Hand chain hoist hook test: a key link to ensure lifting safety

Hand Chain Hoist hook test: a key link to ensure lifting safety
In industrial production and Material Handling,hand chain hoists, as a common light and small lifting equipment, play an important role. As a key component of hand chain hoists, the quality and performance of the hook are directly related to the safety and reliability of the entire equipment. In order to ensure that the hook can withstand the specified load and does not break or deform dangerously, strict testing is essential. This article will explore the relevant content of the hand chain hoist hook test in depth.

The importance of hand chain hoist hook test
The hook is the part of the hand chain hoist that directly carries the heavy object, and it is subjected to huge tension and various stresses during the operation of the equipment. Once the hook has defects such as breakage, deformation or cracks, it may cause the heavy object to fall, causing serious equipment damage and casualties. By testing the hook, its potential quality problems and safety hazards can be discovered in advance, so that corresponding measures can be taken to repair or replace it, effectively avoiding accidents, and ensuring the life safety of operators and the normal operation of equipment.
The hook test also helps to verify whether the manufacturing quality and performance of the hook meet the relevant standards and design requirements. During the production process of hooks, the product quality may vary due to factors such as materials and processing technology. Through strict testing, hooks that do not meet the requirements can be screened out to ensure that the hooks put into use have sufficient strength and toughness and other properties, thereby improving the overall quality and market competitiveness of hand chain hoists.

Related standards and specifications
Domestic standards
JB/T 7334-2016: This is an important industry standard for hand chain hoists, which clearly stipulates the hook test. For example, on a material testing machine, gradually load to 2 times the rated load through the center of the hook cavity, stay for 1 minute, then unload the load, check the deformation of the hook mouth, which shall not exceed 0.25%; continue to load to 4 times the rated load, and the hook should be able to reliably support 1 minute.
T/ZZB 0724-2018: For hand chain hoists with multiple chains, single-chain hand chain hoists are allowed to be used for alternative tests. When the rated lifting capacity is not more than 25t, the hook shall be tested in accordance with the provisions of Article 10 of JB/T 4207.1; when the rated lifting capacity is more than 25t, the mechanical properties and materials of the hook shall comply with the provisions of GB/T 10051.1.
International Standard
ISO 12853:2008: Cranes - Hand Chain Hoists - Safety Requirements. This standard stipulates that the hook material should have sufficient strength and toughness, its performance should meet the requirements of relevant standards, and the hook should be able to withstand the specified load test.
DIN 15405: German Industrial Standard, which has strict requirements on the load capacity, materials, manufacturing process and test methods of hand chain hoist hooks to ensure the safety and reliability of the hook under various working conditions.

Specific method of hook test
Static load test
Clamp the hand chain hoist on the universal material testing machine, and the diameter of the clamp at the connection with the hook is about 1/3 of the hook cavity diameter. If the test machine is limited by the stroke, it is allowed to remove the upper and lower hooks for testing separately. Gradually load the center of the hook cavity to 2 times the rated load, keep it for 1 minute and then unload it, observe the deformation of the hook mouth, and its deformation rate shall not exceed 0.25%. Then increase the load to 4 times the rated load, and the hook should be able to support it reliably for 1 minute without breaking or permanent deformation that affects its use.
Dynamic load test
Load with 1.1 times the rated load, make the hook perform lifting, swinging and other actions, simulate the dynamic stress of the hook in actual use, check whether the hook and the connection parts are loose, stuck, cracked and other abnormal phenomena, ensure that the hook can work normally under dynamic conditions, and the coordination of various components, without abnormal sound and vibration.
Deformation test
Use professional measuring tools to accurately measure the deformation of the hook mouth, hook body and other parts of the hook. When the hook is subjected to different loads, its deformation degree is measured respectively and compared with the allowable deformation specified in the standard to determine whether the hook is within the specified deformation range, so as to determine whether the elasticity and stiffness of the hook meet the requirements.
Fatigue test
The hook is installed on the fatigue testing machine and a certain range of alternating loads are applied to simulate the repeated loading of the hook during long-term use. After a certain number of fatigue cycles, check whether the hook has fatigue cracks or failure phenomena to evaluate the anti-fatigue performance of the hook and ensure that the hook has sufficient service life and reliability during frequent use.
Destructive test
The hook is loaded step by step until it breaks and the damage load and damage form of the hook are recorded. By analyzing the damage results, the load-bearing capacity and fracture mechanism of the hook under the limit state can be understood, which provides a basis for the design optimization, material selection and safety factor determination of the hook, thereby improving the safety and reliability of the hook.
Test equipment and instruments
Universal material testing machine
Used to perform static load test and partial deformation test on the hook. It has a large load range and accurate loading control system. It can load the hook according to the preset loading rate and load value, and monitor the deformation and stress state of the hook in real time.
Fatigue testing machine
Specially used for fatigue test of hooks, it can simulate the alternating load conditions of the hook in actual use, can accurately control the load size, frequency and number of cycles, and provide reliable test data for evaluating the anti-fatigue performance of the hook.
Hardness tester
Used to measure the hardness of the hook material. Hardness is one of the important indicators to measure the strength and wear resistance of the material. By testing the hardness of different parts of the hook, it is possible to preliminarily judge whether the quality of the material and the heat treatment process are reasonable, and provide a reference for the performance evaluation of the hook.
Vernier caliper, micrometer and other measuring tools
Used to measure the dimensional accuracy of the hook, such as the hook mouth size, hook body diameter, thread size, etc., to ensure that the manufacturing size of the hook meets the design requirements and avoid safety hazards caused by dimensional deviation.
Ultrasonic flaw detector
Using the propagation characteristics of ultrasonic waves in materials, non-destructive flaw detection of hooks can be performed, which can detect defects such as cracks, pores, inclusions, etc. inside the hook, and timely discover potential quality problems, providing important basis for quality control and safety assessment of hooks.

