The patented process allows for compression molding at lower pressures, saving on equipment capital costs for panel production. #adhesives #outside the autoclave #sheetforming compound
It may look like a wooden door, but it is actually a layered replica of the SMC surface, made using Acell’s new SMC molding process. This process uses a phenolic foam core to create doors and other building panels through low-pressure one-time molding. Source: Asell
This image shows the installation of the press. Note the raised rail visible in the upper left that supports the PiMC robotic spray system for powder coating. Source: Italpresse
Cross-section of a pressed panel (without wood framing) showing how the SMC resin penetrates the open cells of the foam core, creating a mechanical interlock to prevent delamination. Source: Asell
Acell panels are available in hundreds of finishes, including marble patterns, as shown here. Source: Asell
Step 1: During casting, a nickel-plated aluminum mold is first created using a composite master to recreate the desired surface finish. This bottom face is a typical door panel. Source: Asell
Step 2: The negative of the glass-filled molding compound (SMC) is placed on the tool; in a production scenario, a surface veil is first applied to the mold to maintain a consistent surface quality. Source: Asell
Step 3: The door panel usually includes a wood frame, allowing you to drill hardware holes into the finished door or panel and cut it to fit your installation. Source: Asell
Step 4: Acell’s patented phenolic foam (essentially fire/smoke/virus) is placed in the wood frame. Source: Asell
Step 5: Place the top sheet of SMC on the styrofoam and wood frame and form the other outer skin of the SMC and styrofoam sandwich. Source: Asell
Step 6: Compare the finished panel with the form. Note that loose foam allows you to reproduce the contours of the panels. Source: Asell
“If you build it, they will come” may be a Hollywood catchphrase, but it also describes the advancement strategy the composites industry sometimes employs – introducing compelling innovations in the hope that the market will evolve over time. Adapt and accept it. Acell’s sheet molding compound (SMC) technology is one such innovation. Patented worldwide in 2008 and introduced in the US in 2010, this process provides a combination of material and process for high performance custom sandwich molding. The capital equipment cost of the panels is much lower than conventional compression molding.
The inventor of this innovation is the Italian chemical technology group Acell (Milan, Italy), which has been producing a unique open-cell phenolic foam core for fire-resistant building structures for 25 years. Acell wanted to find a wider market for its foam products and developed a method of using foam in combination with SMC to efficiently manufacture doors and other panel products for the building market. Technical partner Acell Italpresse SpA (Bagnatica, Italy and Punta Gorda, Florida) designed and built a complete production line for the production of composite panels according to specified parameters. “We believe in our business model of creating processes and products for global use,” said Acell Chief Commercial Officer Michael Free.
Perhaps he is right. This generated a lot of interest in the industry. In fact, Ashland Performance Materials (Columbus, Ohio) has formed a strategic alliance with Acell to promote this technology in North America. The Acell process was also awarded the 2011 Composites Excellence Award (ACE) by the American Composite Manufacturers Association. (ACMA, Arlington, Virginia) Process Innovation category.
The new molding process is a crystallization of a large amount of research and development of sandwich panels. Dave Ortmyer, COO of Italpresse USA, explained that existing composite door designs are manufactured through a multi-step and labor-intensive process that includes fabricating the inner frame, laminating the SMC skin, assembling the components, and finally, polyurethane foam is poured inside for thermal insulation. In contrast, Acell’s process produces an equivalent door panel in just one step and at a significantly lower initial cost. “A traditional SMC door skin mold can cost up to $300,000,” Ortmyer said. “Our process can give you a finished door in one go, the cost of tools will be $20,000 to $25,000.”
Materials play a key role in the process. Unlike most phenolic foams, which are soft, brittle and fragile (like the green florist foam used for flower arrangements), Acell foam is a combination of proprietary ingredients to create a stronger structural foam. m3 (5 to 50 lb/ft3). The foam has thermal insulation properties, fire, smoke and toxicity (FST) resistance, and sound-absorbing properties. It’s also available in a variety of cell sizes, Free said. The glass-filled SMC used in the door panels is made by Acell, he said. Because SMC is prone to outgassing during molding, Ortmeier says, the foam acts as a breathable material, allowing gas to escape the mold through the holes.
However, the key issue is accessibility. Ortmeier said the partners hope to provide cost-effective tools to small-scale producers or those producing multiple products on short notice. In typical SMC compression molding, the tools are bulky and expensive, he says, not only because the parts are bulky, but also because they have to withstand the wear and tear caused by the movement and flow of the many SMC “charges” lined up in the mold. . under necessarily high applied pressure.
