CW Blog

By: Karen Mason 29. April 2019

Reusable vacuum bags go digital

“A lot of our ideas about how vacuum bags work come from our own experience,” says Max Caprez, technical sales manager at Industrial Technologies (Akron, Ohio, U.S.), as he recounts the company’s history. Starting out more than 20 years ago as a fabricator of composite tools, Industrial Technologies experienced firsthand the challenges of maintaining vacuum integrity across a component, as well as consistency from component to component, in both autoclave and resin infusion applications. As it developed solutions that helped to reduce material costs, labor costs and fabrication time associated with vacuum bagging, the company also leveraged its reusable vacuum bag (RVB) technology to market RVB products to other composites fabricators.

Today at Industrial Technologies’ 25,000-square-foot facility, the company produces silicone reusable vacuum bags, as well as cauls, intensifiers and mandrels, as one of its main product lines. The majority of the company’s customers come from composites fabrication and maintenance, repair and overhaul (MRO) operations for the aerospace industry. Industrial Technologies continues to make RVB products from conventional silicone materials — semi-cured and cured silicone sheet — but has also advanced RVB technology to a patent-pending cast vacuum bag system. CW sat down with Caprez to learn more about the company’s cast bags and to glean some advice for composites fabricators as they work with various vacuum bag systems.

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Composite materials and innovations are constantly evolving. In addition to industry news, features, blog posts and podcasts, CW also maintains a comprehensive collection of product announcements provided by companies. This roundup includes links to regular posts concerning the latest products of interest to the composites industry.

Recent innovations include:

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One challenge to kitting prepreg fabrics or unidirectional (UD) tapes is figuring out what to do with trimmings that are too small or whose fibers are incorrectly aligned for reuse in another project. Although nesting software and cutters have reduced scrap significantly, trimmings still often go into a landfill, which adds to material and part costs as well as environmental burden. However, a Dutch company, Van Wees UD and Crossply Technology BV (Tilburg, Netherlands), is helping improve sustainability by developing a new technology — and the machines that make it possible — to reuse thermoplastic tape offal.

Founded in 1945 and with deep roots in the textile industry, Van Wees is a full-service provider that designs, produces, installs and commissions machines and production lines to produce advanced composites (thermoset or thermoplastic, carbon or glass fiber) with a focus on high-quality, high-volume production methods. The company makes prepreg impregnation lines (including creels) — primarily for epoxies on the thermoset side and for materials ranging from polypropylene (PP) to high-temperature polyamides (PAs) on the thermoplastic side — as well as crossply and multiaxial UD tape placement machines, which can process either thermoplastic or thermoset tapes. A sister company, Eltra Engineering BV (also in Tilburg) specializes in industrial automation technology and supplies electrical controls and software for Van Wees machines.

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Though the company’s base is most certainly filament winding, CompoTech has pushed that process into new applications via pin-based winding, overwinding and innovative tooling and materials concepts. The result is a fluidity in process that often achieves new levels of performance via hybridization, for example, with metals and manufacturing methods like 3D printing and its own version of automated fiber laying (AFL).

CompoTech produces parts for a wide range of applications including industrial equipment (vacuum gripper assembly, top left) and agricultural equipment (sprayer boom, top right) from its facilities in Sušice, Czech Republic (bottom). SOURCE:  Bilsing Automation (gripper, top left), Hardi International (spray boom, top right) and CompoTech.

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As conventionally powered passenger vehicles become more electronic and need bigger batteries to run onboard systems, protecting cells during severe crashes becomes more difficult. While the structure around batteries already is high strength and provides adequate protection for normal crashes, during severe crashes the protective structure itself can deform and puncture the battery, rendering it inoperable. In such cases, additional battery protection is desired, but ideally without sacrificing design or other safety features, without adding much weight or cost, and without impeding battery service or replacement during the vehicle’s life. As a result, a new part, called a battery impact shield, has been developed to protect larger 12-volt batteries in severe crashes and is a growing application for composites.

The already difficult U.S. Federal Motor Vehicle Safety Standard (FMVSS) 208 now requires automakers to test at a 30-degree offset during frontal-barrier testing. The test’s impactor is designed to completely miss frame rails so that a corner of the bumper takes the full hit before being pushed into the engine bay. The severe crash loads this test simulates have led General Motors Co. (Detroit, Mich., U.S.) to beef up battery trays and to develop battery impact shields, which serve the purpose of distributing crash loads over a greater area, thereby protecting batteries longer from being punctured and shorted out by surrounding components as the vehicle front end is crushed. This buys enough time for onboard diagnostics to detect the crash and send an “offboarding” safety call to first responders before the battery stops working — a feature that saves lives when occupants are unconscious or pinned and unable to make a call. These shields are designed to sit on metallic battery trays and wrap around those portions of the battery nearest engine bay components that crash simulation has identified as most likely to damage the battery in a severe crash. In use, control modules and other components connected to the battery hang off the shield and hold it in place so there are no noise/vibration/harshness issues. The shield is simply removed during maintenance or battery replacement and put back afterward.

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