This page is comprised of various commonly asked questions Best Technology is often asked about part cleaning, passivation, electropolishing, wet and dry processes while researching new equipment to fit a customer’s manufacturing process needs.
Part Cleaning Equipment & Process FAQs
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What is ultrasonic degassing? How to degas ultrasonic cleaning tanks
What is degassing? For ultrasonic cleaning equipment, degassing is the process of removing gases such as air dissolved in a liquid cleaning solution.
Air and other gases dissolved in a cleaning solution will impact performance of ultrasonic cleaning tanks. Gases in the cleaning solution absorb some of the cavitation energy that would otherwise go toward cleaning, and thus reduce effectiveness. Removal of these gases from the cleaning solution will result in maximum ultrasonic cleaning performance.
Any water that comes from a pressurized water supply will naturally contain dissolved gases, and therefore the water will need to be degassed when first dispensed.
Options to degas ultrasonic cleaning tanks
- Let it sit – Degassing solution is easily achieved by letting the solution sit out for a number of hours. This is why a glass of water tastes “different” when first out of the faucet vs. drinking it hours later.
- Let it run – Run the ultrasonics just as you would ordinarily, but without the parts to be cleaned. Running the ultrasonics will expedite the degas process significantly, typically down to 5-10 minutes. Keep in mind that the cleaning solution only needs to be degassed when first dispensed from a pressurized supply.
- Fast degas ultrasonic cleaning system – Although 5-10 minutes is much shorter than hours, it’s still too long to wait for our parts cleaner machines to degas each time the solution is pumped from the storage tank to the process tank of the ultrasonic cleaning system. Our system features a fast-degas feature at the start of the ultrasonic cycle which allows the solution to degas in a matter of seconds vs. minutes.
The fast degas feature can be heard in the video below. Note high pitch of ultrasonic degassing and tuning amplified for video demonstration.
How to tell if a solution is degassed or not?
The cleaning solution de-gases simply by releasing the dissolved and entrapped air in the solution. During a degas process with ultrasonics, fine bubbles will suddenly appear and begin to rise to the surface of the solution (similar to that seen after first pouring a glass of beer). This implosion or cavitation of the solution with dissolved gases can result in a high-pitched audible sound from the ultrasonic tank until the solution is degassed as heard in the video above.
Once a solution or fluid is degassed either by letting it sit, ultrasonic cavitation energy, or heating, it does not need to be degassed again unless the solution replaced with new fluid.
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How do I convert my vapor degreaser to a new solvent?
As the clock runs out on the 3M™ Novec™ phaseout, many manufacturers are wondering how to switch their vapor degreasers to a 3M™ Novec™ replacement solvent such as BestSolv™ Engineered Fluids.
Here are the steps to use when converting your vapor degreaser to a new solvent.
Remove Old Solvent
Completely remove the old solvent from the vapor degreaser before adding the new solvent. Any residual old solvent left in the lines may be flushed with the new solvent. Do NOT use water to clean the vapor degreaser or flush the lines.
Add New Solvent
Review the Safety Data Sheet for the new solvent prior to first use. As always when handling solvents, use appropriate protective equipment as mentioned in the Safety Data Sheet. Since most solvents are designed to evaporate quickly, be careful not to leave the solvent container open any longer than necessary.
Identify Boiling Point of New Solvent
The boiling point on your new solvent may be different from that of the old solvent. Vapor degreaser settings are based on the boiling point of the solvent used, and should be adjusted when a new solvent is used in the degreaser.
Use the Safety Data Sheet, Technical Data Sheet, or other publicly available source to identify the boiling point of the new solvent. For BestSolv™ Engineered Fluids, you can find this information through our Technical Data Sheets page.