Specific steps of hook test
Static load test steps
Place the hand chain hoist stably on the test bench and ensure that it is in good working condition.
Use a clamp to firmly clamp the hand chain hoist on the universal material testing machine. Note that the diameter of the connection between the clamp and the hook should be about 1/3 of the diameter of the hook cavity. If the stroke of the testing machine is limited, the upper and lower hooks can be removed for testing separately.
Connect the load sensor of the testing machine to the hook, and ensure that the connection is reliable and can accurately transmit the load.
Turn on the testing machine, set the loading rate to slow and uniform mode, and start to gradually load the hook until it reaches 2 times the rated load.
Keep the load at 2 times the rated load for 1 minute, observe the stress and deformation of the hook, and use the measuring tool to measure the deformation of the hook mouth and record the data.
Remove the load, observe the unloading of the hook, and check whether the hook has abnormal phenomena such as permanent deformation or cracks.
Reload to 4 times the rated load, keep for 1 minute, and check the condition of the hook again to ensure that it has no breakage, significant deformation, and other conditions that affect its use.
Dynamic load test steps
Install the hand chain hoist on a special test device to ensure that it can freely perform lifting and swinging movements.
Hang a weight of 1.1 times the rated load on the hook to ensure that the load is evenly distributed and well matched with the hook cavity of the hook.
Operate the hand chain hoist to make the hook lift and lower at a normal working speed. The lifting distance each time should be no less than 200mm. Lift and lower continuously for more than 3 times, observe the overall operation of the hook and hand chain hoist, and check whether there are problems such as stagnation, looseness, and abnormal noise.
During the lifting and lowering of the hook, swing the hook appropriately to simulate the swinging conditions of the hook in actual work, and check whether the swing of the hook is smooth and whether there is any interference or collision with other parts.
During the test, closely observe the force and deformation of the hook. If there is any abnormality, stop the test immediately and check it.
Deformation test steps
Prepare the required measuring tools, such as vernier calipers, micrometers, etc., and calibrate them to ensure the precision and accuracy of the measuring tools.
Install the hook on a suitable fixture or bracket so that it can be stably measured for deformation.
Load the hook step by step, and measure the deformation of the hook mouth opening, hook body bending degree, etc. under different loads. For example, measure under rated load, 1.25 times rated load, 1.5 times rated load and other working conditions, keep stable after each loading, and measure and record data after the deformation is stable.
Compare and analyze the measured deformation with the allowable deformation specified in the standard to determine whether the deformation of the hook is within the allowable range. If there is an out-of-tolerance situation, further analyze the cause and take corresponding measures.
Fatigue test steps
Correctly install the hook on the fatigue tester to ensure that the force direction of the hook is consistent with the loading direction of the tester, and the connection parts are firm and reliable without looseness and shaking.
According to the rated load of the hook and the requirements of relevant standards, set the alternating load range, frequency and number of cycles of the fatigue tester. In general, the fatigue load can be cyclically changed between 0.5 and 1.5 times the rated load. The frequency can be selected according to the actual use conditions of the hook. The number of cycles is usually set to tens of thousands or even hundreds of thousands of times to simulate the fatigue load of the hook during long-term use.
Start the fatigue tester and start the fatigue test on the hook. During the test, closely observe the operating status of the tester and the force of the hook. If there is abnormal sound, vibration or failure of the tester, the machine should be stopped immediately for inspection and the test should be continued after the failure is eliminated.
After reaching the predetermined number of fatigue cycles, turn off the testing machine and conduct a comprehensive inspection of the hook. Focus on checking the stress concentration areas such as the hook mouth, hook body, and threaded connection parts of the hook to check whether there are fatigue damage phenomena such as fatigue cracks, surface peeling, and deformation. If necessary, non-destructive testing methods such as magnetic particle testing and penetrant testing can be used to further test the hook to ensure the safety of the hook.
Destructive test steps
Select a suitable hook specimen. Usually, a hook with the same material and the same manufacturing process as the actual use should be selected for destructive testing to ensure the representativeness of the test results.
Install the hook on a universal material testing machine or other test equipment that can provide sufficient load to ensure that the force direction of the hook is correct, the contact between the loading device and the hook is good, and there is no influence of eccentric load and lateral force.
Turn on the test equipment and gradually load the hook at a slow and uniform loading rate, while closely observing the deformation and stress state of the hook. During the loading process, record the load-deformation curve of the hook to analyze the mechanical properties and failure law of the hook.
As the load continues to increase, the deformation of the hook gradually increases until it finally breaks. Record the breaking load value and the form of the hook, such as whether it is a ductile fracture or a brittle fracture.
Perform macroscopic and microscopic fracture analysis on the broken hook. By observing the morphology and characteristics of the fracture, analyze the cause and mechanism of the hook's fracture, and provide a reference for the design improvement, material optimization and quality control of the hook.

