Spring is In the Air
The MCA president shares that there are new resources for cleaning standards and specifications on the association’s website.
Time has sprung forward, and we are no longer driving to and from work in the dark. The month of March truly came in like a lion with harsh cold weather and seems to be leaving like a lamb, in some parts of the country, as trees and flowers bloom. Speaking of spring, many of you may take advantage of the longer days and gentle weather to do spring cleaning.
One of the benefits of being a part of a cleaning association is that if you have any questions or need direction regarding maintenance cleaning in your facility or cleaning your product, the MCA is the place to get the answers. However, when it comes to your house, your garage, or your car, you might want to ask family and friends.
We have recently accumulated a list of resources for cleaning standards as well as specifications and posted the links on the Industry Standards page of our website. These resources will help you get a head start on your cleaning. The additions complement our Technical Resources section, which is coming along with new technical papers and webinars being added regularly. If what you are looking for is not there, reach out to us, and we will connect you to someone that can help you get the answers you need. We are also working on a discussion forum, so keep checking back to see our progress.
Happy Spring!
Upcoming Webinars
Fundamentals of Vapor Degreasing
March 29, 2022, 11 a.m. EDT
This overview of solvent vacuum degreasing technology provides a comparison to aqueous cleaning technology. Presenter will explain environmental advantages of the process as well as running costs, safety, EHS, solvents used, and more.
Member Profile
Jomesa North America Inc.
Since delivering its first automated microscope system for particle analysis in 2001, Jomesa has grown to be a leader in automated cleanliness analysis microscope systems in accordance with ISO 16232, VDA19.1 and many other company-specific standards.
Contact:
248-457-0023
Mission Statement
It is our mission to deliver the highest quality automated microscope systems and cleanliness analysis accessories to the world of manufacturing.
About Us
Since delivering our first automated microscope system for particle analysis in 2001, Jomesa has grown to be the leader in automated cleanliness analysis microscope systems in accordance with ISO 16232, VDA19.1 and many other company-specific standards. Jomesa operates globally and has direct representation in all major automotive manufacturing markets. Jomesa offers optical and SEM automated analysis systems as well as high quality filter membranes and accessories for use in the cleanliness analysis process.
Our Team
Jomesa employs approximately 100 people around the world, spread across our six global offices. All engineering and product development takes place in our Munich, Germany, headquarters. Accessory production takes place in Munich, as well as Shanghai, China.
Our Products/Services
- HFD Optical Analysis System
- Precision Scan for Elements – SEM/EDX Analysis System
- Filter membranes for cleanliness analysis
- Filter membrane handling and archiving solutions
Awards and Recognition
- World leader in cleanliness analysis microscope systems
- ISO 17025 accredited for Particle Standard certification (first and only lab in the world)
Chemistry
Heat’s Impact on Parts Cleaning
Aqueous cleaning tanks that must last several weeks, months, or Originally published by Production Machining and Products Finishing
Thermal dynamics is important for assisting in the cleaning of a part. Adding heat or energy influences the cleaning process through its impact on chemistry, the water within the washer and its effect on drying.
MARTY SAWYER, CEO
TRIMAC INDUSTRIAL SYSTEMS LLC
Machine shops and manufacturers use cleaning technology to remove contaminants (including oils, metalworking fluids, grease, metal fines and even fingerprints) from parts and/or remove rust or other surface compounds left on parts from a prior operation. Adding to the complexity is that “clean” is a relative term. What might pass quality control in one operation might not for a different application. Once how “clean is clean” has been defined for an application, then the next challenge is determining the most cost-effective method(s) to achieve it.
And, in some cases, heat can play a significant role in the chosen parts cleaning process.
Thermal dynamics plays into the process of cleaning a part, but its effect is sometimes misunderstood. That’s because adding heat or energy influences the cleaning process through their impact on chemistry, the water within the washer and their effect on drying.
