How Electroplating On 3D Parts Add Strength to Your Products

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Since its initial development in the 1980s, 3D printing has been gaining momentum in the manufacturing industry. Instead of subtracting from a block of raw material or injecting into a mold, a part is created by building the structure layer by layer using a computer file as the “recipe” and raw material typically in the form of a powder, resin, or synthetic filament.

While 3D printing is praised for its ability to create geometric shapes and accommodate design changes with greater ease than traditional manufacturing, there are material restraints that must be considered. The lightweight plastics and resins used are susceptible to damage or delamination under certain stresses and do not conduct electricity.

Electroplating and Metalizing 3D-Printed Parts

Parts can be 3D printed using metal coatings to avoid some of the above-mentioned pitfalls. However, this option is relatively expensive and not yet considered practical for large scale production. Continuing to 3D print with plastic material keeps the part lighter than the metal equivalents. Maintaining a lightweight product is notably important in the aerospace and automotive industries as they strive to maintain fuel-efficiency in a time when fuel costs and usage are on many minds. How can these 3D-printed parts be utilized on a larger scale unless they maintain a crucial strength and corrosion resistance?

Plating on 3D plastic couples additive manufacturing and metal plating; resulting in a final product that is lightweight and functional. The layer of metal deposited onto the 3D print provides the corrosion resistance, strength, and electrical conductivity necessary to allow the part to be treated like a traditionally manufactured part without the material waste or extra weight.

What 3D-Printed Materials can be Metalized and Electroplated?

With so many options for print material, it wouldn’t be practical to list them. There are a few properties that can improve your ability to metalize the polymer.

  • Chemical Resistance: Plating processes use acids and salts that can cause chemical reactions with some materials. This can contaminate the plating solutions requiring costly repairs.
  • Porosity:  The more you can fill your 3D print, the better chance you have in plating the material. The part will travel through several plating baths and a variety of chemistry. Each one needs to be effectively cleaned off the part before traveling to the next step. If the material traps solution, it will leach out in a subsequent step while decreasing the integrity of the deposit.
  • Heat Resistance: Some chemical plating baths are heated. This requires the material to be able withstand a minimum of 200F without deformation.
  • Glass or Mineral Reinforcement: Although not required, a 10% to 40% reinforcement has been proven to increase adhesion.

Learn More about plating on plastics and composites.

Properties Added by Electroplating 3D-Printed Parts

Most subtractive or injection molding parts require a final coating or treatment of some kind to protect the substrate from corrosion and improve longevity within the final application. By applying this necessity to 3D prints, manufacturers have more flexibility in creating large and small batches of a variety of designs without the need to invest in new, expensive equipment and hours of calibration. Applying plating on plastic parts increases the mechanical properties by protecting the substrate, adding conductivity, and strengthening the part overall.

  • Strength: Resin used in 3D printers tend to be brittle and break easily. Adding a layer of metal to a 3D printed part will increase the ultimate tensile strength of the part.
  • Conductivity: Plastics are insulators and metals are conductors. Adding metal plating to plastic, even selectively, allows the part to become electrically conductive. This added conductivity to plastic is very useful in the electric vehicle market and can be utilized in plating plastic connectors.
  • Wear Protection: Depending on the thickness, a metal coating on 3D printed parts can have long-term wearability and corrosion resistance against external elements. Metals like gold and electroless nickel have very good abrasion resistance. Keep in mind that the thicker the plating, the heavier the part will become.
  • Cosmetics: This is typically not what we focus on here at INCERTEC, but plating can be used to improve the appearance or be used as an identifier to a printed part.
  • Electromagnetic Shielding: Plating is used to reduce or eliminate electromagnetic interference (EMI) or radio frequency interference (RFI) in the electronics industry.

Types of Metal Best Used With 3D Prints

Virtually any finish can be applied to a plastic substrate once it has been metalized.

