MOLDING A NEWMETALWORKING FLUID

Photo: ueaphan - Fotolia

1 COPYRIGHT 2017, LUBES’N’GREASES MAGAZINE. REPRODUCED WITH PERMISSION FROM THE JULY 2017 ISSUEBY MARY MOON

Gelatin, the substance responsible
for everyone’s favorite jiggly
dessert, is breaking the mold formetalworking fluid formulations.
This novel additive can improve
antiwear and cooling performanceof finished lubricants, in addition
to other benefits.
Gelatin is a mixture of molecules that are soluble in hot waterand associate to form a solid atlower temperatures, depending
upon concentration. In addition
to molded desserts, gelatin isused in gummy bears, marshmallows, yogurts, ice creams, aspics,
sausages and a plethora of otherproducts.
A specific form of this everyday
substance, hydrolyzed gelatin,shows promise as an additive formetalworking fluids, said Lara
Niemann, marketing director atGelita USA. Headquartered in
Eberbach, Germany, the Gelita
Group is a leading global producer of gelatin and other collagenproteins for food, health, nutritionand pharmaceutical applications.
Gelatin is obtained from collagen, the main structural protein in
the bodies of humans and otheranimals. Collagen proteins arelong, chain-like molecules composed of amino acids. A single collagen molecule consists of threeamino acid chains twisted together to form a helix, resembling aspring or a piece of yarn. In animals, these molecules pack

together and form microscopic
fibers onto which cells and minerals deposit to form muscles, skin,bones, teeth and many organs.
Gelita operates one of theworld’s largest gelatin factories in
Sergeant Bluff, Iowa. Collagen is
obtained from the bones, hides
and connective tissue of cows andpigs. These sources are treated tobreak down the structure of collagen fibers and remove fat, minerals and other substances. The collagen then undergoes hydrolysis,
in which reactions with water
break certain bonds between
amino acids to decrease the molecular weight of the protein molecules. The proteins are thenextracted and purified into a highly concentrated fluid called aliquor. Additional steps convert
this liquor to gelatin powder.
For Novotec CL800, Gelita’s
metalworking fluid additive, theproteins are further processedwith specific enzymatic hydrolysis
reactions followed by filtration,evaporation and sterilization. The
result is a highly concentrated liquid of hydrolyzed collagen that iscompletely soluble at any concentration in water.
The company recently patented
the Novotec family of protein
products, intended as a new classof performance additives for metalworking fluids, cleaning agentsand detergents, Neimann said.
These proteins contain certain

COPYRIGHT 2017, LUBES’N’GREASES MAGAZINE. REPRODUCED WITH PERMISSION FROM THE JULY 2017 ISSUE 2

chemical groups that adhere tohydrophobic (water repellent) surfaces,
as well as other chemical groups thatattract water molecules. As a result, theproteins form hydrophilic (waterattracting) films of hydrated moleculeson various surfaces.
The CL800 protein, which has beenused in field trials in Germany for nearly two years, was developed as an additive for water-miscible metalworking
fluids. Supplied as a liquid concentrateof approximately 50 percent specificdrives these oils and polymers toadsorb on metal surfaces of workpieces
and tools, where they reduce metal-tometal contact and friction during metalworking operations.
Using the Reichert Abrasion Wear Test,Gelita compared its additive with commercially available mineral oil based andwater based metalworking fluids. A lubricated ring was oriented cross-wise against
a test cylinder, both made of 100Cr6
bearing steel, under an applied load of
350 Newtons and rotated at 1.7 meters

Hakuform A805, formulated with hydrolyzed gelatin, was tested
in a CNC machine during a field trial at Heidelberger
Druckmaschinen. (Photo: Gelita)

protein in water, along with trace levelsof citric acid and potassium sorbate as
antioxidants, the company claims theshelf life of unopened containers is 12
months from the date of manufacture.
TESTING THE WATERS
Eric Yezdimer, research and businessdevelopment manager at Gelita, andhis colleague Melissa Simon, director ofsales, explained that the protein molecules in their product adsorb on carbon
and stainless steels, aluminum alloys
and other metals. Typical semi-synthetic
and synthetic metalworking fluids areformulated from emulsified oils andpolymers such as polyglycols, respectively, in water. The hydrophobic effectoxidation reactions and lose their effectiveness.
Formulating traditional oils and polymers in water-miscible metalworking
fluids improves lubricity but interfereswith cooling. Thermal conductivity ofwater is several times greater than oils.
Adsorbed oils and polymers separate
metal surfaces from water and interferewith heat transfer during metalworking
operations.
Niemann, Simon and Yezdimer assertthat Gelita’s product combines the best

Test cylinders after Reichert Abrasive Wear Test using (left toright) water, 5 percent solution of a commercially available cooling lubricant, and 5 percent solution of Novotec CL800. (Photo:Gelita)

per second (960 rotations per minute)for a travel distance of 100 meters, orone minute. The size of the wear scar on
the cylinder corresponds to the antiwear
performance of the lubricant. The company reported that solutions of 6 to 10
percent weight per weight diluted
Novotec CL800, without any other substances in the solution, outperformed
fully formulated products.
In water-miscible coolants, water ismore than a solvent for emulsified oilor polymeric lubricants; it is the primary means of carrying heat away fromworkpieces and tools. This cooling
effect is particularly important because
heat causes oils, polymers and additives
such as corrosion inhibitors to undergo

features of emulsified oils or polymers
and water: efficient lubrication andcooling. Polar amino acids help the protein molecules adsorb on metal surfaces where they form films and provide lubricity. Water molecules associated with adsorbed molecules help transport heat and cool hot parts and tools.
To study heat transfer, the company
collaborated with an academic laboratory at Theodor-Frey-Schule in Eberbach.
A metalworking lathe was used tomachine AlSi12 aluminum alloy pistons.
After machining at relatively highspeeds, piston surfaces that were lubricated with 2 percent Novotec CL800
solution appeared comparable to thosethat were lubricated with a fully formu-

