1. The Heat Shrinkable Tube mainly has parameters such as length, inner diameter (ID), outer diameter (OD), wall thickness (W) and shrinkage rate. The length, inner diameter, outer diameter and wall thickness are relatively easy to understand. The inner diameter can be divided into factory inner diameter, factory wall thickness and inner diameter and wall thickness after heating recovery according to the shrinkage of the heat shrinkable tube. Shrinkage refers to the ratio of the factory inner diameter to the inner diameter after heating recovery.
So, how do we choose the appropriate size of heat shrinkable tube? Let's introduce the key points of heat shrinkable tube selection
How to choose a suitable heat-shrinkable tube depends not only on the size of the heat-shrinkable tube, but also has a lot to do with the shrinkage ratio of the heat-shrinkable tube. Many customers will choose according to the parameters such as inner diameter, outer diameter, wall thickness and shrinkage rate of the heat shrinkable tube. These parameters are detailed and listed on the website. Welcome to refer to the relevant chapters.
However, when many customers choose, they often ignore the impact of the shrinkage ratio of the heat shrinkable tube on the performance of the heat shrinkable tube. After the heat
Shrink Tube is heated, the size will change. So choosing the right size heat shrink tubing for your application, is not that easy.
(1) In order not to affect the insulation, waterproof, and sealing properties of the heat-shrinkable tube, the factory inner diameter of the heat-shrinkable tube should exceed at least 20% of the diameter of the applied object. (2) When the heat-shrinkable tube is heated and recovered, the inner diameter of the applied object must be at least 10% higher than the inner diameter after recovery.
For example, the factory inner diameter of RSFR-100 series heat shrink tubing is 1.0", and the inner diameter after recovery is 0.5". The suitable diameter range of the application object is as follows: 0.5+0.5x10%=0.55", 1-1x20%=0.8", so the most suitable application object diameter range is 0.55-0.8". This does not mean that the quilt cover exceeds this range It cannot be used, but only affects the performance of the heat-shrinkable tube. For example, if it exceeds 0.8", it may not be so easy to apply the heat-shrinkable tube, and after the heating is restored, the insulation and waterproof performance of the heat-shrinkable tube will be reduced. If it is less than 0.55", it will cause a loss of sealing due to the restored internal diameter of 0.5".
Also, when choosing the color of the heat shrink tubing, remember that the color of the heat shrink tubing will become lighter as it expands. This means that the color of the heat shrink tubing may be slightly different after use than when it was first received, but this is not a defect. The parameters for the color of the heat shrink tubing are also listed on the website. Color shift is also a factor to consider when applying.
Second, the correct measurement method of heat shrinkable tube parameters
Due to the stretchability and softness of heat shrink tubing, it is not easy to measure its size.
Inside diameter (ID) measurement
(1) The heat-shrinkable tube is stretchable. Many people use the traditional size measurement method. The vernier caliper may cause the heat-shrinkable tube to stretch and deform, resulting in wrong measurement results. The heat shrink tubing was stretched and deformed during the measurement, resulting in erroneous inner diameter measurements.
In order to solve the problem of dimensional deformation during measurement, a set of plug gauges of known size can be used to solve this problem. According to the size of the heat shrinkable tube, select the appropriate plug gauge (first use a plug gauge with an outer diameter smaller than the inner diameter of the heat shrinkable tube, and then replace the plug gauge with a larger size step by step until the size is suitable). It is necessary to gently and slowly insert the plug gauge into the heat shrinkable tube, so that the correct inner diameter of the heat shrinkable tube can be obtained, that is, the outer diameter of the plug gauge.
Outside diameter (OD) measurement
(2) When measuring the outer diameter of the heat-shrinkable tube, the external force of the vernier caliper may cause the heat-shrinkable tube to compress, resulting in a smaller measurement result.
(3) The method of correctly measuring the outer diameter of the heat-shrinkable tube is like measuring the inner diameter, inserting a plug gauge of a suitable size, and the outer diameter of the heat-shrinkable tube can be easily measured. The measurement method is as follows
(4) Correct outer diameter measurement and wall thickness (W) measurement of the heat shrinkable tube:
Once the inner and outer diameters are measured, the wall thickness can be easily calculated in the following way.
The measurement of the above parameters of wall thickness W=(OD-ID)/2 are all factory parameter tests. After heat recovery, these parameters will change.
(5) Length shrinkage measurement
The measurement of the shrinkage rate of the length requires heating the heat-shrinkable tube, and measuring the length change rate before heating and after heating recovery. The change in length is generally expressed as a percentage, and the change range is generally -10%-0% (not all heat shrinkable tubes have this value). However, this rate of change can be measured and calculated using the following formula.
Length shrinkage=(L1-L2)/L2X100%
(6) L1 is the length after contraction recovery
(7) L2 is the length before contraction
In addition, although it seems easy to measure the length shrinkage, it may cause errors in the measurement results due to some improper operations. For example, the accuracy of the measuring tool is not enough, and the heating of the heat shrinkable tube is insufficient, resulting in incomplete shrinkage. These problems can be solved only by ensuring thorough heating and high precision of the measuring tool. In addition, the heat-shrinkable tube is easy to stick when the oven is heated. When the oven is heated, the heat-shrinkable tube needs to use a wire product to prevent the heat-shrinkable tube from sticking.
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