From enhancing the visual characteristics of a part to shielding it from environmental damage, protective coatings have become a vital part of metal fabrication and finishing. While there are several different ways to apply a coating to metal, one of the most efficient and commonly used methods is roll coating.

Roll coating is the process of applying a base, intermediate, and/or topcoat coating to a flat substrate with a series of rollers. But how exactly does roll coating work?

What is the Process Behind Roll Coating?

Roll coating is a process that uses three rollers to apply a coating to a flat substrate: a soft application roll, a highly polished steel roll, and a metering (or doctor) roll. First, the substrate travels between the soft application roll and the steel roll. The application roll picks up the coating as it rotates and transfers the coating to the flat sheet of metal as it passes through. The metal sheets are then transferred to an oven where the coatings are baked and cured.

Roll coating offers a few benefits over other metal coating technologies. It’s critical to uniformly deposit the exact thickness when applying a coating to a flat metal substrate. With roll coating, the amount and viscosity of the liquid deposited on the substrate can be precisely controlled by the metering roll. The closer the metering roll is to the application roll, the thinner the coating, and vice versa. This makes roll coating one of the most precise coating methods currently available.

Another reason why roll coating is so frequently employed is that its deposition time tends to be faster than other coating technologies, such as spray application or screen printing. In addition, the coatings used can help protect metal from harsh environments while enhancing ink adhesion prior to any embossing or other finishing steps.

What Makes Roll Coating at Boyd Unique?

To meet a variety of project needs, Boyd has two types of roll coaters; one that does direct roll coating, and the other that can do both direct and reverse. Reverse roll coating works similarly as direct coating, but the application roll rotates in the opposite direction of the substrate’s travel. Reverse roll coating can apply a thicker coating than direct due to the different travel direction. This additional coating thickness is useful when the design requires a greater depth of color and environmental durability.

Boyd’s coating family includes acrylic, polyester, and urethane coatings, each offering a different level of thickness, malleability, and resilience against heat and UV radiation. Each coating employed at Boyd is custom formulated by our material scientists to meet a wide array of project needs.

At Boyd, we have years of experience using roll coating for products in a variety of industries, such as automotive, appliance, and personal care. To learn more about Boyd’s custom roll coatings and how they can help your next project, schedule a consultation with our experts.

Pressure-sensitive adhesives (PSA) have made it possible to permanently adhere two dissimilar substrates together. While bonding two surfaces together, there are several factors that need to be considered including surface tension and texture of the substrate, bond strength, surface area, environmental conditions, design, and product application. However, one crucial factor that influences the selection of adhesive is the surface energy of a substrate. Surface energy is the excess energy that flows on the surface of the substrate and is measured in dynes/cm. The dyne level is the actual reading of the critical surface tension.

How Does the Surface Energy Influence Adhesive Selection?

Based on the surface energy, substrates can be broadly categorized into three groups – high surface energy (HSE), medium surface energy (MSE), and low surface energy (LSE). With high surface energy ranging from 250-1103 dynes/cm, metals like copper, aluminum, zinc, and stainless steel are some of the most popular HSE substrates. The surface energy takes a big dip to 38-50 dynes/cm for MSE substrates such as polycarbonate, polyester, nylon, acrylonitrile butadiene styrene (ABS), and acrylic. Finally, materials with surface energy below 37 dynes/cm fall into the category of LSE. The widely employed LSE substrates include polyethylene, polyvinyl alcohol (PVA), ethylene vinyl acetate (EVA), and polypropylene.

To understand the importance of surface energy in bonding substrates, let’s consider “wetting”. Wettability is the ability of an adhesive to spread on the surface, thereby increasing the contact area and creating a stronger bond. In most cases, when you pour water on a HSE metal such as copper, the water will quickly spread across the surface and form puddles. On the other hand, when you pour water on ABS, it will form small beads, thus preventing the surface from wetting. Simply put, HSE substrates aid the wetting of the adhesive, while LSE substrates avert the wetting. The surface energy of the substrate dictates the strength of attraction and therefore remains as one of the most critical aspects in bonding.

There is a wide variety of PSA solutions available, each of them offering a unique set of advantages and disadvantages. For example: 3M offers approximately 25 different PSA solutions, with 100MP, 200MP, 300MP and the 300LSE being the most dominantly utilized adhesives. While the high-performance acrylic adhesive family such as the 100MP and 200MP, strongly adheres to most HSE substrates, the 200MP is frequently preferred for MSE substrates, and 300LSE is usually chosen for both MSE and LSE substrates. It is the interplay of several factors that ultimately dictate the selection of the adhesive, thus the optimal solution varies from one application to the other.

With years of process innovation and material science experience, Boyd has the capabilities to not only tailor adhesives to match your unique application, but also address any other bonding needs and challenges. To learn more, schedule a consultation with our experts.

