Product category:
Robotics, Handling and Storage
News Release from: Camlok Lifting Clamps | Subject: Lifting clamps
Edited by the Engineeringtalk Editorial
Team on 08 August 2003
Get a grip on lifting
In materials lifting applications most problems tend to occur at the interface between the hook and load being lifted.
In materials lifting applications most problems tend to occur at the interface between the hook and load being lifted To ensure maximum productivity, to minimise costs and to ensure a safe lift it is essential to choose the correct attachment for the specific lifting application
This article was originally published on Engineeringtalk on 18 Oct 2001 at 8.00am (UK)
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Gone are the days when you could throw a piece of rope or chain around a load and hope that it holds or so you would think.
Taking shortcuts, crossing your fingers and hopping for the best just isn't good enough when safety is at risk.
It may come as no surprise to realise that there are still some businesses using incorrect methods for lifting materials.
It may be that the initial cost of purchasing the correct equipment is off-putting, although this needn't be expensive.
They may not be aware that the equipment is available or even that they are using the "wrong tools" for the job.
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Every company has a legal as well as morel obligation to ensure the safety of its workforce by providing equipment that is suitable for the duty it has to perform and fit for the application in question.
Consider the handling of rolled sections such as I-beams, joists, bulb section and channels.
There is inherent danger involved in the lifting and transporting of such material if an incorrect lifting method is applied.
The handling of such loads requires the use of specialist clamps to ensure safety as well as productivity.
Traditionally it has been common practice to use a chain sling and hooks to lift beams by attaching the hooks to either end of the beam.
Once the beam was lifted a choke hitch or sling would be placed around the beam for the final lift.
Initially, all the load would be placed on the tip of the hook.
Hooks are designed to take the load in the bowl of the hook and not on the tip.
Any movement of the beam during the lift would cause slippage of the hook and the load becomes unstable.
Once the beam is of sufficient height from the ground the choke hitch would be positioned.
At this point the beam would have to be supported while the hoist or crane was detached and repositioned, attaching it to the choke hitch.
The lifting point would have to be placed at the centre of gravity of the beam, which is not as easy as it may sound.
If the load tilts during a lift the sling could slip and so might the beam.
If two slings are used they may slide together and you are faced with the same problem.
To use this method would involve two or three separate lifting manoeuvres, not to mention the time taken to place supports under the beam while the hoist or crane is disengaged and re-attached.
There are clamps available that have been specifically designed for this application.
With the use of a clamp the load is quickly attached, lifted and positioned safely in one operation.
A considerable productivity increase can be achieved by selecting the correct clamps to suit the specific application.
After all, why use a cumbersome chain and several operations when a clamp can do it in one lift.
The clamps operate by griping the load via jaws and a series of links to prevent the load slipping.
Clamps can be supplied for lifting beams in the "I" and the "H" (vertical or horizontal flange) position and for attachment to the end or the side of the beam.
If a beam is to be lifted in the "H" (horizontal with flange vertical) position then a clamp with a hook ring near to the centre of gravity of the beam should be selected.
These clamps are attached on opposite beam flanges and when used with a lifting beam result in a near horizontal lift.
There are vertical girder clamps available in pairs supported from a two-leg chain sling with a split bottom toe enabling the clamp to be attached to the end of the beam.
With this clamp no time is wasted trying to find the centre of gravity of the beam.
There are vertical girder clamps also available for use when a beam needs to be lifted from the side in the "I" or vertical position with the flanges horizontal.
For long beams two clamps and a lifting beam are recommended.
The clamps are positioned on opposite beam flanges providing a safe and stable lift.
Whatever the requirement, there is probably already a clamp available; and if there isn't, any major manufacturer should be able to design a clamp to suit a specific application.
In the present economic environment companies find themselves placed under growing pressure to reduce costs.
The increasing influx of low-cost lifting equipment from Eastern Europe and Asia may, on face value, provide a tempting solution.
However simply because some of this equipment may be supplied with certification does not necessarily mean it is suitable for specific applications: beware of terms such as "generally in compliance with".
Other factors have to be taken into consideration such as frequency of use, temperature, operating environment and the quality of manufacture and material.
If a clamp is not used in compliance with its rating and recommended operating instructions or if it is damaged and not regularly inspected and maintained it can be just as dangerous as using the wrong equipment.
It has to be said that a low price does not inevitably mean equipment is unsuitable.
The short-term savings may seem attractive but poor quality equipment has to be inspected and repaired more frequently and a reduction in working life should be expected to say nothing of the potential downtime if equipment should fail.
It is the responsibility of the buyer to ensure the purchase of correct and suitable equipment for the required application: caveat emptor, or buyer beware, really does apply.
Many reputable companies offer general-purpose clamps for steel.
When selecting a clamp there are of course considerations.
What is being lifted? What is the aim of the lift? How heavy is the object? What size is the object? Are there any special requirements? And does the clamp that has been selected meet all the criteria.
When lifting long loads with clamps it is recommended to use two clamps and a lifting or spreader beam.
Clamps can be used on most types and grades of steel within the clamps specifications.
The clamps are also suitable for certain grades of aluminium sheet and brass.
Clamps operate by forcing the teeth of the clamp into the surface effectively becoming one with the material.
The necessary grip required to lift a plate is achieved by increasing the force applied to the clamp from the lifting sling by a system of links.
The gripping force is therefore proportional to the load lifted and self-actuating, the greater the load applied to the clamp the greater the gripping force.
When clamps are used on stainless steel an increased wear rate is experienced, this can shorten the normal working life of the clamp.
If the surface of the material needs to remain unmarked there are a series of specifically designed non-marring clamps available.
The working load limit of the clamp should be as close as possible to the actual load to be lifted to ensure efficiency, however excessive wear and a reduction in working life can be caused if a clamp is continuously used to lift the same thickness material.
All clamps, regardless of price need to be regularly inspected and maintained by qualified personnel.
There are products already on the market for a wide variety of lifting applications and industries.
By using the correct equipment productivity can be increased, saving time and money.
Putting off investing in safe handling equipment might cost financially when the Health and Safety Executive pays a visit, but that's nothing compared with the price paid by those whose safety is compromised each year in industry due to unsafe working practices.
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