Curved, finished and complete – What you should know about architectural stretch forming

Henry Ford Int MI

Henry Ford Museum in Greenfield Village, Dearborn, Michigan, built in 1929, was renovated with large, arched top windows using stretch-formed, finished aluminum framing members 
Credit: Courtesy of Wausau Window and Wall Systems

Stretch forming was invented during the 1940s with the rise of the aerospace industry for the curving of aluminum aircraft parts to reduce weight, and thereby, fuel consumption. It expanded into car components and eventually, into the architectural industry. Architects and designers pursued new opportunities to create curved facades and building components.

The process of stretch forming is more of an art, than a science. It takes years of experience to become a skilled craftsperson that can stretch form consistent, successful, curved aluminum components for architectural projects.

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Stretch forming is a metal bending process in which a lineal shape, such as an aluminum extrusion, is stretched and bent simultaneously over a form, called a die.

Stretch forming is a metal bending process in which a lineal shape, such as an aluminum extrusion, is stretched and bent simultaneously over a form, called a die. Each form is built to the required radius. These forms may be customized for a special curvature and used only once, or re-used for more popular, repeating arcs.

Opportunities with stretch forming

Stretch forming capabilities typically include portions of circles, including half-circles and eyebrows, ellipses and arched shapes. These shapes can be formed with straight leg sections at one or both ends of the curve. This method of curving eliminates several conventional fabrication and welding steps.

The variety of shapes and cross-sections that can be stretch-formed is almost unlimited – from muntin bars and panning for windows, cladding and spirals for handrails, large mullions for building envelopes to serpentine shapes for canopies. Stretch forming allows architects, designers and builders to realize forms as graceful as they are sturdy and functional.

In most cases, the stretch-formed aluminum component’s curvature is so highly precise that even intricate multi-components and snap-together curtain wall components can be formed from metal without loss of section properties or original design function.

To achieve this level of precision, the basic stretch-forming machine has two arms or carriage beams that hold multiple-positioning gripping jaws. Both ends of the extrusion are inserted into the gripper jaws and stretched to their yield point. The jaws are attached to hydraulic tension cylinders that stretch the extrusion. The arms swing by rotating on large, machined pins with bearings that allow the extrusion to wrap around and against the form. This produces perfectly contoured products, while limiting or even eliminating wrinkling inside the arc. When the wrapping is completed, the stretch force is released and the gripper jaws are opened.

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It takes years of experience to become a skilled craftsperson that can stretch form consistent, successful, curved aluminum components for architectural projects.

Stretch forming maintains close and consistent tolerances with excellent repeatability, and alignments of complex profiles and compound curves. There should be no visible surface marring, distortion or ripples. These benefits inherent in the stretch forming process yield a smooth and even surface. Each component must meet the project’s specifications and warranty conditions.

Structural vs. non-structural application

Aluminum has proven to be a suitable, reliable material for load-bearing structures for more than 100 years. However, the application of the parts being curved dictates the process used.

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Vancouver’s PARQ Resort and Casino features a 23,000-square-foot façade with curved corners and curtainwall details made possible with stretch-formed aluminum framing members finished in clear anodize.
Credit: Courtesy of Gamma North Corporation

After being pushed through an extrusion press, extrusions are cut and placed into a tempering oven to harden and give them structural integrity. When they are fully hardened to a T5 or T6 temper, they are too hard to curve. If the parts to be curved have been fully tempered, they will need to be annealed before curving. To do this, the part is placed in a large oven and heated to a peak temperature range of 700 to 800 degrees Fahrenheit for two to three hours.

Annealing makes the extrusion soft again—enabling it to be curved. Metal that is annealed cannot be hardened again. Once it is softened, it will remain soft. In applications where the parts are expected to carry a structural load or have another structural application, annealing generally is not an acceptable practice.

PARQ-Vancouver-all-stretchforming-(8WEBFor structural or load-bearing applications, the best practice is to have extrusions tempered to a soft state of T1, T4 or to a T52 state. Material tempered to a T1 or T4 can be bent without annealing, and can be tempered after the curving process to a T5 or T6 that is typical in structural applications. T52 is a very stable temper and can be curved without annealing, and it maintains its properties after curving without the need for additional tempering.

