Tech Focus: Sandwich
Flow Mat –Importance & Benefits
The next level of development for a hand lay-up unit is to migrate to a mechanized molding format. The most popular such method is the closed molding process, with proven options like L-RTM. To enable this migration of technology, molders have to make changes at various stages of product development. This requires several changes in design of the component, lay-up sequence, raw materials and the finishing process.
Here we will focus on a different kind of glass reinforcement designed exclusively for the closed mold process. We are looking at a revolutionary product which imparts great design flexibility if you are using L-RTM or Resin Infusion process and Vacuum bagging etc., to manufacture your components. Let us look more closely at its importance and benefits.
Efficient resin flow:
One of the trickiest stages of the closed mold process is to design the resin flow and ensure it works. When the reinforcement is laid in place, the resin flow is obstructed by closely-held glass fibers made up of stitched mat or fabric. The flowing resin tends to carry with it glass strands creating ‘wet’ (resin rich) or ‘dry’ (resin deficient) spots. This creates a completely different product which will fail when unmolded, because of the improper strength distribution. It could also be damaged beyond repair. When you use a Sandwich Flow Mat, this hassle can be avoided.
Fast wet-out:
Economies of scale call for a fast process. So the resin has to spread through the component and
enable fast wet-out-to-cure time. Flow mat has a sandwich construction with three layers. The central core layer made of polymeric non-woven fibers works as the resin flow conduit. The glass reinforcement sits on either side of this to impart strength. Various GSMs of glass and central core are available to enable design flexibility and decide the glass loading required. The correct design allows producing components with higher glass content and optimized strength distribution within the component.
Sandwich Mat
Simplified tooling:
Due to easy resin flow along the length and breadth of the component, mold design using the Sandwich Flow Mat becomes very simple. This helps reduce the numbers of ‘in’ & ‘out’ ports for resin on the mold. The result is an overall less complicated set-up requiring reduced maintenance effort.
Optimized design:
The component lay-up sequence can be very easy and the flow mat works well with other forms of reinforcements like surface tissue, woven or non-woven fabrics or metal inserts in the component. Fabrics can sit over the flow mat and use the central core to supply resin along the component. With less demanding components, the flow mat alone satisfies the glass requirements. This completely does away with the need for other forms of reinforcements.
Improved surface finish:
Good resin flow and wet-out imparts a uniform surface finish along the entire component. The finer textures, contours and bodies on the component are molded with ease and accuracy giving the ‘perfect’ finish desired. This gives a dramatic reduction in finishing process time!
To summarize, these are the advantages of using the Sandwich Flow Mat:
• Optimised resin flow in thick parts. Suitable for polyester & epoxy resins.
• Time saving due to improved resin flow & fast wet-out
• High component quality due to controlled glass content
• Excellent & consistent surface finish
• Available in various options of GSM & core thickness
Link Composites is practically the sole distributor of this product in India, and stocks the entire range. Please contact us for a product demo or enquiry.
Last Word
Warm wishes on India’s 65th Republic Day!
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