Why is coil coating so difficult?

Recently, we published an article about measuring color inline. Coil coating is one area where inline color measurement is very effective for achieving the most cost benefit by focusing on speed, quality, and accuracy.

The coil coating process has been around for more than 30 years, allowing companies to produce durable and attractive products. However, to achieve cost benefit, the focus must be on speed, quality and accuracy. Coil coating gives manufacturers a way to paint the metal while it is still in sheet form. This is important, because trying to paint metal after it has been formed into parts makes it difficult to achieve a uniform coating.

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The coil coating process is fast, and mistakes must be caught immediately to avoid expensive waste. X-Rite’s Coil Coating Inline Color Measurement System incorporates the ERX50 or the TeleFlash® 445 Inline Spectrophotometer and the GlossFlash 6060 Inline Gloss Meter to help manufacturers ensure color and gloss quality and consistency, real-time, during each step of the process.

Today we’ll explore the coil coating process and learn how an inline system can help achieve quality and accuracy.

The coil coating process

The coil coating process is fast… with coil strips moving up to 700 feet per minute! Each step is critical to producing superior color quality and coating consistency. Here’s how it works.

  1. The coil strip is unwound, cleaned, and brushed.
  2. A chemical treatment is applied, and the strip is dried.
  3. A primer is applied to one or both sides of the strip.
  4. The strip is then cured in an oven, removed and cooled.
  5. The coating is applied to one or both sides of the strip.
  6. The strip passes through a second curing oven and is cooled.
  7. Finally, the coated coil is rewound.

What can go wrong? A lot.

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Heat can affect color consistency. The sheet is cured in an oven at least twice during the coating process, and the time spent in the oven combined with variations in oven temperature can impact color.

Paint variations can cause metamerism, where the color looks right under one type of lighting, but changes under a different lighting condition.

The gloss of the paint will affect the appearance of the color, making it look lighter or darker.

Variations in the paint thickness will also affect the color. The coating must be consistent throughout the entire process to achieve uniformity.

Add to that the fast pace of the production line, and you can see why it’s a challenge for coil coaters to meet vigorous color standards.

A five-step solution for controlling color

X-Rite has developed an inline system to monitor the entire coil coating process. Using the ERX50 Inline System or the TeleFlash 445 Inline Spectrophotometer together with the GlossFlash 6060 Gloss Meter, manufacturers can measure color and gloss with a high degree of accuracy during each step – in the lab, on the production line, and through final quality control reporting and documentation.

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  1. It starts in the lab, where a laboratory spectrophotometer with a heating table helps the paint supplier formulate and define the coil coating color standards. The standard is measured while using a heating system to show how temperature changes will impact the color.
  2. After the color standard is set, it is shared it with everyone involved in the workflow, including the paint supplier, workstations in the production control booth, at the color coating line, and at client sites, so each user has access to the same color data.
  3. Once the coil coating process begins, X-Rite systems provide a continuous evaluation of the color quality of the entire length and width of each coil. A traversing beam holds and moves the inline spectrophotometer vertically and horizontally so it can measure while the coil is moving. Since samples are taken a distance from the coil, the device and coil are both safe from harm, even under the most severe conditions. This process also provides accurate measurement of uneven coil surfaces.
  4. Results are shared in real time, so anyone in the network can monitor color quality and consistency. If a color tolerance is exceeded, graphics and alerts will make everyone aware before color deviations turn into costly mistakes.
  5. X-Rite’s Coil Coating Inline Color Measurement System even provides complete documentation in the form of color quality records based on international standards to ensure the integrity of the program and customer satisfaction.

Best of all, everything happens without having to stop or slow down the production line, so coil coaters never have to choose between accuracy and production schedules.

Check out our white paper to learn more about how X-Rite solutions make the coil coating process faster and easier.

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