Painted or anodized finishes

Similar to the curving process, the end-use application of the part will determine the best practice for how curved parts should be finished. If an extrusion has been painted or anodized, and has been tempered to a T5 or T6 hardness before being curved, the parts will need to be annealed. The high heat associated with the annealing process likely will cause painted finishes to burn and anodized finishes to discolor or craze. For this reason, when parts require annealing, it is best to finish them after the curving process has been completed.

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Orlando International Airport’s new South Intermodal Terminal Facility showcases a segmented barrel vault skylight featuring aluminum framing that has been stretch formed, thermally improved and finished in Bright Silver 70% PVDF architectural coatings.
Credit: Greater Orlando Aviation Authority

For extrusions tempered to a T1, T4 or T52 hardness, parts can be finished before curving. However, some marring or slight damage to the finished surface should be expected due to the parts being stretched across the form’s hard surface during the curving process. Depending on the tightness of the radius, anodic coatings also may craze or discolor as a result of being curved. If the T1 or T4 tempered extrusions require oven-aged tempering after curving, the high heat will likely damage the coating.

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The stretch forming process yields a smooth and even surface with each component meeting the project’s specifications and warranty conditions.

Regardless of the effect the curving process has on the finish, nearly all manufacturer and applicator warranties are voided when extrusions or brake metal are finished prior to curving. To obtain the best finish quality and to keep parts fully warranted, it is best to finish after curving—regardless of the temper of the extrusion. The American Architectural Manufacturers Association (AAMA) publishes industry-accepted specification standards for anodize and paint finishing of architectural aluminum components.

Thermally improved curves

Rolled-TB-Extrusion-web136At least one U.S. finishing and service provider also offers thermal improvement services for curved and radius, finished aluminum extrusions backed with an industry-leading warranty. The thermal improvement processes may be specified as either a full pour-and-debridge of radius material, both structural and non-structural, or a fully crimped thermal strut system. The service provider places no restrictions to the degree of curvature, and finishes may be specified in liquid paint, powder coat or anodize.

Installing the thermal barrier in the metal after it has been curved helps minimize stress on the thermal barrier and ensures performance as specified. Choosing the thermal strut system provides the additional design flexibility of dual finishing, where the interior and exterior surfaces may be finished in different colors and formulations.

Ensure that aluminum products’ thermal improvement options strictly comply with its material suppliers’ standards and AAMA’s quality assurance processing guidelines. For optimal quality and convenience, some finishers provide a single-source solution where stretch forming, thermal improvement and finishing are synchronized and retain the full warranty. When available, utilizing the finisher’s trucks also can reduce material handling and packaging to minimize the opportunity for damage, while saving costs and time.

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The basic stretch-forming machine has two arms or carriage beams that hold multiple-positioning gripping jaws. Photos courtesy of Southern Stretch Forming

 

Will it bend? Understanding stretch forming aluminum

big-8800-1Choosing a single partner to curve and finisher your architectural aluminum products offers a more efficient process with a higher quality result. At Linetec, our paint and anodize finishing options are both possible in combination with stretch forming services. Not only does this provide you with a single point of contact, it saves time and costs, and ensures a full warranty on the finished, curved materials.

What is stretch forming?

curved-metal-rack-698X400Stretch forming shapes aluminum sheets and extrusion profiles into simple or complex contoured curves with tensile and bending forces. The material is kept under constant tension, while wrapping it around a form, or die, to produce the desired arc.

Born from the aerospace industry, stretch forming maintains precise dimensions throughout a curve and produces perfectly contoured products while limiting, or even eliminating, wrinkling inside the arc.

Yale Peabody Closeup CTWhat shapes and sizes are possible?

Half circles (180 degrees) and eyebrow (usually 135 degrees) curves are the most popular requests that Linetec receives. These curves may be coupled with straight legs to create a larger opening as a window or door frame. Gothic arches also are common, especially for historic retrofit projects.

Larger arc lengths typically are specified on more modern facilities. Linetec can accommodate a maximum arc length of 260 inches. Those exceeding 260 inches can be reviewed and discussed. We can curved material up to 10 inches in width.

We can advise on accurate measurements to confirm the material dimensions meet your project’s requirements. A template will be needed for compound curves, which have more than one radius, and usually require a custom die.

Can thermal improvements be made to curved aluminum framing members?

Rolled-TB-Extrusion-web136At Linetec, not only can we coordinate the curving of your material and finish it in your choice of paint or anodize, we also can thermally improve the aluminum framing. We offer either a fully crimped, insulating, thermal, polyamide strut system or a three-step, pour-and-debridge process.

Both options separate the inside and outside aluminum framing members of a window, door, skylight, storefront or curtainwall system to reduce the amount of heat transfer, therefore saving energy and increasing occupant comfort.

Installing the thermal barrier in the metal after it has been curved helps minimize stress on the thermal barrier and ensures performance as specified.

What else can affect lead times, costs and warranties?

In addition to maintaining strict, factory-controlled standards by a single point of contact, relying on Linetec for your stretch forming, finishing and thermal improvement services also saves you time and money. You don’t need to coordinate between multiple suppliers’ facilities for logistics and freight. Which also minimizes handling and decreases the chances of your materials being damaged during loading and transport.

Nearly all manufacturer and applicator warranties require that the aluminum sheets and extrusions are finished after curving. When customers ship us their aluminum, Linetec alleviates this worry and performs all the services in the proper sequence and in the same place to retain the full finish warranty.

To learn more about how Linetec can support your next project with our stretch forming, finishing and thermal improvement services, please contact our regional sales managers, email sales@linetec.com or call 888-717-1472.

Thermal strut supports energy efficiency, curves and corners, dual finishes

strut05-webAdding insulating, thermal, polyamide strut to aluminum framing members separates the inside and outside metal, which greatly enhances a window, door, skylight, storefront or curtainwall system’s thermal performance. This thermal break reduces the amount of heat transfer, therefore saving energy and increasing occupant comfort.

At Linetec, we offer a fully crimped thermal strut system. We have no restrictions on the degree of curvature in aluminum framing members. For corners, our 90-degree thermal strip process not only saves time and labor, but also minimizes inconsistencies and waste, holds customer-specified tolerances for U-Factor and shear testing, and delivers a high-quality finished product.

two-tone2-webOur thermal strut also presents a cost-effective opportunity for dual finishing options, where one finish type or color is used on the exterior and another on the interior. Our finishes may be specified in nearly any color of liquid paint, in decorative wood grain finishes, or in anodize including our no-patina copper or brushed stainless finishes.

For more information on our thermal improvement and dual finishing services, please contact Linetec’s regional sales managers , email sales@linetec.com or call 888-717-1472.

Thermal pour-and-debridge services enhance energy efficiency and comfort

Aric-Dave-3-2017-lowresContributing to commercial and residential properties’ energy efficiency goals, high thermal performance has become an expectation when selecting window, skylight, curtainwall, storefront and entrance systems. Polyurethane pour-and-debridge systems are formulated for these exacting applications and suitable for withstanding the most demanding climates and conditions with the highest performance in impact resistance, sheer strength and heat distortion.

At Linetec, we use a three-step pour-and-debridge process, which can include an Azo-Brader or Lancer method mechanical lock. When needed, we also offer skip debridging and double debridging services. Our process results in thermally improved aluminum frame that helps building owners save energy and keeps building occupants comfortable.

Building owners and architects do not need to compromise performance for aesthetics if they want a radius instead of a rectangle, We offer a full pour-and-debridge of radius material, both structural and non-structural. We have no restrictions on the degree of curvature in aluminum framing members, including 90-degree corners.

As always, our finishes may be specified in nearly any color of liquid paint, in decorative wood grain finishes, or in anodize including our no-patina copper or brushed stainless finishes.

For more information on our thermal improvement and finishing services, please contact Linetec’s regional sales managers, email sales@linetec.com or call 888-717-1472.

Linetec’s painted finish and thermal improvement services boost energy-efficiency of University of Pennsylvania’s New College House

UofPa_NewCollegeHouse25-72dpiThe University of Pennsylvania’s $127 million New College House opened for the 2016-17 academic year as the first new student residence on campus since 1972. Designed by Bohlin Cywinski Jackson (BCJ) in collaboration with the University, the first purpose-built College House brings together undergraduates, faculty, staff and graduate students in a shared suite-style community. The 198,000-square-foot, 350-bed building promotes sustainable, 21st century living and learning, and is pursuing LEED® Silver certification.

Supporting the project’s energy-efficiency goals, Wausau Window and Wall Systems’ curtainwall, windows and sun shades were installed with painted finishes and thermal improvement systems by Linetec, a long-standing leader in environmentally conscious practices, paint finishing and thermal improvement services. These services were key contributors to the window systems’ energy-efficiency, visual appeal and durability.  read more

UofPa_NewCollegeHouse31-72dpiNew College House’s large, vertical transparent towers frame the views of Penn’s surrounding campus community and Center City Philadelphia. Bounded by Woodland Walk and 34th and Chestnut streets, the seven-story building with a publicly accessible, lifted lawn serves as a pedestrian gateway to campus.

