FEP shrink tubing is offered in either 1.3 to 1 or 1.6 to 1 shrink ratios. The shrink ratio has to do with the amount the tubing will shrink whenever heat is applied based upon the starting pre-shrunk diameter. For example, a one inch starting diameter on a piece of 1.6 to 1 shrink tubing ends up with a recovered inner diameter of about 0.60 inches after shrinkage, with a variance of 0.025 plus or minus 0.005 inches.
Diameters Determine the Amount of Shrinkage Experienced with FEP Shrink Tubing
There are few things which can constrict and control the amount of shrinkage achieved when using FEP shrink tubing. First and foremost is the diameter of the wire or cable you are using as a mandrel. If the diameter is larger than the recovered inner diameter of the shrink tubing, it will not fully shrink down, and may also impact the wall thickness. On the other hand if the diameter of the wire or cable is smaller than the recovery rate, the tubing does fully shrink but will not be fully tight and secure.