Over time I have seen may organisations try and put their interpretation on takt time. Most try to put some form of ‘fudge factor’ into the calculation. This is normally so they can accommodate and ‘efficiency ratio’ or some form of equipment efficiency measure. But why do they do this?
Well most of the time it is because the organisation has completely missed the point of using takt time as a tool. Most understand that takt time is the ‘beat of the customer’, but few really understand that is is also a measure of waste within the process.
It’s also an Abnormality management tool………..
Used properly it is very easy to understand the cost of stoppages, for example, if our production line is planned to run for 40 hours and produce 2400 units (takt time = 60 seconds) but we only produced 2000 units, then we have a loss of 400 units. it is very easy to see we would have to run 400 minutes overtime to catch back. This in turn we can attribute a true cost to. But the reality is that it makes little sense to add cost to the process in this way. So we have to consider another alternative.
Within the Takt time calculation the key phrase is ‘Available time’. It is quite acceptable to include ‘Planned down-time’ into the calculation so long as it is planned ahead of time.
So we could choose to build into the calculation and amount of time for maintenance and TPM activities to that when we run the process during the planned up-time we can measure the success of our TPM and maintenance.
This is why companies like Toyota do not generally run 3 shift operations. They choose to spend time each day working on preventative maintenance so that when the bulk of the manpower is on site, the lines run to pure takt time. That way they can look for not only at the quality of the equipment maintenance, but also look for small incremental losses. The trick is to have a very good capture system and have the infrastructure to put into place good countermeasures.
The moment you add ‘fudge factors’ into the calculation you are sending the message that some inefficiencies are OK and you loose the ability to put pressure on the organisation to find and fix its inherent abnormalities.
So before you try to make up your own takt time rules, think about the message you are sending and is there a way you can organise the operation in a different way to drive people to improve and look for small losses.
The word Takt is derived from the German word for beat. In the case of Lean, this refers to the pace of the process as dictated by the customer. If the customer orders 10, then 10 must be produced, not 9 or 11.
The best way to visualise this is by imagining an orchestra with the conductor at the front. He is the customer. The conductor moves his baton up
and down to indicate the ‘beat’ of the music he requires. The musicians follow this beat, all at the same speed, completely synchronized. If he speeds up, the entire orchestra speeds up with him. As he slows down, so do the musicians.
This is the concept of Takt time. A process should adjust its output based on ‘true’ customer demand and not keep running at its maximum speed.
Takt time can be calculated on virtually every task in a business environment. It can be used in manufacturing e.g. machining parts, drilling holes etc. In administration e.g. processing orders, call centre operations etc or in a production line environment, to pace the line.
When implemented correctly, running a process to Takt time provides many benefits. Just a few of these are:
- Since you produce only what is required by the customer, inventory is reduced
- Since the ‘product’ moves along the process at a given speed, bottlenecks are easily identified.
- Since problem processes are easily identified. repeat issues, like breakdowns, can be understood and fixed.
- Since the process moves at a fixed speed, work is balanced across all operators. If it is not bottlenecks will occur.
A lot of confusion can be generated around Takt time calculations. The simplest way of calculating Takt time is to calculate the Takt time for the output of the process. Work from the perspective of the customer.
In order to calculate Takt time, two pieces of information are required.
- Available Time – this is the shift time minus any breaks, clean up time etc.
- The Average Customer Demand – how many does the customer actually require in a given period.
Work in fixed periods (days or weeks) and apply the following calculation.
A store card company receives 2,100 applications per month. And on average they work 20 days per month.
Workers are paid for 7.5 hours per day. They have two 15 minute coffee breaks per day – which are paid.
So the Takt time is calculated as follows:
From the 7.5 working hours 30 minutes must be deducted (for breaks). 7 hours = 420 minutes
2100 / 20 = 105 applications per day
Therefore the takt time calculation is as follows:
420 minutes = 4 minutes
So if we were processing applications to Takt time, you would expect to see an application being processed every 4 minutes. Running with a Takt time of 4 minutes means that the process is set up to deal with the customer demand as efficiently as possible.
This Is an extract from the book Tools for Success, by Barry Jeffrey and Graham Ross. If you would like to know more why not follow the link www.kaizentrainer.com
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 !
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 .
