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Poka-Yoke and Visual Management

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Tony Haythornthwaite

on 24 October 2013

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Transcript of Poka-Yoke and Visual Management

Visual management helps you:
Understand and indicate work priorities
Assess if performance was met
Identify the flow of work and what is being done
Identify when something is going wrong or not happening
Show what standards of work should be
Communicate to everyone what performance measures are in place
Demonstrate all the elements required for safe and effective work
Provide real time feedback to everyone involved in the whole process
Cut down on meetings to discuss work issues
There are two types of errors:
Input Errors: Broken machines, poor materials etc.
Output Errors: Non-conforming or damaged parts, broken tools...
The rule of 1-10-100:
The further down the process line a mistake is made the more cost to the manufacturer...
£1 ------Ordering process
£10 ------Manufacturing process
£1000 ------Customers sharing their experience with other potential cutomers
The Importance of Poka Yoke in Business
Poka yoke can affect the performance of business in three different ways:
Improvements in these areas result in greater customer satisfaction and increased margins.
Visual Management
Visual management is one of the lean techniques, the current status of an operation can be assessed at a glance.
Implementing Poka-Yoke through visual management
Halting system
The halting system means there is an immediate stop to any process which is going on!
Halting system pros:
Immediate feedback
Catch errors as they happen
No chance of the error reaching the customer

Halting systems are sometimes implicated as a safety mechanism for immediate stopping when danger arises.

Warning system pros:
Up to the operator to decide i.e. problem may not be serious enough to stop production completely
Cheaper (line is not stopped for every small error)

Warning systems are preferred in mass production environments where it would be expensive to stop a system completely. As long as the error has been recognised it can be rectified as seen fit by management.

Warning systems are a method of visual management which can be implemented as a part of Poka-Yoke.
Poka-Yoke Definition
Poka-yoke is known as "mistake proofing"; it is a device or a process which helps to prevent human error or flag it before it passes through the system.
There are two types of errors that Poka Yoke attempts to identify: Input & Output Errors

Detection of errors can be done in three ways:
The contact method
The fixed-value method
The motion-step method
When an error is detected within the system there are two possible outcomes which are:

The whole process is shut down so that the system and products are not damaged and there is no danger to human health.

A warning is sent so that the error can be fixed as soon as possible.
Stages involved in Poka Yoke
Firstly the problem needs to be identified!
Immediate action is then taken as appropriate, i.e. on a process line, a defect or error is removed if possible. If this is not possible then it may be the case that the process has to be STOPPED!
Techniques Used in Visual Management
The organisation should then look to make improvements in the process; a blend of EXPERIENCE and YOUTH is key to ensure fresh but safe and valid improvements are made.
1: The Workplace Itself:
Marked floor areas
Direction of process flow shown on floor or wall
Shadow boards to visibly store items frequently needed
Identified equipment & locations
2: Visual Information:
Process documentation
Skill & training boards
3: Visual Production Control:
Visual process indicators
Maximum work-in-progress levels show to prevent over-production
Production status boards
Kanban visual signals
The main solution in Poka Yoke is 100% inspection; this leads on to the idea of ZERO DEFECTS!
4: Autonomation:
The machinery automatically stops when there is a problem and attracts attention
5: Visual Performance Measurement:
Quality charts
Performance charts
Status of the organisation
6: Visual Safety Management:
Safety warnings
Precaution information
It is then of paramount importance that the process is continually reviewed to further minimise defects in the manufacturing environment.
If businesses fail to address the need to constantly be reviewed and improved then there can be exponential financial repercussions...
Reactive warning systems can be incorporated using:
- Sensors such as contact sensors or light gates
- Visual signals such as lights
- Oral signals such as buzzers or alarms
Poka Yoke through Visual management could be effectively applied through the use of human factors, social and industrial standards to provide warnings, instructions, directions, and reminders at a glance.

• Step 1- Identify the problem. i.e Lack of essential information.
• Step 2- Propose solutions - Key information required to operate safely and effectively.
• Step 3- Design a route to inform future users at a glance.
• Step 4- Evaluate the solution- i.e compare current situation with historical data.
• Step 5- Finalise the solution - Make the solution permanent.
Visual Management in the Industry
Management team use:

• Charts
• Signs
• Electronic display boards
• Visual queues
100% inspection attempts to catch every error!!!!!
Defects can be minimised by limiting variation on:
Poor proceedures

Human error can never be completely removed from any system!!
Pros of halting
& warning systems
Poka-Yoke in Lean manufacturing context
The products and interface features must have a particular purpose.

"Defects arise because errors are made; the two have a cause-and-effect relationship…yet errors will not turn into defects if feedback and action take place at the error stage" - Shigeo Shingo
In other words, users make mistakes, but those mistakes are detrimental only if they aren’t corrected immediately.
Visual Management - What Get's Measured Gets Improved !
Manufacturing gone Poka-Yoke through visual management:
Preventative Measures:
A control that physically prevents an action that could potentially damage the system or the user:
'How it's used at different levels'
Office Employees:
Work-Floor Employees:
Such as : HR, Accountants, Sales Team , etc.
Colour Coding - Files, paperword and correspondence
Visual Display boards - Displaying realtime updates of inventory, floor starts, etc.
Office layout - To maximise efficiency.
Pictorial procedures - Procedures towards the "Goal".
Visual performance measurement - Departmental Performance measures.
visual controls including coloUr coding, marking or labelling parts to facilitate correct assembly;
exaggerated asymmetry to facilitate correct orientation of parts;
a staging tray that provides a visual control that all parts were assembled, locating features on parts.
Advantages of
Poka Yoke
Disadvantages of
Poka Yoke
Easy to implement
Detects errors at an early stage
Reduces waste
Increases efficiency
Lowers quality costs
Increases customer satisfaction
Initial cost of implementation
Not 100% effective, zero defects not possible in reality
Validations slow down processes
Advantages of
Visual Management
Disadvantages of
Visual Management
Can be globally understood
'Idiot proof', No specific set of skills are required
Errors and Detection
Visual impairment may hinder understanding
Too technical
Could be ignored easily
Poka-Yoke is a method of preventing or detecting errors before it is too late!!
The technique originated from Toyota's manufacturing regime and the term Poka Yoke was invented by Shigeo Shingo
Preventing measures include designing of components so errors are impossible to make through visual management
Detection systems include:
1- Halting systems - an automated measure that stops the entire production line to detect errors or faults
2- Warning systems - the operator is warned against defects and it is up to the operator to act on it
Visual controls including colour coding

Exaggerated asymmetry to facilitate correct orientation of parts

A staging tray that provides a visual control of all parts that were assembled
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