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Monitoring exposure to Hand-Arm Vibration - an innovative method for use with grinding machines

Monitoring Hand Arm Vibration

This case study reports on an innovation introduced by Carl West of J West Engineering Company Limited to tackle the challenge of monitoring exposure to vibration in steel fabrication. It could be considered for any type of industry where grinding disks are used for similar tasks, as Carl explains:-

For us the Guidance to The Control of Vibration at Work Regulations 2005 highlighted areas for controlling exposure and provided welcome advice on matters such as:

It seemed that once an initial survey of the vibratory equipment had been undertaken and controls, information, instruction, training etc had been put in place, the focus should turn to monitoring.

Our early thoughts centred on the time that individuals were exposed to vibration and the damage that this could cause. For most, a simple guide for maximum and minimum times seemed to work. Colour coded equipment to differentiate magnitude levels; glossy tables laminated on workshop notice board that employees were encouraged to read also had an influence

Trust

Trust between employer and employees was the name of the game, especially when it came to exposure times with maximums and minimums being recorded by the employee and passed to their supervisor at the end of each shift. This seemed to work, and work well, until we discovered that stock levels of the disks somehow did not tie up with the weekly tally of exposure times.

The Innovation

As a result, we thought about how we could achieve greater accuracy. Eventually we came with the idea that if we obtained the average life expectancy of a disk (41/2” or 7” in our case) we could use that information to develop a reactive monitoring system at very low cost to help:

Using four 41/2” disks under normal working conditions we used a stopwatch to record the trigger times (the times for when the machine was under power and grinding) to see how long each disk lasted. Adding the totals together and dividing by 4 we came up with what we considered to be a decent average. You can use as many disks as you like to reach the average you feel most comfortable with. Once this had been established we introduced stock control into the system. Here employees were required to hand their old (fully used) disks in and sign for a new ones at Stores. This provided proof of receipt and allowed the supervisors and/or Stores to inspect the used disks. We were suddenly on our way to a simple housekeeping/stock control/hand arm vibration system all in one.

Figures and Data

With the aid of a spreadsheet that uses the data from Stores and is updated monthly, we can find and analyse the exposure times without the use of charts, completing forms or having meetings at the end of each shift. Therefore, if X signs for three disks per day we have a record of this and can quickly find out who is being exposed to what throughout the company at the push of a few buttons

Cost Effective Benefits of the System

The main purpose of the system is to monitor exposure limits. However, looking further into the system, there is more to it than just helping companies comply with The Control of Vibration at Work Regulations 2005 for it can help with

The costs for implementing such a system are relatively minimal. It can be set up in-house and updated accordingly.

Recognition

The innovation has already been recognised by industry peers:

Summary

  1. Obtain the average time for the life of a disk used for a task. This can be done by setting up a trial work piece and recording the trigger time (starting the stopwatch when grinding starts/stopping when grinding ceases). Remember when testing to find the average use as many disks that you feel comfortable with to produce a fair result.
  2. Tool Box Talk / Training: All employees briefed about the new “system” that requires them to hand in their old disks and sign for new ones. You could include this as a training session or information on vibration talk.
  3. Record the handing in and checking of used/old disks. Signature of acceptance of the new disk
  4. Information collated and recorded. Used to identify exposure times and stock control

HSE recognises that those who create the risk are best placed to manage it. Such monitoring is only likely to be appropriate in specific cases, for example where there is a need to ensure a strict limit on an individual worker's exposure. J West Engineering Company Limited adopted routine monitoring through choice, and the information above describes how it achieved this.

2011-07-21