The ‘Cost of Quality’ is not the price of creating a Quality product or service. The true ‘Cost of Quality’ is the cost of NOT creating a Quality product or service.
A lot of companies do not fully understand the effect that a poor Quality process has on the business. Poor Quality not only affects customers, it also has a dramatic effect on lead times, delivery, and most importantly profitability.
Consider that every time rework is undertaken, the cost of Quality increases. Obvious examples include:
• The correction of a bank statement
• The reprinting of a lost document
• The reworking of a manufactured item
• The retesting of an assembly
• The replacement of a over cooked meal in a restaurant
These costs would not have been incurred if Quality were perfect. In order to fully understand this concept, consider the costs that would be eliminated if Quality within the process was perfect. Consider costs such as: incoming raw material inspection; corrective engineering change orders, scrap, in-process control systems, downtime, material and labour rework charges, Quality personnel labour costs, field service repair personnel, returned goods processing, customer warranty claims and many others.
These are all costly processes and consume resources and time. They are normally considered necessary non value added steps. In other words, they cannot be eliminated because of significant risk to the customer.
Calculating the Total Cost of Quality.
In order to calculate the Total Cost of Quality the cost of the following operations need to be considered:
• Internal Failure
• External Failure
The overall Cost of Quality (COQ) is calculated using the following equation:
COQ = Prevention Costs + Inspection Costs + Failure Costs
Prevention Costs are defined as all activities which have been designed into the process to specifically prevent poor Quality in products or services. Examples of these costs include:
• New product development reviews
• Supplier development work including capability surveys
• Internal process capability development and evaluations
• Quality planning activities
• Quality improvement team meetings
• Quality education and training
Costs are defined as all activities associated with measuring, evaluating or auditing products or services to assure conformance to Quality standards and performance requirements.
Examples of these costs include:
• Incoming and source inspection and testing of purchased material
• In-process inspection processes
• Final inspection and test
• Internal audits
• Maintaining of records
• Calibration of measuring and test equipment
• Purchase of associated equipment, supplies and materials
Failure costs fall into two clear categories, Internal and External failure.
Internal Failure Costs
Internal failure costs are the costs that occur prior to delivery of a product or service to the customer. Examples of these costs include:
• Scrap costs
External Failure Costs
External Failure costs occur after delivery of the product or service to the customer. Examples of these costs include:
• Processing Customer returns
• Rework under Warranty claims
• Processing customer complaints
• Replacing the product
• Product recalls
By far the most expensive of all these categories is failure. Both internal and external failures. The cost of the original product, the cost of the replacement, the cost of processing, can cost up to three times the cost of the original product or service.
This is an extract from Practical Quality by Graham Ross and Barry Jeffrey. If you would like to know more why not follow the link
Having spent years working in a Toyota plant, I know how it ticks. But one of the skill’s that the team had there that I have yet to experience with
such commitment anywhere else is to perform a technique called Yokoten
The direct translation of Yokoten is “Across everywhere” or “Best practice sharing”
When a problem, be it safety, quality, breakdown or supply chain, occurs, firstly the problem is addressed, and the countermeasure is confirmed as good.
Then a very simple question is asked “Could the problem exits of occur somewhere else?” The Toyota production system then requires the team to religiously perform checks to find out the answer, as a matter of priority.
If the answer is yes, then the fix from the original problem is put in place in all locations that a similar potential problem, thus preventing a future issue occurring.
This is done, even if there is a cost or time implication, because the cost of a further breakdown or quality issue would be far greater in the long run.
The question is asked every time by managers at problem reviews. Importantly, no blame is apportioned; the philosophy is ‘to find a problem once, is good, it’s an opportunity to improve. But to find it a second time means the system has failed.’ The focus is on prevention of re occurrence.
When an A3 report is used, the final two question boxes as ‘does this issue exits elsewhere’ and has ‘Yokoten’ been completed. Only when these two questions answered, is the problem considered closed.
Yokoten is also strengthened through the regular departmental and Production Working Group meetings, which is made up of representatives of all plants and reports directly to top management, with careful attention paid to “Best Practice” at all the facilities.
This level of the use of Yokoten helps to ensure that all plants “level up” to the best performance in the group.
A very powerful tool to quickly improve a processes reliability, but it requires great commitment and discipline.