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Regular Heat Shrinkable Tubing with different shrinkage ratios of 2:1 , 3:1 , or even 4:1 , and the most commonly used heat shrinkable tubing on the market is 2:1 shrinkage ratio.
First of all, make sure the size of object that needs to be covered by heat shrinkable tubing. If it is a round product such as a wire, you can directly measure the outside diameter to know what sizes of heat shrinkable tubing you can choose. However, if it is an irregular object, measure the circumference length of object and divide by 3.14 （PI π）.
For example, if you want to cover a wire with a diameter of 4mm, or a square with a circumference length of 12.56mm （Using the formula 12.56/3.14π to find out the number is 4mm）, then you can choose a heat shrinkable tubing with a shrinkage ratio of 2:1, and the inner diameter of 5, 6, 7, 8mm will be suitable tubing.
In a different way to think, if the heat shrinkable tubing with an inner diameter of 6mm has an inner circumference of 6mm*3.14 （PI π）=18.84mm, which can cover the object with a circumference of less than 18mm.
However, because the friction of the objects is different, choosing a heat shrinkable tubing with too small diameter may encounter problems that are difficult to pull and move. But if you choose too big heat shrinkable tubing, maybe it is easy to pull and move but difficult to be fixed. Also, it will take a long time to shrink and be fixed on position during shrinkage.
Therefore, the best way is to ask us Good Gi Co.,Ltdfor a sample of the heat shrinkable tubing to test and find the suitable tubing your products.
Usually, Polyethylene heat shrinkable tubing is suitable for most application environments, such as automotive, consumer Electronicss, home appliances, etc.
But if there are the following special requirements, KYNAR heat shrinkable tubing can be used, and the material is polyvinylidene difluoride （Also called PVDF）, which is a type of Teflon. Widely used in the chemical, semiconductor, pharmaceutical, and military industries. The characteristics of the material used to produce tubing include lightweight, heat insulation, wear resistance, chemical resistance and high-temperature resistance （175 °C）, and other excellent properties.
Its surface hardness is higher than that of nylon and polyethylene but with poor ductility. So, PVDF shrinkable tubing is not suitable for frequent bending and bending applications, which may cause cracking.
However, after adjusting the formula of material, Good Gi Co.,Ltd developed a PVDF material with soft properties, KYNAR heat shrinkable tubing, which has better resistance to bending and softness than other companies’ products.
Once you have a clear understanding of the heat shrink ratio, selecting the appropriate size of shrink tubing for your specific needs becomes easier. It's important to determine the expanded and recovered inside diameters required for your application and choose the heat shrink ratio accordingly. If you have any doubts or questions, don't hesitate to reach out to our experienced sales team. You can contact us through the online inquiry system or any other means. We are here to assist you and can even provide sample tubing to ensure it meets your requirements in terms of form, fit, and function.