Machine
shops spend ten times or more money on tools for machining
than they spend on coolant. Sometimes not much thought goes
into which coolant is used or how it is used. In today’s
market new methods of machining are being explored with
tools designed to vastly increase production. Along with
the “new” tools come “new” concerns
regarding coolant. Today, you need to ask more than just,
“which coolant is the best for the job?” but
also, “what can I do to improve my total process?”
Here,
we are going to explore the steps necessary for saving big
money on your coolant usage, including ideas on waste disposal
and how to improve your total machining process.
1.
Water
All
water is not created equal. Most people agree that spring
water or water from a well tastes better than distilled
or treated city water. Well water tastes better because
it is rich in minerals. But what tastes good may be robbing
you of tool life and finish.
You
might think that softened water would help, but softening
merely removes the calcium and magnesium from the water
and replaces those ions with sodium ions. The trouble starts
when those sodium ions are mixed with a coolant that contains
chlorine compounds. The result? This mixture produces sodium
chloride—that’s table salt—and you end
up with rust problems.
If
you want to save 20-30 percent on your total coolant usage,
the answer is not to soften your water but instead to treat
it to improve its quality.
De-ionized
(a.k.a. DI) and Reverse Osmosis (a.k.a. RO) are two methods
of removing water contamination and improving your total
process. Your local water treatment company is familiar
with both types of systems and can discuss which water process
is best for your operation.
When
you improve the quality of your water supply, your coolant
will not only last longer but you will also realize another
money-saving benefit—you will greatly reduce your
coolant disposal costs.
2.
Tramp oil
Tramp
oil is the uninvited dinner guest that shows up when and
where it is least wanted. This being the case, we can’t
ignore this party crasher’s presence.
Tramp
oil sneaks in from leaking hydraulics, gear and way oils,
and from parts coated with oil that are ready for machining.
Tramp
oil offers no advantages, only disadvantages. For example,
it shortens coolant life; aids bacterial growth; interferes
with rust protection and, perhaps worst of all, it prevents
adequate separation of metal fines.
A
common method for removing tramp oil from your coolant is
with the aid of an oil skimmer. Oil skimmers come in a variety
of shapes and sizes, some of which are advertised in this
magazine. They vary in price almost as much as they vary
in design. Regardless of which skimmer type and price you
choose, an investment in removing tramp oil will always
result in an improved process.
3.
Metal fines
Once
you’ve treated your water supply and put skimmers
on all your machines, the next step is to remove metal fines.
This is not the same as removing chips from the machines.
There are many different mechanical devices designed into
most machining centers that carry chips into a hopper for
easy removal and disposal.
When
we talk about removing metal fines, we are talking about
removing those particles of metal that are so tiny they
exist at the micron level. This will require filtration
such as paper rolls or cloth bag filters. It’s most
important to minimize those particles that could interfere
with exceptional machining finishes. Very fine metal particles
prevent tools from working at optimum performance. Machining
aluminum, for example, yields aluminum chips and fine particles
of aluminum. As the coolant becomes saturated with these
aluminum particles, the coolant’s ability to continue
to provide rust protection is impaired. The aluminum particles
oxidize into aluminum oxide—the same material used
as an abrasive for grinding wheels and sharpening stones.
It is easy to see how this same aluminum oxide will interfere
with achieving an excellent finish by getting between the
tool and the work piece.
Similar
problems exist when machining all types of metal. Anything
you can do to improve filtration will extend coolant life.
And once again, longer-lasting coolant improves your total
process.
4.
Concentration control
One
of the easiest and least expensive steps you can take to
improve coolant life and performance is to regularly monitor
the coolant concentration with the use of a refractometer.
Maintaining coolant concentration at a consistent level
helps avoid both rust problems that arise when coolant is
too weak and skin irritation issues that flare up when the
coolant is too strong.
A
very good quality refractometer can be had for less than
$100. You will save more than the cost of a refractometer
just from the first drum of coolant you use while monitoring
its concentration.
5.
Using the right coolant to begin with
We’ve
all heard the old saying, “You have to spend money
to make money.” Well, sometimes, “You have to
spend money to save money.” Let me explain how this
works regarding coolants.
If
you go through the process of improving your water, removing
tramp oil and metal fines, and even invest in a refractometer,
you might still be making a mistake if you are not using
a high quality coolant.
There
are many different coolants available today. They vary in
color, price and quality. Just as there have been major
improvements in the quality of tooling available on the
market, there have been similar improvements made in coolant
formulations. Yes, these new and improved coolants may cost
more but your added investment will reap better tool life,
improved sump life, and increased operator acceptance.
I
must also add that you will see improved cost-effectiveness.
Let me give you some examples.
Let’s
say that you are using a coolant that costs $10 per-gallon
and the recommended use concentration is 5 percent to 6percent;
however, you know that you will get better tool life if
you run the coolant at 10 percent to 12 percent range. A
new, high performance coolant that costs $15 per gallon
will actually cost less to use, if you maintain the concentration
at the 5 percent to 6 percent level.
Another
example that must be shared is the idea of buying coolant
based on cost-per-gallon. One of my salesmen came to me
with a sample of a competitor’s coolant and told me
his customer was paying only $6 per gallon for this coolant.
Then he asked if I could make a similar product. Upon analysis
of the sample I discovered that the coolant concentrate,
right out of the drum, contained 80 percent water. My response
to my salesman was, “Yes, we can make a coolant that
is 80 percent water, but we never will!”
Look
at it this way. We could very easily take a $12 per-gallon
coolant and add 50 percent water. But why would we have
our customers pay so much to ship water across the country?
Please
consider carefully the coolants that you are buying. If
the cost-per-gallon is less than $9, I can tell you with
certainty, based on current raw material costs, that your
coolant contains a high percentage of water. Don’t
take my word for it; send a sample out to an independent
laboratory for a water analysis. The best way to compare
coolants isn’t by cost-per-gallon but performance.
This includes longevity in the sump.
Conclusion
Using
the recommendations outlined above, you could very easily
save 25 percent to 30 percent on your total coolant usage.
The best way to get started is to ask your current “full
service” supplier to help you out. If you can’t
get the answers you are looking for, find a coolant supplier
you trust and I’m sure you will improve your total
process.
This article originally appeared in Shop Talk magazine in May of 2006. Shop Talk is published
by Magellan Publishing.
