Common testing methods for bolts
There are many detection methods for bolts and screws. Its testing generally requires testing

hardness, tensile strength, torsional strength, etc. The required equipment includes: Rockwell

hardness tester, Brinell hardness tester, bolt and nut tension tester, bolt tension and torsion

tester, ductility tester, torque strength tester, penetration tester, screw in torque tester, etc. With

these testing equipment, we can more scientifically detect the corresponding data of screws.

1. Ductility test
1.1 scope of application: all kinds of self tapping screws

1.2 test purpose: check whether there is a risk of head brittle fracture when the product is assembled,

rotated or tightened or subjected to impact stress in the above process

1.3 test device: A. ductility test seat. B. small hammer

1.4 recommended minimum test quantity: 8 pieces per batch, and each batch shall not exceed 250m

PCs

1.5 test procedure: A. place the screw into the appropriate hole in the test seat. B. hit the top of the

head with a hammer to make the bearing surface of the test piece consistent with the seat surface

of the test seat. C. check

1.6 bad: if the head is completely separated from the screw handle, it is a bad test

1.7 adverse factors of the product: a. the hardness of the core is too high. B. the carburized layer is

too deep. C. the punching is too deep

D. The inner diameter under the head is too small

2. Torsion strength test

2.1 scope of application: all kinds of self tapping screws

2.2 test purpose: check that the product rotates or turns off during assembly due to insufficient torque

2.3 test device: A. screw clamp. B. clamp holder. C. screw measuring holder. D. torque wrench with

accuracy within 2%

2.4 recommended minimum test quantity: 4 pieces per batch, and each batch shall not exceed 250m

PCs

2.5 test procedure: A. put the screw into the test fixture, and then put the fixture into the fixture support

seat. The screw should have at least two teeth in the fixture and two teeth outside the fixture. B. fix the

support seat on the measuring fixed seat. C. torque the wrench until the screw breaks. D. record the

damage value

2.6 bad: the screw breaking value is less than the specified value

2.7 product adverse factors: a. the hardness of the core is too low. B. the surface hardness is too

low. C. The effective carburized layer is insufficient. D. the minimum diameter (tooth bottom diameter)

is too small

3. Penetration test

3.1 scope of application: all kinds of self tapping screws except type 25

3.2 test purpose: check whether the product will fail due to thread breakage during assembly

3.3 test device: A. test steel plate. B. torsion tool (electric tool can be used, but it shall not exceed

500rpm)

3.4 recommended minimum test quantity: 4 pieces per batch, and each batch shall not exceed

250m PCs

3.5 test procedure: A. lock the screw into the test steel plate until the first complete thread passes

through the steel plate, and the screw of plain can be coated with a little oil. B. check whether the

thread is broken

Note: this test can be carried out together with screw in torque test and hydrogen embrittlement test

3.6 bad: the thread is broken after the screw is screwed in

3.7 product adverse factors: A. insufficient effective carburizing layer. B. too low carburizing hardness.

C. too hard test steel plate. D. too small test hole

4. Screw in torque test

4.1 scope of application: thread rolling (triangular tooth) self tapping screw

4.2 test purpose: check whether the product is difficult to assemble due to high screw in torque

during assembly

4.3 test device: A. test steel plate. B. torque wrench with accuracy within 2%

4.4 recommended minimum test quantity: 4 pieces per batch, and each batch shall not exceed

250m PCs

4.5 test procedure: A. screw the screw into the test steel plate with a torque wrench until the first

complete thread passes through the steel plate, and a little oil can be applied to the screw of plain.

B. record the maximum torque value

Note: this test can be carried out together with screw in test and hydrogen embrittlement test

4.6 bad: the maximum screw torque is greater than the specified value

4.7 product defects: a. the thread is not properly formed during rolling. B. the carburizing hardness

is too low. C. the carburizing depth is insufficient. D. the test steel plate is too hard. E. the test hole is

too small. F. the product needs to be oiled or waxed

5. Hydrogen embrittlement test

5.1 scope of application: all electroplated self tapping screws

5.2 test purpose: find out in advance to prevent the plated self tapping screw from cracking 24 hours

after locking due to hydrogen embrittlement

5.3 test device: A. test steel plate. B. torque wrench with accuracy within 2%. C. flat Huawei

5.4 recommended minimum test quantity: 8 pieces per batch, and each batch shall not exceed 250m

PCs

5.5 test procedure: A. take the average torque strength as the benchmark and multiply it by 80% as

the locking torque. B. insert the flat washer into the screw, then screw the screw into the test steel

plate, tighten it to the locking torque and place it for 24 hours. C. loosen the screw and then tighten

it to the locking torque

5.6 defective: no screw shall be broken from the beginning of the test to the end of the test

5.7 product adverse factors: A. not dried after electroplating. B. the screw is locked with high locking

torque. C. not inserted into Huawei, resulting in too high clamping torque. D. too deep hole depth

6. Attack speed test

6.1 scope of application: only for self drilling screws

6.2 test purpose: it is found that the tapping speed of self drilling screw is too slow or the tapping

problem is caused by production problems

6.3 test device: A. attack speed tester. B. test steel plate, thickness 0.060 "- 0.064", hardness

HRB 60-85

6.4 recommended minimum test quantity:

a. 6 pieces below 5000 pieces
b. 5001-15000 PCs. 12 PCs
c. 15001-50000 PCs. 18 PCs
d. 50001-250000 PCs. 25 PCs
Note: each batch shall not exceed 250000 pieces
e. If one of the above sampling tests exceeds the minimum attack speed requirements, double

inspection can be carried out according to the following sampling plan
Sampling number slow attack speed 1 too slow attack speed 2
12 1 0
24 1 0
36 2 1
50 3 1
Note 1: "slow tapping speed" refers to that the sample exceeds the maximum tapping time but not

more than twice
2: "Too slow tapping speed" refers to that the sample exceeds twice the maximum tapping time

6.5 test procedure: A. install the test piece into the testing machine. B. adjust the testing machine

so that when the test piece penetrates the steel plate and exceeds one complete tooth, the testing

machine can stop and record the penetration time. C. record the test time

6.6 defect: when testing according to the above sampling table, the test time exceeds the specified

value

6.7 product adverse factors: a. the sample is drilled with rough edges; e. the test steel plate is too

thick

b. Carburizing hardness is too low F. axial load is too tight
c. Insufficient carburizing depth g. too slow tapping speed
d. The test steel plate is too hard h. the surface coating is too thick

7. Selection table of self tapping screw test steel plate

7.1 Type A
Dimensional ductility test
Minimum angle minimum torque strength
Lb in. Test steel plate (HRB 70-85)
Thickness  0.002 aperture  0.001

Stainless Steel Adjustable Feet Parameter

Stainless Steel Adjustable Feet Size

Stainless Steel Adjustable Feet Material

Stainless Steel Adjustable Feet Describe

Application.

Stainless Steel Adjustable Feet Scope of application

About us.

KTC.

The company is headquartered in the Shunyi District Niushan Industrial Zone, Beijing ,The company adopts advanced international production testing equipment and professional intelligent production management system and professional process flow,Current production KT Casters（KT CASTER）,KT Adjusting foot（KT FOOT）High quality products such as multi function,High quality horizontal adjustment of the casters,Shock proof casters,High load casters ,The adjusted feet are widely used in the world's advanced automation equipment and semiconductor equipment and other industries. The company is making the world's highest level of product,Use the most advanced processing technology and equipment,New products emerge in an endless stream.KTC sales network is all over the world,And has set up a company in South Korea,Favored by users from all walks of life around the world