Inspection and evaluation after the test
Appearance inspection
After the test is completed, first conduct an appearance inspection on the hook to check whether there are cracks, fissures, wear, deformation, corrosion and other problems on the hook surface. If obvious defects such as cracks or severe deformation are found on the hook surface, it should be stopped from use immediately and replaced or repaired.
Dimension measurement
Use measuring tools to measure the key dimensions of the hook, such as hook mouth size, hook body diameter, thread size, etc., to ensure that its dimensional accuracy meets the design requirements. If the hook has a dimensional deviation during use or testing, it may affect its normal performance and safety. It is necessary to further analyze the cause and take corresponding measures.
Performance evaluation
Based on the data recorded and observed during the test, the performance of the hook is comprehensively evaluated. The evaluation content includes the load-bearing capacity, deformation, fatigue life, and anti-destruction ability of the hook. Compare the evaluation results with relevant standards and design requirements to determine whether the hook meets the use requirements.
Safety evaluation
Based on the test results and performance evaluation, the safety of the hook is comprehensively evaluated. If the hook shows good performance in the test and has no obvious safety hazards, it can be determined that the hook is safe and reliable and can continue to be used. On the contrary, if the hook has safety hazards, corresponding measures need to be taken, such as reducing the load, repairing or replacing, etc., to ensure safety during use.

Common problems and solutions
Hook deformation out of tolerance
Reason: The strength of the hook material is insufficient, or there are problems such as processing stress concentration during the manufacturing process, which makes it easy to deform during the test or use.
Solution: Choose materials with higher strength and more reliable quality to manufacture the hook, optimize the manufacturing process of the hook, and reasonably design the structure of the hook to avoid the occurrence of stress concentration. During use, operate strictly in accordance with the rated load of the hook to avoid overloading.
Hook cracks or breaks
Reason: There are defects inside the material, such as inclusions, pores, etc., or there are process defects such as welding and forging during the manufacturing process, which reduce the strength and toughness of the hook. In addition, long-term fatigue loads can also cause cracks and breaks in the hook.
Solution: Strengthen the quality control of raw materials, strictly control the manufacturing process of hooks, conduct non-destructive testing, and promptly discover and deal with defects in materials and manufacturing processes. Regularly inspect and maintain the hooks, promptly discover defects such as cracks, and take repair or replacement measures.
Loose hooks and connecting parts
Cause: The connection method between the hook and the connecting parts is unreasonable, or in the long-term use process, it is affected by factors such as vibration and impact, resulting in loosening of the connecting parts.
Solution: Optimize the connection structure between the hook and the connecting parts, and adopt a more reliable connection method, such as adding anti-loosening devices. During use, regularly check the tightness of the connecting parts, and adjust and tighten them in time.

