SINT Technology

Specialist in Residual Stress Measurements &
Production of Measuring Systems

Residual Stress

SINT Technology is a specialized residual stress laboratory and a residual stress analyis centre.
The constant analysis and monitoring of residual stresses, allows to preserve mechanical components and materials from possible fractures or malfunctions in time.

Residual stresses, indeed, limit the loading capacity and safety of those components during operation and in some cases it is neccesary to be able to quantify those stresses. Actually, residual stresses, can be casual or desiredand could involve also polymeric materials and composite materials

Turbine blades and other metal components are often built with internal residual stresses to limit cracking and fatigue. In those cases, it is necessary to perform strong controls and careful calibrations to determine the desired level of stress during the production
process.

In the case of polymeric materials, residual stresses concern in particular the surface: their presence can cause a failure of the material and its permanent deformation.

How residual stresses are caused?

Residual stresses can be caused by many factors. One of the main cause of residual stresses is welding, ma also heat treatments:

Non-uniform heating or cooling of a component during manufacturing or during
casting, welding, molding processes.
Machining processes to remove shavings or plastic deformation (turning,
milling and forging)
Surface heat treatments (tempering, nitriding and cementation)
Surface treatments (shot peening and sand-blasting)

All materials involved by internal residual stresses are particularly at risk of cracks, environmental degradation or other form of damages. In general, residual stresses may cause failure of manufactured products and reduce they performances.

The Hole Drilling Method

SINT Technology developed a specific system for measuring residual stress by the hole drilling method, RESTAN – MTS3000. It is internationally marketed by HBM.
The hole-drilling method allows accurate experimental stress analyses at moderate costs. It consists in drilling a small hole (typically 1.8 – 2.0 mm) which changes the initial deformation allowing redistribution of the residual stresses locked in a material.

MTS3000 – Restan

Automatic system for the measurement of residual stresses by the hole-drilling method of, according to ASTM E837-13.
The system consists of an opto-mechanical drilling, an electronic control unit, a management software to control the test and one for data processing.

MTS-3000 Ring Core

SINT Technology developed also the RESTAN-RINGCORE system.
It use the ring core method to determine residual stresses up to a depth of 5 mm.

Similar to the Hole Drilling Method, the Ring Core method consists in drilling a core around a special 3-element strain rosette. It is applied on forgings or castings of rotating machinery components (compressors, turbines etc).

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