  • Gold – A noble metal when under normal conditions, does not oxidize or react chemically. Gold plating is frequently used in electronic and connector applications due to its oxidation resistance and durability.
  • Electroless Copper – Typically used as a base layer on plastic substrates, electroless copper is conductive, ductile and deposits in a uniform layer over the substrate.
  • Electroless Nickel – A co-deposit of nickel and phosphorus that mirrors the surface finish of the substrate with a Rockwell C hardness ranging from 41-51 when plated at a high or mid phosphorus co-deposit. Electroless nickel plating for 3D printed parts creates a uniform deposit onto the substrate since it is not dependent on an external DC current.
  • Silver – A white luster semi-precious metal that boasts the highest thermal and electrical conductivity of all metals available in matte, bright, and semi-bright. Silver also has excellent solderability and lubricity.

When electroplating 3D prints, tin, cadmium and zinc-nickel are also suitable finishes to add to a plastic substrate. Contact us for a quote or to learn more.

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INCERTEC Plastic Plating Services

INCERTEC handles a wide variety of plating on plastic as well as plating on other unique substrates like composites, magnets, and ceramics. Contact us to discuss your plastic plating needs.

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INCERTEC Awarded Products Finishing’s Elite 2023 Top Shops Distinction

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Every year, major coating and finishing shops across North America participate in Products Finishing’s Top Shops program helps finishers identify optimal shopfloor practices and improve business operations and procedures. Based on the Top Shops Benchmarking Survey, Top Shops is much more than awards program. Reports containing a data driven analysis of the shops performance in numerous key operating metrics help shops measure their performance against their peers in the industry.

“This is the 9th year we’ve conducted the Top Shops Benchmarking Survey, offering industrial finishers with a non-biased way to evaluate their shop’s performance,” says Products Finishing editor-in-chief Scott Francis. “The goal of Top Shops is continuous improvement — and we take that message to heart. Over the past year we’ve been investing additional resources into the program and working to improve the turnaround time of the benchmarking reports.”

Qualifying as a Top Shop has become an important distinction for shops in the finishing industry.

INCERTEC has been selected as a Products Finishing Top Shop in electroplating and anodizing for 2023, based on data analytics from this year’s Top Shops Benchmarking Survey.

“Sincere congratulations to the team at INCERTEC upon achieving status as a 2023 Products Finishing Top Shop,” Francis says. “The selection process for Top Shops is based on numerous aspects of your business, and qualifying as a Top Shop is a reflection your team’s hard work and cause for celebration.”

Hundreds of shops participate in Top Shops each year, resulting in a collection of data and statistics that prove invaluable for discovering and assessing areas for growth and improvement, including finishing technology, performance and practices, business strategy and human resources.

To learn more about Top Shops Benchmarking visit

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Benefits of the Tin Electroplating Process

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What is Tin Electroplating?

Tin electroplating is the process of using an electrical current to create a chemical reaction to produce a layer of tin plating onto a ferrous or nonferrous substrate. The electrical current travels through an aqueous solution of tin chemistry and a positively charged tin anode, causing the tin in the solution to attract onto the metal parts attached to a negatively charged cathode. The result is a soft, silver-white deposit of tin on the desired substrate.

What Are the Different Tin Plating Processes?

The type of method used for tin plating relies heavily on the configuration of the part and on customer requirements. No plating method is inherently better than another, but one will be more appropriate over another based on the limitations of a part.

  • Barrel Plating – Barrel plating is typically reserved for small parts that can withstand being slowly tumbled in a rotating barrel that is dipped into the plating solution. Due to the nature of how the parts make electrical contact with the cathode, this method can take longer to achieve uniform coverage. Parts that are very thin or made of a soft substrate should not be barrel plated.

Small metal pieces being hung on a rack

  • Rack Plating – Rack plating is ideal for larger parts or parts that are thin and flat that would otherwise be damaged in the barrel method. Rack plating mitigates the chance of damage, shadowing or adhesion issues that can otherwise occur from thin and flat parts sticking to one another. Metal wire is either wrapped around the part or threaded through a hole or slot of the part then hung from special racks that allow the negative charge to pass through and make electrical contact with the part to plate.
  • Vibratory Barrel – A vibratory barrel is a specially designed basket with a vertical shaft in the center. A generator emits a pulse through the shaft causing the parts to gently vibrate around the axis. While gently vibrating around the axis, the parts maintain electrical contact with the cathodes at the bottom of the basket creating a uniform deposit. This method is usually reserved for thin, fragile parts with fine points or contact pins.

