The chain quality of hand cranked chain hoists (hand cranked lifting equipment) directly affects the safety, service life, and operational reliability of the equipment. The influencing factors can be systematically summarized into five dimensions: materials and processes, design standards, use and maintenance, environmental adaptation, testing, and compliance. The specific analysis is as follows:

1、 Materials and Manufacturing Processes

Material selection

Steel type: High strength alloy steel (such as 20Mn2, 20MnV, 25MnV) is the mainstream choice, which needs to meet the requirements of tensile strength, yield strength, and elongation; Poor quality materials (such as impurities and low hardness steel) are prone to chain breakage and increased wear.

Heat treatment process: quenching+tempering treatment determines the balance between hardness and toughness of the chain; Improper heat treatment (such as temperature deviation, abnormal cooling rate) may cause brittle fracture or premature fatigue failure.

Surface treatment: anti-corrosion processes such as galvanizing, blackening, and Dacromet coating can enhance corrosion resistance; Surface defects such as cracks and burrs can become stress concentration points, accelerating fatigue crack propagation.

manufacturing precision

Consistency of chain link size: The diameter and pitch deviation of the chain link must comply with standards such as ISO 3077 and GB/T 20947; Exceeding the size tolerance may cause chain jamming and uneven force distribution.

Welding quality: The welding part of the chain link should be free of defects such as porosity, slag inclusion, and lack of fusion; Insufficient welding strength can easily lead to welding fracture.

Surface smoothness: Rough surfaces increase friction and wear, and the friction coefficient needs to be reduced through polishing or grinding treatment.

2、 Design and standard compliance

structural design

Safety factor: The design must meet a safety factor of 4-6 times the rated load (such as ASME B30.16 requiring ≥ 4 times); Low safety factor design can easily lead to overloading and fracture.

Link shape: Circular, elliptical, or irregular rings need to optimize stress distribution; Sharp corners and edges design can easily cause stress concentration.

Connection method: The connection between chain links must ensure that there is no risk of looseness or detachment; The connecting pin shaft needs to have anti loosening design (such as split pins, locking plates).

Standards and Certification

International/Domestic Standards: Must comply with ASME B30.16, OSHA, EN 13157, JB/T 7334-2016 and other standards, covering requirements for materials, strength, testing methods, safety factors, etc.

Certification and testing: The production process requires ISO 9001 quality management system certification; The finished product needs to undergo tensile testing, fatigue testing, and non-destructive testing (such as ultrasonic and magnetic particle inspection) to verify its quality.

3、 Usage and maintenance factors

Operating Specifications

Overloading is strictly prohibited: Overloading is the main cause of chain breakage; It is necessary to clearly indicate the rated load, and operators need to receive training to avoid blind overloading.

Operation direction: The zipper direction should be consistent with the chain direction to avoid uneven force on the chain caused by diagonal pulling or twisting.

Lifting method: Loose binding or center of gravity deviation may cause additional stress on the chain; Special lifting equipment is required to ensure even distribution of the load.

maintenance

Regular inspection: Check the wear of the chain (such as thinning of the chain ring diameter and elongation of the pitch), cracks, and corrosion; If the wear exceeds 10% or cracks appear, it needs to be replaced immediately.

Lubrication management: Regularly apply specialized lubricating grease (such as lithium based grease) to avoid the use of corrosive lubricants; Insufficient lubrication can increase friction and wear, while excessive lubrication may adsorb dust and cause jamming.

Cleaning and rust prevention: Regularly clean the surface dirt and dust of the chain; In humid environments, it is necessary to strengthen anti rust measures (such as applying anti rust oil and storing in a dry place).

4、 Environmental adaptability

Temperature influence

High temperature environment: The strength of the chain decreases with increasing temperature; The rated load should be adjusted according to the temperature range or a high-temperature resistant model should be selected.

Low temperature environment: chain toughness decreases and brittleness increases; Low temperature lubricating oil or antifreeze type should be used (such as in environments below -40 ℃).

Humidity and Corrosion

Damp environment: easy to cause rust and reduce chain strength; Anti corrosion coating, stainless steel material or drying equipment should be used for rust prevention.

Chemical corrosion: Special anti-corrosion chains (such as galvanized or plastic coated models) should be selected for acidic, alkaline, and salt spray environments.

Dust environment: Dust accumulation can increase friction and wear, requiring regular cleaning and installation of dust covers.

Space and Layout

Installation space: Sufficient travel space should be reserved in the vertical direction, and excessive bending or twisting of the chain should be avoided in the horizontal direction.

Safe operating distance: Operators need to maintain a safe distance to avoid injuries caused by heavy objects falling or equipment malfunctions.

5、 Detection and Fault Prevention

regular testing

Non destructive testing: Ultrasonic and magnetic particle inspection can detect cracks and defects inside the chain.

Tensile testing: Verify whether the tensile strength of the chain meets the standard.

Fatigue testing: Simulate actual working conditions to verify the fatigue life of the chain.

Fault prevention

Early warning: Identify early chain faults (such as abnormal noise and vibration) through vibration monitoring, sound analysis, and other means.

Emergency response: In case of chain breakage, jamming or other malfunctions, the operation should be stopped immediately, emergency plans should be activated to ensure personnel safety.

The main equipment produced by Hebei Makita: stage electric hoist, electric chian hoist, wire rope electric hoist，Hand chain hoist, lever hoist, pneumatic hoist and other lifting equipment