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Safe-to-sewer solutions simplify disposal

Ecofriendly cleaners, lubricants allow for neutralized wastewater discharge

The type of cleaning solutions and lubricants a stamping manufacturer uses determines whether it must dispose of them as hazardous waste or simply discharge them on-site to municipal sewering systems. Photo courtesy of Walter Surface Technologies.

It doesn’t take long for stamping manufacturers to learn that the costs of lubricants, rust inhibitors, and cleaning chemicals don’t end with the product purchase. They’ve learned to consider the total cost of ownership. After the lubricants have glided the metal into submission and rust inhibitors have done their inhibiting, they must be cleansed from the part. Removing the resulting soup of water, lubricants, rust inhibitors, and cleaning chemicals wastewater then falls into one of two major categories, depending on the chemistries therein: that which must be collected and transported to a hazardous waste facility or that which can be safely discharged to sewer. Obviously, the latter is ultimately less expensive and environmentally preferable.

The hazardous chemicals of concern are targeted for special waste handling because they are carcinogens (cancer-causing), bioaccumulative (continue to accumulate in human and animal cell tissue to the point of excess); toxic (poisonous) to aquatic, animal, and plant life; or because they overfertilize waterways, promoting excess algae and plant life in them.

In the U.S., the substances are regulated by the U.S. Environmental Protection Agency via authority by the Congress-passed Clean Water Act and Clean Air Act. Even if current U.S. political figures relax regulatory pressures, liability concerns, global standards, and market forces are likely to sustain the flow toward ecofriendly solutions.

STAMPING Journal consulted with industry experts, such as lubricant, cleaning chemicals, and rust inhibitors producers, to advise on the topic.

Joe Hough, vice president/director technical services, Tower Oil & Technology Co.; David Enright, business manager, metalworking fluids, watercare, Chemetall; Lon Fanning, director R&D and technical support of metalworking, DuBois Chemicals; Steven Cassin, product manager, environmental solutions at Walter Surface Technologies; Stefan Noack, director, Raziol Lubrication; and Joe McChesney, global products line manager, solvents, Kyzen, contributed their input.

1. What types of challenges are metal stamping manufacturers currently facing regarding the ecofriendly use and discharge of lubricants, cleaners, and rust inhibitors?

Hough, Tower: To qualify a metal stamping process as ecofriendly and suitable for discharge to a wastewater sewer, the metal forming lubricants and rust preventives need to be oil-free, totally synthetic chemistries. The cleaners must have a pH from neutral to 9.0.  Because the cleaner picks up mill oil from the coil stock, that oil may need to be skimmed off before the wastewater can be discharged to the sewer.

Enright, Chemetall: The use of chlorinated and boron-containing raw materials are of environmental concern. Also, petroleum distillates and petroleum-derived raw materials can cause discharge and treatment problems.

The use of solvents, especially chlorinated solvents, in washing solutions is highly regulated and controlled. Many manufacturers have successfully adopted aqueous cleaners as a result. These aqueous products need to overcome challenges such as adequate drying and protection from subsequent corrosion, but when properly designed, they provide a dramatic environmental advantage. They offer additional gains when effective soil removal programs are implemented such as oil separators and filtration that permit longer cleaning cycles and generate less wastewater.

Rust inhibitors continue to have challenges related to volatile organic compounds (VOCs) and a reliance on petroleum as a source. Great strides have been made with synthetic, oil-free alternatives to reduce this impact.

Figure 1
Some lubricant and cleaners manufacturers, such as DuBois Chemicals, have become partners in the EPA’s voluntary Safer Choice program to validate its ecofriendly claims. Photo courtesy of DuBois Chemicals.

The next forward-looking, ecofriendly movement is treating and recycling the wastewater from lubricants, cleaners, and rust back into the process effectively—and currently this is one of the biggest challenges. Certain chemical additions, skimming, and membrane filtration can remove oils, debris, and waste from the baseline solution so that it can then be recycled back to the process.

Fanning, DuBois: In terms of industrial stamping and drawing compounds, the biggest concern is the disappearing pool of raw material choices because of regulation. Synthetic stamping compounds typically contain a phosphorus component for its extreme-pressure properties, but with the Great Lakes Restoration Initiative, the use of phosphorus has fallen out of favor. Similarly, chlorinated paraffins have been a target of the U.S. EPA for years, and with the European Commission’s REACH [Regulation, Evaluation, Authorisation and Restriction of Chemicals], many of the emulsifiers we’ve come to rely on are disappearing due to lack of support. The new Globally Harmonized System (GHS) hazard warnings are steering us away from many nonionic surfactants and specialty amides.