To maintain the visual and functional integrity of your metal automotive trim ornamentation, including sill plates, liftgates, center stacks, steering wheel badges, and door trim, it is essential to use coatings and/or screen printing inks having superior scuff resistance.

Currently, there are many scratch and mar tests that are known throughout the industry and are employed by accredited testing laboratories. While these tests accurately gauge some real world environmental forces to which your ornamentation application will be subjected, they fall short of capturing the effects of one significant key real world destructive force: scuffing.

Boyd’s Scuff Resistant Coating and Ink Families:

Therefore, to ensure that our customer’s products could maintain their beauty and functionality throughout their life cycle, Boyd’s in-house chemists formulated a proprietary anti-scuff family of custom coatings and inks identified. Coatings and inks in this family withstand the real-world harmful scuffing forces that automotive trim components encounter regularly throughout their lifetime to preserve the original aesthetic and functional needs of the component for a prolonged period. The coatings underwent a variety of qualitative and quantitative tests in order to prove the superior scuff-resistant properties of this additive. One such rigorous test subjected the coating samples to aggressively brushing the surface with steel wool as the abrasive material at selected weights in multiple directions, known as our steel wool abrasion test.

Boyd’s scuff-resistant coatings are a significant improvement to our existing coating chemistry. The improved coatings and inks still have the same solvent resistance, stain resistance, and formability. This breakthrough coating technology can be applied to either aluminum or stainless steel constructions with low to high gloss without having any aesthetic effects, while maintaining its performance benefits in a wide variety of severe environments, from high heat to extreme cold. Our steel wool abrasion test results showed that the average product will scuff when subjected to two to three double rubs of steel wool pads when under a downward pressure of 3000 grams. Coatings and inks with the new additive could exceed 100 contacts with the steel pad under the same conditions with little to no scuffing.

During our battery of tests, we were able to validate that this family of coatings meets the industry standard specifications for the following:

Adhesion:

• Humidity resistance (GM4465P) – a test where the sample is exposed to 100% relative humidity at 38°C (100.4°F) for a specified time.
• Impact cross-hatch tape pull (ASTM D-3281) – a one-pound ball or cone is dropped at a specified vertical distance to an area that had been cut with a knife or crosshatch tool. The sample is tested with adhesive tape for any coating removal.

Scratch and Mar:

• Taber abrasion (ASTM D4060-1) – test samples are placed on a Taber rotating plate with a grit wheel of a specified
  grade and are abraded for a number of cycle turns with a given weight applied on each grinding wheel. The samples
  are graded by number of cycles for wear through point of the coating.
• A new type of scratch and mar test using steel wool – this test uses 000 steel wool that is rubbed back and forth with
  the weight of 3,000 grams applied. The end point is measured by the number of “double rubs” the sample could
  sustain before the coating began to wear through.

Solvent Resistance (GM9509P):

• This is usually tested by using a solvent that is specified by the paint supplier (commonly MEK). A soft solvent-saturated cloth is rubbed back and forth on the sample a number of times using the firm downward pressure of a gloved finger. The number of “double rubs” specified for a “pass” varies, but it typically ranges from 10 to 50 rubs.

Improved Film Properties Including:

• High durability in all environments of radiation and moisture
• Increased resistance to abrasion, scratching, and marring
• Improved adhesion and film flexibility
• Better impact resistance
• No detectable effect on accelerated xenon-arc exposure, helping to protect the color or gloss level fading over time

Boyd has years of process innovation and material science experience in the automotive industry. Learn more about our eMobility capabilities.

When it comes to stainless steel, there are many colors and textures that can be added to enhance the visual and tactile attributes of a component. With an endless number of patterns and hues from which to choose, Boyd can support your development with virtually any desired combination.

Versatility of Stainless-Steel Finishes

In addition to creating textures mechanically, Boyd can also create textures organically to have linear, geometric and micro patterns. Linear patterns can be in the form of pinstripes with the lines varying in thickness for accent/highlight purposes, geometric patterns that are structured to have bold distinctive values or micro patterns that are subtle patterns of tightly aligned shapes and/or lines. Organic textures can also be natural patterns that look handcrafted, such as woodgrain. Textures can be created to be transparent, tinted, opaque, or colored, with high or low gloss values and varying tactile values. All textures can be combined with custom colors that which can be applied overall or selectively deposited.

Subtle Stainless Steel Finish

For subtle designs and harmony considerations, customers often lean towards choosing 430 stainless steel using a No. 4 brushed finish. This combination is often layered with black, silver, or grey tints and a fluid pattern such as a micro or organic texture. Muted tone finishes are typically seen in home appliance suites across multiple applications, such as on microwaves, dishwashers, washers, dryers, and refrigerators that are within view of one another.

