Aluminum Coil Coating Line: A Beginner's Operational Guide

Are you interested in learning how to operate an aluminum coil coating line? If so, you&#;ve come to the right place. In this beginner&#;s guide, we&#;ll walk you through the basics of running an aluminum coil coating line, so you&#;ll have a better understanding of how to safely and effectively operate it. Let&#;s get started!

The company is the world’s best aluminium coil coating line supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.

 

Prepping the Aluminum

The first step in operating an aluminum coil coating line is to prepare the aluminum for coating. The main goal of this procedure is to create a surface that is free from dust, dirt, grease, and other contaminants so that the coating will properly adhere to the metal surface. This typically involves several processes, including cleaning, surface preparation, and pre-treating.

 

Cleaning

The most common cleaning processes for aluminum coil coating are degreasing and deoxidizing, which may require the use of specific cleaning agents and methods. For example, some popular choices include detergents, acids, and solvents, ensuring they don&#;t damage the aluminum surface. 

Once the surface has been degreased and deoxidized, it is important to rinse the aluminum thoroughly with water to remove any residue that may be left behind. And, when it has been rinsed, it should be allowed to air dry or dried with a lint-free cloth to prevent any paint defects such as bubbles or drips.

 

Surface Preparation

Once the surface has been cleaned, you must further prepare it for coating. This can be done by sanding, brushing, or grinding, with the goal of creating a smooth surface that is free of defects such as scratches or dents. And, if there are any deep imperfections in the surface, you may need to fill them in with a special filler material. 

 

Pre-Treatments

In some cases, a pre-treatment may be necessary to ensure that the coating adheres to the aluminum surface. Commonly, pre-treatments can include chemical treatments, etching, or powder coatings in order to create a stronger bond between the coating and the metal surface. 

 

Applying the Primer

Applying the primer to the aluminum coil is an important step in the aluminum coil coating process since it will act as a base for the final coat of paint and provide added protection from corrosion and other damage. So, in order to ensure that your aluminum coil is properly prepared, you must carefully apply a thin layer of primer over the entire surface of the coil. And, once the surface is bone dry, and in case you think this is necessary, repeat the process until the desired number of coats of primer has been applied.

 

Applying the Paint

When it comes to applying the paint to your aluminum coil coating line, there are two methods for doing so: spraying and rolling. 

Well, if you decide to spray, you will need to have a quality airless sprayer to ensure even coverage and minimize overspray. Also, make sure to use enough pressure and adjust the nozzle to the correct angle and distance from the material. 

The other option is to roll the paint on the aluminum. This method works well when you have an even surface and are looking for a uniform finish. However, to roll on the paint, you will need a high-quality paint roller with a nap length that is suitable for the type of paint you&#;re using. And, once you&#;ve chosen a roller, apply the paint in thin, even coats, starting from one end of the aluminum and working towards the other end. 

By and large, no matter which method you choose, be sure to apply multiple thin coats of paint until you reach the desired coverage level. 

 

The Curing Process

Curing is the final step in the aluminum coil coating process that helps to ensure that the coating adheres to the aluminum and provides a long-lasting, durable finish. Overall, there are two main types of curing processes used for aluminum coil coatings: thermal curing and ultraviolet (UV) curing.

 

Thermal Curing

During thermal curing, the painted aluminum is exposed to high temperatures for an extended period of time, ensuring a strong bond between the coating and the metal forms. The most common temperature range for thermal curing is between 200 and 400 degrees Fahrenheit, and depending on the type of paint being used, the curing process can take anywhere from a few minutes to several hours.

 

UV Curing

In essence, UV curing is a quicker process than thermal curing, meaning the paint is exposed to ultraviolet light, which causes a chemical reaction that helps to cure the coating. This method is often used when quick turnaround times are needed. However, because UV curing does not provide as strong of a bond as thermal curing, it is typically only used for thin-film coatings.