How Heat Affects Chemistry
Time, temperature, pressure, agitation and chemistry are all critical elements of successful parts cleaning. Basic thermodynamics tells us that all organic
matter desires to be at the same temperature. For example, a bucket of hot water in a cold room, given time, will eventually be the same temperature as the room because the water’s heat transfers its energy to the room’s air. This heat transfer happens because the molecules of the hotter matter (water) are moving faster than the cooler matter (air). The energy of the hotter movement is transferred through radiation, conduction of convection to the cooler molecules, inciting them to move more as they absorb the heat.
Heat is a form of energy. The addition of heat to a system speeds chemical reactions and interactions based on the laws of physics and chemistry. For parts washing processes, adding energy through heat to a cleaning operation offers many benefits. First, every 17°F increase in temperature can double reaction rates, which can drastically accelerate the process. Second, heat
improves the cleaning process itself, thereby reducing the amount of chemistry required to do the same work. However, the level of heat also affects the chemistry. Not enough heat can cause chemistry foaming, and too much or improperly managed stack temperature can damage pumps or create acid rain. A well-designed parts washer will manage these issues and keep the operating tank temperature at an optimal 120° to 160°F, depending on the requirements of the chemistry and the bonding of the contaminants to the substrate.
Heat improves the cleaning process because hotter or faster moving water molecules do a better job cleaning than slower moving molecules because the surface tension is reduced. When this happens, the process displaces the dirt for the water to remove through the spray or immersion action. When washing, the soap molecules attach to the oils on a part, enabling water to seep in underneath. The particle of oil is then pried loose and surrounded by soap molecules to be carried off by the spray water.
How Heat Affects Spraying
Heating the water in a cleaning process not only improves cleaning results but also reduces the water pressure that is needed to dislodge dirt and contaminants. However, spraying that water has its own challenges. First, the water in the tank must be heated. Depending on the tank size, this can be done through electric elements or by using a gas burner, which typically involves an immersion tube or an external heat exchanger. The goal is to quickly heat the water with the ability to maintain the temperature. Conduction transfers the heat from the water to the physical tank itself. Heat loss from the tank walls to the exterior air needs to be taken into account. This loss can be minimized by insulating the exterior tank walls, but the return on investment will be unique to each project.
Water is sprayed on the dirty parts to clean them. Regardless of the washer design, once the water is sprayed, it is atomized. Once water is atomized through the spraying process, the surface area of the water is significantly increased. When this occurs, the rate of evaporation increases with the surface area ratio. Adding heat to the water further increases the evaporation rate as the water is exposed to the cooler air through the spraying process. Spray washers will have some type of walls to contain the spray. When the sprayed water comes into contact with the cooler washer walls and the parts themselves, that process also reduces the water temperature.
Although these heat loss effects cannot be prevented, they can be accommodated in the washer design. As the sprayed water is returned back to the tank, it is reheated to keep it at a constant temperature for optimum process control. Insulation can reduce the heat loss process, but it is an equipment investment decision compared to the utility consumption of heating the water. Insulating the water tank will provide the best economic and heat containment benefit followed by insulating the cabinet walls.
How Heat Affects Drying
After a parts washer has completed the cleaning step, a wet part is the result. To accelerate the drying process, air movement and heat should be present. Trapped and pooling water can best be removed through a targeted airflow. Air knives are the easiest way to move large amounts of water that gravity does not remove, but, if that does not dry parts well enough, then a regenerative blower can be implemented. This will add about 40°F of heat to accelerate the process. Even more heat can be added to the blower, if faster drying is needed. An oven can also be used with either convection or infrared processes to speed the drying process.
Working with an experienced parts washer original equipment manufacturer will ensure optimum design and performance for a particular application. If a part or process is unique, most manufacturers can perform testing to ensure an outcome to certain specifications. Depending on its construction of mild or stainless steel, a well-designed parts washer should last a minimum of 15 years to boost return on investment while meeting customers’ specifications for part cleanliness.
