IBEX 365 News

How to Flow Resin for Successful Infusions

News Date: August 19, 2021

Construction & Repair Materials and Products

New in 2020

The key to the success of the resin infusion process is the transport of liquid resin from a container into the dry fabrics and core materials placed on the mold and vacuum bagged. This requires a network of flow channels that the resin can run through and a strategy for feeding resin into the channels, planned to make sure resin is transported into the dry fabrics and core materials before curing occurs.

The resin flow network is typically split into flow media and flow lines. With the resin flow media covering most of the part, so resin can reach every portion of the part surface. Resin flow media are commonly meshes sitting on the part surface. The resin flow lines have high-speed resin flow, providing a flow front along a length into the resin flow media. Spiral tubing is a commonly used resin flow line.

Resin Flow Mesh allows resin to flow more quickly than it can through the fiber reinforcement. Flowing resin over the part surface and down into the fabric layers on the mold. Airtech provides a range of resin mesh to suit the requirements of different parts shapes and resins types. Selection is typically based on simple flat panel testing.

Knitted Resin Flow Mesh is a highly flexible knitted filament mesh that can be easily applied over complex shaped parts. It also provides a good resin flow path and high-speed resin flow can be achieved, ideal for larger parts. Knitflow 160 is an inexpensive high-speed resin flow mesh that is available up to 72” wide. Wide-format knitted flow mesh, like Greenflow 185, are available up to 141” wide for larger parts. High-temperature mesh Knitflow 105HT can be used for warm infusions and hot cures.

Extruded Resin Flow Mesh are diamond shape extruded strand nets. They provide efficient resin flow in a low-profile mesh construction that minimizes resin waste. Greenflow 75 is a flexible extruded polypropylene mesh available up to 60” wide, that provides good resin flow speed and low resin waste, with a low price point.

Flowlease laminated flow media provide labor-saving benefits during infusion preparation. Airtech can supply any of the mesh products pre-bonded to a release film or peel ply fabric. This avoids extra work required laying up vacuum bag materials and simplifies the process to reduce the risk of mistakes and quality problems further down the line. Flowlease 160-37P16 is a fast flow mesh bonded to low-cost high slip release film, ideal for reducing cost in Marine infusions. Other combinations can be made by Airtech to suit customers’ preferences.

Spiral Tube Resin Flow Lines are a simple, low-cost resin flow option. The Airtech product range has a range of sizes to choose from for low, medium, and high-speed resin flow. Spiral tube can be placed directly on-top of a resin flow mesh and held in place with a hot-glue shot or adhesive tape. Spiral tube can be difficult to remove after cure when filled with solid resin. Spiral tubing can easily be stretched, opening up the spiral and care need to be taken this does not result in crushing by the vacuum bag and choking of the resin flow.

Flowrunner PP2, is a low-cost spiral tube and wrapped in porous non-woven polypropylene fabric. This resin flow line can be held in a vacuum bag pleat off the part surface. This makes removal much easier after cure, due to the self-releasing PP fabric and leaves no imprint on the surface.

Flowlease is a lay-flat resin feed line that sits flat on the laminate, requiring no vacuum bag pleating. Resin flows at high speed through the internal mesh and the lay-flat format has a high contact area for efficient resin transfer into the part. Flowlease can be release if placed on top of a release film or peel ply. Where the internal surface will not be visible, Flowlease can even be left on the part after cure.

Flowlease PP4 features a self-releasing polypropylene outer sleeve so the flow line can be placed directly on a laminate or a flow mesh and will remove easily after curing.

Flowstrip PP4 Max from Airtech Advanced Materials Group is a lay-flat resin feed channel with very high resin flow speed for Resin Infusion processes which releases off cured laminates. The internal high-speed 3D mesh combined with a spiral channel provides high resin flow speed without excessive thickness. The highly porous non-woven polypropylene outer sleeve contains the flow media and provides easy release off the cured laminate. The self-release sleeve and flexible mesh mean the Flowstrip can peel easily to remove after cure.

Benefits are many for new and experienced infusion molders. Flowstrip PP4 Max rolls up into a compact roll that can be easily rolled out into position. It is extremely easy to position and fix in place. The lay-flat form makes vacuum bagging easy, without additional pleating required. Flowstrip PP4 Max has a very high resin flow speed for large infusion setups. The spiral and mesh provide an open flow path for resin transport. The lay-flat construction also provides a high contact area for efficient resin transfer into parts. The outer self-releasing polypropylene sleeve can be removed from cured laminates without leaving resin flash or imprint on the laminate, which is common with large diameter spiral only feeds and omega type flow channels.

Flowstrip PP4 Max reduces setup times, improved resin flow during infusion, and reduces debagging times. With improvements in part quality in addition.

As a specialist in vacuum bagging and composite tooling, Airtech has continued to make progress in the development of new materials for all aspects of the process, including – Fabric and Core positioning adhesives, Peel Ply fabrics, Release Films, Resin Flow Media, Vacuum Bag Films, Sealant Tapes, Resin Flow Channels. Significantly, Airtech has also developed Custom Engineering capabilities to provide Pre-shaped materials, Combination materials, and Kitted materials to provide substantial reductions in labor for the composite fabricator.

Airtech Advanced Materials Group


Airtech Advanced Materials Group is the largest manufacturer of vacuum bagging and composite tooling materials for prepreg/autoclave, resin infusion, and wet lay-up processes up to 799°F (426°C). Our product line consists of: vacuum bagging films, release films, pressure-sensitive tapes, mold releases (non-liquid), peel plies, breathers & bleeders, sealant tapes, vacuum bag connectors & hoses, rubber, pressure pads, cutting tools, vacuum leak detectors, shrink tape, PTFE coated fiberglass, tooling prepregs and resins, and carbon and glass reinforcements.

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