Mon, 27.05.2013

Test for Stone Impact Resistance in Thermamax Test Laboratories

Durability of Tmax-Integral Insulations

Physical durability, normally referred to as Stone Impact Resistance, of insulation systems installed in vehicle underfloor locations, particularly involving exhaust piping, DPF and SCR modules, is of critical importance. Tmax-Integral Insulations developed for this application are subject to a Stone Impact Test in the company’s own test laboratories.

Complex high-temperature insulation systems for turbochargers, exhaust systems and exhaust aftertreatment systems play an important role today in helping to increase efficiency and  compliance with statutory requirements. Requirements of the OEM naturally centre on the thermal and/or acoustic efficiency and the durability of the system in vehicle applications is always a key criterion. Peter Cappellucci, Technical Director at Thermamax: „When you consider the thin wall thicknesses of the metallic sheet used in lightweight construction insulations, achieving a high mechanical durability is no easy task !“ 

In order to increase the mechanical durability of this type of insulation system Thermamax has developed designs such „embossed sheet“ and their so-called „bionic“ product Tmax-SKELTEC. In order to tailor these insulation systems to customer requirements, the various products and components are subjected to extensive testing – including for example the Stone Impact Test.            

Tmax-Integral Insulations are systems that are fitted directly to components handling hot gases. Designing for a particular application can significantly reduce surface temperature of the hot components, and simultaneously increase exhaust temperatures in the exhaust system. Fitting a Tmax-Integral Insulation with stainless steel outer shells – usually with a wall thickness of just 0.1 to 0.25mm – creates a secure basis for the insulation system. These low thicknesses also reduce the additional weight to a minimum. By using the latest embossing and shaping tools the outer shells of the Tmax-Integral Insulation can be perfectly formed to suit the contours of the component to be insulated, even when dealing with complex geometries. 

The Stone Impact Test, or Multi-Impact Test as it’s also known, provides information on the  behaviour of different coatings to damage levels caused by low-mass, high-velocity particles in road and rail vehicle applications. In the test a measured quantity of particles with a precise shape, material and surface finish are impinged onto the probe with a specified energy level and a defined angle of impact (54°). The effect of the impact loads can be judged by a visual examination, (sample comparison), or by a subsequent corrosion test. Tests are in accordance with DIN 55996-1 – „Testing for Stone Impact Resistance of Coatings – Part 1 – Multi-Impact Testing“.

Peter Cappellucci again: „As a systems provider we have just one target: in practical applications our products have to last longer than those of our competitors. With our Test Laboratories we’ve established the conditions for that – and that includes Stone Impact Testing“.