And, regardless of which curing type you&#;ll utilize, it is important to monitor the curing process closely, as well as adhering to the manufacturer&#;s instructions for best results.

 

Bottom Line

With the right preparation and steps, operating an aluminum coil coating isn&#;t an impossible feat. Just be sure to clean the aluminum prior to coating, apply a primer and paint in the correct order, and finally, properly cure the end product. By taking these simple steps and following instructions as indicated, you are to confidently operate any aluminum coil coating line.

 

E-coating Aluminum- Finishing For Aluminum Casting

6 Things You May Concern On

E-Coating Aluminum

E-Coating (Electrostatic Coating) is a surface finishing technique that utilizes charged paint particles for coating metal parts. The paint electrostatically adheres to the surface through electrophoresis and results in a uniform thin film of paint. E-coating Aluminum is one of the popular surface finishings for aluminum parts.

It has been a widely adopted surface treatment method for aluminum parts due to its increased efficiency and economy. This guide will highlight the important aspects of e-coating to help you choose the right e-coating solution for your die cast or machined aluminum parts.

Sunrise Metal is a leading aluminum die casting and CNC machining manufacturer. We have multitudes of surface treatment facilities including e-coating. Need a supplier that can provide you with a one-stop solution for design, manufacturing, and finishing? Sunrise Metal wants to help.

 

1. E-Coating Aluminum Process

E-coating is known by various other names in the industry such as electrocoating, electrophoretic deposition, electrophoretic painting, electrodeposition, etc. Regardless of the differences in names, they all refer to the same process.

The coating process takes place in multiple steps. The entire process of e-coating aluminum parts may be divided into the following steps.

 

Loading Parts

 

The treatment facility is equipped with a good number of immersion tanks. Usually, the manufacturers move the parts from one tank to another using conveyor belts. A human operator sorts the aluminum parts onto the e-coating line.

The parts must be hanged into the coating line in a manner so that it will not entrap any air when dipped into a tank. From there, the parts are carried into the pretreatment facility.

Pretreatment

 

In order to e coat paint an aluminum part, you must ensure that there are no impurities present in

the parts. Impurities can severely damage the surface of parts. It will also compromise the consistency and performance of the applied coating.

So, aluminum parts are thoroughly cleaned in a pretreatment facility first. A typical pretreatment facility consists of multiple chambers/tanks for rinsing the parts with demineralized water and other cleansing acid/chemicals.

 

Deposition

 

Once pretreatment is done, the conveyor belt carries the parts into a paint tank for deposition. Conveyor belts may not be suitable when dealing with large parts like automotive chassis. In such cases, another mechanism is used for handling the parts.

The paint pigment remains suspended in the liquid and electrostatically charged through an electric current of high voltage. The aluminum parts act like an electrode here and attract the charged paint particles.

The charged paint particles adhere to the part&#;s surface and form a thin film. The thickness of the coating can be regulated by modifying the voltage of the current. Higher Voltage will result in a thicker coating.

Rinsing

 

The dipped parts need to be rinsed again to remove the excess paint. They are carried into the cleaning chambers again, and thoroughly rinsed with water and chemical solutions. Once done, they are sent to the oven.

 

Curing

 

E coat paint needs to be cured in an oven for cross-linking the paint particles. This allows the paint to perfect its chemical composition and improve its properties. Curing substantially improves the adhesion of paint to the part&#;s surface and the paint won&#;t come off without aggressive means of removal.

Unloading Parts

After Curing is done the parts are allowed to cool down for a while and then they are unloaded from the e-coating line. Then a new batch of parts is loaded onto the e-coating line.

These processes can be performed manually as well. But when dealing with a large volume of parts, automation can substantially increase the efficiency of the process. Here&#;s a video that explains the e coating process in brief.

 

 

2. E-Coating Classifications

E-coating may be classified into the following categories based on the polarity used for coating.