Types of Tin Electroplating

Matte Tin Plating – Matte tin has a dull surface appearance because it does not contain any brightening additives. The lack of brighteners allows matte tin to maintain excellent solderability and ductility.

Bright Tin Plating – Bright tin contains additives that tighten the grain structure of the deposited metal, creating a shinier, more cosmetic appearance. Due to the tightened grain structure, bright tin is also more resistant to discoloration over matte tin. However, there is a risk of the bright tin burning when soldered due to the addition of the brighteners.

Tin Lead Plating – Lead alloy is added to pure tin to combat the phenomenon of “whiskers” occurring in the pure tin. The common co-deposit of these two alloys are 60/40 tin lead and 90/10 tin lead. The added lead alloy lowers the tin’s melting point from 450ºF to 361ºF. This lowered melting point makes tin lead an optimal choice in electrical applications for its superior solderability.

Bismuth Tin Plating – Bismuth tin is an increasingly common RoHS-compliant alternative to tin lead with a co-deposit of tin and bismuth. Bismuth tin is capable of withstanding long-term cold exposure, combating the condition known as tin pest. The added bismuth deposit also makes the tin whisker resistant.

The Benefits of Tin Electroplating

  • Excellent Solderability – Compared to other heavy metals, tin has a very low melting point of 232ºC/450ºF and even lower melting point of 182ºC/361ºF when co-deposited with lead. This makes tin an ideal candidate for soldering applications and increasing the overall solderability of the substrate.
  • Ductile – Tin is a soft metal that is very flexible. Manufacturing companies can easily form, stretch, and mold the plated substrate into different shapes without cracking or harming the adhesion of the plating.
  • Cost-Effective – Tin electroplating is cost-effective and easy to obtain compared to other electroplated metals like silver with similar soldering properties and can be plated onto almost any metal.
  • Corrosion Resistant – Tin has good corrosion resistance in protecting the substrate.
  • Non-Toxic – Tin is widely considered non-toxic and often used in the form of tin cans covered in lacquer. The ductility of the tin allows the tin to be formed, stamped, and shaped without damaging the tin adhesion.

Tin Electroplating Considerations

Whiskers – Whiskering is a phenomenon that causes metal filaments to occur on the surface of pure tin plating. Whiskers can appear soon after plating or take years to appear. These crystalline structures can be .0001 inch in diameter and can stretch 3/8 inch or longer, with the capacity to carry current. In the majority of applications, the growth of whiskers is not an issue. However, pure tin is not recommended for applications with low-voltage electrical equipment where items are closely spaced. As the whiskers can cause electrical shorts or current arcs and critical disruptions in the electronics. Underplates like nickel can help reduce the risk of whiskers or co-depositing the tin with a minimum of 2% lead or bismuth.

Low Melting Point – While the low melting point of tin is ideal for soldering applications, the limited temperature window of tin restricts the number of appropriate applications outside of soldering. Tin on steel faces difficulty due to the high temperature typically needed to relieve the steel of the embrittlement.

Tin Pest – Also known as tin disease. Occurs when the structure of the pure tin molecules expands and moves away from its cubic structure. The molecular change becomes greatly unstable in the presence of low temperatures. Due to the unstable nature of the structure, the tin can lose adhesion to the substrate and loses conductivity. Ultimately, the tin becomes incredibly brittle and disintegrates at an increasing pace. Tin pest is at great risk of forming in temperatures in -22ºF to -40ºF, but still poses a risk at prolonged temperatures of 56ºF and cooler. Tins co-deposited with lead or bismuth do not experience the same risks.

