The significance of metalworking fluids is widely recognized, but very often treated as a support function (necessary but not important). The average MWF cost in any industry will be approximately 10%-20% of the Total Production Cost. The TCO (Total Cost of Ownership) of MWF has 2 components: MWF Purchase and MWF Management. Of these, MWF Management is a significant contributor of TCO. Any lapse or gaps in fluid management beginning with proper fluid selection will result in a planned failure today (“parts” quality issues) and tomorrow (machine tool deterioration). To properly manage MWFs, we need to have a robust process.
Some predominantly common issues or challenges in a machine shop include: smell, skin irritation, tool life, corrosion, residue, paint peel off, foam, etc. It is very difficult to pinpoint the root cause of these issues because these variables (which include concentration, pH, water quality, tramp oil, filtration, etc.) could interact with one another or help to mask the root cause. Many times a solution to an issue or problem in one organization/machine shop may not be the proper solution for all shops or even a similar machine. In this case, you need to have preventive measures in place that will deter any of those challenges, yet remain within operational limits.
The Coolant Management Concept described here as “6C,” is a fundamental, systematically choreographed process, to effectively manage metalworking fluids. It works to hold the variables within operational limits, thereby increasing productivity and performance in all areas of the metalworking application.
This article starts with the assumption that the right coolant has been selected for the application. You may ask why I’ve made this assumption – that the coolant selection process is “application-manufacturer” dependent. As the process variables are relatively large and highly interactive, the same coolant may not be necessarily suitable for the same application across different industry segments or sometimes even within same industry at a different location. Therefore, coolant selection must be done in conjunction with the manufacturer. However, the 6C-MWF Management concept presented here is generic and “application-manufacturer” independent.
All types of coolant, whether expensive or economical, have a designed life expectancy as determined by its chemistry when it is created and produced. However, the coolant life expectancy is determined by the biology (bacteria/fungi) of the coolant environment where it’s used. Even though most coolant manufacturers claim their coolant life as x+ years as compared to their competition – this figure is based purely on the design chemistry, and does not take external factors like environment and biology into account.
As a concept, 6C is presented here is to demonstrate how to institutionalize a coolant management system that will effectively increase coolant life to its designed life expectancy levels thereby reducing consumption, improving performance of the machine tool (in terms of tool life, component finish, machine down time) and reducing disposal costs.
With this background, we’ll proceed by describing each “C” in the process. This article will address the first “C”: Circulation.
The method of mixing for circulation forms an important beginning in the coolant management cycle. “Premixed coolant” addition is generally the best way to add new coolant into the machine. This ensures homogeneity in the fluid. Premix is done either through automatic mixers or manually mixed by hand. Especially when handling emulsion products by hand, one must ensure to add coolant OIL (Oil In Last) into agitated water to set the fluid emulsion. This fluid emulsion has small oil droplets suspended in water phase that penetrate the point of cut better and reduce carry off of the fluid system. Note: adding water to the coolant oil will form a reverse emulsion or thick emulsion and this is not what we want to achieve!
On most shop floors, coolant mixing is an outsourced activity and the person involved is rarely trained to do the pre-mix. Thus the 1st C of the “6C” concept emphasizes the importance of having good mixing and circulation process which forms the foundation for realizing effective coolant value. It is generally recommended to utilize an automated mixer which could be a low end venturi type or high end proportional pump. Depending on size and usage volume, the benefits of purchasing a mix system would be shown within 6 months.
The next installment of this article, which will cover the next two “Cs” in the 6C process, will appear in the January issue of the MWF Newsletter.
M. Krishna is the Managing Director at Master Chemicals India in Pune, India. You can reach him at firstname.lastname@example.org.
Other articles from this issue: