THE WORLD'S FIRST

NETFIL's Glimmer Inertia FEP Film introduces a macro-textured surface that gets imprinted onto every layer of a 3D-printed composite. This simple but powerful change drastically improves the mechanical performance of resin-printed parts, making them significantly damage tolerant. To understand why, let’s break it down step by step.

In traditional resin 3D printing, layers adhere mostly through chemical bonding. However, the shear strength between layers is relatively weak, leading to poor stress transfer across them. This is why many resin-printed parts fracture when quickly loaded. This high strain-rate related fracture failure is due to pores or defects present in the resin. It is also due to the inability of chemical bonds to resolve high strain-rate related stresses and strains effectively in the composite due to their very small length scales.

With Glimmer Inertia FEP Film, a macro textured pattern gets imprinted onto each cured layer, creating a physical interlock between layers, similar to how bricks macro-mechanically interlock in a wall. This interlocking increases the shear modulus (G) of the printed component, meaning that when a force is applied, the layers resist sliding against each other much more effectively under higher loading rates or strain rates.

• A higher shear modulus (G) means the part behaves more like a continuous solid, rather than a stack of weakly bonded layers ,and prevents the plane strain loading condition related fracture mechanics from immediately showing up during rampant loading.

• This also greatly enhances bending stiffness, because bending stiffness relies on layers resisting shear forces efficiently.

Bending stiffness (EI) is what determines how resistant a part is to bending forces. It is given by:

EI=E×I

Where:

• E is the elastic modulus (stiffness of the material itself).
• I is the moment of inertia, which describes how the material is distributed relative to the bending axis.

If we can increase I, we dramatically increase the part's resistance to bending and improve its damage tolerance over a number of  loading cycles when the material strain rate can be very high.

The moment of inertia (I) is a mathematical quantity that represents how far the material is from the neutral bending axis. The formula is:

I=∫r2 dAI = \int r^2 \, dAI=∫r2dA 

Where:

• r is the distance from the neutral bending axis.
• dA is a small area of the cross-section.

• Material located farther away from the neutral axis contributes much more to I , because it’s squared in the equation.
• A macro textured surface on the outermost layers pushes material farther away from the neutral axis of bending.
• This massively increases I, which increases EI, making the part much stiffer and damage tolerant, with the ability to resolve stresses and strains better under fast loading conditions or scenarios.
• It is well known that the mechanical strength of a part depends on the amount of porosity within the part or structure, and it should also be understood that the measured peak strength value of a part or component may be very high or low depending on the applied stress or strain rate employed in a quasi-static test. In this particular context, our macro textured sheet/ pattern vastly improves the high strain-rate fracture tolerance of a 3D- printed component.
• For eliminating porosity, we offer our proprietary degassing solution we call as NETFIL INDUSTRIAL PROCESSING for all 3D -printed composite resins including chairside resin composites.

When a part bends, some areas experience compression, and others experience tension. The line in between—where there is no stretching or compression—is called the neutral bending axis.

Key insight:

• The farther material is from this axis, the more it contributes to the bending stiffness.
• Glimmer's macrotexture places ridges farther from the neutral axis, increasing the second moment of inertia (I) drastically.

• If you double the distance of some material from the neutral axis, its contribution to I increases four times (because of the r2 factor).
• By imprinting macro textures , Glimmer effectively multiplies the bending stiffness and damage tolerance of the 3D-printed composite.

• Low shear strength between layers → weak bending stiffness.
• Breaks along layer lines due to poor stress transfer at high strain rates.
• Limited mechanical performance for engineering applications.

✅ Macro texturing locks layers together, dramatically improving shear modulus (G) at high strain -rates of loading.
✅ Enhanced moment of inertia (I) makes parts much stiffer and resistant to bending.
✅ Better stress distribution means stronger and more durable and damage tolerant parts.
✅ Does not change resin chemistry, making it easy to adopt in fields such as medicine and dentistry where biocompatiblity matters.

The Glimmer Inertia FEP Film is a game-changer because it leverages simple physics and mechanics to overcome fundamental weaknesses in resin printing. Instead of trying to improve resin chemistry, it improves how layers interact mechanically, unlocking far greater structural performance than conventional prints.

With higher bending stiffness, better durability, damage tolerance during high rates of loading and improved structural integrity, resin-printed parts can now be used in more demanding applications, from engineering and aerospace to high-performance dental and biomedical components.

This is not just a small improvement—it’s a revolution in how 3D-printed composites behave.

Mechanical Testing of our GLIMMER Macrotextured FEP

Mechanical testing of our Macrotextured FEP demonstrated an increase in secant modulus during bending evaluation, indicating improved effective bending stiffness of the laminated structure.

This increase should not be confused with flexural modulus increase. Flexural modulus is an intensive property, meaning it represents the inherent stiffness of the material itself, and is independent of geometry or specimen size.

Bending stiffness (EI), on the other hand, is an extensive structural property. While it is influenced by the material’s elastic modulus (E), it also depends on the second moment of area (I), which is governed by geometry and structural configuration.

The macrotextured architecture of our FEP film enhances macro mechanical keying between the layers , thereby increasing effective bending stiffness (EI). The observed improvement in secant modulus therefore reflects enhanced structural performance rather than a change in intrinsic material stiffness.