Adjust Vapor Degreaser Settings
Use the new solvent’s boiling point as a reference for changing the following settings on your vapor degreaser:
Vapor Degreaser Setting Set Point Liquid Temperature Control (LTC) Boiling Point plus 7-10 °F High Temperature Control (HTC) Boiling Point plus 10-15 °F Solvent Vapor Control (SVC) Boiling Point minus 10 °F Vapor Up Control (TH-1) Boiling Point minus 10 °F For example, a solvent with a boiling point of 165 °F would have a Vapor Up Control (TH-1) set point of 155 °F (165 – 10 = 155).
That’s it! Your vapor degreaser is ready to return to precision cleaning with your new solvent.
NOTE: Vapor degreaser controls differ by manufacturer. Some may not contain all of the settings described.
For further information about vapor degreaser settings, see the reference section below.
Vapor Degreaser Settings Reference
- Liquid Temperature Control (LTC): Set 7-10 °F above the boiling point of the solvent being used. A 10 °F rise in the boiling point indicates that the boiling sump has accumulated the equivalent oil solution of approximately 30% by weight, along with any other contaminants. Boil down and addition of fresh solvent is recommended.
- High Temperature Control (HTC): Set 10-15 °F above the boiling point of the solvent being used. A 10 °F rise in the boiling point indicates that the boiling sump has accumulated the equivalent oil solution of approximately 30% by weight, along with any other contaminants. Continued operation may be hazardous.
- Low Level Control (LLC): A safety to turn the heat off if the liquid level falls below a safe level.
- Refrigeration Control (RT): Regulates the temperature of the cooling coils. Typically set at 45-50 °F. It is not necessary to change this setting when changing solvents.
- Solvent Vapor Control (SVC): Turns off the heat in the event of high vapor level and must be set at 10 °F below the boiling point of the solvent being used.
- Vapor Up Control (TH-1): Turns on an indicator light when the solvent vapors are up to proper level on the cooling coils. This indicates the equipment is ready to operate. It also inhibits the spray pump(s) when the vapor line is below the normal operating level. The proper temperature setting is 10 °F below the boiling point of the solvent being used.
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Why are automated systems easier to process validate than manual equipment?
Process control and stability are critical aspects to regulated medical device and aerospace processes. It is important to ensure that a process has input and output variable limits which are defined and fully tested during process design, Equipment Qualification (IQ), Operational Qualification (OQ) and Process Qualification (PQ) validation testing. Setting up a proper DOE (Design of experiments) to test these limits is also important as the results of the DOE will give statistical confidence intervals of the limits.
Being that operators and employees perform various process operations different no matter how instructed in work instructions, the variation of operators must also be captured during process qualification (PQ) validation. An automated system typically eliminates many of the operator variability in the manufacturing process and this process “input” elimination also allows for tighter process output controls.
For example, in our automated passivation system, the elimination of relying on an operator to move the parts basket from stage to stage ensures that the parts remain in the appropriate (wash, rinse, acid passivation, etc) solutions for the process defined times and in accordance with the proper ASTM A967, AMS2700, etc specification. If a parts basket is immersed in the acid passivation solution too short or long duration, the passivation can likely fail and be outside specification limits.
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Why does spotting occur on parts after washing and DI rinse?
There are three ways that spotting can occur:
- If there is soil introduced with the rinse (ie: contaminants in the DI bath),
- If soil is introduced in the air stream (ie: either present in the atmosphere and blown onto the parts or circulated from the air supply into the heater and blown onto the parts), or
- If soil is left as residue from the wash process (this could either be soil that was originally on the parts and not completely washed off or it could be residue from the cleaning chemistry that is not completely rinsed off).
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Why are two rinses often recommended after wash cycles?
When parts are washed the parts themselves, as well as the basket they are in, carry some of the wash with them into the rinse tank. This “drag out” means that the rinse solution has to be constantly replaced or will simply become less and less clean over time. The biggest issue is not that the parts will be rinsed off, but that when the parts are withdrawn from the rinse tank, they may have soil redeposited on them. Once the parts are dried this soil can cause spotting on the surface of the otherwise clean parts. A second rinse bath produces a much cleaner final product by rinsing off the soil that is redeposited during the first rinse.