Trimac Industial Systems LLC | trimacsystems.com | 913-441-0043
About the Author
Marty Sawyer is the CEO of Trimac Industrial Systems, LLC. Trimac manufactures the Kemac brand of washers. Call 800-830-5112.
Equipment
Choosing the Right Aqueous Cleaning Operation
Originally published by Production Machining
For most machining processes, water-based solutions can be applied using tailored technologies for specific applications.
When determining the best way to machine a part, dozens of variables must be taken into consideration when choosing the most effective method of cleaning the finished product using an aqueous system. In addition to the customer’s own requirements, manufacturers must also factor in part geometry, the material used, the shape of the chips that will be generated, throughput, and the need for quick change-outs between different types of parts. The temperature of the solution—and of the part itself as it exits machining—is sometimes an issue as well, as is the process being performed. Standard cut parts can often simply be sprayed off, while lapped surfaces require ultrasonic cleaning to remove tiny particulates.
Because so many questions need to be answered by the shop about their customer’s cleaning requirements, it’s no surprise that the Cleaning Technologies Group, LLC, Ransohoff says 80 percent of the systems it sells are custom designed, according to Jeff Mills, national sales manager for the Ransohoff division of CTG.
“Our first questions will generally be ‘what are you making, what are the materials you are using, what is your production time allowance, and what are your customers’ requirements?’,” he says. “From there, we can begin making suggestions about the type of cleaning process that might work best for them and even how robotics might be incorporated. And we don’t take a stock machine and start adding options. The vast majority of the time, we’re designing and building these systems from the ground up according to the customer’s exact specifications. Then, we have the blueprints on file should they need another system or another dozen of them.”
According to Mr. Mills, there are four basic methods to performing water-based cleaning operations in metalworking: standard spray, total immersion, ultrasonics, and high-pressure spray.
Of these, the first and last are referred to as “line of sight” processes, in which anything on a part in sight is cleaned, even at the bottom of relatively shallow cuts and holes.
The two remaining processes call for parts to be immersed in the cleaning solution, and even spun and agitated, in some cases. These work best for more complex parts with deep recesses in which chips and other debris can be hidden.
This article covers how each process is performed, to what parts they are most suited, and the kind of work a machine shop is doing that would lead them to choose one process over another, and even to commission a custom system combining parts cleaning methods.
Standard spray provides great flexibility among parts of different shapes, materials and sizes. Such systems are typically batch loaded for use in general industry, such as companies machining parts for appliances or garden equipment.
Parts are positioned on a rotary table or within a specialized fixture, depending on their geometry, and they are sprayed with water mixed with different concentrations of surfactant, which disperses oil and debris from the surface of the part. Any remaining liquid is blown off using compressed air. More acidic cleaners are used with soft metals such as copper, brass and bronze, while steel products require that attention be paid to the pH level. A solution with a pH of less than seven is considered acidic, while a solution with a pH higher than seven is referred to as basic, or alkaline. A standard spray system can be modified—automated loading/unloading, the incorporation of additional cleaning systems for special applications—and is a simple, straightforward, cost-effective process for a variety of manufacturers.
Total immersion is generally considered first when features or deep recesses on the part prevent direct line of sight inspection. Cutting fluids, chips and other particulate matter can evade even high-pressure spraying, so some parts must be fully immersed in the cleaning solution.
One approach involves loading parts into a basket, which is then introduced into the self-contained cleaning chamber. The parts are first sprayed while the basket rotates in a circle, and then the chamber is filled with an aqueous solution with whatever chemistry is required by the process. The basket is then agitated, plunged into, and then withdrawn from the bath, which serves to channel the solution deep into the recesses, thereby removing any remaining excess chips or fluids. This method basically picks up where a standard spray system leaves off, adding total immersion to the process, and then blowing the parts dry. Automation is also an option, as is the case with all four of the standard categories of aqueous cleaning.
