Heat flow thermography as a non-destructive testing method

What is heat flow thermography?

Heat flow thermography is a non-destructive testing method that can be used to detect defects in components beneath the surface that are not externally visible. The basis of the procedure is the analysis of the heat flow or the thermal conductivity in the components. The heat flow thermography is based on imaging. The advantages are the high inspection and the relatively easy automation capacity.

How does heat flow thermography work?

For the examination the test object has to be warm or heated up. The heating can be either impulse-like or periodic, or the intrinsic heat can be used if a component comes exits the production process already heated. In the subsequent cooling phase, the temperature distribution on the surface of the component is observed with an infrared camera. If there are defects in the material (bubbles, blowholes, cracks, delamination, etc.), the heat flow is disturbed, which becomes visible on the surface in form of temperature differences. The temperature differences can be detected and evaluated by means of the thermographic camera.

What are the methods of heat flow thermography?

Method of heat flow thermography:

Passive Online-

In passive online thermography, the material heated in the production process is moved uniformly on a conveyor belt under a thermography line scan or area scan camera.

Passive Thermography

In passive thermography, the intrinsic heat of an object is used for thermographic examination, for example when a component comes out of the production process already heated.

Active online-

In active thermography, the object is heated before it can be examined thermographically, e.g. by passing it under a heat emitter on a conveyor system.

Pulse thermography

In pulse thermography, the material remains stationary and the surface of the object is briefly (a few milli- to microseconds) heated very homogeneously by a few degrees using fast-acting radiators or flash lamps.

Fields of application of heat flow thermography

Fields of application of heat flow thermography

  • Detection of externally invisible material defects in workpieces (adhesion and adhesive defects, delamination, bubbles, blowholes, cracks or corrosion)
  • Checking for leaks
  • Inspection of weld seams, welding spots and joints
  • Maintenance e.g. of rotor blades of wind power plants
  • Determination of layer thicknesses in composite materials
  • Detection of foreign bodies, e.g. in food



Suitable materials and components

  • Wood
  • Metal
  • Lightweight construction and composite materials (GRP, CFRP)
  • Plastics
  • Food
  • Paint
  • Packaging
  • Leather
  • Blister packaging
  • Rotor blades
  • Electronics
  • and much more

Heat flow thermography in the webshop

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