A recent trend is for the use of “vanishing” compounds that remain on parts and do not require cleaning, therefore reducing or eliminating wastewater discharge. However, many states, including California (South Coast Air Quality Management District, SCAQMD), have implemented new VOC standards that severely restrict the use of these hydrocarbon solvent-based vanishing fluids. The bottom line is that the raw materials we have to select from is limited compared to that of 10 years ago.

McChesney, Kyzen: A lot of stampers face problems with new lubricants that do not react well with their existing cleaning processes. For example, some of the new synthetic lubricants will not clean in the same processor system as organic-based lubricants. Some high-temperature lubricants require more mechanical action and sometimes need a different cleaning chemistry. Various metals need corrosion protection.

Cassin, Walter:  The ultimate, albeit challenging, goal is to find a balance between performance and health and safety. Before the era of greener and healthier industrial liquids, manufacturers were focused solely on performance. As we now know, some of those turned out to clean well but have negative long-term effects. So the challenge now is creating something that performs just as well, but that has few or no side effects on worker health and safety.   

Noack, Raziol: Problems of degreasing can either be found in the raw materials, in the follow-up processing procedures, or in the degreasing process itself. Problems can occur in the interaction between lubricant and applicators.

Today’s magic phrases are “energy savings” and “cost reduction,” but achieving one goal can be at odds with the other. High-performance lubricants provide the proper characteristics that advanced high-strength steel and ultrahigh-strength steels, used to reduce vehicular fuel consumption, require. But this performance can be achieved only by adding solid lubricants such as PTFE or additives that adhere well to the materials—which counters efforts to reduce cost.

Some follow-up processes, such as welding, have a high heat input that can negatively affect specific areas on the blank surface, called the heat-affected zone (HAZ). This can result in a significant alteration of the applied lubricants. The lubricant’s physical change can, in turn, alter the degreasing process. A lubricant with a good initial degreasing characteristic can transform into a lubricant with poor degreasing performance.

Any lubricant that adheres strongly to the blank surface during the forming process can be removed only by using higher temperatures in the degreasing bath. This is contrary to the general trend towards temperature reduction of the degreasing baths and thus energy savings and other cost reductions, as well as efficiency improvements.

2. Which substances or materials used in metal stamping and finishing prohibit wastewater discharge to sewer? What are the concerns or hazards?

Hough, Tower: Petroleum oil is not allowed because it interferes with biological waste treatment processes. Chelators are not allowed because chelated metals are hard to remove from wastewater.

Enright, Chemetall: In addition to petroleum oil and its derivatives, chlorinated paraffins and boron-containing materials are problematic. In cleaning compounds, nonylphenol ethoxylates (NPE), already restricted in Europe and Canada, are targeted in the U.S. because of bioaccumulation and toxicity to aquatic organisms. 

Metal stamping and finishing process chemicals can be affected by the local permit guidelines for discharge, which are based on the actual process and base materials. In other words, levels of metals such as copper, nickel, chrome, and zinc can become elevated as a result of the treatment process. In addition, borates may be of concern in some local municipalities, as well as oil and grease, suspended solids, pH, and turbidity, because of their potential bioaccumulation, high biochemical oxygen demand (BOD), and chemical oxygen demand (COD) levels.

Fanning, DuBois: In my opinion, the term limit is more appropriate than prohibit.  Fats, oils, and greases (FOGs) must be dealt with before being discharged to prevent having a publicly owned treatment works (POTW)-imposed surcharge.

Phosphates are always a concern, even though the replacement chemistry is phosphorus-based. Some companies limit the use of chelating agents that improve hard water stability because of their tendency to solubilize heavy metals into the wastewater.

Amines have been used for years in water-soluble stamping and drawing compounds, but they greatly increase the BOD/COD of the effluent. Once again, these chemistries aren’t prohibited, but their use may incur a surcharge.

McChesney, Kyzen: States’ individual regulations vary but cannot have lower standards than federal ones. Heavy metals, flammables, and corrosive materials must be identified and treated prior to disposal. Most alkaline chemicals used for cleaning, etching, and rust inhibiting can be discharged to the sewer if they are properly treated or if they fall within specific pH ranges. Most solvents cannot.

Stamping manufacturers select different cleaning methods to work with the substrates, lubricants, stamping, and cleaning equipment they use and that are in environmental compliance. It is paramount in today’s world to be aware of recent changes by the Occupational Safety and Health Administration (OSHA), the Environmental Protection Agency (EPA), and ACGIH®.