UofPa_NewCollegeHouse39-72pdi“In this city of neighborhoods, we sought to embrace the many scales of community that define the collegiate experience unique to Penn,” says Frank Grauman, design principal from BCJ. “The New College House is, therefore, both inviting and secure, open and private, embodying the comfort of home, and the power to form a campus gateway worthy of this place.”  read more

 

Thermal improvement matters for energy efficiency in both warm and cold climates

SHORE MEM INT NJModel Energy Codes adopted across the U.S. are directing buildings to achieve more efficient performance. Whether trying to keep the warmth inside in cold climates or trying to keep the heat outside in warm climates – Linetec helps optimize aluminum architectural manufacturers’ systems to meet thermal requirements in all climate zones.

Thermal Barriers

Linetec enhances the thermal performance of architectural metal products, such as window, skylight, curtainwall, storefront and entrance systems.

Using a thermal barrier system improves performance by separating the aluminum profile into two parts, while maintaining the structural and long-term durability of the unit. The two methods for doing this are:

While both methods achieve high thermal performance, thermal strut also simplifies dual finishing, where the interior and exterior surfaces may be finished in different colors and formulations.

Curves and Corners

SONY DSCThere’s no need to sacrifice creative design for thermal performance or condensation resistance. Beyond linear extrusions, thermal improvement services are available for

Installing the thermal barrier in the metal after it has been formed helps minimize stress on the thermal barrier and ensures performance as specified.

Linetec performs all these services in the proper order, to industry-leading quality assurance standards, and in the same location to retain the full warranty.

Learn More

Learn more about thermal improvement and finishing services by clicking here. For personalized assistance in selecting the optimal performance for your aluminum building products, please contact Linetec’s regional sales managers, email sales@linetec.com or call 888-717-1472.

If you’re attending the American Institute of Architects (AIA) national conference and Architecture Expo, please visit us in person at booth #3353 in the Orange County Convention Center in Orlando. The exhibit hall is open April 27 and 28, 10 a.m.-4 p.m.; April 29, 8:30 a.m.- 12:30 p.m.

 

Linetec’s expansions continue: adding 70 more employees

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3-year associate, Scott Yang, and 30-year associate, Rodney Sloan, prepare flat sheet order for customer delivery

Linetec continues to expand capacity and add new jobs to support the market’s increased demand for high-quality finishes and high-performance architectural metal products.

“In the last 24 months, we expanded capacity in both our paint and anodize lines, and added more than 200 new jobs. This year, we already have an immediate need to fill 70 positions, particularly in the paint and thermal services departments. We’re looking for more to join our team of good, hard-working people across all production areas,” says Jane Kessel, Linetec’s vice president of human resources.

Part of the latest job growth is a $3 million investment to double the capacity of the thermal services department. “Continually increasing energy codes are driving our customer base to develop more products that incorporate these thermal services,” explains Andy Joswiak, Linetec’s vice president of operations. “The other driver of the latest job growth is painting volume.”

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Linetec painters ensure specified coverage on all aluminum parts

In late 2016, Linetec expanded its painting capacity by going from a five-day operation to a seven-day operation, using new shift structures and adding 40 new positions. Now, with even higher growth rates so far this year, Linetec has initiated further significant hiring in 2017 for more painting capacity.

Examples of Linetec’s immediate job opportunities include positions in production scheduling, packaging, racking, truck drivers, cleaning and maintenance. Starting rates range from $15 to $16 per hour plus premiums and bonuses. Benefits include health and dental, bonus pay, 401k, paid vacation, and tuition reimbursement.

“Once the new openings are filled, we will have well over 600 employees – some of which have been here 30 years,” Linetec’s president Rick Marshall notes proudly. “We listen to and value our employees. Their input helped establish the Core Values we bring to life every day. The jobs in our industry are sometimes demanding, but we more than offset those challenges with a very positive and rewarding work environment. Our culture and Core Values are what make us unique, and that helps us continue to successfully hire in a very tight labor market.”

For more information about Linetec’s finishing and thermal improvement services, please call 888-717-1472, email sales@linetec.com or visit http://www.linetec.com. For interest in employment opportunities visit http://www.linetec.com/Careers/Careers.html