Anodic E-coating

Cathodic E-coating

Anodic E-coating

In this case, the metal part is used as the anode. It is not a preferable e-coating technique and rarely used. Because it causes some metal ions to mix with the coating. This hampers the durability and corrosion resistance of the parts. However, anodic e-coating can be cured at lower temperatures.

Cathodic E-coating

The aluminum parts are negatively charged in case of the cathodic e-coating process. The part act as the cathode and attracts the negatively charged paint particles. This is the most common scenario for e-coating. It is more efficient and provides better results.

Cathodic e-coating can be done with different types of the coating material. Two such processes are,

Cathodic Acrylic E-coating

Cathodic Epoxy E-coating

Acrylic coatings provide good protection against UV rays and corrosion. It offers a wide range of colors, but the colors are a bit light.

Epoxy coatings provide superior protection against corrosion. But, they don&#;t provide good protection against UV light. So, they are mostly used as a primer in automobile parts and requires an additional coating over it.

3. E-Coating Aluminum Benefits

E-coating is a popular surface finishing technique for aluminum parts. Its convenience and effectiveness are what make it a preferable option to others. Below we have highlighted the major benefits of e-coating aluminum.

Outstanding Durability

E coat paint is extremely durable. The paint adheres to the aluminum surface very well and will not come off under normal conditions. So, it will keep parts protected for an extended period thus eliminate the hassle of maintenance for end-users.

Excellent Protection

E-coating provides high resistance against corrosion for aluminum. So, the coating can withstand highly corrosive and harsh environmental conditions. It also increases the wear resistance of your aluminum parts.

Uniform Film Thickness

E-coating is very efficient and consistent. It offers a uniform film thickness all-around your aluminum parts. You can control the coating thickness by altering the voltage of the current supplied into the tank. So, you can choose a thickness according to your requirements.

Economical

E-coating is very economical compared to other similar coating techniques. It provides premium quality which would be significantly costlier to achieve using other methods. In fact, e-coating has substantially reduced the demand for many finishing methods that were once widely used in the industry.

Versatile

You can e coat almost any metal parts including aluminum. Part&#;s complexity is not an issue with e coating. Since the entire part is dipped into the tank, the paint can reach all recesses of the parts. And you can coat very large parts as well using larger immersion tanks.

Environment Friendly

E-coating can utilize water-based solutions as the coating medium. There is little to no volatile organic compound present in the paint solution. So, unlike most other liquid coating processes, it doesn&#;t have a negative impact on the environment.

4. Application

E-coating has many applications in the manufacturing industry. Some of the common application of e-coating aluminum is discussed below.

E-coating is extensively used in the automotive industry for coating automobile chassis and components. They are more or less a standard as primers for metal or aluminum components. Their superior adhesive properties allow you to apply an additional layer of coating with ease.

E-coating can also serve as a top-coat for your aluminum parts. They are desirable for their resistance to corrosion and wear. So, aluminum housing and frame components can benefit from e-coating. The performance and durability will be better than most liquid coatings.

5. Limitations

E-coating is economical, efficient, and durable. It is a nearly perfect process that is excellent for coating your aluminum parts. But there are certain situations when e-coating may not be the best solution for you. Let&#;s have a look at some of the limitations of the e-coating process.

Limited Color Choice

E-coating is not actually limited to colors. It is possible to achieve a wide range of colors with e-coating. The paint solution can be consisting of different varieties of color pigments. However, it is not as simple as it sounds.

One immersion tank is usually used only for one type of color. If you want to e-coat of different colors then the entire paint tank needs to be refilled. This will take a considerable amount of time and cause a waste of material. So, you will find that the suppliers will offer you a limited number of colors for e coat paints.

Poor UV Ray Protection

Some e-coating materials such as epoxy has poor UV ray protection. This makes them prone to fail in outdoor conditions. However, this can be fixed by providing an extra layer of coating. Normally epoxy coated parts are powder coated afterward to improve their durability and performance.