Cassin, Walter: Wastewater workers’ exposure to chemical hazards and biohazards is of primary concern. These involve harm to the respiratory system and irritations of eyes, nose, or throat as a result of short-term exposure, but there are also risks for repeated exposures that can have long-term effects on internal organs and disease. Any active ingredient not labeled as safe, any solvent-based or “natural” solvent (such as D-limonene) should never go into wastewater. Non-VOC-free products should also never be put down the drain.

Noack, Raziol: Forming lubricants that contain chlorine are known as good metalworking lubricants but also are known to have significant health and environmental risks associated with them.

3. Why are VOCs a concern? What limits or parameters on VOCs exist for metal stamping and finishing operations?  

Fanning, DuBois: The most common VOC in metal stamping and drawing operations is mineral spirits used in vanishing fluids and rust preventives. Mineral spirits can be a problem when used in poorly ventilated areas. Health effects include eye and respiratory tract irritation, headaches, dizziness, and visual disorders—even memory impairment if their levels in the air are too concentrated.

Length of exposure is also an important variable. Exposure to lower concentrations of VOCs over the course of many years can cause cognitive impairment, and there is some evidence to suggest liver and kidney damage can occur. A concentration of 250 milligrams per liter (mg/L) of VOCs in the air is generally considered safe, with 1,000 mg/L at the upper limit of safe exposure.

In terms of the fluids themselves, California, through the SCAQMD (Rule 1144), has imposed a current limit of 50 g/L VOC for vanishing oils and 300 g/L for rust preventives as measured by thermogravimetric analysis. Any fluid with a VOC count higher than the limit is prohibited from being sold in this California district. This method was developed by members of the Independent Lubricant Manufacturers Association (ILMA) and is considered more accurate for metalworking than the old EPA Method 24.

McChesney, Kyzen: All plants are being faced with VOC reduction to address global warming. Phase-out or reduction actions are taking place on a worldwide level. There are ways to identify and address methods to achieve these goals. VOC permits are a looming issue with any end user.

Enright, Chemetall: The main concern with VOCs is their conversion to a gaseous form in the atmosphere that can cause a range of problems from acid rain to increased CO2, which contributes to climate change.

Cassin, Walter:  When VOCs break down, the process causes degradation on health and the environment. Anything considered volatile (like carbon-based compounds, hydrogen, oxygen, and chlorine) must be heavily restricted. The good news is that this is not something people are turning a blind eye to, and awareness continues to grow.

Hough, Tower: From an environmental standpoint, it is best to eliminate VOCs whenever possible. This can be done by using water-based metalworking fluids.

4. What types of industrial fluids—cleaners, lubricants, and rust inhibitors—aid in safe and compliant wastewater discharge?

Hough, Tower: Oil-free, fully synthetic metal forming lubricants that do not contain chelators are compliant for wastewater discharge to sewer. So too are cleaners with a pH from neutral to 9.0 alkalinity, as are rust inhibitors with water as the carrier instead of petroleum distillates and that are biodegradable.

Enright, Chemetall: Low-petroleum-containing products and those that are chlorine- and boron-free enable compliant discharge to a POTW. In washer chemistry, products that allow for simple removal of FOG and BOD- and COD-contributing components are compatible with wastewater treatment programs. Process chemistry that is readily neutralized and precipitated or skimmed from wastewaters without creating difficult emulsions that are not amenable to treatment are preferred for use. 

Fanning, DuBois: Looking at it in broad terms, we are seeing the judicious selection of raw materials and the use of tighter engineering controls to reduce wastewater discharge and ensure that the chemistries that are discharged are safe for the treatment facility and the environment.

Specifically, in terms of industrial cleaners, we are seeing more EPA Design for the Environment (DfE) products that are readily biodegradable and do not contain phosphates, harmful solvents, or hazardous air pollutants (HAPs).

We are seeing companies reduce their discharge to zero using minimum quantity lubrication (MQL) systems to dispense vegetable oil-based lubricants and other, similar ecofriendly chemistries. We are seeing an uptick in companies using dry film lubrication in which a small amount of lubricant is applied to a blank, then cured under ultraviolet light before it proceeds to the drawing presses. In both cases, a precise amount of lubricant is applied to reduce waste and VOC emissions.

Likewise, rust inhibitors are moving toward synthetic, water-soluble chemistries that are biodegradable. These products are very effective in preventing in-process rust or even short- to medium-term in-transit rust protection, but can be less effective for long-term or outdoors protection. 