Because the more structural Acell foam remains “brittle” (deformable) under pressure, normal pressing pressure will completely crush it, so molding pressure must be relatively low. Therefore, the Acell process only uses a thin layer of SMC on the skin. It does not move or flow sideways, so there is no risk of wear on the tool surface. In fact, the SMC resin only flows in the z-direction – the process is designed to provide enough heat in the mold to liquefy the SMC matrix, causing some of the resin to seep into adjacent foam cells as it crumbles slightly under pressure.
“During the molding cycle, the SMC shell is essentially mechanically and chemically fixed in the foam,” Frey explains, and claims that “shell delamination is impossible.” other Too strong tool. The cost of two thin cast inserts (top and bottom) with the required surface detail is only a fraction of the cost required to produce a steel or machined aluminum SMC tool. The result, partners say, is an affordable process offering a wide range of transactions at a nominal cost of capital.
However, affordability and affordability do not rule out adaptability. A number of tests were carried out in which woven materials were included in the laminate. They are simply built into the intermediate layer, increasing the bending strength of the panels. According to Free, woven aramid fabrics, metal honeycombs and even pultruded inserts can be integrated into sandwich panels and pressed during processing for added blast resistance, theft protection and more. “We want manufacturers to understand that this process is very flexible and adaptable,” he explained. “It can produce custom-made thick or thin panels at a low cost without additional processing such as gluing or fastening.”
The process plant, designed by Italpresse specifically for Acell, consists of a 120 tonne downstroke press with heated plates to place the molds for the panels. The bottom platen is designed to move in and out of the press automatically, and Ortmeier says it’s possible to add a second heated bottom platen on the opposite side of the machine to lay on one mold while another is in the press using Layup. station. Slabs are 2.6m/8.5ft x 1.3m/4.2ft for “standard” applications such as decorative doors, but slabs can be custom made to suit specific projects. It is worth noting that it is also possible to modify existing press setups to match the Acell process, provided the pressure can be controlled (via die stops) to avoid overcompression.
Molds are made individually for each panel project and can be made by traditional casting methods. To obtain a high definition mold surface that mimics natural materials such as wood or stone, fiberglass/polyester panels are laid directly on the material of choice to create master patterns for the upper and lower tools. The two master models are sent to the foundry, where the tools are cast in aluminum-nickel alloy. The relatively thin tool heats up quickly and can be lifted and moved by two operators when idle. Other tool options are available, but casting techniques produce tools at a reasonable cost and typically 0.75″ to 1″ (20 to 25 mm) thick.
During production, the mold is prepared according to the desired surface finish of the panel. A variety of molding coatings and finishes are available, Free explained, including molding powder coating (PiMC), a widely used sprayable pigment powder that melts and reacts with SMC to form a UV and scratch resistant coating. Panel surface color. Other options include pouring colored or natural sand over the mold to simulate stone, or applying a printed veil that can add texture and pattern. Next, the surface filament is laid on the mold, then the layer of glass-filled SMC is cut into a mesh shape and laid flat on the prepared mold.
A piece of 1″/26mm thick Acell foam (also cut to mesh shape) was then placed on top of the SMC. The second layer of SMC is applied to the foam along with the second film to facilitate the release of parts and provide a conduit for the volatiles emitted by the SMC. The bottom die, which is placed on top of the heated platen, is then mechanically or manually fed into the press where a process temperature of 130°C to 150°C (266°F to 302°F) is reached. Lower the top mold onto the stack, leaving a small air gap between the molds, and press the intermediate layer with a force of 5 kg/cm2 (71 psi) for about five minutes to form a solid panel as in step 6. During the stamping cycle, the beads slide out and the part is removed.
To create a typical door panel, the process was modified by adding a sandwich wood frame around the edge of the piece (step 3) and installing foam inside the frame. Edged wood allows doors to be cut to precise dimensions and mounting hinges and fittings can be easily installed, Fritsch explains.
While most traditional composite doors are now made in Asia, Ortmayer says the Acell process “allows ‘local’ production on land due to its lower cost. It is a way to create manufacturing jobs at a reasonable capital cost. There are currently seven licensees in Europe using the Acell process to make doors and other panel products, and interest in the US has grown rapidly since receiving an ACMA award in 2011, says Free, who hopes to see more in outdoor building components. Often used, for example, as cladding panels (see photo), this process is excellent in terms of thermal insulation, UV resistance and impact resistance.
Another advantage is that Acell panels are 100% recyclable: up to 20% of the recycled material is reused in foam production. “We have created an economical and green SMC molding process,” Free said. Mike Wallenhorst said the strategic alliance with Ashland is expected to make the technology more widely known. Director of Product Management at Ashland. “It’s an impressive piece of technology that deserves a wider audience.”
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Post time: Sep-01-2023