Inconsistency in Color

It is difficult to control the color of e-coated parts in a batch. Because the outlook of the color can vary depending on the curing process. Parts with more oven time can look different from the ones with less oven time.

Defects During Coating

When you wish to e-coat your aluminum parts, they must not contain any form of impurities. Having even the slightest bit of impurity can cause severe e coat defects and compromise the part&#;s durability and performance. So, all parts need to be thoroughly inspected and cleaned.

Blind spots and sealed corners can entrap air inside the aluminum parts thus leave uncoated areas that would be prone to defects. This issue can be mitigated by immersing the parts in a suitable orientation.

6. E-Coating vs Other Methods

People often confuse e-coating with other types of surface finishes due to their similar outlook. However, there are substantial differences between them in terms of performance and durability. Here we have discussed how e-coating differs from other similar finishing techniques.

For more coil coating machineinformation, please contact us. We will provide professional answers.

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E-Coating vs Powder Coating

Both the e-coating and powder coating process follows the same principle. The paint is electrostatically charged and deposited onto the part&#;s surface through electrodeposition. But e-coating is a wet process where the parts are immersed into a paint tank for coating. While powder coating is considered a dry process where the parts are sprayed with powder paint.

 

Powder coating involves spraying powder paint towards an electrostatically charged aluminum part. The paint particles are attached to the part&#;s surface by the electrostatic attraction. Upon curing, the solid particles melt and strongly adheres to the part surface.

Powder coating and e-coating have a lot of advantages in common and both are eco-friendly processes. However, powder coating is not as uniform as e-coating. And it is difficult to coat certain areas. So, the coating may lack consistency and uniformity when applied to complex parts.

It is often used as a secondary layer over an e-coated surface. Doing so can substantially increase the durability of aluminum parts. And you have access to more types of colors with powder coating.

E-coating vs Electroplating

 

E-coating or Electrocoating is an electrodeposition process where a metal part is coated using organic compounds like paint, epoxy, etc. Electroplating is an electrodeposition process are using metallic compounds to coat the part. Unlike, e-coating, the parts don&#;t have to be metal in this case.

Electroplating is typically done with nickel, gold, zinc, silver, etc. elements. The coating will provide a metallic sheen to the parts and enhance their conductive properties. Electroplated metals usually offer better hardness, and wear resistance for aluminum parts.

 

E-Coating Aluminum vs Anodization Aluminum

Anodizing does not actually involve applying an extra layer of coating on your parts. It is an electrochemical process that increases the natural oxide layer of metal parts to improve its appearance, performance, and corrosion resistance.

 

The appearance of an e-coated and anodized part of the same color may look similar. But their properties are entirely different. E-coating is applicable for almost any sort of metal. But Anodizing is mainly suitable to aluminum and few other metals.

Both of the processes can increase the corrosion and wear resistance of aluminum parts. The E-coated and anodized surface has excellent adhesion and suppliers often use them as a prime coat for other surface finishes.

We hope that this article was able to answer your queries regarding e-coating. If you are curious to know more about e-coating aluminum parts, you can contact Sunrise Metal for assistance.

 

 

A Beginner's Guide To Powder Coating Equipment Systems

If the product you want to powder coat has a lot of debris (rust, laser scale, preexisting paint), then you will likely need a Blast Room. A blast room is an enclosure where you use compressed air to propel abrasive material against the surface of your parts. Depending on the situation, you would typically use either an appropriate blast media (grit) or steel shot to blast all the unwanted debris off your part until it has a clean metal surface that&#;s ready for powder coating. Blast rooms are especially useful for job shops that work with raw materials that aren&#;t pristine, such as plate steel or tube stock that has areas of oxidation or welding residue. (For more information on getting the right blast room, go here.)

