Problems With Metal Coil: Checking for Defects

Machine service & troubleshooting
Rick Zand|June 25, 2024

In the metal roofing and gutter industry, ensuring the quality of your coil is the first step in fabricating perfect panels or gutters. If you end up with camber or oil canning, you can’t be sure it was the machine unless you’ve checked the coil first. Poor-quality coil produces bad panels or gutters, and running it through your machine can damage your rollers—a situation you want to avoid. 

For over 30 years, New Tech Machinery (NTM) has built the highest-quality portable rollformers on the market. However, we do more than manufacture state-of-the-art rollforming machines. We aim to support our customers with training, service, and valuable machine and industry information to help them keep a competitive edge and run an efficient, profitable metal roof, siding, or gutter operation.

In this blog article we’ll dive into the problems associated with poor-quality metal coils and offer insights on how to best address them.

rolls of various metal coils

Accurate Coil Measurements

Coil Width and Thickness Verification 

One of the first steps in ensuring the quality of your metal coil is checking that the coil dimensions match what you ordered. For example, if you’re supposed to receive an 11 7/8 inch coil, but it measures 11 13/16 or 11 15/16 inches, it won’t run straight through your machine without adjustments.

Confirm that the material meets your specs using a tape measure for width and a caliper to check the thickness. Aluminum, for example, should be measured within a small variation (e.g., 0.027 should measure 0.027 or close to it). Steel is measured differently by gauge, and the thickness can vary (e.g., 26 gauge steel is thinner than 24 gauge).

If the thickness doesn’t match your order, contact the manufacturer or distributor immediately.

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Identifying Visual and Structural Defects in Coil

Inspecting Coil Surface and Edges

After confirming the basic dimensions, inspect the coil for visual defects. Lay out an 8’ to 10’ section of the coil and check for oil canning (visible waviness), smooth edges, and mushrooming (where the edges are uneven or warped). Use direct light to identify any imperfections in the coil’s surface. You can angle the light as long as it hits the metal coil directly.

Checking for Coil Camber

Camber refers to a coil’s tendency to curve, making it impossible to run the coil through the gutter machine evenly. To check for camber, place two pieces of coil side by side on a flat surface. They should align perfectly without gaps. If there is a noticeable gap, the coil has a camber and will not run straight, leading to poor-quality gutters or panels.

Mill finish metal coil wrapped in protective plastic

Addressing Supplier and Material Issues

Dealing with Defective Coils

If a coil doesn’t meet the required specifications or shows defects, you face two options: return it to the supplier or adjust your machinery. That said, adjusting machinery to compensate for defective coil can lead to further issues, including possibly damaging the machine, so we recommend returning it to the supplier immediately. Otherwise, if you have to redo the work because the gutters aren’t straight, the issue can be more costly in materials and labor. Therefore, it’s better to return the coil and request a replacement that meets your specifications. Otherwise, you’ll likely be unable to adjust the machine to compensate for the bad coil.

Avoiding Low-Quality Suppliers

Purchase coils from reputable suppliers. Avoid buying cheaper defective coils from less reliable sources, even if they offer significant savings. Be wary of factory discounts and “great” deals from unfamiliar suppliers. These coils often result in more significant problems down the line, including machine damage and added labor costs for replacing defective panels or gutters.

Practical Tips for Quality Assurance

Documentation and Communication

Documenting any defects can help communicate issues with suppliers. Suppliers are often reluctant to accept returns without clear evidence. Be ready to offer proof showing that you performed standard checks. Provide images or coil samples that show the defects. 

If the supplier is nearby and you have an ongoing relationship with them, you can get them to come out and take a look or even ship it back. Developing a relationship with a reputable supplier makes returning coil much simpler as they’ll know you as a valued customer.

Using Quality Materials

Stick to reputable suppliers known for their quality. Using better-quality materials ensures smoother operation and reduces the risk of defects and added costs of replacing coils, panels, or gutters. Also, as mentioned, building a relationship with a solid supplier means that their primary interest is in retaining you as a customer. That means making sure that all your needs are properly met.

(video) How to Feed Coil into a New Tech Nasser MultiPro™ Gutter Machine

Is it the Coil or the Machine?

Whether you’re doing your own installation or running a chop-and-drop operation, you’ll want to ensure the panels you produce are of the highest quality. Some owners assume that if there’s a problem, it’s with the machine. Although occasional adjustments may need to be made, the problem with panels coming out with camber, oil canning, or other imperfections often resides within the coil itself rather than the machine rollers. 

Checking the coil and the panel as it’s running out of the machine will help you eliminate where a problem may have occurred should it show up upon installation. If you’ve inspected the coil, you can immediately rule it out as a cause. If the machine is running straight panels, then the problem may have been with the installation. 

Ensuring the quality of metal coil is vital before running it through your metal panel or gutter machine. By confirming dimensions, inspecting for defects, and choosing reputable suppliers, you can avoid the pitfalls associated with bad metal coils. This proactive approach saves time, reduces costs, and ensures the production of high-quality metal products.

For information about New Tech Machinery portable metal roof, wall panel, or gutter machines and accessories, contact us. For service, reach out to our service department.

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