Is Your Coolant Costing or Saving You Money?
Posted by Michael S. on May 5, 2017 in Manufacturer Focus

If you do any machining in your business, whether it is conventional or computer numerical control (CNC), you have to work with coolant. During my years as a machining and manufacturing manager, I had monthly coolant bills that ranged from $5,000 to $9,500. The coolant costs ensured we could operate at a high level on a 24/7 schedule.


As with so many other areas of manufacturing, we have seen drastic improvement in coolant over the years.


It is good practice to review your current coolant’s performance and your needs on a regular basis. Newer, improved, or specialized coolants may give you more bang for your buck and help save you money.


To get to the bottom of how coolant is affecting manufacturers today, I had a discussion with Michael Harris, one of my former coolant suppliers. He talked to me about how coolant has changed over the years and some best practices to follow when using coolant.


Before talking about specifics, let’s cover the basics. Your coolant should:

  • Control temperature by removing heat from your tool and part.
  • Allow you to push your machine and machine tool to the max.
  • Remove chips.
  • Improve surface finish.
  • Offer corrosion protection for your parts and machine tool.
  • Keep employees, parts, and the environment safe.


Coolants can be grouped into four categories:

  • Neat cutting oils—usually made out of petroleum oils and used without being diluted.
  • Synthetics—no petroleum oils in the formula.
  • Semi-synthetics—have less than 50% oil in the formula.
  • Soluble oils—contain 50% to 90% petroleum oil.


Some vendors might use names like neo-synthetic, nano-technology, or micro-emulsions, but none of these terms have been standardized or accepted in the industry. When you hear one of these terms, ask which of the four major categories the coolant falls into.


Each of the four main categories has advantages and disadvantages. Before calling a coolant vendor, ask yourself the following questions:


  • What metals and alloys are you machining (e.g., steel, titanium, aluminum)?
  • What is your machining application (e.g., milling, grinding, honing, turning)?
  • What is your water quality? What is the pH level?
  • What are some of the issues you are currently experiencing in your machining operations (e.g., tool wear or buildup, odor, operator acceptance, separation, part or machine corrosion, cost)?


Now that you have done your homework and the coolant rep is in-house, ask the following:

  • How can you help me produce the best quality part at the lowest cost?
  • What will you bring to my company?
  • Are you up to date with environmental compliance requirements?
  • What services do you offer (e.g., testing, innovative products, engineering and equipment solutions)?
  • Do you offer coolant maintenance and management programs?
  • Can you help with coolant disposal?
  • Are you global?
  • Why should I buy from you?


Your next step is to understand coolant maintenance. One of the most important aspects is maintaining the coolant concentration. Here are some key coolant mixing and maintenance tips

  • Always fill sumps with water first and then add coolant.
  • Compensate for drag out, evaporation, and other losses with pre-mix.
  • Again, with pre-mix, water goes in first.
  • For most highly machinable alloys, a 5-7% solution will do.
  • For more difficult materials, shift to an 8-10% solution.
  • If you have to operate above a 10% range, consider a coolant that is highly fortified.


Once you select a coolant and have charged your machine, maintenance becomes your number one priority. Don’t take this lightly. Whether you run a central system or each machine has its own tank, this is where you can save a lot of money and time.


Concentration control is important. If your concentration goes out, your coolant will lose its performance and you lose money. If you have relatively few machines, check coolant with a Refractometer. If you have multiple machines or a central system, you should consider automating your monitoring system. There are a variety of inline systems, such as the Houghton ACTS™ Fluid Monitor or the Greenlight™ Fluid Monitor. Some will even provide the ability to monitor remotely. Another thing to consider is the use of bio stable coolant, which minimizes bacterial and fungal growth issues.


Depending on your situation and your maintenance staff’s workload, you may decide to outsource coolant management. This is a good way to ensure you have an expert maintaining your coolant at top capability.


It may not make financial sense to recycle coolant. If you use a low cost, simply formulated oil and emulsifier, in most cases recycling will not pay. In those coolants, the emulsifier is more prone to instability and biological issues. Dispose of it in accordance with environmental regulations. Premium coolants are almost always cost effective to recycle. A simple way is to let the coolant settle, remove the tramp oil from the top (skimmer), and let the chips settle. You can also use a centrifugal system, which helps to speed up the process. Correct the concentration of the reclaimed coolant before returning the clean fluid to your machines.


Working with a good coolant vendor can really help save you money. They know the cost of new coolant and the benefits of recycling.  Ask what they can bring to the table to help you save money. In the past, I had coolant vendors design and build coolant-recycling systems.


When working with potential vendors on developing the best possible coolant solution, be open to ideas. This might be an approach to one coolant for all applications, giving up some benefits in some areas, or multiple coolant solutions for specific applications. A lot of money is riding on your coolant decision—not only the cost of coolant, but also tool life, machine utilization, maintenance, process variations, and operator and environmental health.


One more piece of advice, stay away from vendors that just want to sell you coolant. Also, as with all investments, shop around and get multiple vendors in so you can make the best decision for you and your company.

Michael S. is our Manufacturing guru
I have over 40 years experience in a broad range of manufacturing areas. Starting with an apprenticeship in Germany I’ve worked my way through a variety of positions within the manufacturing field. I got my start as a Tool and Die maker. I next became a supervisor of a class A tool room, then manager of a machining department. I was exposed to lean manufacturing in the mid 90s and adapted the lean philosophy. Loving and teaching the lean approach, I moved on to become a Continuous Improvement manager which led to a job as a manufacturing manager. I joined Acuity in 2015 as their manufacturing expert. I hope to evolve how manufacturers deal with and think about insurance companies, as well as be a resource to my fellow employees – enabling them to better understand the unique needs of manufacturers.

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