Ultrasonics can be layered on top of the standard spray and total immersion processes, adding the powerful element of cavitation to the cleaning system. Once spraying has been completed to remove gross contaminants, the chamber is filled and high-intensity sound waves are introduced into the solution, forming vacuums within the crevasses of the parts being cleaned. Depending on the frequency of the sound waves, contaminants are removed at the lower end of the scale while material can actually be removed from the part surface at higher exposures. Basically, the vacuums collapse or implode, bringing the solution into contact with the surface in a burst of energy that carries contaminants away. Mr. Mills says the company has managed to meet cleanliness specifications down to 50 microns.
The types of parts for which this process is well-suited include transmission shafts, turbine blades and medical implants. Ultrasonic cleaning is ideal for precision machining applications with stringent cleaning requirements. Aerospace, electronics, automotive and medical markets have the strictest requirements.
High-pressure spray, “a line of sight” process, is primarily used in deburring applications. Whereas sanding or grinding can take away too much material from the part’s surface, a high-pressure spray can remove burrs without damaging the underlying substrate. With an upper range of 10,000 psi, the Ransohoff line of high-pressure washers generally operate in the 3,500-psi range for materials such as aluminum and approximately 5,000 psi for parts made of steel.
Aqueous systems can be designed to fit almost any part cleaning application and are safer than using solvents, which contain highly regulated chemicals such as alcohol and trichloroethylene and must be operated under a vacuum so no fumes are released into the working environment. In fact, most of the aqueous solutions we supply are safe enough to go right into the sewer system,” Mr. Mills says. “It’s contaminants introduced by the machining process such as oil, greases and lapping compounds that have to be filtered or disposed of properly.”
Whatever system is chosen, CTG offers laboratory testing to ensure that the final customer specifications for cleanliness are met. In fact, the company’s tech center houses a cleanroom rated at class 10,000 using gravimetric Millipore filters to conduct microscopic particle size analysis.
“If a company will provide its required production rate and cleaning specifications,” Mr. Mills says, “we’ll run a lab test before delivery as proof that the machine will perform as promised.”
When it comes to maintaining existing cleaning equipment, CTG offers a two-day preventive maintenance service in which a technician visits the facility and runs tests to determine how efficiently the system is operating. Again, many factors come into play, beginning with the type of machining process being performed, as well as how efficiently it is running. As the word “system” implies, increasing connectivity between once-separate systems mean how one is operating can affect the other. If there are too many particulates found in the spent solvent, a pre-spray could be added so that the parts aren’t carrying unnecessarily high amounts of debris into the cleaning system, clogging its filters. If an obstruction causes problems with the flow of the solution through the system, the machines are programmed to alarm out and shut down. They are also capable of running in “gray mode” when no parts are being loaded, essentially powering down to avoid excess energy costs.
Just as robots have revolutionized many areas of manufacturing, recent years have seen automation introduced into parts cleaning systems in ways that have increased flexibility and productivity. Mr. Mills is quick to add, however, that there is a significant difference between aftermarket or “peripheral” systems that can be added to a machining cell after the point of purchase and the newer integrated systems that are wired into the cleaning system and monitored through its Programmable Logic Controller (PLC). The PLC allows for seamless interaction between the robot and the cleaning machine while loading and unloading parts. In addition, the results can be fed into the company’s facilities information system for both documentation and process review.
Providing a streamlined footprint, a more efficient use of space on the shop floor, and the ability to conduct lights-out machining, are other benefits to robotic loading and unloading.
Mr. Mills says he has seen increased interest in efficient cleaning systems over the span of about five years and more automation being incorporated into machining/cleaning cells in the past three years. “Ninety percent of our customers who request a quote have a cleaning specification they have to maintain, whether that be visual inspection, a white glove test or a complete lab test that determines the size and weight of particles left suspended in the solution,” he says. “Parts cleaning is becoming more of a priority than ever before.”
