Differences Between Chopped Strand Mat And Woven Roving

Here are differences between fiberglass Chopped Strand Mat (CSM) and Woven Roving (WR).

                             Chopped Strand Mat (CSM)                     Woven Roving (WR)

Firstly, Chopped Strand Mat (CSM) is a random fiber reinforcement, composed of chopped fiberglass of various lengths, randomly dispersed to provide equal distribution in all directions. Chopped Strand is designed for use with polyester and vinyl ester resin systems. Because it uses a styrene monomer soluble binder, to hold strands in place, it’s not compatible with epoxy resin systems. Chopped strand mat (CSM) is commonly used in laminates to minimize weave print through, due to ease of wet out, the good bond provided between layers of woven roving or cloth, and is comparatively low in cost. 

Regarding Woven Roving (WR), it is continuous strands of glass fiber, grouped together to form a twisted yarn. The roving is then woven into a coarse, square, lattice-type open weave to form the material. Woven roving provides great tensile, flexural, & impact strengths, at moderate cost. It’s more difficult to wet out than chopped strand mat or cloth however, and because of the coarse weave, it is not used where surface appearance is important. A layer of chopped strand mat is used between each layer of roving, to fill the coarse weave, when more than one layer is required. Compatible with most resin systems.

Woven Roving (WR) is a more like a cloth. Long glass strand have been woven uniformly to form the cloth. Different weaves will create different cloths for different purposes of use. Depending upon what directions load is wanting to be applied along the cloth. You can have very thin sheathing cloth through to heavy cloths. Cloth that is bi-directional and even tri-directional.