Type of sensing Devices :

Type of sensing Devices :

1. Limit switches, Micro switches
2. Proximity switches
3. Photoelectric switches
4. Beam sensors
5. Sensor to detect changes in physical condition like temperature, pressure etc. (Pressure switches, thermostats etc.)

Contact V/s Fixed Value V/s Motion Reading Methods for Poka-Yoke classification

C. Contact V/s Fixed Value V/s Motion Reading Methods for Poka-Yoke classification :
These use the principle of physical or energy contact with the product using sensing devices. They range from guide pins, limit switches, photo electric beams, etc.
Contact methods often take advantage of parts that are designed with an uneven shape. We can use guide pins or blocks that don’t allow the product to be seated in a machines jig in the wrong position.

Alarm V/s Shutdown V/s Control

B. Alarm V/s Shutdown V/s Control :
•Alarm : Signals in form of buzzers, blinking lights are to warn when an abnormality, has occurred (defect) / about to occur (predict)

•Shutdown : Normal function of machine or process is stopped when defect predicted / detected.

•Control :
1. In Prevention type Poka-Yoke : control means that even intentional errors are impossible or methods by which the cause of defect if starts happening, it is automatically prevented from happening (feedback mechanism)
2. In Detection type Poka-Yoke : Control means that the process is not stopped but the defective items are automatically separated out & are not allowed to pass on to next stage.

Prediction V/s Detection -POKA YOKE

A. Prediction V/s Detection :
When a Poka-Yoke is designed in a way that it helps the operator to recognise the defect before it is about to occur, it is called a Prevention or Prediction type Poka-Yoke.

When a Poka-Yoke helps the operator to know immediately on the occurrence of the defect then it is called Detection type Poka-Yoke.

Detection is “after” the defect is produced. The merit of this type of Poka-Yoke is based on the stage at which the defect is detected.

Basic classification of Poka yoke

•PREDICTION V/s DETECTION
•ALARM V/s SHOTDOWN Vs CONTROL
•CONTACT V/s FIXED VALUE V/s MOTION READING METHODS

Pokayoke for eliminating defects -How ?

ERROR ARE INEVITABLE BUT CAN BE ELIMINATED
People always make mistakes. These can be reduced or even eliminated. Some of the Poka-Yoke devices, which can help to avoid defects are:
-Guide Pins / Locators of different sizes
-Error Detection Buzzers & Alarms
-Limit Switches, Proximity & Photo sensors
-Counters
-Checklists

Pokayoke for eliminating defects

Poka yoke is a technique for avoiding simple human errors at work.

Poka is a Japanese word meaning “Inadvertent error” and
Yoke comes from Japanese word Yokerie meaning “to avoid”.

This has been termed as “Mistake / Fool Proofing”.