Tin Oxide – Care should be taken while handling and storing tin-plated items. Tin oxide naturally occurs in a clean, dry atmosphere with continuous airflow, but the oxidation rate is very slow. If the tin is stored in a warm, humid environment with little airflow, the oxidation occurs at a much more rapid rate. A thick dull gray oxidation layer will form requiring the oxide to be broken through before successful soldering can occur. Using a resistance paper during packing or storage of a tin-plated part will help slow down the oxidation and mitigate tarnishing.

Staining – The structure of the tin makes it susceptible to staining and discoloration as it absorbs moisture and oils verify easily and is not easily cleaned without burnishing the finish. Gloves are recommended in handling tin-plated parts to avoid staining or discoloration.

Fretting – When used as a contact, micro-motions and repeated mating and disconnecting of the contacts can cause fretting corrosion and wear away the tin coating. The amount of fretting can depend on the thickness of the tin deposit on the contact and can be countered with lubrication. Note: gold and tin should never be mated as a connection.


Close up of an airplane in the skyMultiple industries utilize tin electroplating for its desirable properties — like low cost, high ductility, and high solderability. INCERTEC specializes in tin electroplating complex parts for the aerospace and defense industries and testing them in accordance with strict NADCAP requirements.

Most of the parts tin lead and bismuth tin plated at INCERTEC are electrical components, standoffs, and electrical housing. These electrical components are later assembled into circuit boards with standoffs and housing that allow for the continued air circulation.


Tin electroplating is only one of the plating services offered at INCERTEC. The goal at INCERTEC is to always have the space and capacity open to partner with customers to scale production through dedicated plating lines.

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How determination and innovation laid the foundation of metal finishing on uncommon substrates at INCERTEC

Deutsch Automotive Group, a California-based connector company, was creating connectors for the power module in Renault’s new electric automobile the Fluence Z.E. This connector was made of PBT (Polybutylene Terephthalate) a thermoplastic polymer often used by engineers and manufacturers for its high strength, heat resistance, electrical insulation, and chemical resistance properties. Thus, creating a durable cost-effective product without compromising performance.

All that remained was for Deutsch to make the PBT connector electrically conductive by adding a layer of metal. Even though a few companies in Europe had meager success in plating PBT, it was (and still is) widely acknowledged as “non-plateable” by US metal finishing companies who routinely plated composite materials.


A plating shop in Fridley, MN was eager to take on this challenge. Established in 1993 as Spec plating and newly renamed INCERTEC to reflect the company’s dedication to innovation, certifications, and technical abilities, INCERTEC was determined to prove out its new name.

Product development manager Jerrid Matson and INCERTEC’s onsite chemists got to work testing different forms and combinations of pre-treatment on the PBT substrate. Solidifying this process was imperative to the success of the entire project. Creating an initial bond by increasing pore sites in the base material enables it to receive the proprietary chemistry and become seeded, creating the metallization layer. Once a part has been metalized, it is no different than any other non-ferrous or ferrous metal and could be plated with typical electrolytic or electroless plating processes.


Adhesion of the metal plating to PBT connectors was not the sole obstacle INCERTEC had to contend with. The team had to selectively plate and define demarcation lines where the substrate was to remain untouched by the metallization process. Custom rubber masking molds were procured with the intent to mask off specific areas efficiently and effectively, but the masking molds could not create a strong enough seal to prevent the plating from leaking into the undesired areas.  INCERTEC had to reallocate internal resources to hand mask the plated PBT connector resulting in a heavily involved multi-step process cycling with pretreatment and post finishing.


Weeks went by as the research and development team frequently put in 14-hour days testing and fine-tuning processes and determining the best method for the selective plating. Days were long, but spirits were high as the team continually moved closer to success, driven by the internal motivation to prove to Deutsch and themselves that INCERTEC had the quality and the expertise with plating on plastic to tackle a seemingly impossible feat. Within 3 months of taking on this Goliath of a project, INCERTEC was successfully plating the un-plateable PBT.


By early May 2011 INCERTEC proved out the process with continued success and received its first skid of Deutsch connectors. This was the first full-volume project INCERTEC had seen. Everyone came together as a team to accomplish the unprecedented high volume, repetitive work. The workflow was then simplified to a dedicated plating line style process. Creating easy-to-understand work instructions and training with the ability to pull in more resources, while still creating repeatability.

