Waste Minimization and. Wastewater Treatment of Metalworking Fluids

Metalworking Lubricant Defmitions

a publication of the Independent Lubricant Manufacturers Association

Research and Development Committee 651 South Washington Street Alexandria, Virginia 22314

Phone 703/684- 5574

Research & Development Committee Chair Ralph Kelly, Cincinnati Milacron

Research & Development Committee Vice Chair Paul Dacko, Ideas, Inc.

Research & Development Project Director Raymond M. Dick, Cinannati Milacron

F ~ x 703/836-8503

Reprinted with permission h m the Independent Lubricant Manufachnm Association.

Copyright 0 1330 Independent Lubricant Manufacturers Association.

"Metalworking Fluid Additives for Waste Minimization" by Jean C. Childers, Shu-Jen Huang and Michael Romba is reprinted by permission of the Society of Tribologists and Lubrication Engineers. All rights reserved

The information contained herein is being made available by the Independent Lubricant Manufacturers Assod- ation (ILMA) in the interest of disseminating knowledge about waste minimization and wastewater treatment of metalworking fluids. Neither ILMA nor the individual authors make a n i warranty or representation, express or implied, with respect to the accuracy, completeness, or usefulness of the information contained in this publication. ILMA assumes no responsibility for liability or damage which may result from the use of any of this information.

wasre Minimanon ana wmewmer Treatment chapter 1

Metalworking Lubrication Definitions Elllot S. Nachtman, Ph.D

Tower Oil G Technology Company

Introduction Metalworking is a term which describes two different kinds of metal shaping operations:

1. Chip producing - metal removal. 9

2. Deformation induced shaping - metal moving.

Cutting or grinding are chip producing operations that result in a desired shape through metal removal. Turning, drilling, milling, boring, broaching and shaping are metal cutting operations. Surface grinding, centerless and plunge grinding, cylindrical and internal grinding are some typical grinding operations.

Deformation of metal produces a desired shape by remov- ing metal as a result of plastic deformation. Rolling of sheet, plate, billets or shapes, drawing, blanking or stamping of strip or sheet, wire drawing, tube bending, roll forming, forging, cold heading and extrusion are some typical metal deformation prdcesses.

Lubricants are used to facilitate metalworking operations. They must also satisfy requirements of health, subsequent operations, environmental concerns and disposal. Defini- tion of some of the terms used relative to use of metalwork- ing lubricants is complicated by the absence of generally accepted definitions. However, the following definitions we believe can be useful in communications conceming metalworking lubrication.

Definitions 1. LIQUID OR FLUID LUBRICANTS are of three types solutions, emulsions and suspensions. The fluid lubricants are frequently called coolants although in many applica- tions cooling is only one of several important characteristics such as lubrication, rust protection, stability, and cleanabil- ity required of metalworking lubricants.

a. SOLUTIONS. Fluids whose base may be mineral oil, vegetable oil, water or a synthetic fluid are formulated with additives that are completely soluble in the base fluid. The present practice is to call the oil base solutions 'oils," the water base solutions are inappropriately called 'synthetics" and the true synthetic fluids used to make metalworking solutions are also called "synthetics." Correct chemical nomenclature suggests use of: (1) Oil base solutions (OBS)

- -42) Water base solutions (WBS)

(3) Synthetic base solutions (SBS)

b. EMULSIONS. When two or more mutually insoluble fluids are mixed together they will separate into separate layers unless surfactants of appropriate ionic character are added to the mixture. Then the surfactant system acts to suspend particles of one fluid in another. This system is called an emulsion. Its color varies depending upon particle size and chemisuy, from milky white to almost water dear when the system has a continuous phase consisting of water and a discontinuous phase or particles consisting of oil. Frequently these emulsions are called "soluble oils;" again the nomenclature is misleading since the oil is not soluble in the water, rather it is in the form of particles suspended in the water. Additives which may be soluble in either phase are added to provide desired metalworking lubricant characteristics (rust protection, anti-foam, biostates). 'Semi-synthetic" fluids are misnamed and are really emulsions.

c. SUSPENSIONS. Solids such as graphite, sodium carbonate, and molybdenum disulfide are suspended in a fluid carrier such as oil, water or a synthetic fluid. These suspensions depend upon specific gravity, particle size and viscosity relationships to primarily achieve relatively stable suspension.

2. PASTES are formed when water soluble polymers and soaps added to a base fluid thicken the fluid (water or mineral oil). A gel is formed which has good film strength and maintains good viscosity under relatively high pressure and temperature. Pigmented soap pastes are used under more severe metalworking conditions (press work, wire drawing, cold heading). The so called pigments are really solid lubricants (graphite, sodium carbonate, mica, etc.).

