In the fast-paced automotive industry, competition is hot and manufacturers work intensively to create more efficient, reliable vehicles. When the race is head to head, there is no room for failures. Finding ways to avoid failures and produce a more reliable vehicle, provides a competitive edge.
New technologies such as FIPG (formed in-place gaskets) which contribute to a more efficient, reliable system, can provide that needed edge. As a replacement of traditional gaskets such as cork and rubber, FIPG sealant is stronger and more reliable. An adhesive applied directly on the factory floor, FIPG increases efficiency and cuts down on waste. The adhesive also makes a stronger seal than traditional gaskets and can tolerate more wear so failure rates decline significantly. However, with this new technology, comes new specifications and assembly processes.
The integrity of FIPG relies on the surface cleanliness of the part prior to sealing. The part’s surface must be clean and clear of chemical contaminants to maintain a strong seal and avoid failures. In the past, cleanliness in the automotive industry only presented a concern with moving mechanics so grit and dirt were the primary threats. But, when applying FIPG, contaminants can be more than grit and dirt; various assembly liquids—mold releases, detergents, cutting fluids—exist in the manufacturing processes and can derail this imperative bond.
There exist several cleaning processes such as parts washers and solvent wipes to clean surfaces in the automotive industry, however, without a way to monitor and verify these cleaning processes, the level of surface cleanliness remains unknown.
An engine block manufacturer and supplier to one of the big three U.S. automotive manufacturers utilized a parts washer to prepare their engine blocks for sealing. While the manufacturer had the ability to manipulate variables in parts washers such as duration of wash and solvent type, they did not have a way to determine which variables produced the desired results. The only way to discover the success of the parts washer was by failures in the field. This method simply left too much up to chance and the manufacturer knew they needed a change.
The engine block manufacturers required a way to verify each step of their process prior to bonding to avoid failures in the field and to verify bond quality prior to application of FIPG.
BTG Labs’ fast, easy, accurate, quantitative surface cleanliness gauge the Surface Analyst dissected each step and variable in the washer process. The instrument took contact angle measurements on different engine blocks and after manipulating different variables in the washing process. Up to 12 areas across the same part were measured to examine cleanliness uniformity.
The integrity of FIPG relies on the surface cleanliness of the part prior to sealing. The part’s surface must be clean and clear of contaminants to maintain a strong seal and avoid failures. In the past, cleanliness in the automotive industry has been vague, undefined and subjective.
The Surface Analyst quantified the abilities of various parts washers and specific variables in each one. The manufacturer was able to see, on an objective scale, which washer provided the cleanest and most uniform surface and which settings on the variables worked best. With a way to verify and monitor the parts washers, the manufacturer gained the ability to optimize their wash process and gained confidence that their seals would hold.
The manufacturer used the instrument to build specifications to ensure consistency. This eliminated waste and more importantly, failures in the field. The engine block manufacturer developed (using the Surface Analyst) a process for their washing system that reduced scrap, reduced waste and delivered quality product to their customers.
In 2014, a large manufacturer of automotive exteriors and interiors encountered a problem consistently adhering paint to their dashboards due to an inappropriate use of their flame treatment.
Flame treatment is a popular and notable procedure that can successfully modify the surface chemistry of a polymer, readying it for adhesion. Although flame treatment is an effective solution, determining the amount of treatment can be a delicate procedure. The over-flaming of these highly sensitive polymers can lead to polymer reorientation due to localized melting and ultimately, destruction of the surface.
In this case, however, the manufacturer was not utilizing flame treatment to monitor their surface cleanliness. Instead, they used it to deflash excess material on the edges of their dash boards. The edges of the dashboard were being over-flamed, hindering the polymer’s surface adhesion ability. This, in turn restricted paint from correctly adhering to the edges of the dashboard. The company needed a way to determine the appropriate amount of flame treatment.
At the time, the company enlisted dyne inks for their surface cleanliness tests. However, their low energy polymer was outside of the dyne ink range and because dyne inks are destructive, the manufacturer’s parts were damaged during the testing process.
BTG Labs got involved and quickly assessed the problem and fixed the issue. Collaboratively, a method was developed to determine appropriate flame treatment for optimal surface cleanliness. The surface was measured before and after flame treatments, then paint was applied to the surface, and a paint peel test was performed to determine the surface’s adhesive ability to the paint under different flaming treatments. They adjusted their flaming process by flaming closer, further, faster, or slower to the surface of the dashboard.
Because of these tests, and use of the Surface Analyst, the manufacturer was able to determine the desired surface cleanliness parameters and appropriate flame treatment process. With the suitable flame treatment process resolved, the surface regained the ability to adhere to the paint. Not only did the Surface Analyst provide more accurate testing, it decreased the amount of wasted materials by $230,000 that dyne inks caused in the destruction to tested materials.
The Surface Analyst provided a fast, easy, accurate, and nondestructive way to monitor surface cleanliness. The manufacturer replaced their dyne ink methods with the Surface Analyst and use it successfully to this day. The company now obtains precision measurements, decreases amount of waste, and collects accurate and quantitative data.
Creating a Bond to Perform
Room Temperature Vulcanizing (RTV) adhesives brag several benefits over traditional gaskets including, cost effectiveness and faster and easier application. However, RTV silicone does not perform well with hydrocarbons which are highly inevitable in the automotive industry. When RTV is replacing gaskets, its adhesive ability is pinnacle, requiring clean surfaces for optimal adhesion. This requires a method in which to monitor and measure surface cleanliness on a sensitive, objective level.
