Defining ‘Autonomation'

Jidoka or Autonomation means "intelligent automation" or "humanized automation".  In practice, it means that an automated process is sufficiently "aware" of itself so that it will:

  • Detect process malfunctions or product defects
  • Stop itself
  • Alert the operator

A future goal of autonomation is self-correction.  This is generally not justified by current cost-benefit analyses. (1)

Examples

Autonomation deals with product defects and process malfunctions.

Product Defect:  A press shapes a piece of metal.  Sometimes the piece breaks under the force.  Manual inspection would require a worker to look at each piece to see if it broke. 

Autonomation would move the output piece onto a jig with a weigh scale.  Then, if the piece does not fit securely, or if the weight is out of tolerance, the press would stop and an alarm would alert the worker.

Process Malfunction:  One machine places output pieces onto a conveyor belt.  The pieces move into a second machine – the press from the first example – for further work.  Sometimes the press stops.  If the first machine and the conveyor belt continue running, the pieces will pile up and spill somewhere.  Manual inspection would require a worker to watch the press, and then stop both the first machine and the conveyor belt.

Autonomation would receive a signal from the press, or notice (by weight, perhaps) that the previous piece was not picked up by the press.  Both the conveyor belt and the first machine would stop, and an alarm would alert the worker.

Problems Without Automated Error Detection

It is difficult for workers to detect all defects, even when alert.  Some of this depends on the machine cycle times, and on the type of testing required.

It is difficult for workers to remain alert and engaged in detecting defects for a full shift.  Workers generally are more satisfied in productive tasks than in full-time error-detection roles.

Depending on the cycle time of a machine or process, the worker may not be able to react quickly enough to prevent damage.

Continuing to run a flawed process will send defective work-in-progress down the line.  More cost will be incurred processing these products which ultimately will be scrapped or re-worked.

Continuing to run a flawed process may damage more equipment – pieces may be jammed into a receiving machine, for example.

Continuing to run a flawed process may damage work-in-progress, if pieces fall off a conveyor belt because the receiving machine is jammed.

If the worker's primary focus is on meeting a production quota, there will be little incentive to detect defects and correct the problems.  Even if quality control and error detection are rewarded, the simple act of working to produce something will take some of the worker's attention away from error detection.

Other Improvements With Automated Error Detection

As more manufacturing and error detecting tasks become automated, it becomes possible for workers to "supervise" multiple machines.  This usually involves setting a worker in a cluster of machines, so that the worker has easy access to each machine.

Summary

Autonomation:

  • Improves the speed of detecting defects
  • Reduces costs by reducing damage to work-in-progress and equipment, and by preventing further processing on flawed work-in-progress
  • Improves operator morale, particularly if the operator is trained to resolve problems (rather than simply calling for a technician)
  • May reduce direct labor costs by permitting one worker to "supervise" several machines

History

Jidoka is a Japanese term used for autonomation and being widely used in Toyota Production System (TPS), Lean Manufacturing and Total Productive Maintenance (TPM).  Concept is to authorize the machine operator and in any case if a problem occurs on flow line, operator can stop the flow line. Ultimately defective pieces will not move to the next station. This concept minimizes the production of wasted defects, over production and minimizes wastes. Also its focus is to understand the causes of problems and then taking preventive measures to reduce them.

History of Jidoka is back in early 1900's, when first loom was stopped due to breakage of thread. This loom was developed by Toyota, and it stops working immediately, if any thread broken.   Taiichi Ohno is considered to be the inventor of this idea and he describes this tool as one pillar of TPS. Shigeo Shingo called it as pre-automation. (2)

The concept of automated line is being used to relieve workers and minimize human related errors. If machine detects any defect or problem, it should stop immediately. The common causes of defect are:

  1. Inappropriate operating procedures
  2. Excessive variation in operations
  3. Defective raw material
  4. Human or Machine error

Jidoka concept was developed due to many reasons, the common reasons are:

  1. Overproduction of goods
  2. Wasted time during manufacturing at the machine
  3. Wastage of time during transportation of defected material from one place to other
  4. Waste of time during defective piece re-processing
  5. Waste of inventory

The purpose of Jidoka implementation is to diagnose the defect immediately and correct it accordingly. Now, human related judgment of component quality is minimized and worker will be only attentive, when machine will be stopped. This concept also helps in sequential inspection of components and ultimately good quality products are produced and also not much burden of final inspection is put on the shoulders of worker. Inspection is carried out by machine and when machine stops working, designated person or skilled person rush towards machine and try to resolve the problem. Jidoka focuses to investigate the root cause of that problem and make necessary arrangements so that this defect may not occur again. Defect prevention can be achieved by using Poka Yoke technique.

Jidoka is being effectively used in TPM, Lean Manufacturing and providing substantial benefits to the organizations. Common benefits obtained by its implementation are:

  1. Helps in detection of  problem at earlier stages
  2. It helps in becoming world class organization
  3. Human intelligence is integrated into automated machinery
  4. Defect free products are produced
  5. Enhances substantial improvement in productivity of the organization

When utilizing Jidoka philosophy, Taiichi Ohno had some specific goals of this tool in mind. But with the advancement in its scope, following goals are being achieved through its application:

  1. Effective  utilization of manpower
  2. Product produced will be of top quality
  3. Shorter delivery time of products
  4. Reduction in equipment failure rate
  5. Improve level of customer satisfaction
  6. Increase quality of final product
  7. Lower costs (Internal, External, and Appraisal cost etc.)

By Oskar Olofsson

References:

Michel Baudin: Working with Machines: The Nuts and Bolts of Lean Operations with Jidoka

Shigeo Shingo:Zero Quality Control: Source Inspection and the Poka-Yoke System

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