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

MOLDING A NEWMETALWORKING FLUID

Photo: ueaphan - Fotolia

Gelatin, the substance responsiblefor everyone’s favorite jigglydessert, is breaking the mold formetalworking fluid formulations.This novel additive can improveantiwear and cooling performanceof finished lubricants, in additionto other benefits.Gelatin is a mixture of mole-

cules that are soluble in hot waterand associate to form a solid atlower temperatures, dependingupon concentration. In additionto molded desserts, gelatin isused in gummy bears, marshmal-lows, 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 LaraNiemann, marketing director atGelita USA. Headquartered inEberbach, Germany, the GelitaGroup is a leading global produc-er of gelatin and other collagenproteins for food, health, nutritionand pharmaceutical applications.Gelatin is obtained from colla-

gen, the main structural protein inthe bodies of humans and otheranimals. Collagen proteins arelong, chain-like molecules com-posed of amino acids. A single col-lagen molecule consists of threeamino acid chains twisted togeth-er to form a helix, resembling aspring or a piece of yarn. In ani-mals, these molecules pack

together and form microscopicfibers onto which cells and miner-als deposit to form muscles, skin,bones, teeth and many organs.Gelita operates one of the

world’s largest gelatin factories inSergeant Bluff, Iowa. Collagen isobtained from the bones, hidesand connective tissue of cows andpigs. These sources are treated tobreak down the structure of colla-gen fibers and remove fat, miner-als and other substances. The col-lagen then undergoes hydrolysis,in which reactions with waterbreak certain bonds betweenamino acids to decrease the mole-cular weight of the protein mole-cules. The proteins are thenextracted and purified into a high-ly concentrated fluid called aliquor. Additional steps convertthis liquor to gelatin powder.For Novotec CL800, Gelita’s

metalworking fluid additive, theproteins are further processedwith specific enzymatic hydrolysisreactions followed by filtration,evaporation and sterilization. Theresult is a highly concentrated liq-uid of hydrolyzed collagen that iscompletely soluble at any concen-tration in water. The company recently patented

the Novotec family of proteinproducts, intended as a new classof performance additives for met-alworking 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

BY MARY MOON

features of emulsified oils or polymersand water: efficient lubrication andcooling. Polar amino acids help the pro-tein molecules adsorb on metal sur-faces where they form films and pro-vide lubricity. Water molecules associat-ed with adsorbed molecules help trans-port heat and cool hot parts and tools.To study heat transfer, the company

collaborated with an academic laborato-ry 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 lubri-cated with 2 percent Novotec CL800solution appeared comparable to thosethat were lubricated with a fully formu-

drives these oils and polymers toadsorb on metal surfaces of workpiecesand tools, where they reduce metal-to-metal contact and friction during metal-working operations.Using the Reichert Abrasion Wear Test,

Gelita compared its additive with com-mercially available mineral oil based andwater based metalworking fluids. A lubri-cated ring was oriented cross-wise againsta test cylinder, both made of 100Cr6bearing steel, under an applied load of350 Newtons and rotated at 1.7 meters

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 been

used in field trials in Germany for near-ly two years, was developed as an addi-tive for water-miscible metalworkingfluids. Supplied as a liquid concentrateof approximately 50 percent specific

oxidation reactions and lose their effec-tiveness.Formulating traditional oils and poly-

mers in water-miscible metalworkingfluids improves lubricity but interfereswith cooling. Thermal conductivity ofwater is several times greater than oils.Adsorbed oils and polymers separatemetal surfaces from water and interferewith heat transfer during metalworkingoperations.Niemann, Simon and Yezdimer assert

that Gelita’s product combines the best

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

protein in water, along with trace levelsof citric acid and potassium sorbate asantioxidants, the company claims theshelf life of unopened containers is 12months from the date of manufacture.

TESTING THE WATERSEric Yezdimer, research and businessdevelopment manager at Gelita, andhis colleague Melissa Simon, director ofsales, explained that the protein mole-cules in their product adsorb on carbonand stainless steels, aluminum alloysand other metals. Typical semi-syntheticand synthetic metalworking fluids areformulated from emulsified oils andpolymers such as polyglycols, respec-tively, in water. The hydrophobic effect

per second (960 rotations per minute)for a travel distance of 100 meters, orone minute. The size of the wear scar onthe cylinder corresponds to the antiwearperformance of the lubricant. The com-pany reported that solutions of 6 to 10percent weight per weight dilutedNovotec CL800, without any other sub-stances in the solution, outperformedfully formulated products.In water-miscible coolants, water is

more than a solvent for emulsified oilor polymeric lubricants; it is the prima-ry means of carrying heat away fromworkpieces and tools. This coolingeffect is particularly important becauseheat causes oils, polymers and additivessuch as corrosion inhibitors to undergo