Cassin, Walter: Acceptable substances and materials include products that are biodegradable, biorenewable, and have zero VOCs.

For cleaners, there are two main cleaning technologies that aid in safe and compliant wastewater discharge. The first is a water-based, biorenewable cleaner. The second uses bioremediation. This technology yields waste byproduct that is safe to handle. They contain live microorganisms that ingest contaminants like oil and grease and transform them into harmless products such as carbon dioxide and water. This is an acceptable solution, as enzymes are actively breaking down contaminants. If the formulation was simply dissolving grease and oil, those contaminants would still be polluting the waste stream. However, bioremediation ensures that there are no disposal costs, zero waste, and no harm to the environment.  

Noack, Raziol: Chlorine-free and mineral oil-free, partially in volatilizing punching oils, fine-cutting oils, and drawing lubricants, guarantee a high environmental compatibility and a long service life of the tools.

McChesney, Kyzen: This broad-range topic gets back to an initial understanding of stampers’ processes and needs. That can provide a path for users to follow for a best work practice, lower emissive volume (air, liquid, and solids), and it varies, depending on the materials, lubes, and process.

5. What are some current and critical developments you’re seeing?

Enright, Chemetall: The possible banning of chlorinated paraffins is creating a demand for chlorine-free products. The SCAQMD efforts in California brought a great deal of awareness to the issue of VOC reduction and the effective use of alternative chemistries. 

New efforts to more effectively evaluate and monitor VOCs in metalworking and rust preventives have

resulted, aided by societies like the ILMA and the Society of Tribology and Lubrication Engineers (STLE). These efforts appear staged to migrate into other geographic locations and the need to address air pollution continues. Emphasis on the use of sludge-reducing technologies (for example, using a cationic polymer rather than a larger volume of an inorganic coagulant) to neutralize waste solutions is gaining in popularity.

Fanning, DuBois: Improvements in lubrication systems that make MQL application viable and reliable have been important. Making these changes costs time and resources (money), though. New roller technology and mist application systems are making MQL practical when reduction in lubricant costs justifies the capital expenditures.

Unfortunately, this is coming at a time when the industry is being pressured to provide chlorine-free chemistries. For light- to medium-duty jobs using coated dies, this is not a problem, but in more difficult applications such as fineblanking of thick material (greater than 5 mm) and stainless steel, it’s a concern. 

Many of our customers are dedicated to using chlorine-free chemistries, and we are working with them to make that happen.

McChesney, Kyzen: A lot of stampers and metal formers are working to eliminate chlorinated lubricants by finding replacements products, then verifying that the new products can be cleaned at production rates/specifications/quality/cost. Then they have to ensure that they are in environmental compliance. Several traditional metal cleaning solvents are being phased out or are coming under stricter regulations. Personnel exposure levels are being more closely monitored and if too high, can lead to litigation and penalties.

Cassin, Walter:  Both lubricant manufacturers and stamping manufacturers are feeling the pressure of government regulations. With these come strict timelines to remove products from shelves, halt use of certain products, and seek alternative solutions. We believe, however, that regulatory developments drive positive change, as they push manufacturers to think greener and safer.  

We have a system in place to monitor proposals and discussions that will bring change rather than wait for government decisions to be officially made effective. We see new regulations as an opportunity to provide cutting-edge products. Regulatory changes allow us to offer niche, premium products that help our global customers in every industry without having to compromise on performance, health, safety, or productivity.

6. What is your company doing to address these challenges?

Enright, Chemetall: We have initiated a number of research projects designed to eliminate the troublesome raw materials without losing performance in critical metal forming, cleaning, and rust protection operations. We are always developing and implementing chemical treatments that minimize waste generation, assist in the process of water recycling, and also meet all critical discharge requirements on the local level for our customers.   

Fanning, DuBois: Our Treo line of ecofriendly cleaners was designed in partnership with the EPA to attain the DfE designation. DuBois has been recognized by the EPA as a partner in its Safer Choice program (see Figure 1).

We have invested heavily in testing equipment to make the conversion from hazardous chemicals to environmentally responsible chemicals possible for our customers. In this way we are forming partnerships to make the transition as painless as possible. We don’t expect to be successful 100 percent of the time. We don’t think it’s possible to replace chlorinated paraffins across the board, but for those applications where it makes sense, we help in any way we can. 

McChesney, Kyzen: We are constantly working with end users, regulatory organizations, process equipment manufacturers, and lubricant developers to analyze market requirements and address those needs with new, environmentally compliant cleaning chemistry —both aqueous and solvent—that will provide superior cleaning at minimum concentrations, energy consumption, at required production levels, and meet user-friendly approvals.