Precautions for hook test in actual operation
Preparation before test
Equipment inspection: Before conducting the hook test, it is necessary to conduct a comprehensive inspection of the test equipment to ensure that the equipment is in good working condition, all functions are normal, and the loading system, measurement system and control system can work accurately. Check whether the load sensor, deformation sensor, etc. of the testing machine are calibrated, and whether the measuring tools are accurate to ensure the accuracy of the test data.
Hook inspection: Carefully check the appearance quality of the hook to see if there are obvious defects, damage or abnormal conditions. If necessary, preliminary cleaning and maintenance work can be carried out to ensure that the surface of the hook is clean, free of oil and impurities, so that the deformation and force of the hook can be accurately observed and measured during the test.
Precautions during the test
Safety protection: The hook test involves a large load and potential safety risks. Therefore, strict safety protection measures must be taken during the test to ensure the personal safety of the operator and the safe operation of the equipment. Operators should wear personal protective equipment such as safety helmets, protective gloves, and protective glasses to prevent injuries when the hook breaks or other accidents occur. At the same time, a safety cordon is set up in the test area to prohibit non-operating personnel from entering to avoid casualties caused by misoperation or other accidents.
Loading control: During the loading process, loading should be carried out strictly in accordance with the requirements of the test standards and test plans to ensure that the loading rate is uniform and stable, and avoid loading too fast or too slow to affect the test results. During the loading process, closely observe the deformation of the hook and the operating status of the test equipment. If there are any abnormal phenomena, such as cracks on the hook, excessive deformation, abnormal noise from the test equipment, etc., the loading should be stopped immediately for inspection and processing.
Data recording and monitoring: Arrange a dedicated person to record and monitor the test data to ensure the integrity and accuracy of the test data. During the test, record the load value, deformation, test time and other data of the hook in real time, and monitor the test process throughout the process so that the test data can be analyzed and evaluated in detail after the test. At the same time, the data acquisition system can be used to automatically collect and store the test data to improve the efficiency and accuracy of data recording.
Post-test processing
Unloading and inspection: After the test, slowly unload the load, observe the unloading of the hook, and check whether the hook has abnormal phenomena such as permanent deformation and cracks. Carry out a comprehensive and detailed inspection of the hook after the test, including appearance inspection, dimension measurement, non-destructive testing, etc., to ensure the safety and reliability of the hook.
Data collation and analysis: collate and analyze the data recorded during the test, draw load-deformation curves, fatigue life curves and other charts, and evaluate whether the performance indicators of the hook meet the relevant standards and design requirements. According to the test results, make an objective and accurate evaluation of the quality, performance and safety of the hook, and put forward corresponding improvement measures and suggestions.
Report writing: write a detailed test report. The report content should include the purpose of the test, test equipment, test methods, test process, test results, data analysis and conclusions. The test report should have standardized language, accurate data, and clear charts, which can comprehensively and objectively reflect the whole process and results of the test.

Summary
Hand chain hoist hook test is an important means to ensure its safety and reliability. By conducting static load tests, dynamic load tests, deformation tests, fatigue tests and destructive tests on the hook, the performance and quality of the hook can be comprehensively evaluated, and potential safety hazards and quality problems can be discovered in time, so as to take corresponding measures to improve and optimize. In the actual operation process, strictly follow the relevant standards and specifications to ensure the accuracy and reliability of the test, and provide strong guarantee for the safe use of hand chain hoists. At the same time, we continue to pay attention to the latest research results and technological developments in the field of hook testing, constantly improve test methods and means, improve the scientificity and effectiveness of hook testing, and promote the healthy development of the hand chain hoist industry.