How a wood window is made from start to finish

Step inside our Bayport, Minnesota manufacturing facility to see how more 1,000 production associates leverage state-of-the-art machinery to make our clad-wood 400 Series windows. Guiding you along will be Tyler Grace and Nick Schiffer of the Modern Craftsman podcast — let's go!

Here’s a summary of the steps covered in manufacturing 400 Series windows.

Inside Minnesota’s largest milling operation

The video starts with Grace and Schiffer explaining how we start with raw timber and mill our own window profiles for quality assurance purposes, rather than outsourcing this step. This is done because windows need to fit together tightly for the best possible performance. In-house milling gives us the control needed to make sure window profiles meet our standards. Grace shows the quality assurance gauge — a measuring tool that shows the exact specifications a profile must meet — and demonstrates how it is used to measure the beginning, middle, and end of each profile piece. Any profiles that don’t match specifications are reclaimed.

Grace and Schiffer explain a bit about how sawdust is reused. They point out the metal piping that connects to the machinery, which helps collect sawdust so it can be reused in various ways including heating the plant and producing Fibrex® material (our alternative to vinyl). In fact, the reuse of sawdust to produce Fibrex material has contributed to preventing the harvest of over 130 million board feet of timber.

Next, the builders explain the steps included in milling. A production associate is shown feeding rough cut timber into a machine that trims it to the correct length. Once the timber is cut to length, it goes to the moulder, another machine, to be shaped into profiles. After the profiles are shaped, they are sent to a machine that applies a water-based sealant that will help the wood withstand the elements. Then, the profiles are cured in an oven. The final step in the milling process is to send the profiles to the “supermarket” where they are stored by size and profile type. This allows for quick sourcing of the correct profiles that are needed when an order is received.

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Flexacron® finish for protection and aesthetics

Flexacron finish is applied to the window profiles in a proprietary way so instead of showing that process, Grace and Schiffer explain a bit about it. They compare Flexacron paint to powder coating. It provides an even mill layer that both protects from the elements and applies an aesthetic finish — including color. Importantly, it is applied to all profile parts before they are assembled. This is done to make sure that if there were ever any movement in the frame and the profiles became exposed, they would be protected. Schiffer also addresses the question: Does pre-coating result in weaker joints? He explains how both the glass and mechanical fastening process used to screw the profiles together lend strength to the frame.

As Grace and Schiffer stand in the supermarket explaining the coating process, the misters turn on. The misters, which are not so different from the ones that keep produce fresh in the other kind of supermarket, are there to keep the right level of humidity in the air. Schiffer explains how wood contracts as it dries and expands with humidity. Everywhere in the plant that milled wood is kept, misters are used to avoid any cracking, warping, shrinking, or other issues that could occur before the profiles are finished with Flexacron paint. This attention to humidity levels helps maintain the integrity of the wood and the end product.

Both Grace and Schiffer have profile pieces in hand. Grace holds two unfinished profile pieces and demonstrates how they fit more loosely together, whereas Schiffer holds finished profile pieces that have been coated in Flexacron paint and demonstrates how they fit more tightly together. The coated profile pieces are a tighter fit because the coating thickness is taken into account when they are milled. Schiffer holds the fitted profile pieces together just by the top piece to demonstrate the tight fit — even without any fasteners yet attached, it is strong enough to hold against gravity.

The two hop back on the golf cart to see what happens after the finishing process.

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Vinyl sheaths for seamless protection

Their next stop is at a rack holding aluminum molds that are the same size as our standard wood windows. These aluminum molds are used to form the vinyl sheaths that protect our 400 Series frames. Grace explains how the frames have air and water ducts built into them. These ducts are key to the 40-second process that’s used to create the vinyl sheaths.

As Grace explains the process, the camera cuts to showing it in action. First a piece of vinyl is laid over the aluminum frame. Steam is applied and the vinyl is suctioned down onto the frame until it conforms perfectly to the mold. Once the vinyl is formed, cold water is circulated underneath the frame through the water ducts to harden the vinyl. After it hardens, air is blown through the tiny pinholes built into the mold to release the vinyl from the aluminum. With that, the sheath is formed.