We try to look at the whole picture from initial substrate forming to cleaning through corrosion protection to final packaging. By performing this entire scope, we can best serve our existing customers as well as new ones.

Sometimes the entire process must be changed to meet end goals. For example, several forming operations for deep-drawn stainless steel components use chlorinated lubricants to handle the heat generated during forming. Chlorinated lubes are best cleaned using chlorinated solvents. With chlorinated solvents being phased out or restricted, users are looking for different solvents that are environmentally preferred. Some are actually exiting solvent degreasing and going to aqueous processes. That means investing in new equipment and new chemistry such as vacuum degreasers using modified alcohols or hydrocarbons. This approach reduces solvent consumption and encloses systems to eliminate personnel exposure and meet air permit conditions.

For a stamping manufacturer to make this switch, they have to make a big investment of time to validate the process, select the right equipment, match the chemistry with substrates and contaminants, and then purchase and install equipment. We offer to validate this process in our lab so that the stamper does not have to interrupt its normal production schedule. We can test various solvents and simulate equipment processes to provide cleaning standards to ensure that the chemistry and process will work before the manufacturer makes a substantial investment. We do this for our customers at no charge.

We also provide a complete scope of operations cost from initial chemistry to makeup to waste disposal, thus allowing the manufacturer to know the details before real production implementation and that they meet environmental regulations.

Sometimes when a user switches from one type of metal to another, we analyze the process to verify if a corrosion protector is required. We then perform tests in our lab to make sure they meet the desired storage protection duration.

When a user experiences a process change—such as part staining or rusting or etching—we’ll inspect the site, obtain all information possible, take samples of the lubricants’ chemistries, detail the equipment operational conditions, and then thoroughly analyze and identify the criteria that are creating the problem to help the manufacturer resolve that problem.

Cassin, Walter: Our biorenewable formula (CB 100TM) removes the toughest contaminants while remaining nonflammable, noncorrosive, biodegradable, and VOC-free. The formula lifts oil from a metallic surface through Nature Boost™—an exclusive ingredient derived from vegetable extracts. It can be sponged off easily and the absorbent pad disposed responsibly. Our line of industrial parts washing systems, Bio-Circle® Liquid L, Aero, and Ultra, use bioremediation, which renders the result safe to handle.

We are in tune with an overwhelming response from clients who seek high-performance green solutions designed to improve worker health and safety in industrial applications. Just recently we conducted a vast competitive study and have launched a new maintenance, repair, and overhaul (MRO) product that is a nonconductive, nonflammable, premium electronic cleaner. It is emblematic of our ability to strike that perfect balance between performance and safety.

In the last 15 years, we have eliminated 15,000 solvent tubs in maintenance settings. This means that approximately 7,500 workers are no longer exposed to dangerous solvents on a daily basis; 825,000 gallons of solvents have been removed from the workplace and taken out of the industrial waste stream; and 3 to 6 million pounds of VOCs no longer threaten the environment.

Noack, Raziol: Our focus is on products with increased environmental compatibility and advanced performance characteristics. We offer a range of high-performance lubricants and the appropriate application systems that allow the interaction between lubricant and applicators without problems.

The Raziol Fluid series comprises water-based, highly viscous forming lubricants that can replace mineral oil-based lubricants. This concept was rewarded with an innovation prize. The used degreasing bath solution can be reprocessed, which results in a reclassification of the wastewater.

Our CEP series chlorine substitute product often can be used as a high-performing alternative.

This spring we will introduce a new series of partially evaporating stamping and drawing lubricants, called the ND (NoDanger) series, that do not need to be labeled with the hazard symbol GHS 08 or H304. This constitutes a major step forward in reducing VOCs in the metal forming industry.

Hough, Tower: Our new product development projects continue to keep environmental, health, and safety of the people using our products in the forefront. This is why most of our products do not require hazard pictograms on the GHS labels and SDSs.

Editor's Note: EPA’s metal finishing discharge standards guidelines are available online (40 CFR Part 433) for more in-depth information.

Chemetall, www.chemetall.com

DuBois Chemicals, www.duboischemicals.com

Kyzen, www.kyzen.com

Raziol, www.raziol.com

Tower Oil & Technology Co., www.toweroil.com

Walter Surface Technologies, www.walter.com

About the Author

Kate Bachman

Contributing editor

815-381-1302

Kate Bachman is a contributing editor for The FABRICATOR editor. Bachman has more than 20 years of experience as a writer and editor in the manufacturing and other industries.