The next generation of VOC-free vanishing lubricants

Disappearing compound, vanishing oil, evaporative, and solvent are among the many names for basically the same product. Manufacturers use these lubricants for numerous metal forming operations, such as drawing, forming, punching, and perforating. They get their name from the nature of their use. When applied to the workpiece, they soon "vanish," leaving a clean, dry part.

The advantages of using such a lubricating fluid are many. Depending on the additives contained in the base fluid, the residue may be dry to the touch, oily, sticky, or nonexistent. The residue provides in-process rust protection without the need for additional application. The disappearing effect or evaporation may take place in a relatively short time frame, 20 seconds or up to one hour or more, depending on the lubricant's flash point, the amount applied, and the environment in which it is used.

The application method is very important to the operation. If too little lubricant is applied, it may evaporate before the operation is completed, which causes galling or tool wear. On the other hand, if too much is applied, the fluid may fail to evaporate, which can negate the originally intended use and leave the parts wet when they are packed or arrive at the next operation.

Flash Point

One method of categorizing vanishing oils is by their flash points. The flash point of a flammable liquid is the lowest temperature at which the liquid emits enough vapor to ignite if there is an ignition source. These types of products have a flammability rating of 2.

One way to determine how fast a vanishing oil will evaporate is to review its flash point. There are basically three groups or ratings: 105 degrees F, 125 degrees F, and 140 degree F (or high flash, as it is sometimes called). The lower the flash point, the faster the base lubricant evaporates.

Speeding up the Process

Additives to the lubricant also can affect the evaporation rate. In some instances, a secondary method is introduced to make the fluid evaporate faster. Fans can be used to help circulate the air to facilitate drying. Even heat tunnels can be employed to accelerate the drying. In some operations, the heat generated during the forming or cutting process enhances the drying time.

Restrictions

Vanishing oils have found a prominent place in the manufacturing environment. Unfortunately, current and pending regulations are making them more difficult to use and monitor. Just as emissions controls for vehicles in California have made their way to other states, stronger restrictions and regulations regarding this family of lubricants will spread across the U.S. and make it tougher for manufacturers to use them.

While the advantages of using vanishing oils are many, several disadvantages are creating a need for alternatives.

Smoggy Combination

Because these lubricants are petroleum distillates, they inherently contain high levels of volatile organic compounds, or VOCs as they are more commonly known. While VOCs are not hazardous alone, they do react with nitrogen oxides (NOx) in the air and form ground-level ozone, or smog. The Environmental Protection Agency (EPA) and the Clean Air Act regulate man-made emissions of both VOCs and NOx. Under the Clean Air Act, many areas of the U.S. do not meet national standards for ground-level ozone. These areas are referred to as "nonattainment areas" and must meet reductions in emissions until they comply with the standards. (Visit www.epa.gov for more information and a map of areas affected.)

Complying With Regulations

Many state and local governments have developed regulations that industries must follow, based on the guidelines from the EPA. In many instances, these guidelines limit or restrict the use of vanishing oils in manufacturing. Once these restrictions have been decreed, it is then up to the manufacturer or fabricator to determine how to change its processes to comply with regulations and reduce their own VOC generation.

Now there are a few decisions to make. Does the manufacturer pursue the necessary permits to continue as in the past? Does it go back to washing parts after fabricating them with an oil or another lubricant, adding additional costs to the operation? Over the past several years, huge strides have been made in synthetic technology in regards to lubricants. Gone are the days of the sticky, tacky residues that were once common-place when the switch was made from petroleum oils to synthetics. There are a few solutions to this complex situation. To remove VOCs from the manufacturing or abricating process, alternative lubricants need to be explored. Past perceptions need to be discarded. A fresh look at the latest technologies can reap rewards that were not considered in the past.

VOC-free, Water-extendible, Synthetic Fluids

One path to compliance is to explore VOC-free, water-extendible, synthetic fluids. This family of lubricants, which can mimic the benefits of the solvent-based fluids in many applications, is supplied in a concentrated form and then diluted with water on-site. The source and type of water used for this dilution must be evaluated and tested as well. All water is not the same, such as soft water and hard water that is treated either with a softener or reverse-osmosis system. Some water sources harbor microbial growth, and some water can cause spotting, rusting, or staining. Before using the water-extendible synthetic, the manufacturer needs to analyze its water for compatibility with the particular synthetic.

It's All in the Mix

One drawback to these water-extendible fluids is inconsistent mixing. All too often operators are left to mix these fluids as they need them, using buckets out on the plant floor. Despite best intentions, very seldom will two operators mix up the lubricant to the same dilution or ratio as another, which creates variability in the process. Why did one production run have dry-to-the-touch parts, when the next shift's parts were sticky and tacky? If the dilution is not the same, problems can arise. Installing a simple mixing station (Figure 1) can achieve a consistent dilution. In the mixing station in Figure 1, the valve pulls the lubricant into the mixing chamber through a sized orifice, creating the proper ratio of water to lubricant for the operation. With the relatively low cost of these units, multiple units can be installed to achieve different ratios for various jobs.

The Best of Both Worlds

A new generation of fluids combines the best features of both vanishing oils and water-extendible fluids. They eliminate VOC completely, can be used straight out of the drum, have similar drying times, and can be used on mixed metals. No mixing station is needed.

The absence of petroleum distillates in these lubricants precludes the need to monitor and track VOCs emitted, for there are none. They are nonflammable, making them safer to handle and store, and available in several variations that contain no oil, sulfur, or chlorine, or hazardous ingredients. This family of products has been formulated to offer in-process corrosion protection and allows for the residue to be welded over without hazardous or unpleasant fumes.

Figure 2 compares the wetting characteristics of a petroleum-based vanishing oil, water-extendible vanishing oil, and a next-generation fluid. The cold-rolled steel coupons were uniformly coated with 0.5 ml of lubricant. Several characteristics are compiled in Table 1 to reflect similarities between the three fluids.

Table 1