By late 2011, INCERTEC transitioned the Deutsch plating operations to its new state-of-the-art metal plating facility in Empalme Sonora Mexico and continued plating PBT connectors until Deutsch was bought out by TE in April 2012.

We took something that said it couldn’t be done in the US, and inside of 3 months it was being run by people who had no idea how difficult what they were doing actually was.

-Jerrid Matson looking back on the successful endeavor.


Since the plating of the first Deutsch connectors, INCERTEC has continued to increase its capability of plating on unique substrates like composites, magnets, and ceramics. If you have any questions about how we can help you solve a plating challenge, contact us today to learn more!

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What is Fluorescent Dye Penetrant Testing: Why Utilize It?

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While this inspection method is relatively simple, fluorescent dye penetrant testing expedites the testing of non-porous materials. we can effectively identify any flaws in your part without using harsh chemicals or substances that may damage its functionality.

In addition to its non-destructive qualities, fluorescent dye penetrant testing provides:

  • Faster identification of flaws in the material: This process makes the flaw indication much larger than the flaw itself. This makes it possible to identify flaws that are not visible by the naked eye, such as those smaller than 0.08 mm.
  • High reliability for flaw detection: There is a high level of contrast between the flaw indication and the background material with this process.
  • A testing solution for a wide range of materials: It’s possible to use this method for   metallic, non-metallic, magnetic, and electrical insulator materials.
  • An effective way to test large amounts of material: The simplicity of fluorescent dye penetrant testing means that it streamlines the inspection process.


Identifying flaws in a part eliminates the possibility of having to scrap it further down the line in production. We take a proactive approach to inspection to enhance the predictability of your operations. When you can be sure that your part is not hiding any flaws, you can be certain that it will work the way you expect.

Testing to these standards requires experience and a familiarity with the industries that demand near perfection in their parts. INCERTEC assures quality for those in aerospace, medical and other industries that need a surefire plating solution.


At INCERTEC, we provide services with the utmost transparency for our customers. If you have any questions about our ASTM E1417 fluorescent dye penetrant service testing standards or how we can help you solve a plating challenge, contact us today to learn more!

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How to scale production with a dedicated plating line

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Dedicated Plating Line Services

The Ultimate Partnership

Metal finishing is a service industry charged with turning customer parts quickly and accurately. But what happens when a metal finisher hits capacity constraints? Or worse, encounters quality issues that snag a whole project?

What is the plating line process?

Line plating is the practice of depositing metal alloys onto a metallic surface through a process of chemical baths. Most plating baths have an electrical current to coat the metal. Other plating baths have no electrical current, known as an autocatalytic chemical process. The parts move from bath to bath through means of automated machinery or by hand by a plater. Once the parts have gone through the plating line process, a new layer of metal coats the part. This new layer of metal preserves the substrate, increasing the corrosion resistance. Electrical conductivity may also change depending on the chosen deposited metal.

Most finishing shops attempt to capture a diverse customer base by catering to many industries, building an inventory of standardized tooling and one-size-fits-most technology. This mentality is not suited for high volume, repeatable work. Creating repeatable, high-quality results, requires the equipment to remain dialed in to precise specifications. This can be accomplished with a dedicated plating line process.

What is a dedicated plating line?

A dedicated plating line uses the plating line process but is designed, planned, and equipped to only run a customer’s specific part or part family within a plating shop. Simply put, finishing tanks and equipment are designed for a single customer at their disposal, including dedicated labor.

The customer controls what, when, and how much goes through the line. When parts are outsourced for plating, the metal finisher dictates the price and lead time based on information from the purchase order and print. The lead time can also vary depending on the finisher’s backlog and available labor.

A dedicated line can be designed around meeting price targets, lead times, quality requirements, line contamination and FOD.

When considering a dedicated plating line, it is important for the customer to reflect on what organizational goal and competitive advantage is being accomplished through the dedicated line. What is important to the organization?

