At a glance
- GF15 and GF30 are different formulation classes, not simple quality grades.
- Higher glass content generally increases stiffness but can also increase anisotropy and surface/processing challenges.
- Mold design, gate location and fiber orientation strongly influence actual part performance.
- Complete grade data should be compared at the same conditioning and test conditions.
What to verify when reviewing PA6 GF30 vs GF15
- 01GF15 and GF30 are different formulation classes
not simple quality grades
- 02Higher glass content generally increases stiffness but can also increase
anisotropy and surface/processing challenges
- 03Mold design, gate location and fiber orientation strongly influence
actual part performance
- 04Complete grade data should be compared at the same conditioning and test
conditions
What GF15 and GF30 mean
GF15 and GF30 commonly indicate approximately 15% and 30% glass-fiber reinforcement by weight in the compound, subject to the supplier's actual grade specification. The glass fibers reinforce the PA6 matrix and substantially change the behavior of the material compared with unfilled resin.
The percentage alone does not fully define the compound. Fiber type, coupling, stabilizers, impact modifiers, color and other additives can create meaningful differences between two grades with the same nominal glass content.
Typical tradeoffs as glass content increases
A higher glass-fiber level generally raises stiffness and can improve load-bearing capability, while also changing molding shrinkage and dimensional behavior. At the same time, higher reinforcement can make surface appearance, flow, weld-line behavior and tool wear more important considerations.
- Higher stiffness and structural rigidity
- Different tensile and flexural behavior
- Lower polymer-dominated shrinkage but stronger directional effects
- Greater sensitivity to fiber orientation
- Potentially rougher or more fiber-visible surface
- Different flow and pressure requirements during molding
What matters in a GF15 / GF30 comparison
- Current compound
- Part geometry and gate design
- Strength / stiffness target
- Surface and dimensional requirement
- Molding machine and process window
Why part geometry matters
Glass fibers tend to orient with melt flow. This means the same compound can show different properties in different directions, especially in thin or highly oriented flow regions. Gate location, wall thickness, weld lines and cooling therefore become part of material selection.
For precision components, dimensional validation on the actual mold is more useful than comparing only isotropic textbook values.
How to choose between GF15 and GF30
Choose the lowest reinforcement level that reliably meets the mechanical, thermal, dimensional and cost targets of the part. GF30 may be appropriate when structural stiffness is limiting, while GF15 may be preferred where a lower reinforcement level provides sufficient performance with easier flow or surface requirements.
Final selection should use the specific supplier TDS, conditioned-property data and molding trials for the actual geometry.
Applied support
STRANTOP reinforced-grade support
STRANTOP can coordinate with affiliated engineering-plastics resources to compare reinforced PA6 candidates against an incumbent grade or part requirement. We focus the discussion on the customer's actual performance limits, not only the nominal fiber percentage.
Discuss your material requirement →Questions we hear from buyers and processors
Is PA6 GF30 always stronger than GF15?
GF30 generally provides higher reinforcement, but the actual result depends on the complete formulation, test direction, conditioning and part design.
Does more glass fiber reduce shrinkage?
Glass reinforcement generally changes and often reduces bulk molding shrinkage, but it can also increase directional anisotropy.
Can GF15 be replaced with GF30 without mold changes?
Not automatically. Flow, pressure, shrinkage, fiber orientation and dimensions should be validated on the actual tool.
Technical review
This resource is maintained by STRANTOP's technical and commercial team with input from affiliated PA6 polymerization and engineering-plastics resources. It is intended to help customers frame a material discussion; grade-specific specifications, processing conditions, compliance claims and final suitability remain subject to the applicable supplier documentation and customer validation.