When a large, American automotive manufacturer began to notice engine leaks in the field, they required a change in their surface cleaning processes. The most commonly used materials in engine manufacturing included diecast and machined aluminum. Their aluminum cleaning methods comprised of washing, plasma treatment, and conversion coating.
When using a material that requires optimal surface cleanliness for successful bonds, supplier and assembly checks are necessary to understand how clean or contaminated the material is before it enters the cleaning process. Because of this, the company also required a way to check incoming materials from suppliers.
The company first employed dyne inks to determine the surface cleanliness levels on their metals after performing their specified cleaning processes, but to no avail. There was too much subjectivity in the inks; the suppliers couldn’t tell for sure whether or not the metal was clean, and their engines still omitted leaks.
Interpreting the Surface
An employee of the automotive manufacturer discovered BTG Labs on the internet and recruited the Surface Analyst™. They took 10,000 measurements with different cleaning processes to analyze the varying surface energies. After interpreting the results, they settled on a pass/fail qualification. This would articulate to all of the manufacturers within the entire company, on a completely objective scale, whether or not their newly prepared surfaces met the desired cleanliness levels to bond RTV. The company now had a way to check incoming supplier materials as well as assembly checks.
Conventional methods are too subjective and destructive leading to bong failures and wasted material. The Surface Analyst delivers a quantitative, nondestructive, and non-subjective way to measure surface cleanliness and insure reliable and successful bonds.
When manufacturers supply products to customers, they want to have the highest confidence in the quality of those products. But, when proper measures aren’t accessible or available to guarantee quality, a major need arises.
A recent customer, a manufacturer of automotive oil filters, had finally reached a critical point in their business as a result of problems with product quality, specifically regarding adhesion.
Adhesion failures in the field damage brand reputation, the user’s productivity, and in today’s lightning fast social media blogosphere, word of these failures can quickly spread. After a year of product failures, the manufacturer decided upon a proactive approach and brought in BTG Labs.
The hydraulic filters, which comprised of nylon polymer caps and a mesh filter were coming apart upon removal out of the hydraulic system.
When the customer needed to change the filter, the cap would come apart from the rest of the piece due to poor adhesion. Leaving the rest of the filter stuck in the system caused more delays as it was difficult to remove and created a mess.
When looking into an adhesion issue, BTG Labs first asks the question: what is the in-place surface preparation process?
The Materials & Process
The manufacturer was using a 2-step process which included plasma treatment on their end caps followed by a heat cure.
Plasma treatment is a very effective way to treat a surface. However, there existed a potential for leaving contaminants on the surface because the technicians did not have a way to verify the amount of plasma to utilize. Thus, treatment levels varied.
The second step–heat cure process–has the ability to remove some of the contaminants left behind, and in theory could make the adhesive more tolerant of contaminants, but this didn’t solve the problem as failures still ran rampant.
The problem came through the varying amount of plasma treatment levels. Because there was no consistency, no definitive process, and no way to verify the characteristics of the surface, no one knew the appropriate treatment level to ensure adhesion. Furthermore, the caps to these hydraulic filters came from several different suppliers which created even more inconsistency.
Knowing the nature of these contaminants would be an initial step in modifying the process. All of these suppliers were asked to refrain from using a silicone based mold release. Silicone, a highly hydrophobic substance, is a huge contaminant and will prevent a bond from properly adhering. Knowing that there existed no silicone mold release on the surface of these caps, BTG Labs ran some analysis tests.
The Measurements & Solution
BTG Labs’ engineers used the Surface Analyst™ to measure surface energy, or surface cleanliness of the caps.
They obtained two caps from each supplier, one treated, one untreated. When the drop of water contacted the surface of the cap, the drop reacted rather strangely. What BTG Labs saw was dynamic wetting: the behavior of a drop of water that lands on a hydrophilic surface and spreads out over time as it absorbs the substance. The testing revealed an inconsistent contact angle, which is not ideal.
BTG Labs then treated a different section of the cap with a solvent wipe, followed by another inspection using the Surface Analyst. The measurement remained the same.
This indicated that the surface held a contaminant that the solvent wipe was removing. Furthermore, because of the behavior of the water droplet, the contaminant was assumed to be of a hydrophilic nature. So, while the suppliers were adhering to the non-hydrophobic solution, they were using a hydrophilic soap. This soap was leaving a residue on the caps.
BTG Labs went one step further and using their fully equipped Materials & Process Laboratory, tested the caps with their XPS Mass Spectrometer which supported this claim. There was, in fact, a hydrophilic substance on the surface of the caps. Furthermore, this substance showed high levels of potassium which is common in soap mold releases. When the specs were originally designated, the manufacturer only wanted to avoid hydrophobic mold releases. However, these tests prove that the hydrophilic mold release also caused contamination on the cap. And depending on the level of plasma, the soap remained on the surface as a contaminant even after treatment. This meant the specs for suppliers would have to change.
Using the Surface Analyst, the company was able to discover the presence of an unwanted substance on the surface of some of their incoming products.
The next steps would be to reevaluate their assembly process. New specs would need to be in place, a determination of proper surface cleanliness must be decided, and a new surface treatment process must be constructed.
This included a requirement for the supplier to wipe the part with a solvent prior to shipping. Then, the manufacturer would also use a solvent wipe before plasma treatment. This ensured that the soap did not remain as a contaminant on the surface. Consistency and coherence, we created. Consequently, all of the parts could now confidently arrive from suppliers. The technicians could then clean and treat to a specification number to pass on to customers for successful implementation.