Modern, Brilliant Stainless Steel Finish

For a modern look, customers frequently choose a higher gloss for a more brilliant finish. An example of this this would be 430 stainless steel with a No. 8 BA (bright annealed) polish. This finish is known for its blue hue, reflectivity, and lack of visual grain structure. Customers typically combine this finish with white or black coloring and/or geometric texture accents. Applying the brush in multiple directions can add gradation and tactile value to the geometric pattern. Colors applied selectively can be used to offset sections of a pattern. Boyd provides a variety of options for different looks and finishes to enhance the look of stainless steel applications. To learn more about our metal decoration and fabrication capabilities, reach out to our experts.

Boyd offers a wide variety of stainless-steel decorating capabilities including custom coatings, printed graphical images and patterns, and mechanical finishes. Of these options, one of the most popular metal decoration capabilities is adding a brushed mechanical finish. Brushed finishes distort the light reflection pattern on a part, and in turn can heighten visual contrast, increasing the perceived value of the part to which it is affixed.

What Are Brushed Mechanical Finishes?

Brushed metal finishes are produced by mechanically polishing or wearing away the outer surface of the metal. Brush finishes can be applied overall or selectively, in one or multiple directions. To create a selective mechanical brush or a spun finish, a screen-printed resist ink is applied to the metals’ surface prior to it being subjected to the mechanical brushing wheel. In doing so, the area protected by the resist ink will maintain its original brilliance, as it will not come in contact with the brushing wheel. Brushed metal finishes for both stainless steel and aluminum can be linear or oscillating (overlapping).

Wet Number Four Stainless Steel Finish

Of the many options, the most common finish used is a wet number four polish. The uneven brush strokes of a number four polish/brush highlight the metal’s brilliance on stainless steel without being too reflective. It provides a uniform look from the elongated brush pattern, and can withstand everyday wear by scuffing, scratching, and fingerprints. Common applications for a number four brush finish include automotive trim such as sill plates and arm rest trim, in addition to a number of home appliance uses.

Bright Annealed Stainless Steel Finish

By contrast, a BA (bright annealed) finish is a high-luster, brilliant chrome finish that is used frequently in the automotive industry for decorative parts. While various levels of reflectivity are achievable, the number eight BA finish is the most reflective. This finish is created by treating the surface with a series of fine abrasives, then buffing the surface to create a mirror like appearance. The buffing improves the corrosion resistance of the number eight finish, as it polishes away any minor surface imperfections where particles may stick and initiate the corrosion process. With its corrosion resistant properties, the number eight finish is commonly used for exterior applications requiring brilliant, highly reflective surfaces.

While these are two of the most popular options, this is far from a full list of metal finish options. Mechanical brush finishes can also be combined with a number of different colors, textures, and metals to add even more visual contrast to a part. To learn more about stainless steel options at Boyd, visit our blogs on Stainless Steel Alloys or Stainless Steel: Colors and Textures. To discuss your own custom metal finishing needs, reach out to our experts.

While stainless steel is a durable material for many applications, not all steel alloys are created equal. As one of the most common materials for parts used in extreme environments, stainless steel has applications in industries ranging from automotive to home appliance. With extensive experience working with and fabricating stainless steel components, Boyd can help customers choose the correct stainless steel alloy for their application.

Which Stainless Steel Is Right For Your Project?

Each stainless steel alloy is unique in element composition and elongation, resulting in differing performance capabilities, visual characteristics, cost profiles, and elongation ratios. Elongation is the amount of expansion a metal under stress can endure given its original length. The two most common alloys employed in automotive and major appliance parts are the 300 and 400 series.

Stainless Steel 300 Series

With superior elongation, the stainless steel 300 series is non-magnetic and employed where severe metal forming is required. Prevalent in the automotive industry, the 300 series is also known for extreme corrosion resistance, crack resistance, and non-yellowing when subjected to high temperatures. The automotive industry favors the 300 series for sill plates, liftgate trim, and other vehicle accents that are exposed to rugged environments. For its durability under high temperatures, the 300 series is used in many stovetop ranges for the home appliance industry as well.

Stainless Steel 400 Series

By contrast, the stainless steel 400 series is magnetic and has a smooth surface finish that is ideal for home appliance products, but can be more susceptible to corrosion than the 300 series (as it contains less chromium and nickel). Due to this, the 400 series is more cost effective than the 300 series. The 400 series is the alloy of choice for cost-sensitive appliance applications, such as dish washers and refrigerators. While these two are commonly used, this is far from an exhaustive list of steel alloys. In addition to help selecting the right stainless steel alloy, Boyd can provide customers with industry-leading metal decoration capabilities including selective mechanical finishing on stainless steel. Boyd’s mechanical metal finishing capabilities include but are not limited to brushing, spinning, and tooled patterns. In addition to mechanical finishing, Boyd offers a number of finishing options including premium coatings and inks. Boyd has years of material science and process innovation experience. For more information about some of our metal decoration capabilities, visit our Scuff-Resistant Coatings Blog or schedule a consultation with our experts