Category: Metal Working Fluids

Coolant concentrate cost isn’t just what you pay per gallon—it’s what your process makes you consume. The chemistry of the concentrate drives how well the coolant solution “sheds” off chips and finished parts. When shedding is strong, chips dump drier, parts come out cleaner, and less coolant leaves the sump with every load of scrap or finished product. That typically allows makeup solutions closer to ~2% instead of 5–7%, cutting concentrate use dramatically in high-production environments where top-offs happen every shift. Add in the effect of water quality—where hardness can quietly reduce coolant performance and increase carry-off—and it becomes clear: controlling shedding, makeup concentration, and water condition are three of the fastest ways to lower coolant spend without sacrificing machining performance.

How the Coolant Concetrate Affects the Cost

First, we need to consider the coolant concentrate; that product purchased to enhance your machining performance. The chemistry behind the product is the foundation, having a product which focuses on improving the “shedding action” of the coolant solution from chips and finished parts produced in the process. (With our Metal Working Fluids, we custom tailor each customer’s coolant to best suit their specific product and equipment needs.)

This shedding action can be confirmed by drier chips in the chip hopper, fluid running out of the chip hopper when dumped, and by the finished part itself being cleaner as it is taken out of the machining cell.  The coolant solution is removed from the machine by chips and finished parts, more coolant solution (coolant concentrate + water) needs to be added to the machine sump.  In high production situations, these additions can happen with every shift change.

Make up solutions can be pre-set to save you money.

• One other sign of heavy coolant consumption can occur when proportional mixing systems are pre-set for the make-up concentration to keep the machine concentration at a targeted percentage.
• Coolants with excellent shedding action require a much lower make up solution of around 2%, coolants that don’t have the shedding characteristics will be in the 5-7% range depending on the machining application.  With a coolant that sheds the coolant solution from the chips and finished parts, water evaporation plays a bigger role with the make-up coolant solution allowing you to target the 2%.
• In other words, if the machining center’s coolant sump solution should be maintained at 7%, then the makeup coolant solution should be approximately 2%.  Any percentage above that 2% should be viewed as a possible carry-off problem.

Water Quality Effects Carry-off.

Another dominant influence impacting high carry-off is water quality.  If not using conditioned water, such as RO or DI, water hardness begins to climb with every addition to the machining sump.  Eventually, the water hardness becomes so high in the system that the coolant solution will begin to lose its effectiveness, losing the very qualities that it originally had at the beginning of a machine sump changeout.

Signs your water is effecting your coolant

• The coolant solution tends not to shed, but clings to finished parts, chips, and even the surfaces of the machining cell.
• Windows become foggy with residue, along with sticky residue inside and outside the machine.
• Get close to the machine and it feels like walking on fly paper.

Operator Indifference

Lastly, coolant consumption can also be caused by operator indifference. Most coolant concentrates have a target percentage for the solution to machine based on the application.

Let’s use 7% for this target as an example, which should be checked daily, if not per shift, with a refractometer.  The refractometer reading, when calculating the refractive multiplier of the coolant will give accurate machine sump concentrations.  Keeping the machining sump at the correct and consistent concentration will improve tool life, part finish, and coolant consumption.

Other variables do play a part in coolant consumption.  Air blow-off of part before it leaves the machining cell, angle and speed of the chip conveyor, chip size and shape, and the configuration of the part itself, all play a part in coolant consumption.

If your sump target is 7% but your makeup mix has to be set well above ~2% to hold that number, treat it as a signal—not a normal setting. Start by confirming carry-off (chip/part wetness and residue), then check water quality, and finally tighten daily concentration control with a refractometer so the coolant stays consistent shift to shift. Once those basics are locked in, you can fine-tune secondary contributors like blow-off practices, conveyor angle/speed, and chip characteristics. The result is simple: less concentrate leaving the machine, steadier performance, and a lower true cost of coolant.