Warp Knitted Fiberglass Fabric: What the Machine Side Decides
A warp knitted fiberglass fabric is not woven and it is not bonded together after the fact. The glass yarns are fed in parallel to the fabric edge and held by a separate fine yarn that is formed into loops around them, so the reinforcement itself stays straight and the loop structure does the holding. That single mechanical fact is why the fabric spec on a supplier roll is really a description of a machine setup, and why two fabrics with the same glass content can come off completely different lines.
Search this term and you get two kinds of pages: fabric catalogues that list roll specs, and research papers that measure what the fabric does under load. If you are buying the line rather than the roll, neither answers the question you actually have — how many yarn systems the machine has to lay in, what gauge it runs, and which fabric family your drawing belongs to.
How the loop holds a fiberglass layup together
Warp knitting feeds yarn parallel to the fabric edge and forms it into loops, which is the opposite of weaving, where every yarn has to bend around another one. In a fiberglass non-crimp fabric the glass never has to make that bend. Work on the in-plane shear behaviour of glass fiber non-crimp fabrics describes the construction plainly: several layers of parallel yarn sheets are fixed by a binding yarn formed into loops, and the loop formation itself is what gives the fabric its basic structural stability.
That is also why a review of 3D warp knitted structures calls warp knitting the most flexible and versatile route to producing non-crimp fabrics. The stitching yarn is a light polymer thread doing a mechanical job; changing it, or changing how tightly it is set, changes how the fabric drapes and how well it survives handling before it ever sees resin. Nothing about the glass changes.
The practical consequence for anyone specifying a machine: the fabric argument and the machine configuration argument are the same argument. You cannot buy a layup the machine cannot lay in.
Three fabric families, three machine answers
Most of what gets sold under this term falls into one of three groups, and each one asks something different of the equipment.
| Fabric family | What the roll looks like | What the machine has to do |
|---|---|---|
| Multi-axial (non-crimp) | Layers laid at the industry angles of 0°, 90°, +45° and -45°, sold as biaxial, triaxial or multiaxial grades depending on how many of those directions are present | Lay in each direction as its own yarn sheet, then stitch the stack together |
| Stitch bonded | Yarn sheets or a web held by a stitching yarn, the classic Malimo and Maliwatt style constructions | Run the stitching system at a gauge fine enough to hold the substrate being bonded |
| Unidirectional with mat | One glass direction combined with chopped strand mat, supplied as a single fabric | Handle a second, non-yarn feed alongside the unidirectional sheet |
Those three sit on related but not interchangeable equipment. Our multi-axial warp knitting machine page covers the first group, the Malimo and Maliwatt stitch bonding pages cover the second, and the glass fiber warp knitting machine page is where the glass-specific builds are listed. Where the fabric feeds straight into a composite process, the composite warp knitting machine page is the closer match.
Guide bars and gauge: settle these two before anything else
Fiberglass stitch bonding machines are published with one to four guide bars, and in gauges quoted as an F number across a range from F7 to F22. Those two numbers do more to fix what you can produce than any other line on the quotation.
The bar count sets how many separate yarn systems the machine can bring in at once. The gauge fixes how closely the stitch rows sit, which is what decides whether a coarse roving stack and a fine mat can both be held properly on the same machine. A gauge that is comfortable for one is usually wrong for the other, so a line asked to cover both ends of your product range needs that trade-off argued out with the builder before the order, not after.
Two things are worth counting yourself before you talk to anyone. Count the yarn systems in your own fabric drawing rather than the layers: a 0/90/+45/-45 stack plus a mat feed is not simply a four-bar job, because the mat is not a bar. Then ask specifically how the +45 and -45 directions are laid and whether they share hardware, because that is where a quoted bar count and a real capability most often part company.
If your fabric is this, the machine question is that
If your drawing calls for two or more glass directions at the standard 0/90/+45/-45 angles, then your question is a multi-axial one and the bar count has to cover every direction you need, with room for the direction you will be asked for next year. If your drawing is one glass direction plus mat, then your question is a feed question rather than a bar question, and the thing to nail down is how the mat comes in and whether the combination is made in one pass. If you are bonding a web or a substrate rather than building a structural layup, then you are in stitch bonding territory and gauge, not bar count, is the number that decides the outcome.
This does not apply if your reinforcement has to be woven for a specification reason, or if the fabric is bought finished from a converter and you have no say in how it is made. In both of those cases the machine argument belongs to someone else and the questions above will not get you anywhere.
What to confirm before you commit to a line
Write down your fabric drawing as a list of yarn systems and feeds, put the required gauge against it, and take that one page to the builder instead of a roll sample. Ask for the bar count and the gauge as separate answers, ask which of your fabrics the quoted gauge was chosen for, and ask what changes if you add a direction later. The specifications for the machines behind these fabrics are listed on our equipment pages above, and the sales side of the same range sits at grandstarcn.com. If you want a configuration checked against a drawing you already have, send it through our contact page and describe the layup rather than the roll.
Frequently Asked Questions
Is warp knitted fiberglass fabric the same thing as non-crimp fabric?
In practice the terms overlap. Non-crimp describes the result: the glass yarns stay straight instead of bending around each other. Warp knitting is the method that gets you there, by laying parallel yarn sheets and fixing them with a stitching yarn formed into loops. A review of 3D warp knitted structures describes warp knitting as the most flexible and versatile way to produce non-crimp fabrics, which is why most non-crimp glass fabric on the market is warp knitted.
What is the difference between stitch bonded and multi-axial fiberglass fabric?
Multi-axial describes what is being held: several glass directions, typically drawn from 0 degrees, 90 degrees, +45 degrees and -45 degrees, sold as biaxial, triaxial or multiaxial depending on how many directions are present. Stitch bonded describes how anything is held, including webs and substrates that are not a structural layup at all. A multi-axial fabric is stitch bonded, but plenty of stitch bonded fabric is not multi-axial.
How many guide bars do I need for a 0/90/+45/-45 fiberglass fabric?
Count the yarn systems in your drawing rather than the layers, then take that count to the builder. Fiberglass stitch bonding machines are published with one to four guide bars, so a four-direction layup sits at the top of that published range. Anything fed in that is not yarn, chopped strand mat being the common case, is a separate feed and is not covered by the bar count.
Can you get unidirectional fiberglass fabric with mat in one fabric?
Yes, unidirectional glass fabric combined with chopped strand mat is sold as a single warp knitted fabric. What varies between suppliers is how the mat is brought in and whether the combination is produced in one pass, so ask that question directly rather than assuming it from the product name.
What gauge do fiberglass stitch bonding machines run?
Published gauges for fiberglass stitch bonding machines are quoted as F numbers and run across a range from F7 to F22. Which one suits you depends on how closely the stitch rows need to sit to hold your substrate, so a machine specified for coarse roving stacks and one specified for fine mat will not land on the same figure.
Hey, I’m Vincent!
Solving complex challenges with precision and creativity in the warp knitting industry. Passionate about advancing textile engineering and turning innovative ideas into reality. Shaping the future of warp knitting.