When are dedicated plating lines appropriate?

Dedicated plating lines are scale driven. Most plating companies cannot handle a large daily increase in capacity and still effectively serve its customer base. A dedicated plating line comes with all the benefits of vertically integrating, minus the day-to-day headaches.

Many manufacturers prefer to focus on their core competencies with no desire to vertically integrate the metal finishing operations. Others lament the amount of overhead frequently wasted on additional quality and purchasing efforts from outsourcing metal finishing to multiple vendors while attempting to meet their customer’s lead times. A dedicated line solves both.

Disadvantages of Vertically Integrating Metal Finishing

Vertically integrating metal finishing has a high barrier to entry. Waste treatment and disposal, EPA regulations, skilled labor, special certifications (NADCAP, ITAR, AS9100, ISO 9001) are all expenses and responsibilities that cannot be ignored.

Vertically integrating involves a certain level of risk. For example, plating facilities are notorious for starting on fire. It is one thing to bring down a plating operation, but it is detrimental if it brings down the rest of the manufacturing process.

Questions to Ask Before Creating a Dedicated Line

There are a few circumstances to consider when talking about dedicated plating lines.

  • What is the longevity of the project?
  • Is this existing work that has been running for years and will likely continue for years to come?
  • Is this work a new part or part family that could run for several years?
  • Does it make sense to the bottom line?

Dedicated plating line services come with a price tag and need to generate a certain level of sales per square foot while meeting customer price targets to make sense. The ROI should benefit everyone involved.


The goal at INCERTEC is to always have the space and capacity open for dedicated plating lines.  INCERTEC has grown significantly based on this principle of partnership. Partner with us and we will work with you to find the best solution.

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Electroplating In Mexico

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INCERTEC’s facility in Empalme, Sonora, Mexico specializes in metal plating and finishing services for the aerospace, electronic, medical device industries. The location also acts as a general job shop for metal plating.

By working with INCERTEC, one of the top providers of industrial electroplating in Mexico, aerospace companies currently producing in Mexico are able to avoid shipping parts north for metal finishing processes, and then shipping them back to Mexico for final assembly. This vertical integration can lower their manufacturing costs and allow them to grow their business more profitably.

INCERTEC is committed to bringing the most sought-after commercial electroplating services to Mexico. In addition to Nadcap, ISO and other certifications, we’re pursuing approvals for Bombardier, Embraer, Cessna, Beechcraft projects. The facility is also certified in non-destructive testing (NDT), a highly valuable technique that can save both money and time in product evaluation, troubleshooting, and research. INCERTEC has increased its technical staff to ensure consistency and quality between its U.S. and Mexico, and there is close alignment in operations between the two facilities.


Industry Week profiles INCERTEC and their Mexico operation, “By adding this location, we can provide manufacturers doing business in Mexico the same consistency, quality and delivery provided by our U.S. location.”

As the aerospace industry ramps up to fulfill pent-up demand, Empalme, Mexico is emerging as the site of a leading cluster of suppliers and service suppliers including INCERTEC.

INCERTEC launches the company’s new operation in Empalme, Mexico, offering metal plating and finishing for the Aerospace industry in Mexico.

INCERTEC partners with The Offshore Group to bring highly-engineered custom plating solutions to Empalme Mexico.

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RoHS Compliant

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INCERTEC provides RoHS compliant finishes.  The RoHS directive aims to restrict certain dangerous substances commonly used in electronic and electronic equipment. RoHS is also related to the Waste Electrical and Electronic Equipment (WEEE) Directive, developed as part of a legislative initiative to solve the problem of large amounts of toxic e-waste through setting the collection, recycling, and recovery targets for electrical goods.


what substances are tested for with RoHS Compliant components?

Any RoHS compliant component is tested for the presence of

Lead (Pb)
Cadmium (Cd)
Mercury (Hg)
Hexavalent chromium (Hex-Cr)
Polybrominated biphenyls (PBB)
Polybrominated diphenyl ethers (PBDE)

What is allowed for RoHS Compliance?