The camera returns to Grace and Schiffer standing next to the frames. Schiffer addresses the question of how sheaths are created for custom size wood windows, which can be specified down to 1/8 of an inch. He explains how unlike the monolithic molds used for standard sizes; custom molds are pieced together to match custom window sizes. The custom molds can't circulate water through them the way the monolithic molds can, which means the vinyl cures slower. The slower process means fewer windows can be produced per hour, and this is a reason for an increase in price that comes with custom windows.

Next, the builders show the vinyl sheeting that’s used to create the sheaths. Schiffer explains how the vinyl comes in powder form and sheets are created from that. He points out the holes for the nailing flange which are punched before the sheathings are molded. Then, an associate is shown loading a sheet of vinyl into a machine that will circulate it into the steam bath and vacuum. The process of forming a sheath is shown again as Schiffer explains how the fans above help dissipate the steam in a mere matter of seconds, helping the cooling process.

Once the process is complete, an associate is shown moving a stack of sheaths to the machine that will cut out the center to make room for the glass. The sheaths are fed into a machine that cuts out the excess vinyl perfectly. An associate removes the sheaths from the machine and stacks them on a rack. The excess vinyl gets spit into a container. From there, it will be recycled into another sheet. This recycling process happens a number of times. When it’s no longer possible to make another sheet, the vinyl is ground up for use in Fibrex material. Grace concludes by pointing out that a major advantage of the vinyl sheathing is that it is monolithic, which means there are no seams or potential leakage points. This protects the window from water intrusion.

The next stop is seeing how all these pieces come together to make a window.

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Assembling a wood window

The next step is putting together the coated profiles and vinyl sheathing to create window frames. The builders go to the place where profiles from the supermarket are taken and organized prior to assembly. An associate is shown gathering the profiles needed to create a joined unit of three casement windows. He places the profiles into a machine. Then, the mechanical fastening begins. Grace points out how the profile pieces can be stapled together from both sides at once, mitigating the safety issue of having multiple employees stapling toward each other at the same time. Once the unit is fastened together, an associate inspects it to make sure it was properly done. He then grabs a vinyl sheath, and a machine applies a proprietary adhesive evenly to its back side. The associate then attaches the sheathing to the assembled frame and adds a ticket that gives instructions about which way the casements will swing, hardware, and other details. His last step is to feed the unit into a machine that will apply pressure to make sure the vinyl sheathing is properly adhered to the frame.

Once the frame is through the machine, other associates apply hardware according to the instructions outlined in the ticket attached by the last associate. Their work is eased by adjustable workstations that allow for better ergonomics and can be flipped in all directions to make adding the hardware easier.

The window is then passed along to associates who install the insulated glass units (IGU). Working two at a time, associates each take one end of the IGU, place it in the unit and screw it into place. They also show how fixed-glass units are installed from below and pressed into place.

With IGUs in place, windows get boxed up. Their next stop will be a distribution center. Before the video ends, Grace and Schiffer backtrack to show a key step in the manufacturing process.

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Continuous weatherstripping for a stronger seal

They show an associate adding continuous weatherstripping to a casement window. The weatherstripping is on a spool that gets unwound as the associate spins the window around to install it very quickly all around the perimeter. She then tucks in the end where it meets the beginning for a single seam. Grace explains how continuous weatherstripping is applied differently to different types of windows. This is done in order to place the seam in the least vulnerable place on each type of window. Schiffer then explains how this approach is an advancement from the previous practice of applying weatherstripping in four separate pieces with gaps at each corner. With four separate pieces, it’s more likely that there will be movement over time resulting in more air leakage. Continuous weatherstripping helps avoid these gaps at the vulnerable corners for a better sealed window overall.

The lean manufacturing practices shown in the video allow us to be agile, to be sustainable, and most importantly of all — to manufacture the best quality windows. But manufacturing is only one aspect of the formula that makes our products top quality. Learn more about the rigorous testing we undertake to engineer our products in our Research, Development, and Innovation (RD&I) Center.

See how we test our products Learn about the 400 Series

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About the modern craftsman

Grace and Schiffer are the voices behind the Modern Craftsman, which is a podcast and community network dedicated to promoting excellence, education, knowledge, and respect in the building industry. With their audience of trade professionals, they discuss all aspects of life within the industry and life itself — from mental health to leadership and everything in between. They pride themselves on working with brands and people who strive to make the industry better and advocate for a better life in the trades.

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chris galvin doing a podcast with modern craftsmen

chris galvin doing a podcast with modern craftsmen

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