Processing Guides

A material is only as good as the process it enters. These guides cover how our fabrics and prepregs behave in the main molding routes, and the mistakes that most often cost a trial program its result.

Choosing a Processing Route

Process	Suitable materials	Typical use	Watch out for
Hand lay-up	Fabrics with loose weave; prepregs with long out-time	Prototypes, low volume, large parts	Resin-rich areas and voids if wet-out is rushed
Vacuum bagging	Prepregs; fabrics with compatible resin	Medium volume, good quality-to-cost ratio	Vacuum leaks, resin flow paths, insufficient drainage
Autoclave	Thermoset prepregs (epoxy, BMI)	Structural parts, aerospace-grade quality	Pressure cycling and porosity control
Press / thermoforming	Thermoplastic prepregs and laminates	Short cycle, high volume, flat panels	Heating uniformity — cold spots cause incomplete consolidation
Automated tape placement / winding	UD tows, UD prepreg tapes	Large structures, pipe, closed sections	Tension control and compaction

Consolidation Is Where Quality Is Won or Lost

For thermoplastic processing in particular, consolidation is the decisive step: the material is heated to melt the matrix, pressure is applied, and the layers must fuse into a single solid. Most defects in finished parts trace back to insufficient or uneven consolidation during this stage rather than to the material itself.

• Bring the whole stack to temperature uniformly — a partially cold laminate will not consolidate, and the bond lines remain weak
• Apply pressure after the matrix has begun to flow, not before — pressing a cold laminate simply locks in the geometry and traps the gaps
• Hold pressure through cooling to full solidification; early release creates residual voids

Common Failure Modes

Problem	Likely cause	What to change
Voids / porosity	Incomplete impregnation, air trapped in lay-up, moisture	Improve wet-out sequencing; dry materials; use vacuum or pressure
Dry spots / resin-rich areas	Insufficient resin flow or poor compaction	Increase pressure and hold time; check resin content matches design
Delamination between plies	Contamination, insufficient tack or incomplete consolidation	Keep surfaces clean; check out-time; verify consolidation temperature
Fiber waviness	Tow tension too high during lay-up or winding	Reduce tension; use tension control on winding equipment
Twist and drape difficulty	Tow grade too heavy for the geometry	Move to a lower filament count for better drape

Storage Before You Process

Thermoset prepregs are stored frozen or refrigerated to hold shelf life, and every roll carries an out-time budget. Thermoplastic prepregs need no cold storage but do need to stay dry and clean. Both topics are covered in detail in our article on material selection and in the storage guidance on our technical blog.

Need a Process Recommendation?

Tell us the part geometry, target cycle time, available equipment and annual volume on the contact page. We will tell you which material and which process fit — including when the honest answer is that a simpler process will give you a better part.