Kanban

In this article we want to talk about another classic from Lean Management Kanban or the so called Pull System.

The word Kanban itself has its roots in the Chinese Japanese language and means card, label or sticker. In industrial manufacturing planning systems or general in logistics control Kanban describes a replenishment system for consumed parts according to the amount used steered by cards that give the signal following the Pull Principle.

The material in the Kanban System is exclusively oriented to the consumption of your production process. The cards are a key element of this kind of control system and provide proper information transfer. Kanban control loops from the work station of flexible production control and serves to smooth material flow through your inbound or even outbound logistics. In addition Kanban serves you to implement a sustainable reduction of material stocks, increases the ability to deliver and saves you pure cash.

In an ideal world Kanban would control your entire value chain from the supplier to the end customer. In this way you would have installed an complete smooth supply chain with almost no chance of interruption and massive stocks. And now comes the but – to steer production with Kanban – a continuous monitoring is required for a smooth material supply. To make it short: it requires discipline from all involved parties along the supply chain.

Lets have a look to the development of Kanban.

The first Kanban System was developed by none other than Taiici Ohno (of course) at Toyota Motor in the 1940s. One of the main reasons for the implementation of Kanban was the low productivity and efficiency of Toyota compared to western competitors. With the Kanban System, Toyota achieved a significant change towards flexible and efficient production control that had a massive impact on productions output while at the same time reducing the costs for inventory in raw material, work in progress (WIP) and finished goods.

To give the complete picture it wasn’t implementing the Kanban system itself to drive the success of Toyota, there are other key factors that together where making the difference. Just to name Just in time as an example of key elements of the Toyota Production System. It is and always will be a combination of different methods and philosophy that brings you forward.

In the 1970s the Kanban Concept was adapted in the industry in the USA and Germany. As they haven’t known better, they pretty much copied the complete Toyota Production System (TPS) in order to get the principles running.

Pull or Kanban System

Either way you call it, the material flow is controlled by boxes or cards. Kanban Cards serving in a simple way all information needed to identify what parts are needed in what quantity at what place. The amount typically is defined by the replenishment time at the work station. With the so called two box principle you make sure that the operator never runs short on components. Nowadays there are also digital version of it called eKanban, but the principle behind is the same. The trigger of supply is the Kanban Card starting of the pull chain of material.

To use Kanban efficient, it is not suitable for all parts. Kanban is perfect for small parts with a small amount of variants and a consistent demand. For this reason, you’ll see Kanban Systems in the industry mostly used for C-Parts management. The rest of the components are steered with the support of MRP. Only in rare cases you find that even the supply of big components are controlled with the Kanban methodology.

One nice side effect with Kanban, you can set up the way you can steer your bottleneck. That means, when you have done a proper value stream analysis you know the capacity for your bottleneck and will only order what this process step can handle.

Poka Yoke

Poka-Yoke is any mechanism that helps to avoid unplanned mistakes. Poka-Yoke is that the application of straightforward, error-proof mechanisms to systematically avoid incorrect assembly, mix-ups or the downstream movement of defective parts. As a result of stable and high-quality methods begin long before the assembly section, simple Poka-Yoke measures will be enforced preventively within the construction and coming up with phase to make sure quality. Poka-Yoke is implemented to avoid: going away out or forgetting process steps, process or operational-related mistakes, incorrect or missing parts, setup or installation errors.

POKA YOKE ポカヨケ ("stupid mistakes - avoidance") is associate ideology that takes a spread of approaches to optimize production processes, particularly assembly. The main target of Poka-Yoke is strive for zero-defect production and to attain it approximately. If defects are detected, the cause is determined. If the cause can be avoided, it's eliminated pretty much as good as doable within the sense of Poka-Yoke and at the best doesn't occur again at all. Poka-Yoke was originally an initiative of Dr. Shingo, Shigeo (新郷 重夫), who is additionally a co-founder of the Toyota production system, of that Poka-Yoke is a core component. Poka-Yoke is beneath the umbrella of Kaizen 改善 ("continuous improvement for the better").

Poka-Yoke may be about recognizing the root causes in time and so eliminating them. Mistakes shouldn't solely be corrected, however prevented the in the longterm by eliminating their root causes. Within the ideal case, in the sense of Poka-Yoke, there are measures that utterly rule out a discovered error by eliminating the cause in the future, e.g. as a result of incorrect mounting is not any longer doable because of fixed given mounting ways (e.g. fitting shapes). Poka-Yoke demands product style ability to make a product design that forestalls errors (avoid incorrect operation) and is powerful against errors (despite incorrect operation no faulty processes). Thus the philosophy of Poka-Yoke doesn't solely begin within the production, however already in the product design.

A widely known everyday example is that the plug of the electric devices and the power outlets, that can't be inserted into the socket the incorrect way round. Measuring instruments may also be designed or programmed in such a way that they will not be misused. Poka-Yoke principles can also be found in other cases, e.g. ATMs dispense your credit card before the payout takes place. Fuel dispenser faucets solely work into the right tank for diesel or petrol, creating it tougher to refuel incorrectly. And so on.