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

Hakuform A805, formulated with hydrolyzed gelatin, was testedin a CNC machine during a field trial at HeidelbergerDruckmaschinen. (Photo: Gelita)

lated, 5 percent mineral oil emulsionused for the regular machining of thesepistons—there were no visible residuesof oxidation byproducts or metal debris.Using the mineral oil emulsion at

slower speeds, residues welded to sur-faces; this did not happen with the pro-tein solution. These observations sup-port Gelita’s claim that water-misciblemetalworking fluids formulated withthis material can cool more effectivelythan those formulated with oil.Yezdimer explained that worked

pieces and chips tend to carry outmuch less Novotec CL800 than oils andother polymers because the product ismore water soluble. Less carryoutresults in less consumption of the lubri-cant, leading to reduced costs andwaste. This means metalworking shopsusing formulations with the proteinadditive can decrease additionalexpenses and chemical waste associat-ed with cleaning parts before they arewelded, phosphated, painted or other-wise processed.However, Yezdimer stressed that

using effective rust or corrosioninhibitors is mandatory for metalwork-ing fluids containing his company’sproduct, because such clean metal sur-faces are naturally subject to corrosionin the presence of water and air.Chemical company Lanxess’ Lubricant

Additives segment worked with Gelitato develop a guideline metalworkingfluid formulation. The pH 9 fluid isbased on water and includes 25 percentNovotec CL800 along with ten otheringredients. Gelita reported that 10 per-cent of their guideline formulation indeionized water gave a 15-square-mil-limeter wear scar in the Reichert test.The company suggested diluting thisformula to between 9 and 16 percentfor tapping or drawing and 5 to 8 per-cent for drilling, grinding, milling orcutting.

ANTS AT THE PICNIC?Since protein is a natural food sourcefor many life-forms, formulators may beconcerned about the potential for

microbial contamination. Yezdimerexplained that many of the diversetypes of bacteria and fungi typically pre-sent in end-use diluted metalworkingfluids can metabolize proteins likehydrolyzed gelatin, though proteins arenot unique in that regard. While thesebugs require additional nutrients inorder to grow and thrive, such nutri-ents are invariably provided by boththe make-up water chemistry and othermetalworking formulation compo-nents.Any complete metalworking fluid for-

mula may require additional stabiliza-tion against microbial growth and cor-rosion, Yezdimer continued, dependingon its work environment. He advisedagainst using formaldehyde-releasingbiocides because Novotec CL800 willeffectively deactivate them. Instead, herecommended other broad-spectrumbiocides such as benzisothiazolin-3-one(BIT) or methylisothiazolin-3-one(MIT), although none of the isothia-zolin-3-one biocides work in as broad arange of formulations as many of theformaldehyde condensates.Consultant and microbial control

expert Fred Passman, president of BCAInc. in Princeton, New Jersey, explainedto 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 proteinbased formulations without formalde-hyde. Chemische Werke Kluthe GmbH,headquartered in Heidelberg, Germany,developed its own formulations includ-ing 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 PUDDINGThe first field trial, at G+FSondermaschinen 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 bandsaw, G+F reported that the formulationimproved the quality of machined sur-faces, especially nonferrous metals;increased the service life of saw blades;reduced foaming and eliminatedresidues.In addition, operators at G+F with

known allergies to conventional metal-working fluids did not report havingskin or other allergic reactions to fluidsformulated with Gelita’s protein.The second field trial took place at

Heidelberger Druckmaschinen AG.Approximately 100 trainees used con-ventional turning, milling, drilling andgrinding machines and CNC machinesto process ferrous and nonferrousalloys as well as composites. During thetrial, the company reported decreasedlubricant consumption, fewer equip-ment maintenance issues, easier clean-ing of machines and tools, and otheradvantages.“Our focus was on lifetime of tools

and skin compatibility. We are very sat-isfied with the results,” said ChristianBeck, head of the training center fortechnical professions at HeidelbergerDruckmaschinen. “Compared to earliertimes, where skin irritation was defi-nitely an issue sometimes, we could notfind a single case of skin intolerance onone 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 expe-rience in the lubricating oil andgrease and specialty chemicals indus-tries. She is skilled in industrial appli-cations of tribology, electrochemistryand spectroscopy. Contact her atmmmoon@ix.netcom.com or (267)567-7234.

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