Industry Glossary - B

Intermediate stage in the reaction of certain thermosetting resins in which the material softens when heated and is plastic and fusible buy may not entirely dissolve or fuse. Also called “resistol” or “resitol.” The resin in an uncured prepreg or premix is usually in this stage.

Process in which the consolidation of the material in the mold is affected by the application of fluid or gas pressure through a flexible membrane.

Applying an impermeable layer of film over an uncured part and sealing the edges so that a vacuum can be drawn.

Equal parts of warp and fill in fiber fabric. Construction in which reactions to tension and compression loads result in extension or compression deformations only, and in which flexural loads produce pure bending of equal magnitude in axial and lateral directions.

Composite laminate in which all laminate at angles of 0� and 90� occur only in + or – pairs (not necessarily adjacent) and are symmetrical around the centerline.

In filament winding, the width of the reinforcement as it is applied to the mandrel.

This is a property of material which describes its ability to be indented. The Rockwell method for measuring hardness forces a steel point into the material and then measures the penetration of the point. The different letters in the Rockwell reading describe the shape of the point and the load applied during the test. Units – Rockwell units with the appropriate suffix letter. The letter and number cannot be separated. Higher numbers with the same letter indicate harder materials. Harder materials have more resistance to penetration by another substance.

The glass as it flows from the bushing in fiber form, before a binder or sizing is applied.

Large temperature-controlled oven, used to heat-clean rolls of glass fiber fabric.

Felted fabrics. Structures built by the interlocking action of compressing fibers, without spinning, weaving, or knitting.

A spool, on which is wound a number of parallel ends of singles or plied yarns, for use in weaving or similar processing operations.

Operation in which many ends of yarn from a creel are combined on a section beam.

Maximum bearing stress that can be sustained. Also, the bearing stress at that point on the stress-strain curve where the tangent is equal to the bearing stress divided by n% of the bearing hole diameter.

Applied load in pounds divided by the bearing area. Maximum bearing stress is the maximum load in pounds sustained by the specimen during the test, divided by the original bearing area.

The result of the chopping operation. A mat of chopped glass fibers that is deposited onto a layer of resin mix on a carrier film under the chopper.

Reinforcing fibers that are arranged in two directions, usually at right angles.

A reinforced plastic laminate with the fibers oriented in two directions in its plane. A cross laminate.

Warp and fill fibers at an angle to the length of the fabric.

Loading condition in which a laminate is stressed in two different directions in its plane. A loading condition of a pressure vessel under internal pressure and with unrestrained ends.

In filament winding, a type of winding in which the helical band is laid in sequence, side by side, with crossover of the fibers eliminated.

A coating applied to the surface of a chopped glass mat or preform which is then cured. The binder holds the previously sized glass bundles or ends together in the roving operation into a stable shape or form.

A large collection of continuous glass bundles which is tangled up and will not run through the guide eye into roving creel. In the field, a large tangled collection of roving which does not run through the tube or guide eyes to the chopper.

Type of polyamide that cures by an addition rather than a condensation reaction, thus avoiding problems with volatiles formation, and which is produced by a vinyl-type polymerization of a pre-polymer terminated with two maleimide groups. Intermediate in temperature capability between epoxy and polyamide.

Glass bundles or chopper fuzz which build up and pack between the blades of a chopper. This blade packing can cause poor choppability. If it falls off, it usually does not wet-through, and this can cause blisters or porosity.

Fiber or fabric plies that have been laid up in a complete assembly and placed on or in the mold all at one time (flexible bag process). Also, the form of bag in which the edges are sealed against the mold.

Woven or non-woven layer of material used in the manufacture of composite parts to allow the escape of excess gas and resin during cure. The bleeder cloth is removed after the curing process and is not part of the final composite.

Flaw either between layers of laminate or between the gel coat film and laminate.

The spool or shipping package on to which textile yarns are wound.

Amount of adhesion between bonded surfaces. The stress required to separate a layer of material from the base to which it is bonded, as measured by load/bond area.

Fiber produced by vapor deposition of elemental boron, usually onto a tungsten filament core, to impart strength and stiffness.

A narrow tubular or flat fabric produced by intertwining a single set of yarns according to a definite pattern.

Opening and closing of a mold to allow gas to escape early in the molding cycle. Also called “degassing”; sometimes called “bumping” in Phenolic molding.

Condition in which fibers do not move into or conform to radii and corner during molding, resulting in voids and dimensional control problems.

or Matchsticks.

In the roving operation, a broken or severed strand (bundle) which causes the forming cake to stop running.

Mode of failure generally characterized by an unstable lateral material deflection due to compressive action on the structural element involved.

Glass bundles or chopper fuzz which collect on the chopper, cot, static bars or machine frame.

Thermosetting resin mixed with short strand reinforcement, filler, and so on, into a viscous compound for compression or injection molding.

A discrete collection of many parallel glass filaments. A collection of individual filaments, a sub-strand.

Plate with holes through which molten glass is pulled to produce glass fibers.

Small tapered protrusions on the bottom of bushings each containing an orifice through which molted glass flows, from which continuous filaments are drawn.