Often times, the second rinse tank includes a heated facility water inlet which constantly overflows the second rinse tank with small amounts of water to ensure water cleanliness. The second rinse tank overflow is sent to rinse tank 1 and then rinse tank 1 overflows to drain. This cascade overflow process ensures constant water quality over time no matter the amount of drag out on the parts and baskets.
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What’s the difference between solvent-based cleaning and aqueous cleaning?
There is an old saying when it comes to parts cleaning: “Like dissolves like”.
This comes from the world of chemistry, and is really quite a simple and useful phrase to remember. In chemistry molecules are described as being polar or non-polar. (Think north and south pole on the Earth) Polar molecules have a polarity that causes them to attract other molecules that have polarity, while non-polar molecules do not.
Water is a polar molecule. Oil is not. At the molecular level this is why “oil and water don’t mix”. Chemically they are dissimilar and cannot absorb each others molecules. By contrast salt IS polar; this is why you can dissolve salt in water.
So when should you use aqueous cleaning and when should you try cleaning with solvents? Solvent based cleaning systems (like Vapor Degreasers) are used when you need to clean true oils from your manufactured parts. Aqueous Cleaning Systems are used to clean water based materials from your parts.
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How does a vapor degreaser work?
If you’ve ever been wearing glasses as you walked into an air-conditioned building on a hot summer day, you already have a good understanding of part of how the vapor degreaser process works. (For those in colder climates, walking outside while wearing glasses on a cold winter day is an even better example.)
So, how does a vapor degreaser work? The vapor degreasing process is a cleaning process that uses solvent vapors (boiled solvent) rather than water to clean parts.
A vapor degreaser has two tanks (sumps) of solvent inside. One vapor degreasing tank boils the solvent (boil sump) which creates a vapor or mist of the solvent. The second sump (ultrasonic sump) is heated but not to the boiling point and is used as the second cleaning stage. The vapor degreaser also has bands of cooling coils inside just above the level of the sumps. These coils cause the vapor to return to a liquid state and fall back into the sump. The effect is like small “clouds” of the solvent are formed between the top of the sumps and the cooling tubes.
As parts at room temperature are lowered through the cooling area into the vapor, the vapor from the boil sump condenses on the parts just like moisture in the air does on your glasses in the examples above. This condensation contains the solvent that dissolves the oils on your parts, and the beading action creates droplets which run across the surfaces of the parts and fall back into the boil sump. The parts are then moved to the ultrasonic sump which contains heated but non-boiling solvent. This allows the parts to be lowered into the sump so that any blind holes or internal features are also thoroughly exposed to the solvent.
Finally parts are raised into the cooling coil area to allow the solvent to quickly dry and and then raised through a second layer of freeboard coils near the very top of the vapor degreaser that insure complete drying and the recapture of the solvent from the parts.
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Is desiccant required in a vapor degreaser?
Desiccants are used to absorb the water found in humid conditions to reduce or eliminate condensation. It can also be added directly to liquids to absorb the water content from the fluid. We are used to seeing the small white bags of desiccant found in packaging for everything from shoes to electronic equipment. Most of this desiccant is silica – typically in gel form. Other common substances used as desiccants are activated charcoal and calcium chloride.
The desiccant used in vapor degreasers is 3 Angstrom Molecular Sieve, small pellets of zeolite clay. Like all desiccants, the zeolite clay adsorbs water from the solvent, and may be reused by baking it dry. Desiccants are most often used in a vapor degreaser if the solvent contains an alcohol. This is often the case with solvents used for defluxing processes on soldered boards and leads. Water found in the separator extracts the alcohol from the solvent and in turn the water and alcohol are absorbed by the zeolite clay. If a degreaser is operated in a very humid environment, a desiccant may be needed to effectively remove the water from the solvent.
