Does below situation happens to your new shoes with a bonding gap or sole-crack for wearing within a short time? Just as below pictures:

What happens?

You might say the quality of the shoes is not so well, so where the problem lies in?

The reason why this situation appears is that the the flexing resistance of the finished shoes is a failure.

The flexing resistance of finished shoes refers to the finished shoes’ durability for the bending or folding under a certain temperature and certain force. General speaking, it’s a repetition twisting process between human foot and shoes.

The test standard for shoes flexing resistance: GB/T 3903.1-2017Footwear,Test Method for  Whole shoe , Flexing Resistance.This test standard is used for test whole shoes and sole, not suitable for the heel excess 70mm, or the part of sole’s flexing more than 25mm,or the finished shoes with strong stiffness.

This is Flexing Resistance Tester:

The testing principle of Shoes Flexing Tester is to use a cutting knife cut a crack with specified length of whole shoes or sole, then to do the flexing test under certain angle and rate. After test, measure the length of the crack and at the same time, observe the changes of the joints of the upper surface, the sole and the bottom (including the fence and the bottom wall).

Move like this:

Is it a similar motion when you are walking?

Each test should need not less than a pair of whole shoes or sole.  The test bending angle should be （50±1）°, the flexing rate should be （230±10）times/min. The test temperature should be （23±2）℃. Do the test for 40,000.00 circles. As below pictures show:

The standard requires the cutting position should be in the middle of the toe flexion of the sole of the shoe, and the sole needs to be cut through.

As showed in the pictures:

Not all the shoes need the cutting crack in advance, different standards requires different specification.

For example:

Sneaker

（GB/T 15107-2013）

It requires not cutting, and it continually bends 40,000 times, the qualified products should not be crack after the bending. The bottom wall, upper bottom the shoe sole should be ≤5.0mm;After folding, the shoe sole shall not have more than 3 cracks, and the longest crack length shall be ≤5.0mm;The sole must not appear Color falling off; air (liquid) cushion should not appear air leakage (liquid) or collapse phenomenon after folding the air cushion shoe.

leisure shoe  

（QB/T 2955-2017）

It requires cutting 5.0mm in advance, qualified products require that the length of the cut opening is ≤ 20.0mm after bending. The new crack length is ≤ 5.0mm after folding, and should not exceed 3 places. After the fold, there should be no cracking on the face, cracking or opening the bottom, and is no testing the fold resistance if the shoe size is below 230mm. Natural leather out sole also does not measure wear resistance.

Test Results:

1.Number of newly generated cracks and longest new crack length, glue failure length of the bonding part of the bottom

2.If there is a pre-cut, record the length of the sole cut

3.Record the upper surface (e.g. split surface) and the sole (e.g. glue failure)，Explain the change of the bottom binding part（e.g. glue failure）

4.The test results of each shoe (bottom) are expressed separately.

Exceeding the cutting limit value or the above abnormal phenomenon indicates that the folding resistance of the shoe is unqualified.

In general, the folding resistance simulates the continuous walking state of the person, the length of the cut after folding from the sole and whether the upper surface is cracked or not. Whether the bonding of the bottom (including the fence and the bottom wall) is glue failure, and comprehensively reflects the wear resistance of the whole shoe. Qualified folding resistance means the whole shoe is durable.

How to choose a shoe with good folding resistance ?

In fact, it is impossible to judge whether the folding resistance of shoes is qualified from the naked eye. However, there are four things you can do to help you get good folding endurance shoes:

1.Odour. Shoes with very irritating odor are not recommended for purchase,The odor is very irritating, indicating that certain materials used in shoes may not meet environmental standards.

2.Hang tag. The information on the tag is clear and complete, and matches the information on the shoes. The quality is generally not bad.

3.Carefully check whether the two shoes are symmetrical, color, and whether there is a large error in the grain.

4.Check the upper stitching line and the bottom seam,and check whether there is a broken thread, whether the suture of the upper is neat, whether the bonding part of the adhesive bottom is flat without gully, no virtual seam and open glue, whether there is obvious appearance problem.