July 30, 2015 / best practices, blade failure, blade life, Cost Management, cost per cut, LIT, preventative maintenance, resource allocation, ROI
As any machining expert will tell you, coolants are a critical part of the metal-cutting process. While they are an added cost and an added step in the production process, the long-term cost benefits of coolants are worth every dime and every minute spent. This is especially true if your goal is optimization. As an article from Production Machining states, manufacturers should view coolants as an asset or, better yet, a “liquid tool.”
Unfortunately, many managers and operators fail to understand the importance of proper lubrication during the metal-cutting process. According to Modern Machine Shop, most manufacturers see lubricant as “the least important factor in the total cost of machining and the last place to look for process improvements.” In fact, it is common for companies to often “cheat” on the proper concentration levels of metal-cutting fluids in order to save money. This may reduce coolant costs in the short term, but the high costs of machine wear and tooling replacement make this a poor management choice.
As explained in the white paper, Understanding the Cut: Factors that Affect the Cost of Cutting, coolants provide lubrication, which is essential for long blade life and economical cutting. Properly applied to the shear zone, lubricant substantially reduces heat and produces good chip flow up the face of the tooth. Without lubrication, excessive friction can produce heat; high enough to weld the chip to the tooth. This slows down the cutting action, requires more energy to shear the material, and can cause tooth chipping or stripping, which can destroy the blade.
Like any manufacturing tool, proper use and coolant management is essential if you want to get the most out of your investment. To help ball and roller bearing manufacturers ensure proper lubrication management in their metal-cutting operations, the LENOX Institute of Technology offers the following five tips:
- Start with a clean machine. As an 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.
- 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. One way to remember the proper technique is by the acronym O.I.L. (Oil In Last).
- 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.” 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.
- 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.
- Make coolant checks part of everyday maintenance. Instituting regular coolant checks as part of a preventative maintenance program or daily operator checks can eliminate unnecessary tooling costs and maintenance downtime. Low coolant levels on a band saw, for example, can lead to premature and uneven wear of band wheels, which typically cost $1,000 each.
While coolants may feel like just another cost item on your consumables list, they play an important role in keeping maintenance costs down and cutting tool performance high. By following a few best practices, ball and roller bearing manufacturers can ensure that their metal-cutting coolants are not a necessary evil, but an opportunity to improve process efficiencies.