Part Passivation Equipment & Process FAQs
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What is the best method of passivation?
Have you ever noticed that many day-to-day things seem to get divided into two opposing camps? Things like asking what’s the best computer quickly become the PC versus Mac debate. Phones? iPhone versus Android. So, passivation? Yup, nitric versus citric.
There are real advantages to each nitric and citric passivation, but that is a topic for other FAQ’s because once you pick one you still have several choices to make. Choices like: which standard do I use? which method do I choose?
There are two primary standards that address passivation. The SAE Aerospace “Passivation of Corrosion Resistant Steels” (AMS2700) and the ASTM “Standard Specification for Chemical Passivation Treatments for Stainless Steel Parts” (A 967).
Each allows for citric or nitric and each allows for several options within each citric and nitric. So what’s the difference? Each standard is copyrighted (and protected) and has to be purchased from the publishing agency, so getting into a lot of detail is not allowed. But here’s a short version of the differences in the various methods:
Concentration of the specific acid – each method varies based on how concentrated the citric or nitric acid is – and in the case of nitric if the nitric acid is used alone or with sodium dichromate.
Temperature of the bath – again, each method specifies a temperature range that must be maintained for the duration of the passivation bath.
Time – the length of time a part must remain within the passivation solution is spelled out as well.
What seems complicated becomes really simple. The standards spell out the concentration, the temperature and the time. Each method simply varies one or more of those three items.
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What’s involved in the passivation validation process?
Within the medical device world there is a need to validate the passivation process. But what does that mean, and how does that work?
Validation is the process of insuring that the passivation process you use will reproduce repeatable and predictable results every time a batch of parts is run through the process. By validating the process you are able to forego subjecting every part to testing to prove that it is properly passivated.
Typically you will hear the validation process broken down into three distinct parts: the IQ, the OQ and the PQ. Let’s look at each part.
The IQ or Installation Qualification is the first part. It is developed by describing the machine – what is it? what does it do? etc. It also looks at what the components on the machine are, gauges, switches, PLC, etc. It provides a description of the machine and its parts – what is it and how does it work?
The OQ or Operational Qualification is the second part. It essentially help you verify the IQ – does the machine operate as it is supposed to? Do the components do what they are designed to do? etc. – does everything work as intended?
The PQ or Process Qualification is the third part of the passivation test. If the IQ is the theory of how things SHOULD operate and the OQ is the practice of how things DO operate, then the PQ defines how CONSISTENTLY the machine operates. You create a DOE (Design of Experiments) that tests the equipment at the top end and bottom end of allowable ranges and run parts to verify the results across the entire range of the variables. Now when the machine operates within the specified range of time, temperature and/or acidic concentration you know that your parts will meet the specs. That is the goal of the passivation validation process.
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Why are automated systems easier to process validate than manual equipment?
Process control and stability are critical aspects to regulated medical device and aerospace processes. It is important to ensure that a process has input and output variable limits which are defined and fully tested during process design, Equipment Qualification (IQ), Operational Qualification (OQ) and Process Qualification (PQ) validation testing. Setting up a proper DOE (Design of experiments) to test these limits is also important as the results of the DOE will give statistical confidence intervals of the limits.
Being that operators and employees perform various process operations different no matter how instructed in work instructions, the variation of operators must also be captured during process qualification (PQ) validation. An automated system typically eliminates many of the operator variability in the manufacturing process and this process “input” elimination also allows for tighter process output controls.
For example, in our automated passivation system, the elimination of relying on an operator to move the parts basket from stage to stage ensures that the parts remain in the appropriate (wash, rinse, acid passivation, etc) solutions for the process defined times and in accordance with the proper ASTM A967, AMS2700, etc specification. If a parts basket is immersed in the acid passivation solution too short or long duration, the passivation can likely fail and be outside specification limits.
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What is passivation?
