Production and selection of lifting slings: how to ensure reliable operation under load
Lifting slings are an element that directly affects the safety of lifting operations. In industry, errors in their selection and use most often do not appear immediately, but at the moment of peak load – with a jerk, skew or uneven weight distribution.
In practice, most of the problems are not related to marriage, but to the wrong choice for the task. Focusing only on the rated load capacity without taking into account the operating conditions is one of the key reasons for failures.
Which slings are used in industry
There are three main types of slings used in manufacturing and construction:
Rope slings
They are used when working with heavy metal structures, equipment and oversized loads. They are resistant to dynamic loads and work well when moving jerkily.
Chain slings
They are used in high-load conditions, when working with abrasive or hot surfaces. They are suitable for tasks where wear resistance and the ability to operate in an aggressive environment are important.
Textile slings
They are used for loads with a sensitive surface, for example, painted or polished. They provide a soft contact, but require monitoring of the condition and working conditions.
What happens to the sling under load
In real conditions, the sling does not work in the "passport" parameters. He is being influenced:
- the angle between the branches
- shifting the center of gravity
- dynamic lifting loads
- uneven weight distribution
For example, when the angle between the branches increases by more than 60°, the load on each branch increases by 1.5–2 times. This means that even with the permissible weight of the load, the sling can work with overload.
An additional risk arises with jerks – a short-term load can exceed the nominal load several times.
Common mistakes
In practice, they are most often found:
- sling selection without taking into account the angular load
- using products "with an eye margin", without calculation
- working with worn or damaged elements
- incorrect location of the hooking points
The situation is especially critical when lifting unbalanced loads – the load is unevenly distributed, and one of the branches may exceed the permissible values.
Why is control important at the production stage?
The reliability of the sling is laid not only in calculations, but also in production. Important:
- the quality of the rope, chain or textile backing
- connection technology (crimping, welding, assembly)
- geometry control
- load tests
In industrial practice, solutions are in demand where the manufacturer takes into account real–world operating scenarios, from lifting metal structures to work.