3 COPYRIGHT 2017, LUBES’N’GREASES MAGAZINE. REPRODUCED WITH PERMISSION FROM THE JULY 2017 ISSUE

lated, 5 percent mineral oil emulsion
used for the regular machining of thesepistons—there were no visible residuesof oxidation byproducts or metal debris.
Using the mineral oil emulsion atslower speeds, residues welded to surfaces; this did not happen with the protein solution. These observations support Gelita’s claim that water-miscible
metalworking fluids formulated withthis material can cool more effectively
than those formulated with oil.
Yezdimer explained that worked
pieces and chips tend to carry out
much less Novotec CL800 than oils andother polymers because the product ismore water soluble. Less carryout
results in less consumption of the lubricant, leading to reduced costs andwaste. This means metalworking shops
using formulations with the protein
additive can decrease additional
expenses and chemical waste associated with cleaning parts before they arewelded, phosphated, painted or otherwise processed.
However, Yezdimer stressed thatusing effective rust or corrosion
inhibitors is mandatory for metalworking fluids containing his company’s
product, because such clean metal surfaces are naturally subject to corrosionin the presence of water and air.
Chemical company Lanxess’ Lubricant
Additives segment worked with Gelita
to develop a guideline metalworking
fluid formulation. The pH 9 fluid isbased on water and includes 25 percent
Novotec CL800 along with ten otheringredients. Gelita reported that 10 percent of their guideline formulation indeionized water gave a 15-square-millimeter wear scar in the Reichert test.
The company suggested diluting thisformula to between 9 and 16 percent
for tapping or drawing and 5 to 8 percent for drilling, grinding, milling orcutting.
ANTS AT THE PICNIC?
Since protein is a natural food source
for many life-forms, formulators may beconcerned about the potential for

microbial contamination. Yezdimer
explained that many of the diverse
types of bacteria and fungi typically present in end-use diluted metalworking
fluids can metabolize proteins likehydrolyzed gelatin, though proteins are
not unique in that regard. While thesebugs require additional nutrients inorder to grow and thrive, such nutrients are invariably provided by boththe make-up water chemistry and othermetalworking formulation components.
Any complete metalworking fluid formula may require additional stabilization against microbial growth and corrosion, Yezdimer continued, depending
on its work environment. He advised
against using formaldehyde-releasing
biocides because Novotec CL800 will
effectively deactivate them. Instead, herecommended other broad-spectrum
biocides such as benzisothiazolin-3-one(BIT) or methylisothiazolin-3-one(MIT), although none of the isothiazolin-3-one biocides work in as broad arange of formulations as many of theformaldehyde condensates.
Consultant and microbial control
expert Fred Passman, president of BCA
Inc. in Princeton, New Jersey, explained
to Lubes’n’Greases that a combinationof bioresistance laboratory tests andlong-term field trials will be needed toevaluate how Novotec CL800 actuallyaffects finished metalworking fluidbioresistance.
Nevertheless, successful field trials
indicate that formulators have alreadyfound ways to produce stable protein
based formulations without formaldehyde. Chemische Werke Kluthe GmbH,headquartered in Heidelberg, Germany,
developed its own formulations including Novotec CL800 for commerciallyavailable metalworking fluids:
Hakuform A803 and Hakuform A805.
Gelita reported results from two fieldtrials using these fluids.
THE PROOF IS IN THE PUDDING
The first field trial, at G+F
Sondermaschinen in Beerfelden,

Germany, included turning, milling andtapping various chromium-nickel alloys,steels and aluminum alloys. After a fullyear of use in a computer numericalcontrol machining center and in a band
saw, G+F reported that the formulation
improved the quality of machined surfaces, especially nonferrous metals;
increased the service life of saw blades;
reduced foaming and eliminatedresidues.
In addition, operators at G+F withknown allergies to conventional metalworking fluids did not report havingskin or other allergic reactions to fluids
formulated with Gelita’s protein.
The second field trial took place at
Heidelberger Druckmaschinen AG.
Approximately 100 trainees used conventional turning, milling, drilling andgrinding machines and CNC machines
to process ferrous and nonferrous
alloys as well as composites. During thetrial, the company reported decreased
lubricant consumption, fewer equipment maintenance issues, easier cleaning of machines and tools, and otheradvantages.
“Our focus was on lifetime of tools
and skin compatibility. We are very satisfied with the results,” said ChristianBeck, head of the training center fortechnical professions at Heidelberger
Druckmaschinen. “Compared to earliertimes, where skin irritation was definitely an issue sometimes, we could notfind a single case of skin intolerance on
one of our trainees. There were also noodors. In addition, the new coolinglubricant is very stable and needs lessmaintenance.” ❚Mary Moon, Ph.D., is a chemist withhands-on R&D and management experience in the lubricating oil andgrease and specialty chemicals industries. She is skilled in industrial applications of tribology, electrochemistry
and spectroscopy. Contact her at
mmmoon@ix.netcom.com or (267)567-7234.

COPYRIGHT 2017, LUBES’N’GREASES MAGAZINE. REPRODUCED WITH PERMISSION FROM THE JULY 2017 ISSUE 4