Karakuri (industry)

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Karakuri (industry) ( Japanese か ら く り , dt. "Mechanism") stands for mechanical automation in industrial production and logistics . It is part of the concept of lean production and is classified as "Low Cost Automation" (LCA). The energy required for propulsion is primarily obtained from gravity (potential energy) and muscle power, and rarely from magnetism. Weights and springs are mainly used as energy stores. The control or regulation takes place z. B. with the help of cables or camshafts. Electrical, electronic, hydraulic or pneumatic elements are largely dispensed with.

designation

The choice of a Japanese term indicates that mechanical automation originated in Japan in recent history. Indeed, the history of the use of automation mechanisms can be traced back to ancient Greece. In view of technological progress, however, the use of electrical and electronic components is now considered state of the art. Current developments are also aimed at increasing digitization . Against this background, Karakuri is a return to simple and therefore economical, safe and environmentally friendly options for automation. This corresponds to the guiding principle of lean production , which also comes from Japan.

The origin of the word Karakuri also refers to mechanical dolls, which have been referred to as Karakuri ningyō in Japan since the Edo period in the 17th century and which have now inspired mechanical automation in the industry. In fact, mechanical dolls have been found in many cultures since ancient times.

technical basics

Exemplary schematic diagram of automation based on the Karakuri principle

Karakuri is used in production and logistics to automate the handling of objects. The components required for this are designed mechanically as far as possible. That concerns in detail

  • Actuators (final control elements). These draw the energy required for their operation primarily from the force of gravity of the transported goods or from the muscular strength of workers, whereby this can be dosed using levers, pulley blocks or the like. Energy is seldom obtained from magnetism. In addition, mechanical components such as B. cables, chains , levers or gears are used. The schematic diagram shown in the first figure shows (1) how an elevator is moved downwards by the weight of a transported item, while a counterweight is thereby pulled upwards. (2) As soon as the goods to be transported have left the elevator on the lower level, the counterweight pulls it back up.
  • Sensors (measuring elements). They record states or events and convert them into signals. In mechanically automated systems, these are usually transmitted directly to actuators, for example with the help of a Bowden cable or lever .
  • Control or regulation : In purely mechanically automated systems, the levels of the automation pyramid above the field level are omitted . The logic required to control the system is contained directly in the mechanical connections between sensors and actuators.
Transport of small load carriers (KLT) according to the Karakuri principle

The second figure shows the interaction of sensors and actuators using an example. At the point marked with the number 1 in the system part shown, a lift lifts a small load carrier (not shown) from the lower level to the upper level. Once at the top, the lift engages in two locks (actuators). One of them can be recognized at the point marked with the number 1. The small load carrier (KLT) rolls over the roller conveyor to the point marked with the number 2. There the role acts as a sensor. If the KLT rolls over it, it pushes the roll down. As a result, two Bowden cables are pulled via an actuating lever, which in turn release the two locks. The lift then descends again to move the next KLT up.

In a conventionally automated system, a sensor at point 2 would first translate the mechanical signal into an electrical signal. This electrical signal would be transmitted via a cable to an electronic control system, where it would be evaluated by a program in order to be transmitted from there as an electrical signal to an electrically, pneumatically or hydraulically operating actuator (1). Karakuri saves this detour and implements everything mechanically immediately. This not only saves electrical energy and expensive components such as an electronic control system and its programming, maintenance is also easier, since errors are immediately recognizable and can usually be rectified by the staff on site.

economics

To assess the economic viability of Karakuri, the effort and benefit must be compared and compared with the corresponding factors of conventional automation.

In terms of benefits, mechanical automation is in no way inferior to conventional automation in many areas of application. A distance can be covered by using the force of gravity of the transported goods on a sloping roller conveyor with the same speed and safety as with the help of a horizontal, electrically driven belt conveyor . Small load carriers can be separated just as reliably with the help of levers and rope pulls as with the use of electronic sensors and electrically operated actuators. Actions can often be triggered just as easily with muscle power without any particular effort as by pressing buttons, which then send signals to electronic sensors and controls in order to finally set electrically driven mechanisms in motion. And energy can be stored not only electrically, but also mechanically, for example as potential energy in weights or as tension energy in springs . In this respect, mechanical and conventional automation are on par in terms of their functionality in many applications.

The difference therefore essentially results from the respective effort. First of all, it is important to consider that conventional automation of mechanical processes also requires mechanical components: a conveyor line for small load carriers remains a conveyor line, regardless of whether it is driven mechanically or electrically. It is therefore crucial how the logic of the interaction of the moving parts or devices is effected.