Looking at Poka-Yoke in production "Nobody makes any mistakes" is the target of the Poka-Yoke methodology. Here a list of some mistakes that can typically be found in production:

• Incorrect positioning of assembly components

• Incorrect change of a die

• Incorrect mounting

• Wrong interpretation of directions

• Incorrect polarity in electrical connections

• Incorrect reading of measured values

• Incorrect connection of hoses

• Incorrect entries in devices

• Assembly of wrong components

• Skipped operations

• Operation/programming errors on machines

POKA YOKE follows three simple steps
Measurement:

If you can’t measure you can’t control. Simple fixtures or sensors up to high performance camera systems can support the right execution of processes and provides feedback about the correct or incorrect task completion. Measures can be taken by cameras, mechanical, sensor for light and colors, position, vibration, voltage or temperature.

Detection of deviation:

E.g. deviations are determined by checking the amount of tasks done during one operation - has had the operator enough movement to do the job? Are enough components used? (actual-target comparison). Or simple exploitation geometric mismatches when pins or special marking at the workstation are still visible or not used.

Regulation

When deviations occur make sure that measures are taken such as pulling the ANDON CORD by the so called stop the line authority. Only when error-causing steps are cancelled out a permanent production of OK parts can be achieved.

Only when living according to the Poka-Yoke philosophy on a daily basis and following the principles of Poka-Yoke you will be able to achieve with smart automation and trained operators long term success. Root Cause Analysis and sustainable counter measurements are key. In addition each operator should be trained to detect their own faults during operation.

It might seam to be waste to train operators to detect failures, but no matter how much you planing and effort you put in design, failures occur during assembly or manufacturing. Just think about wiring that is now crossing moving components, parts where the collision was not seen during design and so on, trust me the list can be endless. Some failures will be detected with smart automation checking devices. But these are typically very costly and need special trained people to maintain and most of the time these little pieces of technology can only do one job. Here joins Poka-Yoke the game. Cost efficient, failures or incorrect assemblies can’t be passed on and each operator develops an eye for deviation.

Just keep in mind that if you have mass production or small to middle series can determine if you should install a 100% check or if simple Poka-Yokes can get you where you want.

The most important part of Poka-Yoke at all is that failures are detected when they occur and the exponentially rising costs of defective parts passed on are prevented.

Point Kaizen

Point Kaizen describes improvement actions concentrated on one workstation = on the spot.

In general, all lean activities are striving to increase the output of your processes by simultaneously increasing the level of quality by shorten lead times and using less resources. But not all lean initiatives are reaching these targets. Typically the cause lies in the lack of clear targets by the management combined with a misinterpretation of kaizen activities and organizational change.

Kaizen is the Japanese term for “change for the better” on a continuous matter. Point Kaizen refers to a compressed focus on one workstation and improvement actions during a few days, where e.g. in the end the station is no more the bottleneck of the line/cell. For many people this is considered as “Lean”, but it is only a small part of the journey to real operational excellence.

As mentioned Point Kaizen is a scheduled event. When you have an own Lean Management Team or Kaizen Manager these are the guys who are in charge for the upcoming days. Once the team is gathered the action starts.

5S all over: Yes! Let’s start! Use the euphoria and sort out, get rid of all unwanted objects. Clean-up and proper arrange tools needed. Install e.g. flow racks following the 2 bin principle to ensure straight material flow. The Kanban System and FIFO can’t be skipped. Once the workstation is transformed - everybody is proud to have been part this lean activity and communicates the success story.

If you continue with Point Kaizen activities you will reach a better performance on each isolated workstation and probably everybody thinks that you have a great lean initiative. But the real long term results are missing out. So why to continue with lean activities?

Take a step back and see what you have so far. With the improvement actions on each workstation you have raised the efficiency of all single steps but didn’t consider the flow of material in between. It might be tiring to put all this effort in and then the management comes along and sees no obvious progress. This is the point when you move from Point Kaizen action to a systematical organizational change. This process is focusing on the underlying targets of the organization, such as raising performance, decreasing lead times, improving quality and making more profit.

The A3 format comes back in the game. Not only the A3-report and A3 problem solving but more the target setting on an A3 format that tells the story of how the targets can be reached by preset measures. Combined with the future state Value Stream Map showing all Kaizen Bursts each representing a Point Kaizen activity. All those measures lead to a future state of material and information flow that drives your organization into new spheres. In the future with the new Value Stream your bottlenecks will shift along this stream and always creating new point kaizen starting points. Bottlenecks by this can be either stocks of material, high process times or a lack of information. All Kaizen activities, no matter concerning material or information flow, are implemented following a prioritized list. You not only will have to reallocate resources, but also actively participate on the process of organizational change. You and your mid-management are in the driving seat, you have to know where your organization is heading, so make sure that you and your management are participating on Kaizen activities.

Point Kaizen is the first brick of the foundation for organizational change. With the systematic identification of bottlenecks, Point Kaizen activities can be planned and conducted. To have quick changes but is still able to deliver, one bottleneck after the other is worked on. Each Point Kaizen delivers one piece of improvement for the overall improvement needed. These superordinate targets are an increased output, reduction of lead times by simultaneously achieving Zero Defects Policy and all this combined with lower labor costs.