Passivation is a non-electrolytic process typically using nitric or citric acid which removes free iron from a stainless steel surface. This forms an inert, protective oxide layer that in turn renders the stainless steel more rust-resistant due to lack of iron to react with atmosphere.
During machining manufacturing processes, stainless steel parts may have imperfections from iron being embedded or smeared onto the surface from the machining tool steels. These free irons on the surface of the stainless steel need to be removed to prevent a corrosive reaction can occur between the two different metals.
The passivation process chemically removes these free irons and forms a passive oxide “film” layer which further improves corrosion resistance. When exposed to air, the stainless steel undergoing passivation will form a chemically inactive or inert surface. This is one advantage of using citric acid or nitric acid for passivation.
For more detailed information, please see our “What is Passivation?” page.
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Why are two rinses often recommended after passivation?
When parts are passivated with citric or nitric acid, the parts themselves, as well as the basket they are in, carry some of the acid into the rinse tank. This “drag out” means that the rinse solution has to be constantly replaced or will simply become more and more acidic over time. The biggest issue is not that the parts will be rinsed off, but that when the parts are withdrawn from the rinse tank, they may have soil redeposited on them. Once the parts are dried this soil can cause spotting on the surface of the otherwise clean parts. A second rinse bath produces a much cleaner final product by rinsing off the soil that is redeposited during the first rinse.
Often times, the second rinse tank includes a heated facility water inlet which constantly overflows the second rinse tank with small amounts of water to ensure water cleanliness. The second rinse tank overflow is sent to rinse tank 1 and then rinse tank 1 overflows to drain. This cascade overflow process ensures constant water quality over time no matter the amount of drag out on the parts and baskets.
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What’s the difference between nitric and citric passivation?
Both nitric acid and citric acid are effective in passivating many grades of stainless steel, and both methods are described in the industry standards ASTM A967 and AMS 2700.
Citric acid passivation offers the following key differences. Compared to nitric acid passivation, citric acid passivation is:
- Newer
- More environmentally friendly
- Safer.
In the past, some manufacturers avoided citric acid due to potential organic growth and molding issues. Today, modern formulations for biocides prevent organic growth in the solution. See our complete write up on the advancements of citric acid for passivation.
These advancements in citric acid have allowed smaller manufacturers that lacked experience with chemical handling and processing to bring their passivation in-house. For a more detailed comparison, please see our “Nitric vs. Citric Acid Passivation” page.
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What’s the difference in passivation and electropolishing?
As a non-electrolytic process, passivation uses solutions like citric and nitric acids instead of an electrical current used in electropolishing to create a inert oxide layer / film and remove free iron and foreign matter from metal surfaces.
Electropolishing, a non-mechanical interactive process, can be used on objects with complex geometries. The electropolishing process uses a combination of electrolytic chemicals and an electrical current to carefully eliminate imperfections and contaminants of metal part surfaces. This particular process is an alternative to abrasive fine polishing.
Electropolishing can be used to polish, deburr, and smooth metal components whereby doing so also causes material removal to occur including the free irons on the surface of the part. Electropolishing would be the more appropriate approach when aesthetics are necessary. A smoother, polished surface can result from electropolishing.
Passivation, on the other hand, does not change or brighten the surface appearance, and is not an effective method for improving surfaces that have been welded with oxide heat effect scale or heat treated.
Part Electropolishing Equipment & Process FAQs
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What is electropolishing?
Electropolishing is an electrochemical process that removes material from a metallic part, typically stainless steel or similar alloys. The part is immersed in a temperature controlled bath of electrolyte (typically mixtures of sulfuric acid and phosphoric acid). The part serves as the anode as it is connected to the positive terminal of a DC power rectifier. The negative terminal of the rectifier is attached to the cathode which is typically made from titanium or other alloys which do not dissolve during the electropolishing process.
Visit What is electropolishing? How does electropolishing work? for more detailed information on electropolishing.
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What’s the difference in passivation and electropolishing?