 

If oils, solvents or chemical residue covers any part of your products&#; surface, you&#;ll want to consider a Wash Station. A wash station is where you spray your parts with a detergent and/or chemical pretreatment agent, such as iron phosphate. Using hot water or steam to clean and then chemically prep parts is quite common. A wash station helps you increase powder adhesion and improve finish quality, even if the parts have already been blasted. Some wash stations require you to apply the chemistry manually using a spray wand. Other washers are automated and the parts travel through the cleaning, rinsing and prep stages on a conveyor.

In some operations, pretreatment requires the use of a Dry-Off Oven. This is commonly an appliance similar to a curing oven, but where the just-washed parts are heated in order to evaporate any water or chemistry still on them. This step can also help parts reach an optimum temperature for powder application.

Pretreatment equipment is incredibly useful for your operation and can make a big difference in the quality of your work, but an elaborate system isn&#;t always required for powder coating. While we can&#;t stress how important it is to have a clean surface before you apply powder, expensive pretreatment equipment isn&#;t mandatory for entry level coating operations where hands-on cleaning (such as with a tack rag and solvent) can be employed as needed.

Application: Powder Guns and Powder Spray Booths

Powder coating application is almost always done with a special Powder Spray Gun. In order for powder coating to work effectively, the powder must be electrostatically charged. The only way to apply this charge is with a spray gun designed exclusively for powder coating. Compressed air moves powder through the gun from a hopper or directly from the box the powder is stored in. The compressed air blows powder out of the gun as a tightly formed cloud. As the powder leaves the gun, it receives an electrostatic charge. Once charged, the powder cloud envelopes the part and the powder sticks to the surface of the grounded part (which is one of the reasons why powder coating equipment is so easy for new operators to use).

If you want to powder coat, you need a powder coating gun. There are many types of powder spray guns available on the market. We always recommend investing in a professional-grade powder gun, as they are more reliable and provide better results.

Once you have your powder gun, you&#;ll need to have a place to use it. Whenever you spray powder, some of the powder will end up on the floor and in the air instead of on your products. This leftover powder is referred to as overspray. Keeping this overspray out of your workspace is one of the functions of the Powder Spray Booth.

The powder spray booth is designed to keep the rest of your shop clean while providing a well-lit area for you to apply powder coating. All powder spray booths will have one or more exhaust fans. The exhaust will use filters to capture at least some of the overspray. If the exhaust works properly and the filters are maintained, the airflow in the booth should keep the overspray inside the enclosure and enable the painter to see what he&#;s doing. If your shop environment includes welding or blasting areas, filtered doors on the spray booth can keep airborne contaminants out of your powder coated finish.

Numerous booth configurations are available, and getting the ideal booth depends largely on what you&#;re coating, your floor space availability, and your workflow requirements. Powder spray booths can be open-faced or have doors on one end. They can also be tunnel style enclosures with the filtration built into the floor or wall(s). If you have space constraints, a Powder Spray Wall may help you get the airflow and filtration you need. A spray wall is just a large filtration system&#;essentially a spray booth without walls or a roof.

If you want to recycle your powder, you need to make sure your powder spray booth is built with a reclamation system. Usually this system will rely on pleated cartridge filters. These help you recover some of the overspray and reuse it. This can be very cost-effective if you are planning to use only one color and type of powder for your coating. The spent powder is trapped in the filters and then dislodged into a recovery bin for reuse. In more advanced systems, the powder is automatically reconditioned, mixed with virgin powder, and then returned to the supply hopper feeding the powder gun(s). If you are planning to reclaim a variety of colors, a set of removable filter modules is required. Unfortunately, the cost of buying multiple reclaim modules can add up quickly because you can only reclaim one color in each filter module.

No matter what type of booth you decide on, you&#;ll need a powder spray booth if you want to get quality results and maintain reasonable throughput from your coating operation. (For more information on what size powder spray booth you might need, click here.)

