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.
