as the time needed to replace the band wheel.
However, understanding the purpose of metal-cutting fluids and actually knowing how to properly use them are two different things. Like any other tool used in your shop, getting the most out of your metal-cutting coolant requires some know-how. Below are some tips to ensure you are properly using metal-cutting fluids in your machine shop:
- Start with a clean machine. As this article from MoldMaking Technology explains, proper metalworking fluid management starts with the draining, cleaning, and recharging of the machine. When changing coolants for any reason, clean and disinfect thoroughly with a fluid advised by the supplier of the coolant. The function of the cleaning is to soften dirt and to kill bacteria in the machine, especially on difficult places such as pipes and pumps. For some detailed cleaning tips, check out this fact sheet from the Ohio Environmental Protection Agency.
- A proper fluid mix is key. Extending the life of your fluids and achieving the best fluid performance starts with proper fluid preparation. Metal-cutting fluids need to be mixed a certain way in order for their chemical makeup to be correct. Experts recommend pouring the water into the mixing container first and then stirring the coolant concentrate into the water. According to an article from Production Machining, one way to remember the proper technique is by the acronym O.I.L. (Oil In Last). When mixing fluids, the Iowa Waste Reduction Center, recommends that concentrate and water should always be mixed in a container outside the sump. Although mixing directly in the sump is a quick and easy method of fluid preparation, it can result in incomplete mixing and improper fluid concentration.
- Remove tramp oil to extend fluid life. Waste oils, which come from the machine or surfaces of the raw materials, are often picked up by the metalworking fluid and are referred to as “tramp oils.” As this article from Modern Machine Shop explains, regular removal of tramp oil from the manufacturing process helps improve fluid performance and longevity, air quality, bacterial resistance, corrosion resistance, and tool life. Typical methods for tramp oil removal include regular inspection and the use of skimmers, centrifuges, and coalescers. There are also several proactive strategies shops can use for reducing contamination from tramp oils. Using concentrated metalworking fluid in the gearbox as a tapping fluid can reduce extraneous contamination, and covering the sumps with screens or solid covers can also help reduce ongoing contamination problems.
- Monitor fluids regularly. Measure, with a regular frequency, the concentration and quality of your fluids. Testing tools include refractometers, which can quickly determine the total amount of solubles in a solution, or titration kits, which are more extensive and are used to analyze fluid concentration in metal-cutting fluids contaminated with tramp oils. Tests for PH levels and alkalinity can also be useful, as pH readings outside the acceptable range indicate a need for machine cleaning, concentration adjustment, or the addition of biocide.