For Cadmium and Hexavalent chromium, there must be less than 0.01% of the substance by weight at raw homogeneous materials level.  Lead, PBB, and PBDE must be no more than 0.1% of the material when calculated by weight at raw homogeneous materials. Any RoHS compliant component must have 100 ppm or less of mercury and the mercury must not have been intentionally added to the component. However, some military and medical equipment may be exempt from RoHS compliance.

INCERTEC finishes available for ROHS compliance

Electroless Nickel
Electrolytic Nickel
Bismuth Tin
Zinc Nickel
Chromate Conversion*

*Note that the availability of RoHS Compliance for chromate conversion treatment is dependent on spec requirements and type of chromate.

Please identify your need for RoHS compliance on your orders and we will likewise note compliance on our material certification. Such certification will be stamped to identify the products as RoHS compliant.


INCERTEC Environmental Policy

As a metal finisher INCERTEC is committed to regulatory compliance, continual improvement and prevention of pollution to ensure that we are doing our part in protecting the environment.

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Anodized Aluminum vs. Stainless Steel Corrosion: How Are They Different?

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Anodized aluminum products are everywhere. From the carabiners on your backpack to the iPhone in your pocket, this electrolytic anodic process is a practical method for manufacturers looking to make their aluminum stronger so it lasts longer in high-pressure situations. The anodized layer of protection resists corrosion and minimizes the impact of blunt forces and scratches.

Another metal that’s manufactured to last longer is stainless steel. This versatile metal thrives in hygienic environments. Medical equipment and cookware need to be durable but easily sterilized so it’s safe to use repeatedly. That’s why manufacturers often turn to stainless steel as their material of choice.

Both anodized aluminum and stainless steel are great options when corrosion-resistance is paramount. But they both offer different qualities depending on the part you’re creating. Anodized aluminum is a third of the weight as stainless steel making it great for aircraft. However, the strength and thermal properties of stainless steel make it the preferred metal for modern buildings.

One of the main differences between the metals is how they corrode, which is an important consideration to make before manufacturing any part.

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How Aluminum and Stainless Steel Corrode Differently

While stainless steel is known for being corrosion-resistant, when it’s paired with other elements, it can respond differently when exposed to corrosive environments. That’s why stainless steel comes in different grades to protect itself given the application. Here are the ways stainless steel can be threatened by corrosion.

  • Pitting corrosion: This localized corrosion occurs when the environment contains chlorides.
  • Crevice corrosion: This occurs when there is a low amount of oxygen and a buildup of chlorides.
  • Galvanic corrosion: This type of corrosion happens when dissimilar metals are in contact with the same erosive force such as rain or condensation.
  • Stress corrosion cracking (SCC): Mainly an issue for austenitic stainless steel, SCC is when a crack grows on the surface of the steel.
  • Intergranular corrosion: Also known as an intergranular attack (IGA), this corrosion occurs when the steel has been continuously exposed to heat between 800 and 1000 degrees Fahrenheit. This type of corrosion begins inside the steel.

Aluminum alone does corrode, but it doesn’t rust like steel. Aluminum is most susceptible to galvanic and pitting corrosion.

Galvanic corrosion occurs when aluminum comes in contact with a precious metal such as steel and copper. Instead of creating rust, the aluminum will break down resulting in a dull appearance.

Pitting corrosion also impacts the appearance of aluminum more than its functionality. This type of corrosion happens when chlorides are present in the environment. Pitting can also happen when the aluminum is exposed to environments beyond the 4 to 9 pH range. The more basic or acidic the environment, the faster aluminum will break down. Concrete, for example, has a pH value of around 12.5 and 13.5. This creates extreme pitting corrosion on aluminum.

Anodizing aluminum will help protect the metal from wearing down and corroding quickly in these difficult environments where exposure to harmful elements are imminent.

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How to Anodize Aluminum

Aluminum anodizing is a controlled electrochemical process in which an oxide (anodic) layer is chemically built on the surface of the metal. This oxide layer acts as an insulator and can be dyed in a wide variety of colors.

