25 terms

Lesson 8: Jidoka

What is the general meaning of the word, "jidoka?"
if the worker feels something is wrong or he/she is creating a defect, then he or she must stop the line.
At Toyota, Jidoka means making defect-free processes by continually strengthening three things:
process capability, containment (defects are quickly identified and contained in the zone), and feedback (so that quick countermeasures can be taken).
Who was the first to intuit the jidoka concept in 1902?
Mr. Toyoda
Who invented "poka-yoke" and what did it achieve?
Mr. Shingo; 100% inspection at a low cost.
What is important about Jidoka?
high defect rates lead to frequent line stoppages, which make flow and pull impossible; kanban system collapses when defective parts are shipped; productivity implodes, lead time and costs increase.
How do you improve reliability?
standardized work; visual management; 5S; reduce human errors
What does poka-yoke translate to?
poka = inadverant error; yoke = prevention
Poka-yoke means
implementing simple low-cost devices that either direct abnormal situations before they occur, or once they occur, stop the line to prevent defects.
What are the requirements of a good poka-yoke?
simple, with long life and low maintenance, high reliability, low cost, and designed for workplace conditions.
Zone control indicates the
controlling of inspection in a particular zone (each management level is encouraged to think in terms of zones); zone control is important for proper and effective inspection and establishing poka-yokes.
What are three types of inspection systems?
judgement inspections (discovering defects), informative inspections (reducing defects), source inspections (preventing defects)
In applying poka-yoke:
inspect 100% of the items, provide immediate feedback to compel countermeasures, source inspections are the most powerful poka-yoke, informative inspections can be effective, especially when based on self-or successive checking.
What are the two types of action in poka-yoke?
shut down and warning
Shut down
these are the most powerful poka-yokes
alerts us to abnormalities by activating a buzzer or light.
What are the three paths to poka-yoke?
work piece deviation, work method deviation, deviations from fixed values.
Work piece deviation
uses poka-yoke uses sensing devices to detect abnormalities in the weight, dimension, or shape of a product
Work method deviation:
uses sensors to detect errors in standard motion; this type of poka-yoke demands that work be organized so that the downstream process has been completed.
Deviations from fixed values:
counters are specially useful in this regard; measure critical conditions such as pressure, temperature, voltage, or other process parameters.
Poka-yoke detection methods:
contact sensors and/or methods; non-contact sensors/devices and methods
Contact sensors and/or methods:
limit switch and microswitch, differential transformers, touch switch
Non-contact senors/devices and methods:
these devices detect disturbances in photoelectric beams, the proximity of solid objects, metal passage, fiber colors, ultraviolet light, vibration, ect.
Implementing Jidoka depends on the success of the following terms:
measure process capability; involve team members; engage team members in their knowledge of poka-yoke; training team members about jidoka and poka-yoke; link jidoka with 5S, standardized and TPM; communicate and promote jidoka.
Jidoka strategy and goals
jidoka should be part of any lean implementation strategy; to sustain jidoka, system must compel improvement; the system should provide guidance on how to improve continuously.
SMART goals of jidoka should be set for items such as:
number or percentage of processes that achieve a specific high rating; number of poka-yokes implemented, kaizen circles, suggestions; percentage of team members trained in jidoka; percentage of team members involved in jidoka.