HYDRAULIC FLUIDS, CUTTING OILS, QUENCHING ... - K-Patents

METALS AND MINING
APPLICATION NOTE 7.01.01_REV1
METALWORKING AND MACHINING 1 (2)
w w w . k p a t e n t s . c o m
HYDRAULIC FLUIDS, CUTTING OILS, QUENCHING OILS
COOLING LUBRICANTS, WASHING LIQUIDS
Typical end products
Metal components and parts e.g. engines, drill bits, washers,
beverage cans, steel coils, turbine blades, knives, blades, scissors,
bearings etc.
Chemical curve: R.I.per BRIX b.w. at Ref. Temp. of 20˚C
Introduction
Metal machining is the process of converting metal
blanks into finished components or parts. All
metalworking operations involve the contact of two
solids, a tool and the work-piece, to create the
finished piece. The process involves high friction,
high temperatures and high stresses, resulting in tool
wear. It is the function of the lubricant, or
metalworking fluid, to minimize or dissipate these
effects. Metalworking fluids accomplish this by
providing cooling, lubrication and corrosion
resistance.
Over time, cutting fluids can become contaminated
by chips and fines, tramp oil, bacteria and dissolved
salts. Therefore, monitoring the pH, water hardness
and fluid concentration is essential in preventing
failure of the fluid. Water evaporation should be
monitored to ensure the coolant-to-water ratio is
correctly maintained. The K-Patents Process
Refractometer provides accurate and continuous
measurements of the coolant-to-water ratio.
Traditional lab sampling by titration is time
consuming. Sampling can be minimized with in-line
Process Refractometer control, especially when
there are multiple stations. Furthermore, portable
handheld refractometers are not ideal tools for
metalworking fluids, as they give a fuzzy borderline
resulting in inaccurate measurements.
Too low a concentration allows bacterial growth,
reduces cutting capacity resulting in longer
machining time, poor surface finish, ineffective
lubrication and debris to tool welding. Too high a
concentration means excessive use of lubricant
(costly) and grease contamination (difficult to
remove).

METALS AND MINING
APPLICATION NOTE 7.01.01_REV1
METALWORKING AND MACHINING 2 (2)
w w w . k p a t e n t s . c o m
Figure 1: Quenching Process:
Figure 2: Induction Hardening Process:
Application
The K-Patents Process Refractometer applications
can be divided into four areas:
1. Quenching / Tempering Process
The physical property of the metal is changed
through quenching. The metal is heat-treated and
then cooled rapidly (quenched) with a fluid in order
to increase the surface hardness (Figure 1). The
metal can also be heat-treated through magnetic
induction heating (Figure 2).
The concentration of the fluid is one important
parameter, which affects the final quality. Fluids are
also used in the casting process. When the
concentration levels are correct, the surface
properties of the finished parts are within the
specifications. Typical liquids used in induction
hardening are PAGs (Poly alkylene glycols).
2. Cooling / Cutting
During machining metal has to be cooled and
lubricated. Coolants are often supplied through a
centralized system but also by local systems at the
point of use. The K-Patents refractometers are
used in both the feed and recycling lines serving
machine tools.
3. Washing
The primary goal of washing is to clean the
machine parts thoroughly of residual oil and dirt.
The washing fluid is sprayed onto the parts at high
pressure. The fluid forms a film that protects the
parts from corrosion during storage.
The K-Patents refractometer detects the correct
concentration to ensure that the excess grease and
oil have been completely removed by the washing
process.

METALS AND MINING
APPLICATION NOTE 7.01.01_REV1
METALWORKING AND MACHINING 2 (2)
w w w . k p a t e n t s . c o m
4. Rinsing
If the parts and components are destined for
welding, the protective film must be completely
removed as residual wash solution affects the
quality of welds. The film is removed in water
rinsing baths.
As the water picks up the residual wash liquid, the
bath must be replenished as the concentration
value reaches its saturation limit. The acceptable
limit varies from plant to plant, but typically it is
around 0.5 Brix.
Instrumentation
The K-Patents Sanitary Probe Refractometer
PR-23-AP is the recommend system for larger
pipes or vessels. The Sanitary Compact
Refractometer PR-23-AC with a flow-cell is suitable
for smaller pipes. An automatic prism cleaning
system is recommended in cases, when dirty
liquids are being processed.
Instrumentation
Description
K-Patents Sanitary Compact Refractometer PR-23-AC for small pipe line sizes of
2.5 inch and smaller.
The PR-23-AC sensor is installed in the pipe bend. It is angle mounted in the outer
corner of the pipe bend directly or through a flow cell and 3A Sanitary clamp or
Varivent® connection.
K-Patents Sanitary Probe Refractometer PR-23-AP for installations in large pipes,
tanks, cookers, crystallizers and kettles and for higher temperatures up to 150°C
(300 °F). Installation through a 3A Sanitary clamp.
Automatic prism wash:
Measurement range:
Prism wash with high pressure water is recommended for dirty liquids.
Refractive Index (nD) 1.3200 – 1.5300, corresponding to 0-100 Brix.