Infrared Heating Processes | Duo-Technik– IR, Hot Air, Hybrid

Wavelength tailored to the material ⇒ more efficient energy transfer & shorter times Fast response times / controllability ⇒ stable quality & less overheating Can be combined with hot air ⇒ reliable moisture removal & robust processes.

Infrared heating is a contactless heat transfer process in which radiation is absorbed by the product and directly converted into heat—often faster and more precisely than convective hot air.

The key is matching the wavelength to the absorption characteristics of water, coatings, polymers, glass, or composite materials.

Practical benefits:

• Higher throughput with the same footprint, because heating/drying times can be reduced.
• Energy savings, as heat is generated only when needed and precisely where it is required.

1) Full IR spectrum: NIR, shortwave, midwave to DarkWave

• Duo-Technik can provide NIR systems for high energy density, fast response, and deep penetration
• Duo-Technik can combine short- and medium-wave emitters and tailor them to the application/system (e.g., modular, zone-controllable)
• DUO#DarkWave™ offers a solution whose emission is optimized for the ~3.0 µm range, which is ideal for water absorption, and combines IR radiation and process hot air from a single energy source.

2) Hot-air heating (convection) – efficient & flexible

Hot-air dryers are widely applicable and benefit from flexible heat sources as well as stable moisture removal via air management.

3) Hybrid and combination processes (IR + hot air)

Hybrid dryers combine rapid IR energy input with effective moisture removal via hot air—for particularly stable and energy-efficient processes, e.g., with high ink loads.

• NIR – Near-infrared

  NIR systems deliver the highest energy density in the infrared spectrum. They are particularly well-suited for applications that require a high concentration of energy in a confined space. Due to the radiation’s deep penetration, they are ideal for thick paint or varnish layers, as well as for heating processes in high-speed systems.

• Short-wave infrared radiation

  Short-wave IR radiation penetrates deep into the material and ensures rapid and uniform heating. It is primarily used for solid materials or at high process speeds when a rapid response is required.

• Mid-wave infrared radiation

  Mid-wave radiation is very well absorbed by water, glass, and many plastics. It is particularly efficient in drying processes for water-based paints, varnishes, and coatings, as well as for near-surface heating tasks.

• DarkWave technology

  DUO#DarkWave technology represents a further development of infrared drying. It utilizes a ceramic radiation source with a peak emission in the optimal absorption range of water-based systems. A unique feature is the combination of infrared radiation and process hot air from a single energy source. This achieves maximum energy efficiency and uniform drying.

1. Infrared Dryers (IR)

Duo-Technik infrared dryers are designed for high speeds, compact machine layouts, and zone-specific energy input; they are adapted to absorption and process requirements.

• DUO#ModulDry™ – modular IR cassette system (platform-based, flexibly configurable)
• DUO#FlexoDry® – custom IR drying solution in the Duo-Technik portfolio for printing/web processes.
• DUO#ModulDry™NIR – NIR-based infrared drying with high energy capacity
• DUO#DarkWave™ – modular IR hot-air system, optimized for water-based applications, with energy-saving potential through spectrum/system concept

1. Hot-Air Dryers

   Hot-air dryers are particularly suitable when sufficient installation space is available and energy-efficient convective drying with stable moisture removal is required; Duo-Technik offers optimized solutions for sheet-fed and web processes.

2. IR Hot-Air Hybrid Dryers

   Hybrid dryers combine the advantages of infrared dryers and hot-air dryers, often relevant for high ink loads and limited installation space.

• Step 1: Understand the material & coating system

Whether paint/coating, water content, polymer, glass, or composite: Absorption behaviour determines which wavelength is most effective.

• Step 2: Design wavelength + power + geometry

The shape and radiation field can be designed so that heat is applied locally and, in a manner, suited to the process. Reflector designs can direct radiation more precisely onto the product, thereby reducing losses.

• Step 3: Integrate control & safety

Fast IR response times support controllable processes and help prevent overheating—especially when combined with temperature monitoring and control.

• Step 4: Ensure moisture removal (hot air / hybrid)

  When a large amount of moisture needs to be removed, hot air or hybrid systems stabilize the process by reliably removing evaporated moisture.

Infrared and hot air can be a solution in virtually all industries where drying, heating, curing, or melting is required.  Real-world examples demonstrate the breadth of applications (heating, drying, fixing, curing, de-icing, etc.)

• Printing / Packaging / Coating - IR drying for stabilizing high-speed processes, compact integration into production line layouts.
• Ceramics industry – High-speed through-drying of ceramic components
• Plastics processing – welding, thermoforming, heating PET preforms, film stretching, crystallization/drying of PET/PPS/PLA, etc.
• Printed electronics
• Glass industry and laminated glass – drying of coatings/screen printing, tempering, laminated glass processes, preheating of bottles.
• Automotive – Drying/curing of coatings, activation/processing of plastics & composites, various thermal processes in assembly/production.
• Textile industry – drying/setting/coating, laminating, heat setting, adhesive activation.
• Food industry – Browning/grilling/finishing, hygienic thermal processes (e.g., short-term sterilization/heating in process steps).

• IR as a “booster” in front of existing dryers
  An upstream IR booster quickly brings the product up to temperature, while the existing dryer maintains the temperature—this can save time, space, and energy and alleviate bottlenecks. Especially with solid products, IR can significantly reduce the time required to reach the target temperature compared to hot air
• Why the “right wavelength” directly reduces costs
  The choice of wavelength strongly influences heating: Medium-wave/DarkWave, for example, is well absorbed by water, glass, and plastics, while short-wave penetrates deeper—when selected correctly, this increases efficiency