If you have stringent finish requirements, you may also need a Clean Room (also called an Environmental Room). This is usually a climate-controlled room built around the powder application area. The purpose of a clean room is to eliminate airborne contaminants and control the temperature and humidity during powder application to prevent any sort of contamination, clumping or consistency issues when applying the powder. Clean rooms are often recommended if your shop environment is particularly dirty or your products require an exact specification for adhesion or salt spray tolerance. (For more about requirements, click here.)

Curing: Powder Curing Ovens

After your product is powder coated, the final step is to place it inside a specially designed Powder Curing Oven. They usually operate between 325° and 450° Fahrenheit. Once the oven is up to temperature, the temperature stabilizes. The coated products are exposed to precisely heated air for a set period of time. Once the curing process is complete, the parts are removed and allowed to cool before being handled.

Some ovens use infrared emitters to heat the surface of the coated parts, but these types of electric powered or gas catalytic ovens can be costly to buy and expensive to maintain. More commonly, ovens rely on electric heating elements or a natural gas or LP-fueled heat system. These more conventional ovens typically rely on heated air moving over the parts for convection curing.

The time it takes to cure the powder varies greatly depending on the size, shape and thickness of the parts being coated. A small, light-gauge bracket can take as little as ten minutes to cure completely, while a 20&#; section of heavy-walled pipe may take over an hour to cure properly.

If you want to powder coat at a professional level, the type of oven you choose is critical.  Not only are brand-name powder curing ovens designed specifically to generate premium coating results, they are also highly efficient appliances in terms of fuel usage and energy costs. It&#;s likely that you&#;ll be using your oven several hours per week, so the cost of an inefficient design can quickly sap your profits.

Similar to powder spray booths, powder curing ovens come in multiple sizes and configurations. (For more information on what size powder coating oven you will need, click here.)

Professional Powder Coating Systems Layouts

There are two basic configurations for any powder coating line: batch or automated.

A Batch Powder Coating Line is usually a system where the parts are prepared, coated and cured in batches of multiple parts, with operators handling up to dozens or hundreds of parts at a time. The products are usually hung on metal rolling racks, which move with the parts throughout the coating process. (Remember: high-temperature or metal casters for your racks are very important!) With a batch line, parts are usually moved from stage to stage manually, and the term &#;batch coating system&#; is also commonly used to describe operations where large objects are coated individually after being moved by hand or with machine.

An Automated Powder Coating Line uses basically the same appliances as a batch system, but connects many or all of the stages via a motorized conveyor that moves the parts through at a constant rate. The products are usually loaded onto the conveyor at a set location and move through each stage, where either manual operators or automated devices clean and prep the parts and apply powder to them. Once coated, the parts move through the curing oven and then cool as they travel along the conveyor to a point where they can be unloaded.

(For more information on whether a batch coating line or an automated coating line is right for your business, follow this link to learn more about the advantages and disadvantages of each system.)

Powder Coating Equipment From Reliant Finishing Systems

Hopefully this Beginner&#;s Guide to Powder Coating Equipment has answered your basic questions about what powder coating is, how it is done, and what you need to start your first powder coating line. If you would like to learn more, please give us a call at (888) 770-. Reliant Finishing Systems&#; specialists can help! We&#;ll guide you through the process of setting up a powder coating shop or adding coating capabilities to your existing fab shop or manufacturing facility. Whether it&#;s your very first powder coating system or you&#;re upgrading to a complete automated line, you can trust Reliant to provide you with sound advice and affordable, high quality equipment.

Updated Content Dec 9,

 

Today I would like to share some tips about the quality inspection of pre-painted aluminum metal coil/sheet for your better learning about this kind of material. Here we go!

Mainly 2 aspects but including some small points.

--Physical Tests

the physical test is important to check that the paint has been applied and cured properly so that it will perform well during the end-use.

--Visual Inspection

Visual inspection is important to confirm that there is no unacceptable visual defect because coil coated metal must meet the aesthetic requirement as well as the one associated with performance.

Followings are the tips of various tests and their importance for assuring the quality of color-coated aluminum coils/sheets.

