The concept Poka-yoke was originally developed as part of the Toyota productions system by Shigeo Shingo. it is a Japanese term that means “mistake-proofing”. By interestingly it was originally named “baka-Yoke”, which has the meaning “Fool-proofing”, but this was quickly changed to the less offensive form.
The name is derived from two Japanese words, Poka meaning “Mistakes” and Yokeru meaning “avoid” and really is applied to any mechanism in a lean manufacturing process that helps an equipment operator avoid making mistakes. Its purpose is to stop the process at the point where a defect occurs. This has two effects. Firstly and most obviously, it stops the defect from being passed on the other processes further down the
line. But also, secondly it allows an error to be investigated at the very point and time the defect originated. This makes problem solving much easier and allows ‘counter-measures’ to be put in place, thus improving quality.
There are 3 main types of Poka-yoke device:
- Contact type, which is designed to identify defects by testing the product’s shape, size, color, or other physical attributes.
- Fixed-value type, which is designed to alert the operator if a certain number of movements are not made.
- Motion-step (or sequence) type, which tests if the prescribed steps of the process have been followed.
Poka-Yoke and its use is not reserved for business. Examples can be seen in everyday life. Here’s just a few:
Fill a car with Fuel. Look at the area around the Filler flap. There are at least 3 examples of Poka-yoke devices present.
- The size of the nozzle varies depending on the type of fuel to stop unleaded being put into a diesel. But you can make the error the other way around, so this is not a perfect example.
- When you take the fuel cap off, the cap is tethered to the main body, stopping the motorist driving off having left the cap on the roof!
- The Cap is fitted with a ratchet to prevent over tightening.
Circuit breakers in houses are designed to prevent electrical overloads . When the load becomes too great, the circuit is broken.
Computer Leads, Look at the back of any computer and you will see a plethora of leads. All of the leads have different type plugs on them to stop them being fitted into the wrong socket.
ATM Machines, return your card before your cash is dispensed to stop you forgetting it. This one works on the basis you are unlikely to forget your cash !!!
In the UK 240v/50Hz electricity is used. This can injure people so electrical plugs are designed so that live electrical pins are never exposed. Two forms of Poka-yoke are used here:
- The ‘3 pins’, Live, neutral and earth are positioned and orientated are such that the plug can only fit one way in the socket.
- The pins are insulated near the plug body so that electric shock is not possible when the plug is being pushed in, this also means that if the plug is not fully inserted the current will still pass, but electric shock is not possible since only the insulated portion of the pins is exposed.
Of course there are many more, but I hope this gives you a few examples you can use in lean training courses, or just impress people at a party with your knowledge of Poka-yoke !
Most leaders do not really have a passion for the products they produce or for what their organisations really stand for. But you only have to look at leaders like Richard Branson, Bill Gates or Michael Dell to see the power of the passion they all have for their businesses. People within an organisation look to its leadership for direction, belief in the process and guidance. In order to be a good lean leader you need to display passion for what you are doing.
2. Communicating openly and often
Good leaders convey their belief in the organisation through such actions as attending Kaizen events, visiting customers and opening up direct channels of communication with the workforce. They take time to listen and discuss possible improvements to the process and focus on sending positive messages in a relentless manner
3. Creating a sense of urgency
In the ever growing global market place and ever growing threat from competitors, the truth is that no company really needs to create a sense of urgency. The Job of a good leader is to harness this and make sure that employees fully understand the gravity of remaining stagnant and not improving.
4. Focusing on the Future, not the past
Companies and employees all too often dwell on past failures or rest on past success. A good leader has the ability to look to the future and begin turning from analysis of the past, to focusing on finding innovative solutions for customers needs.
5. Developing good leaders for the future
The ability to take time to find, groom, train and motivate new leaders for the organisation is a key skill. Thinking to the future and trengthening the organisation will in the long term underpin the improvement activities.
6. Focusing on your customers
Good leaders develop a strong bond with the customer base. They take time to visit and discuss ideas and issues first hand; Building up a strong level of trust and teamwork.
7. Measuring your success
The development of a simple cohesive measurement system that can be easily understood by people in the organisation at all levels is a core fundamental that a good leader will ensure is developed. The system must identify metrics that are linked to the strategic goals and capture the effects of changes to the process. Locally teams must be able to collect, analyse and develop countermeasures by themselves.
8. Maintain discipline and focus
After the ‘flavour of the month’ period wears off, employees tend to slip back into old habits all to easily. Sustaining drive going forward is something a good leader must focus on. Arranging regular reviews, daily, weekly, and monthly to check the organisations performance in vital to keep the company on track.
9. Walk the talk
Good leaders to not manage from the office. They have a high profile in process. Getting involved and demonstrating they are full committed to the success of the organisation.
10. Promoting Continuous Improvement daily
Good leaders promote continuous improvement at every opportunity. They convey the message that every part of a process can be improved, not matter how many times the process has been studied in the past. Good leaders praise successes whilst demanding further improvements tomorrow.
Let’s look at the use of the Value Stream Mapping tool and how it can help you develop a good strategic plan that will help you both clarify your sequence of activities and the organisation can buy in to.
A value stream is the series of steps both value added and non value added that occur in order that the product or service can be delivered to the customer.
Value streams are normally measured from the point where the customer places and order to the point where the business delivers a product or service to that customer.
Each product or process will have its own value stream since normally the processes, parts, volumes and workforce will vary.
A Value Stream Map is a pictorial representation that looks at all of these issues and assists you in understanding exactly what is going on. Although a Value Stream Map is only a snap in time. It allows you to quantify the actual process and not relay on peoples impressions of where
all the problems lie. If you were to repeat the Value Stream Mapping exercise on another day, the detail such as the amounts of inventory or the
numbers of quality issues would be different. However in general the Inventory levels, bottle necks and the value add ratio would remain very similar. So do not get bogged down in the very fine detail.
One of the other very important aspects of a VSM is that will help you calculate the ‘Value Added Ratio’. This is a representative ratio of Value Added vs. Non Value Added activities, within the process under investigation.
As a general rule, the process of producing a Value Stream Map is broken down into 7 key stages
- Identify the product, product family, or service that is going to be mapped.
- Gather together a group of key individuals to work on the map as a team.
- Measure the actual state using predefined key metrics. Walk to the floor and look at the real state, do not use system data.
- Using standard symbols, Draw a current state value stream map, which shows the current steps, delays, and information flows required to
deliver the target product or service.
- Assess the current state value stream map. Focus on removing waste, bottleneck processes and think in terms of creating flow.
- Brainstorm what would be the ideal state if all the issues were fixed and the team had a clean sheet of paper. Draw this as a future state
value stream map.
- Work toward the future state condition.
This is an extract from ‘Tools for success’by Graham Ross and Barry Jeffrey. If you would like to know more about Value Stream Mapping and its deployment why not follow the link .