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The RailTec System was developed for the rail industry and is based on FTI's Split Sleeve Cold Expansion System. The flexibility of the system enables it to be easily applied to all main line or branch line track as part of routine maintenance. Rail with small fatigue cracks can be reworked and safely returned to service. Additionally, the system can be used during the manufacture of rails, frogs, and switches.
The cold expansion process increases the life of a bolt hole by producing a zone of residual compressive stresses around the hole. This is achieved by taking a solid mandrel that is a little larger than the hole and then pull this mandrel through the hole using a hydraulic puller. When the larger mandrel slips through the hole a process called “plastic deformation” happens and the metal around the hole is “pre-stressed” and strengthened.
The hole now has a zone of residual compressive stress around it and this prevents cracks from starting. You can think of it kind of like a rolled up newspaper. There is the hole in the middle of the roll and then there are the forces of the paper pushing against the reverse forces of the rubber band that is holding it all into place.