As a non-electrolytic process, passivation uses solutions like citric and nitric acids instead of an electrical current used in electropolishing to create a inert oxide layer / film and remove free iron and foreign matter from metal surfaces.
Electropolishing, a non-mechanical interactive process, can be used on objects with complex geometries. The electropolishing process uses a combination of electrolytic chemicals and an electrical current to carefully eliminate imperfections and contaminants of metal part surfaces. This particular process is an alternative to abrasive fine polishing.
Electropolishing can be used to polish, deburr, and smooth metal components whereby doing so also causes material removal to occur including the free irons on the surface of the part. Electropolishing would be the more appropriate approach when aesthetics are necessary. A smoother, polished surface can result from electropolishing.
Passivation, on the other hand, does not change or brighten the surface appearance, and is not an effective method for improving surfaces that have been welded with oxide heat effect scale or heat treated.
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How many amps of current will it take to electropolish a part?
The current or amps required to electropolish a part is primarily based on the surface area of the part or total surface area if multiple parts are desired to be electropolished at the same time. More information on electropolishing can be found on What is electropolishing? How does electropolishing work? page
Visit the Electropolishing Current Required Calculation Spreadsheet to calculate the approximate current amperage required for electropolishing
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How long will it take to electropolish a part?
The cycle time required to electropolish a part is primarily based on the current / amps and surface area of the part or total surface area and rectifer current if multiple parts are desired to be electropolished at the same time.
Visit the Electropolishing Current Required Calculation Spreadsheet to calculate the approximate cycle time required for a part or total parts for electropolishing.
What is electropolishing? How does electropolishing work? contains more in depth information on electropolishing.
Chem Film / Alodine Equipment & Process FAQs
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What is aluminum chromate conversion coating?
A chromate conversion coating is a type of chemical conversion coating that is typically applied to aluminum alloys. Other types of chemical conversion coatings include iron phosphate and zinc phosphate coatings, typically applied to steel.
A chromate conversion coating protects the underlying aluminum against corrosion, serves as a base for paint adhesion, and can allow for electrical conductivity when applied as a thin coat.
Chromate coating on aluminum is widely used in the aerospace industry, as well as with everyday hardware such as nuts and bolts.
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What is chem film?
Chem film, also called chemical film, is a chemical conversion coating. It typically refers to a chromate conversion coating applied to aluminum and its alloys. The chemfilm coating provides a layer of corrosion protection and a base for paint and primer. When applied as a thin coat, chem film can allow for electrical conductivity.
Chem film coatings are marketed under brand names such as Alodine®, Iridite® and Chromicoat®.
The chemfilm coating process is often governed by the commonly used MIL-DTL-5541 standard, which specifies different types and classes of chem film coatings.
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Is Alodine conductive?
What is the electrical conductivity of chromate conversion coatings, also called Alodine® or chem film, when applied to aluminum alloys?
Unlike anodizing, Alodine coatings offer electrical conductivity for aluminum parts, when applied according to Class 3 of the MIL-DTL-5541 standard. Class 3 chemical conversion coatings protect against corrosion where low electrical resistance is required.
Coating Thickness
Because Class 3 coatings are thinner, they provide less corrosion resistance than Class 1A, but the trade-off is better electrical conductivity.
Technically the coating itself is not conductive, but rather the Class 3 coating is thin enough to allow the aluminum to retain its electrical conductivity.
Surface Roughness
The other factor that affects Alodine conductivity is surface roughness. A rougher surface finish allows greater conductivity due to breaks in the coating. In contrast, highly polished surfaces have lower conductivity due to lack of breaks in the coating.
To meet the Class 3 MIL-DTL-5541 standard, parts must have electrical resistance of no more than 0.005 – 0.010 ohms per square inch under nominal electrode pressure of 200 psi with a flat contact.
Applications
Common applications for electrically conductive Alodine coatings include parts that need to be electrically grounded.
In addition to electrical conductivity, Alodine coatings offer thermal conductivity and are used in applications such as heat sinks.