3. SOLID LUBRICANTS. Solids such as metallic soaps, graphite, glass and molybdenum disulfide serve as lubri- cants in wire drawing, hot extrusion, cold heading and bar drawing. These solids are most frequently applied as pow- ders.

Aluminum stearate, calcium stearate and other metallic soaps with or without graphite and/or molybdenum disul- fide are frequently the lubricant of choice for wire drawing. Low melting point glasses (850'F and above) successfully lubricate the hot extrusion process for steel ( 2 5 o .

4. COATINGS. A number of coathgs, copper plating and phosphate coatings are used on bar, wire or shapes as primary lubrication films prior to deformation designed to achieve further reduction in size or to achieve .a formed shape. Lime or borax coatings are frequently applied at the bar or wire mill before def6rmation as a lubricant film.

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5

Waste Minimizotion and Wastewater Treatment chapter I

Liquid lubricants are almost always used in conjunction with such coatings. Polymers and resin coatings containing lubricity additives are applied to sheet metal at the finishing mill to provide coil stock which may not require any further lubrication at the press shop. The polymer or resin coatings are generally applied by dip coating followed by heating to achieve the desired film properties.

5. ADDITIVES. Some of the most important additives are listed below. In all cases appropriate chemical judgment must be used in combining additives and selecting base stock in order to achieve desired lubricant characteristics. The additives singly or together provide desired operating properties at an acceptable cost

These additives and their function in metalworking lubri- cants illustrate some, but certainly not all of the chemicals and their function in the lubricant. Frequently chemicals react to form other chemical species particularly when subjected to the high pressure and increased temperature produced during the metalworking operation.

B~liosraPaY 1. Tribology and MetaIm&ng, John A. Schey, American Society of Metals, 1983. 2. Lubricants a?zd Lubrlcaffon in Metalwonking *a- ttons, Elliot S. Nachtman, Serope Kalpakjian, Marcel Dek- ker, Inc., 1985..

Ell Pri Tower Oil & Tcchnolosy emp3nY 205 west Randolph street Chicago, IL 60606 Phone 3W346-0562 Fax 31U346-6873

Elliot S. Nachtman is a principal of Tower Oil as well as Adjunct Professor in the Systems Engi- neering Department at the Univ. of Illinois. Initiilly a chemist on the Manhattan Projeci at the Univ. of Chicago, he later bacame VP and an officer of IaSalle Steel Co., where he was responsible for research and development. Dr. Nachtman also served as a con- sultant to the Organization of American States on metal processes and technology transfer; was a member of the Advisory Panel (Metallurgy) for the National Bureau of Standards; and was on the Panel on Application of DeformationTheory to Practice, Materials

Surfactant Coupler Thickener Detergents

Anti-mistirlg

DiSpeMnts

Plasticizers

Oiliness agent

Extreme pressure

Passivlton Anti-foam Alkaline reserve Solid l u b r i i s Odormask Corrosion inhibitors

Anti-microbi?l agent

Emulsificuion Sodium sulfonate Stability Hayl-glycd Vixosity krylicacidestas Cleanabilii OVabpKd sulfonates Reduce lldciness Glycol - Reduce mist m h Incruse f h svtngth Fatty acid soaps b e n t f a p + = Y - agglomeration Reaction lubricant Sulfur, chlorine, films PdPhon=

compounds Preventstaining O r g . m i C d i z m i n 0 FYwcnKfovning sioxanes conrrolacidity ovabpsed sulfonates

Improve odor Pim oil Gmphite, mica Fdmsvength

Prevent nrst Toluyluirzole, amines

Preventbaaerial Kathon886IUW,Gtot~ infestaton HD2

AaVlSOry aoara, National xience rounaauun. LA. IV~UILIIUII ills published and lectured extensively on various -kchnioll and general management sub-, and he holds 31 U.S. patents. Dr. Nachtman has served on the Board of Directors and as the first chair of the Independent Lubricant Manufacturers Association's Government Affairs, Metalworking Lubricants, and Research and Development Committees. In addiiion, he is a Fellow of the American Society for Metals, a member of STLE and the American Institute of Mining and Metallurgical Engineers. He rece.ived the B.A. degree from Woobter College andthe M.S. and Ph.D. degrees from the Illinois Institute of Technology.

Tower Oil &Technology Co., founded in 1933, serves customers throughout the cont inend U.S. Its product lines include metalforming lubricants, cutting and grinding fluids, rust preven- tives, hydraulic fluids, rmintenancelubrioantsandgreases.T~~~ Oil's regular product line consists of approximately 700 produas, with numerous additional experimental produ- constantly under development and field testing. Tower Oil is a Regular Member of the Independent Lubricant Manufacturers Association.