The Wider Application of Poka Yokes (Mistake Proofing) in

the Mining Industry

ASSOCIATION OF MINE MANAGERS OF SOUTH AFRICA

ANNUAL SAFETY GENERAL MEETING

3 DECEMBER 2010

Lionel Naudé

Index Introduction Examples of Poka Yokes that already exist Background Types of Human Mistakes Where Poka Yoke works well Developing Poka Yokes from Risk Assessments Developing Poka Yokes from incidents Developing Poka Yokes from identified at risk behaviours Examples of Poka Yokes that already exist in the mining industry Practical considerations Poka Yoke on Falls of Ground Risk Assessment Example done on inflatable roof support Conclusion Acknowledgements

Introduction Human behaviour is pivotal to the success of companies. Recognised Incident Causation Analysis Techniques

acknowledge that mistakes can contribute to an event. Mistakes are inevitable. Poka Yoke – avoiding mistakes (errors). Poka Yoke is a concept rather than a procedure. Implementation is governed by what people think they

can do to prevent mistakes in their workplace and not a set of step-by-step instructions.

Low cost devices, usable by all workers, simple to install, do not require continuous attention and provide instantaneous feedback, correction or prevention.

Examples of Poka Yokes that already exist

The first Poka Yoke – A loading tray for springs that reduced the number of faulty switches produced.

This principle could be used in certain applications to eliminate wastage

Examples of Poka Yokes that already exist cont.

Unleaded petrol pipes are a smaller diameter than unleaded or lead replacement pipes to prevent leaded petrol from being put into cars designed for unleaded petrol

Examples of Poka Yokes that already exist cont.

Rumble strips on tar roads to warn drivers of impending danger

Examples of Poka Yokes that already exist cont.

Male and female plugs used on computers to prevent incorrect connections

Examples of Poka Yokes that already exist cont.

Deadman switches / controls that deactivate when the operator releases pressure on the switch that we find on electrical power tools and battery locomotive controllers

Examples of Poka Yokes that already exist cont.

Seat belt warnings – audible and visual Automatic vehicles – gear change and key removal Audible reverse warning on vehicles

Overheating cut-out switches Non-return valves

Background

Mine safety often in headlines Falls of ground in Gold and Platinum mines for 2007 to

2009 - 42% of deaths and 25% of injuries (DMR)

These statistics include significant improvements by some operations and they need to be commended

Most investigations reveal something contrary to training (i.e. a mistake) contributed to the incident

Poka Yoke acknowledges that people make mistakes

Types of Human Mistakes Have any of you ever – Forgotten something? Misunderstood something or someone? Incorrectly identified a hazard? Been taken by surprise by a machine starting unexpectedly? Left out process steps? Left out procedure steps?

These are common human mistakes that we have all made at some stage.

Should someone be injured or die as a result of such mistakes?

Where Poka Yoke works well

Manual operations where worker vigilance is needed Where teams need common sense tools Where training costs and turnover are high

Where mixed model production occurs (different processes such as we find in mining applications)

Where mis-positioning can occur Where adjustment is required

These are common to the mining industry

Developing Poka Yokes from Risk Assessments

Identified risks can be used as a basis for identification of areas where Poka Yokes could be developed

Teams of empowered employees can develop simple solutions to perceived complex problems

Create and test effectiveness of device and continue modifying until incidents are effectively prevented

Developing Poka Yokes from incidents

Determine root cause of incident / non-conformance Review current standard procedure Identify deviation from standards

Identify Poka Yoke device most likely to effectively eliminate the incident / non-conformance

Create and test effectiveness of device and continue modifying until incidents are effectively prevented

Developing Poka Yokes from identified at risk behaviours

Behaviour Based Safety Initiatives identified at risk behaviours

Develop Poka Yokes to address these where possible

Examples of Poka Yokes that already exist in the mining industry

Examples of Poka Yokes that already exist in the mining industry continued

Practical considerations Underground environment is dynamic Greater vigilance required Poka Yoke of mining processes Drilling Blasting Cleaning Support Transport

Incorrect drilling and overcharging of shotholes –improper face shape, hampers cleaning , HW damage, blast outs, compromises safety.

Transport delays.

Poka Yoke on Falls of Ground

Codes of Practice Support standards Selection of support elements and system

These generally pass any scrutiny

Support installation Undetected defects Impact on system integrity System failure Fall of ground incident

This is where the focus is required

Risk Assessment Example done on expandable roof support

Risk Insufficient pressurisation

Potential Poka Yoke Load indicators and self

auditing PSUs

Self-auditing Jackpot with button which indicates

pressurisation above minimum required pressure

Risk Assessment Example done on expandable roof support

Risk Loss of load after

installation

Potential Poka Yoke Load indicators

Load monitoring Jackpot that continuously monitors and indicates the pressure by means of a load indicating pin.

Risk Assessment Example done on expandable roof support

Risk Insufficiently pressurised

expandable roof tendon

Potential Poka Yoke Load indicators

Load indicators on Hydrabolts in un-pressurised and pressurised position

Risk Assessment Example done on expandable roof support

Risk Incorrect pressurisation due

to incorrect pump

Potential Poka Yoke Colour coding pumps and

hoses & varying nozzles

Pumps and fittings are colour coded for different applications

Risk Assessment Example done on expandable roof support

Risk Incorrect pressurisation

Potential Poka Yoke Pressure Relief Valves.

The Combi-Nozzle Pressure Relief Valves (PRVs), which prevent products from being over-pressurised and indicate correct pressure by dumping water from the PRV when at the correct pressure.

Examples of Poka Yokes relative to support installation

An image from a load indicator card showing colours per length and Hydrabolt vs X-Pandabolt.

Conclusion

Poka Yoke has been used successfully in other industries Successes match the mining industry characteristics Potential implications of incidents / non-conformances in

mining industry Poka Yoke can enhance the current safety management

efforts Empower teams that can develop Poka Yokes pertaining

to their jobs and / or the processes that they are associated with

Acknowledgements New Concept Mining for allowing me to present this paper and for providing examples of Poka Yokes that

they have already introduced. www.ncm.co.za

The examples found at www.mistakeproofing.com and pokayoke.wikispaces.com. ( Please consider forwarding other examples of Poka Yokes to pokayoke.wikispaces.com. This website allows anyone to add examples and edit existing ones(just like wikipedia does).

You may also be interested in a mistake-proofing exercise/case study available at http://www.campbell.berry.edu/faculty/jgrout/exercise/index.html.

Deebar Mining Division for providing photographs of the station stopping device and the winder safety interlock. www.deebar.co.za

Information obtained from www.siliconfareast.com/pokayoke.htm

Questions