Chromate conversion coatings such as Alodine are an effective solution for aluminum alloys when both corrosion resistance and conductivity are important.
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Alodine vs. Anodize: What’s the difference?
Wondering about the difference between chem film vs anodize?
The primary difference between Alodine (chem film) and anodizing is that anodizing is an electrolytic process and Alodine (chem film) is not.
Alodine (chem film) and anodizing are both processes used in aluminum finishing to improve corrosion resistance. Both transform the outer layer of the surface of the metal.
But Alodine (chem film) and anodizing are NOT the same.
Anodizing is an electrolytic finishing process that applies electrical current to the metal while it is immersed in an electrolyte solution. In addition to increased corrosion resistance, aluminum anodizing is used for improved lubrication or to allow dyeing (coloring). It is generally more expensive to anodize than to apply chem film and requires greater technical expertise.
In contrast, Alodine (chem film) coatings do NOT apply electrical current to the aluminum. The metal is immersed in a tank, often at room temperature. Compared to anodizing, chem film is less expensive and requires less technical expertise. Unlike anodizing, a chem film coating can allow aluminum to retain electrical or thermal conductivity. This makes chem film the preferred choice when aluminum parts need to be electrically grounded.
Best Technology offers equipment for Alodine (chem film) and titanium anodizing, but we do not currently offer equipment for aluminum anodizing.
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What is chemical conversion coating?
What is a chemical conversion coating and how is it used?
A chemical conversion coating is a surface treatment applied to metals in which the metal undergoes a chemical reaction at the surface. This chemical reaction transforms the metal surface into a thin protective layer.
When applied to aluminum, a chemical conversion coating is sometimes called an aluminum conversion coating.
Chemical conversion coatings provide increased corrosion resistance and a uniform, inert surface for powder coating or paint adhesion.
Chemical conversion coatings are typically applied via immersion in a chemical tank or bath, or by brushing or spraying.
Types of chemical conversion coatings vary according to the metal substrate:
- Iron phosphate coatings – Used with steel
- Zinc phosphate coatings – Used with galvanized steel
- Chromate conversion coatings – Used with aluminum alloys
Best Technology offers phosphating tank lines for iron phosphate coatings and zinc phosphate coatings, and Alodine tank lines for chromate conversion coatings. Our chemical department offers trivalent chromate conversion coating chemistry for use on aluminum alloys.
Titanium Anodizing Equipment & Process FAQs
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Does Anodized Titanium Fade?
Anodized titanium is a popular material used in various applications, from aerospace and medical devices to automotive and jewelry. The titanium undergoes an electrochemical process that creates an oxide layer on its surface. For color anodizing applications (Type 3), the color is achieved by altering the thickness of the oxide layer, which can range from about 300 to 550 angstroms (30-55 nanometers).
The color in titanium anodizing is not a coating or a paint, nor does it use pigment or dye that can peel or fade over time. The prismatic effect in the oxide layer does not degrade with exposure to UV light. So in that sense, no, anodized titanium does not fade. But the surface of the titanium is subject to abrasion.
Does Anodized Titanium Wear Off?
The oxide layer of color anodized titanium may be scratched or scraped off from the effects of friction and wear, and thus remove the color. Unlike Type 2 titanium anodizing, Type 3 color anodizing does not protect from the effects of wear. Exposure to conditions such as harsh chemicals, abrasives or high temperatures may cause the titanium to lose its color or become discolored. In some cases, repeated small abrasions may lead to what could be mistaken for faded color.
Because anodized titanium is biocompatible, it is often used for orthopedic implants. A titanium anodized part will lose its color within 48-72 hours after implantation in the human body. Laser marking the titanium part after color anodizing is an important step for traceability and identification if the implant later needs to be removed.
For quality control in manufacturing, a typical guideline for anodized titanium implants is that they must survive three rounds in an autoclave without deterioration of color.