• Rui Marques

Continuous improvement with Karakuri

INTRODUCTION

How to eliminate waste and better serve your customers with Karakuri Kaizen, meaning process improvement using low-cost automation.


AUTOMATION

Since the beginning of industrialization, efforts have been made to develop and use mechanisms that allow replacing human effort and reducing labor needs.

Thus, in the first industrial revolution, steam and water were used to automate looms and other production equipment. In the second industrial revolution, which began in 1870, electricity was taken advantage of for a new wave of mechanization and automation. From the mid-twentieth century, we witnessed the progressive introduction of robots in manufacturing.

Currently, we can see, more and more, robots replacing human work with advantage in various situations, allowing to perform tasks faster, more accurately and with more repeatability and also to perform high-risk tasks for people.

With the so-called 4th industrial revolution (Industry 4.0) there is a growing enthusiasm in the use of collaborative robots (“Cobots”), which can be integrated into lines or cells where people also work, in adequate safety conditions.

Robotization and process automation, with all their potential advantages, however, have not always delivered the expected results, as we will see below.

The automation or robotization of a production process, to be effectively successful, must be preceded by an analysis of how to eliminate or reduce, upfront, any tasks that do not add value, and a cost-benefit analysis, taking into account all factors, demonstrating that its implementation will deliver true economic benefits.

Unfortunately, and quite often, the automation of processes has not been preceded by the above-mentioned steps, resulting in situations such as the following in which there was no cost reduction, quite the opposite:

  • Reduction of direct labor as a result of automation nullified by the increase in much more expensive indirect labor (maintenance technicians, programming specialists) required for this same automation.

  • Use of robots (in place of operators) to assemble components, but which require additional manual work of positioning these same components so that they can be manipulated by the robot, thus not dispensing with the need for people

  • Use of robots to carry out transport or handling tasks that could have been eliminated, thus dispensing with robotization

Even in situations where the care mentioned above has been considered, robotization may not be the best solution, for the reasons described below:

  • Considerable investment value (despite the downward trend), resulting in long pay-back periods and low ROIs

  • High operating cost:

  • Maintenance

  • Specialized technical assistance

  • Energy

  • Consumables

  • Environmental impact, linked to energy consumption

  • Increase in complexity

  • Vulnerability to equipment failures

An alternative approach, which we will describe later, has proved itself well and should be seriously considered, given the advantages it offers.


KARAKURI

The word Karakuri, in the Japanese language, means device, mechanism, artifice.

In practice, it refers to a tradition of building karakuri ningyo, wooden dolls, true automata, powered by rope and springs, just like clockwork mechanisms.

Although this tradition is said to date back more than a thousand years, the known examples date back to the 17th century.

Among these specimens, the most famous karakuri ningyo is a doll that serves tea. This rope-powered puppet, used to amuse guests, made an approach path when a cup full of tea was placed in its hands. When the cup, after being removed and emptied, was placed back in the puppet's hands, the doll turned around and returned to its original position.


Figure 1: Example of a karakuri ningyo


This example, in fact like other automata developed in the West, show the potential of using truly renewable energies to move objects between two points.

In Japan, the design and construction of this type of automata gave rise to the development of a competence (we can even speak of a culture) that still persists today. Coincidentally, the region where this competence in designing mechanisms powered by rope, springs and gravity was developed is the same region where the Toyota Motor Corporation was originally born and established.


KARAKURI KAIZEN

Karakuri Kaizen can be described as the improvement of work using low-cost mechanisms, aiming at increasing productivity, quality and safety.

Karakuri Kaizen systems are characterized by not using electrical, hydraulic or pneumatic energy, but simple mechanical principles, devices such as levers, pulleys and counterweights, and energy sources such as gravity, springs and the movements of other machines.


Figure 2: Some simple mechanical principles used in karakuri


At Toyota, where Karakuri Kaizen is an integral part of its production system, operators and team leaders are trained in its principles and techniques, in specific training areas (Dojo) and apply these techniques in the daily improvement of work processes. Gemba personnel are trained to not use electrical energy, pneumatics or robotics in the devices they develop.

The cost-benefit ratio resulting from this improvement effort is very interesting, which can explain, among many other factors, the company's competitiveness over the years.

Karakuri devices that are observed in companies that practice this type of improvement are used, among others, to:

  • Bring the product closer to the operator

  • Move products between stations

  • Feed the machine/station with the part to be processed

  • Evacuate the processed part

  • Supply components to workstations

  • Evacuate empty containers

  • Place the part or components to facilitate assembly

  • Feed the right quantity of components

  • Facilitate the handling of heavy or bulky loads

  • Move materials between sectors

  • Prevent or detect mistakes (poka yoke)


Figure 3: Two devices that allow to move the part to the next station


Figure 4: Device that allows the operator to reach the value-adding point


Figure 5: Device to facilitate the evacuation of empty containers


ADVANTAGES OF KARAKURI

Karakuri devices present the following advantages:

  • The investment required is very low

  • Can be developed in very short time

  • Minimal operating costs, as no energy is used

  • Very little maintenance required

  • Can be easily modified and improved

  • No environmental impact

  • Are developed by people on the gemba, who know very well the production process

  • They fit in the spirit of continuous improvement

These advantages make Karakuri Kaizen a very interesting alternative to automation and robotization using sophisticated means.

Unfortunately, there are still few companies that benefit from the advantages of using these low-cost devices. Many companies continue to favor technologically complex solutions, in situations that do not justify them. This reality has been boosted, in some cases, by the enthusiasm generated by Industry 4.0.

Continuous improvement using Karakuri devices requires training production operators in its principles and empower them in their development and implementation.


IN SUMMARY

The focus of continuous improvement must always be to better serve the customer at the lowest possible cost. This requires the continuous identification and elimination of all non-value adding activities, using efficient tools to deliver the required quality.

Karakuri Kaizen makes it possible to tackle, at a very low cost, improvement opportunities related to productivity, quality and safety, involving actively.

And all this involving the true owners of processes and developing their skills.

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