DEMEX Solves One of LFAM Composite Manufacturing’s Biggest Problems

Updated on May 28, 2026 • 5 min read

Large-format additive manufacturing (LFAM) has become increasingly important for composite tooling, structural prototyping and large thermoplastic parts. However, one major limitation has restricted broader structural adoption: weak interlayer bonding.

LEAM Technologies, a Munich-based startup spun out from the Technical University of Munich (TUM), believes it has found a scalable solution.

Its technology, called DEMEX (Directed Energy Material Extrusion), uses localized LED-assisted heating to dramatically improve bonding strength between printed thermoplastic composite layers.

Why LFAM Has a Structural Weakness

Extrusion-based additive manufacturing builds parts bead by bead and layer by layer.

The challenge is that:

• layers must cool quickly to maintain shape
• but polymer diffusion requires heat and time
• rapid cooling limits molecular entanglement between layers

This creates strong mechanical properties in the X-Y plane but weak Z-axis performance across layer interfaces.

The problem becomes even more severe in:

• semi-crystalline thermoplastics
• carbon fiber-reinforced polymers
• high-temperature aerospace materials like PAEK and PEI

For structural applications, this anisotropy can become unacceptable.

Traditional Solutions Were Expensive

Until recently, manufacturers relied mainly on specialized AM-grade thermoplastics designed to slow crystallization and extend the bonding window.

However:

• AM materials can cost €8/kg
• standard injection molding grades may cost only €0.50/kg
• print speed remains constrained by cooling cycles

Large aerospace molds or marine structures suffer the most because long toolpaths create excessive cooling time before the nozzle returns.

How DEMEX Works

DEMEX is an add-on module mounted near the LFAM print nozzle.

The system uses:

• focused high-power LEDs
• localized interface heating
• infrared thermal cameras
• adaptive cooling
• real-time thermal monitoring

The LEDs create a localized melt pool approximately:

• 20 mm in diameter
• 0.5 mm deep

This allows the incoming thermoplastic bead to fuse with a molten interface instead of bonding onto a cold semi-crystalline surface.

According to LEAM Technologies, the process behaves more like polymer welding than adhesive bonding.

Why LEDs Matter

LEAM selected LEDs instead of lasers or infrared lamps because LEDs provide:

• rapid power modulation
• lower system cost
• easier industrial integration
• reduced safety requirements
• better thermal responsiveness

Unlike laser systems, DEMEX can integrate into existing LFAM environments without expensive laser safety cells.

Real-Time Thermal Intelligence

One of DEMEX’s most important capabilities is thermal process monitoring.

Infrared cameras simultaneously monitor:

• melt pool temperature
• substrate temperature

This dual-zone monitoring enables:

• independent thermal control
• adaptive feed-rate adjustment
• localized cooling
• thermal stability management

Every print generates a spatial thermal data map linked to the tool center point coordinates.

This creates traceable manufacturing data that could become important for aerospace process qualification.

Demonstrated Mechanical Improvements

PA6 Carbon Fiber Composite Results

At the Institute of Lightweight Engineering in Munich, researchers tested:

• PA6 with 40% carbon fiber

Results included:

• ~30% improvement in interlayer tensile strength
• elongation at break increased 42.5%
• improved stiffness consistency
• reduced variability between samples

The most important shift was failure mode behavior.

Instead of brittle layer separation, heated samples exhibited cohesive failure where adjacent layers fractured together.

Aerospace-Grade PAEK Results

At the Netherlands Aerospace Centre (NLR), researchers tested:

• aerospace-grade PAEK thermoplastics

Without DEMEX:

• hollow structures delaminated during printing

With DEMEX:

• interlayer tensile strength reached ~92 MPa
• in-plane strength measured ~96 MPa
• near-isotropic performance was achieved

This represents one of the most important breakthroughs for structural thermoplastic LFAM.

Productivity Improvements

LEAM reports that DEMEX also improves manufacturing speed.

Compared with conventional constant layer-time strategies:

• adaptive feed-rate control reduced print times by ~10%
• combining heating, cooling and adaptive control reduced print time by ~50%

These gains were demonstrated on:

• PETG
• polycarbonate
• reinforced thermoplastics

without measurable degradation in mechanical properties.

Maritime and Energy Applications Already Emerging

The maritime sector is becoming one of the first commercial adopters.

Dutch company IMPACD Boats is already using DEMEX technology to manufacture:

• large maritime structures
• recyclable polypropylene boat components
• professional-use watercraft

The broader Dutch LFAM ecosystem includes:

• CEAD
• Dutch Boat Factory
• maritime additive manufacturing developers

Future Potential for Aerospace Structures

DEMEX may eventually enable:

• overprinted stiffeners
• integrated ribs
• composite reinforcement features
• hybrid thermoplastic structures
• structural aerospace tooling
• continuous fiber co-processing

The Manufacturing Technology Centre (MTC) in the UK plans to integrate DEMEX into its LFAM systems in 2026.

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This article is developed based on real engineering experience, machine testing data, and practical production knowledge from Jota Machinery’s work in advanced composite manufacturing.

All technical explanations—including material structure, processing methods, and performance characteristics—are reviewed and verified by our engineering team to ensure accuracy and real-world relevance.

To improve clarity and structure, AI-assisted tools may have been used during content organization and language refinement. However:

• All key technical insights originate from first-hand industrial experience
• All data and claims are manually reviewed and validated
• The content is created with the primary goal of educating engineers, manufacturers, and buyers

We do not publish content solely for search ranking purposes. Every article is designed to provide practical, experience-based value to professionals in the composite materials industry.

Editorial Perspective

DEMEX addresses one of additive manufacturing’s oldest contradictions:

the same rapid cooling required for geometric stability directly weakens structural bonding.

By actively controlling the thermal environment at the exact deposition interface, LEAM Technologies is shifting LFAM from simple shape creation toward genuine structural manufacturing.

The implications are significant for:

• aerospace tooling
• maritime structures
• energy infrastructure
• thermoplastic composite production
• large-format industrial manufacturing

If DEMEX continues proving near-isotropic thermoplastic performance at industrial scale, it could help LFAM compete directly with more traditional composite manufacturing methods in structural applications.