Anodizing provides surface corrosion protection along with an excellent substrate for decorative finishes. The hardness of the aluminum is increased to a hardness of 48 to 55 on the Rockwell C scale. Unanodized aluminum has a Rockwell hardness of 38 to 44.

Hardcoat anodizing is a highly abrasion-resistant, non-conductive aluminum oxide (Al2O3-xH2O) coating that makes an aluminum surface harder than tool steel due to greater thickness and weight than conventional anodic coatings. Anodic coatings form an excellent base for dry film lubricants, Teflon, paint, and adhesives. The hardness of the aluminum is increased to a hardness of 60 to 70 on the Rockwell C scale.

How to Stress Relieve Aluminum

The stress-relieving temperature is normally between 550 and 650°C for aluminum parts. Soaking time is about one to two hours. After the soaking time, the components should be cooled down slowly in the furnace or in air. A slow cooling speed is important to avoid tensions caused by temperature differences in the material, this is especially important when stress relieving larger components.

If necessary, stress relieving can be performed in a furnace with protective gas to protect surfaces from oxidation. In extreme conditions, vacuum furnaces can be used.

Can You Anodize Stainless Steel?

The oxide layer added to aluminum during the anodizing process has the inverse effect on steel and ultimately creates rust. While you can anodize steel, it would do more harm than good.

What you can do to stainless steel to make it more corrosion resistant is use a process called plating or conversion coating. This type of metal finishing helps protect the steel in corrosive environments so it holds together during regular, high-impact use.

How Does Corrosion Occur Between Anodized Aluminum and Stainless Steel?

When joined together in a similar environment, corrosion can occur between anodized aluminum and stainless steel. Localized corrosion occurs because the oxidation of aluminum during the anodizing process makes it passive. The oxidation can dissolve when it contacts strong acid or alkaline solutions. The removal of this oxide film starts the corrosion of the aluminum.

Another risk is when the anodized aluminum and stainless steel are in contact. Alone, aluminum is an unnoble metal and if it comes in contact with a noble metal, such as stainless steel, galvanic corrosion can occur. Theoretically, this will happen if the anodized layer cracks after continuous pressure. The “unlayered” aluminum will be directly exposed to a large area of stainless steel, resulting in rapid corrosion.

While anodized aluminum and stainless steel offer stronger corrosion-resistance than most metals, they can still be exposed over time. And when put together, corrosion can still occur. If you have any questions about anodizing or how you should finish your metal part, our team is more than happy to help you through the process. If you now know what you need, our team is ready to start the anodizing or other metal finishing process.

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Green Initiatives

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The leadership of INCERTEC has been pivotal in forming a comprehensive plan to become an environmentally-friendly plating company.

Green initiatives influence virtually all aspects of INCERTEC’s business practices, from corporate offices to facility floor, to storage rooms. These initiatives are core to our philosophy of operating an innovative, certified, and technology-driven environmentally friendly plating company. INCERTEC works with independent consultants, as well as state and federal entities on an ongoing basis to reduce waste, recycle products and materials, and improve asset recovery.

Through recent business expansion, INCERTEC has increased process capabilities by 500% while reducing the need for natural resources through different innovations such as our water recycling system and replacing of fluorescent lighting. In our commitment to prevent pollution INCERTEC strives to produce plating finishes of the highest quality while reducing the need for natural resources and protecting land and waterways.

INCERTEC reduction efforts include

  • Reducing our carbon footprint by ongoing replacement of fluorescent lighting with LED lighting
  • Recycling 100% of our rinse water
  • Reducing our water usage by 50% while increasing our process capabilities by 500%
  • Recycling of scrap and unused metals
  • Actively using timers on manufacturing equipment to reduce energy consumption
  • Taking proactive maintenance steps to keep our equipment running at maximum efficiency
  • Continuous improvement of recycling programs and reduction efforts
  • Continuous waste reduction efforts

INCERTEC Environmental Policy

INCERTEC is dedicated to environmental improvements that foster a sustainable future and lead to social and economic improvements in the communities in which we do business.

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