ILMA Compoundings September 2016 - 24

VOICES & VIEWS

Controlling Foam in
Metalworking Fluids:
The Great Balancing Act
Monica A. Ford, Ph.D.

It's thick and frothy, but as you look closer you realize it's thousands of little bubbles waiting
to burst into problems in your metalworking fluid formulation. It's the dreaded foam.

oam is one of the most commonly encountered problems
when using certain types of metalworking fluids (MWFs).
MWFs are often used in high-energy applications, where
they are applied through narrow spray nozzles at high speeds.
Unfortunately, these conditions are optimal for generation
of foam, especially in formulations containing emulsifiers and
other surface-active components. The presence of foam can be
harmful, as foam has no lubrication or cooling capacity and can
lead to damage of pumps and metal parts.
Metalworking fluids are designed to provide a few important
functions, two of which are lubrication (typically through an oil
phase with specialty additives) and cooling (typically through
an aqueous phase). You've probably heard the saying "Oil and
water don't mix." That's where emulsifiers come in to bridge the
gap. Formulators use emulsifiers as additives to create fluids that
provide the benefits of both oil (lubrication) and water (cooling)
in a single system. While these additives are necessary, they
come with challenges - they can stabilize the dreaded foam.
Therefore, in order to control foam in MWF applications, a great
balancing act must be performed.

is being circulated over a given time. It is beneficial to utilize
formulations that have been designed to work optimally in the
operations in which they will be used.
Ideally, end-users of MWFs are encouraged to work with their
MWF supplier to identify the best fluid for a given operation.
The MWF supplier takes a number of factors into account
when selecting an MWF formulation to use in a specific type of
operation. Some of the factors that should be considered are:
* MWF type
Semisynthetic formulations tend to have a higher foaming
tendency than emulsifiable oil formulations, which
subsequently tend to have higher foaming tendency than
synthetic MWF formulations. When possible, in operations
that use MWFs at high pressures and high volumes, simply
changing the type of MWF may significantly help in
controlling foam problems. Changing the volume of oil in the
MWF is another useful tool for controlling the level of foam
in a metalworking application, as higher oil formulations tend
to show less foaming than "low oil" formulations.

It's important to note that there are many factors that contribute
to foam problems in a metalworking operation. Some of these
factors are fluid formulation issues, contamination issues,
operating issues such as sump level, clogged flow, etc. This
article will focus on issues related to fluid formulation.
Metalworking fluids are utilized across a range of operations,
which have different levels of intensity under which the MWF
is applied. For example, some high-energy operations, such
as grinding and high-speed milling, are more prone to result
in foam generation from the speed and volume of MWF that

Vol. 66 No. 9 * 24 * September 2016 Compoundings

ILMA Compoundings September 2016

Table of Contents for the Digital Edition of ILMA Compoundings September 2016