Physical Tests:

1. Film Thickness:

Having the right film thickness is critical for the long-term performance of the paint film. For the primer coat, the low film could result in premature corrosion or poor adhesion. For the topcoat, the low film could result in premature failure due to weathering. The high film is also a problem, you know, as it means an added cost, which affects the profitability of the product.

2. Color:

One of the main reasons for buying pre-painted products is to provide a specific colored appearance. As usually customer matches the pre-painted metal to other components of a building or product, so matching the color standard where specified is very important for the great appearance of the final assembled product. For repeat colors, matching the standard on each run ensures that there will be color consistency over time.

Color must be consistent across the width of the strip, as well as between coils of an order. Many factors can affect the color: Paint Formulation & Quality, Film Thickness, Substrate Color, Cure Temperature (PMT), and Dwell Time in curing ovens or even the Contamination with Other Paints.

3. Gloss:

Consistency in gloss is important to provide a uniform appearance to customers. The final product may be made up of several components made from different coils. If the gloss is not consistent, the final product&#;s appearance will be poor and looks not good.

4. Adhesion:

There are several tests conducted to check the various aspects of adhesion, including T-bends, Impact, and Various Scratch Tests.

Pre-painted aluminum coil/sheet may undergo several types of forming to convert it to the final product, like the types of bends in construction of siding or roofing, embossed garage doors, residential doors, ceiling grid, home & office furniture, embossed refrigerators, beverage cans & lids, etc.

One of the key advantages of the pre-painted coil is that it can be formed after painting, so these tests are important to make sure that the paint will not be damaged or removed during the following processing.

Factors that can affect adhesion include Paint Formulation, Film Thickness, Cure Temperature (PMT), Line Speed, Treatment Quality, Aluminum & Steel Quality, and Cleanliness.

5. Cure:

The cure is a term that refers to the degree to which the material is converted from its initial state to the final or cured state.

All coil coatings are baked and 2 things happen during the baking cycle:

1) The solvent in the paint evaporates and is burned in the afterburner.

2) A chemical reaction in the paint film causes the resin molecules to join together (polymerize or cross-link) to form a strong, cross-linked, solid paint film.

Usually, there is no direct way to measure the degree of cross-linking. But a combination of tests can indicate whether the paint is under cured or over cure, such as MEK Rubs, Pencil Hardness, and Adhesion.

Under cured paint will tend to be soft, and will not withstand forming or weathering in its end-use. Over cured paint will tend to be brittle, and may be damaged during forming or weathering.

Visual Inspection:

1. Why Need This Inspection?

From the end customer&#;s perspective, one of the most important aspects of pre-painted aluminum is its appearance. No doubt that the customer expects a uniform, consistent appearance without any unacceptable defect.

Visual defects can be caused by The Aluminum Substrate, The Paint, or The Method of Application & Curing.

2. Pay Attention to Different Appearance Standards

Because of the wide variety of customers and products in different industries, there is also a fairly wide range of specifications for visual appearance. For example, the appearance standards for refrigerator, which is seen up close every day at consumers&#; home, are much stricter than the appearance standards for roofing product, which is only watched from a distance.

Ideally, we would like to have a perfect appearance on all products, but that is not always cost-effective, so some level of variation may be acceptable to customers.

3. Several Defects & Bad Influences

Defects, which are identified during a visual inspection, may also affect the paint performance & life during the end-use. For example:

Craters are not only an appearance problem but also may result in premature peeling or corrosion at that position.

Differences in Textures across the strip or between coils may be an indication of film thickness inconsistency, which will have an effect on the product lifetime.

Dirt Lines are visual defects and can cause low film thickness &#; premature corrosion or peeling could appear at that spot.

4. Benefits of Visual Inspection

Visual defects may start and stop suddenly during the painting process, so thorough visual inspection is important to minimize or avoid the defective material produced. The sooner a defect is found, the earlier it can be corrected, minimizing scrap and customer returns.

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