For a mechanical solution, energy must first be mobilized. This is often fed by the gravity of the transported goods. A suitable mechanism such as a lever may be required for this, and in certain cases also an energy storage device, for example a counterweight or a spring. Furthermore, connections between mechanical sensors and mechanical actuators, for example Bowden cables, may be required. Mechanical automation cannot be implemented entirely without sensors, energy storage devices and actuators.

For a conventional solution, however, considerably more expensive components are usually used. As the example explained above has already shown, mechanical signals are often first converted into electronic signals. These are forwarded to higher-level electronic controls and processed there with the help of complex software. From there, electronic signals go , on the one hand, to the higher-level control level , where computers are used for monitoring and control, and, on the other hand, back to the field level, for example to electrical drives, which often need their own electronic components such as frequency converters . In addition, the speeds of electric motors, which are usually far too high for normal applications, have to be converted into low speeds with the aid of gears , and then sometimes the rotational movements must also be converted into translatory movements.

Gravity energy is available free of charge almost always and everywhere. In contrast, electrical energy for operating electrical, pneumatic or hydraulic components has to be paid for more and more expensively. In addition, the effort for development, operation and maintenance for conventionally automated systems is higher than for mechanically automated systems due to their complexity and the qualifications of the relevant personnel required to cope with them. And the advantages explained below in terms of environmental protection and occupational safety also offer economic advantages. It can therefore be stated that mechanical automation is economically superior to conventional automation wherever it meets the requirements.

environmental Protection

Ecological effects result on the one hand from the production of automation solutions and on the other hand from ongoing operations. Both at Karakuri and in the conventional sector, mechanical components of automation solutions are mainly made of aluminum . The production of this material has a significant impact on the environment . After all, a large proportion of the material can be recycled. In this respect, Karakuri offers no ecological advantages, but neither does it offer any disadvantages compared to alternative solutions. However, Karakuri solutions are advantageous because

  • that they are designed as frameworks . This achieves a good relationship between stability and material use.
  • that the components themselves can usually be reused many times, so that no recycling of the material is necessary.

During operation, it is particularly advantageous to largely dispense with electrically, pneumatically or hydraulically operated components because the energy required for this is saved. And the need for spare parts is mainly limited to mechanical components that have a significantly lower impact on the environment.

Osh

With regard to occupational safety , the same requirements must be placed on Karakuri solutions as on all systems in which energy is converted. This particularly applies to the Product Safety Act . It is not always clear whether a CE certification is required for Karakuri systems , but in practice it is common to do this as a precaution. In individual cases, however, this can be subject to a subjective assessment and the subject of negotiations between the system manufacturer and the system operator.

However, safety precautions and measures are often easier to implement in mechanically automated systems than in systems that use external energy and are electronically controlled. For example, measures due to a failure of the energy supply in accordance with Directive 2006/42 / EC (Machinery Directive) , Annex I, point 1.2.6 or an error in such a supply in accordance with Annex I, point 1.5.1 are not applicable.

A current problem with mechanically automated systems can be a comparatively high level of noise emissions ( Machinery Directive, Annex I, Point 1.5.8) . This applies, for example, to roller conveyors compared to belt conveyors. In this regard, the manufacturers of Karakuri components still have some catching up to do to design moving parts in such a way that the noise they cause is minimized.

Developing Karakuri Solutions

A Karakuri system is usually developed and built directly in production. Representatives of the staff who will later operate the plant are involved in this ( participation ). This corresponds to the philosophy of lean production , that the skills and abilities of all employees are the most important capital of a company. This has the following advantages in particular:

  • The employees working in production can contribute their know-how to development. That usually leads to better solutions.
  • This increases the acceptance of new solutions ( change management ).
  • The employees are able to maintain the systems themselves during operation and to carry out minor repairs independently and on their own responsibility. This reduces response times in the event of malfunctions and increases system availability.
  • The low complexity of Karakuri promotes the process of continuous improvement ( Kaizen ).

This is helped by the fact that only very few, simple tools are usually required to build and maintain Karakuri systems. In many cases an Allen key is sufficient . While conventional automation solutions are usually supplied turnkey by system manufacturers today, this would contradict the idea of ​​lean production with Karakuri systems. In Japan one says in this context: "Monozukuri wa Hitozukuri kara", making things begins with making (educating) people. The values ​​expressed in this way come from the artisan ethics , according to which it is important to bring knowledge, skills and passion into one's own work and to strive for perfection in the sense of continuous improvement ( Kaizen ).

classification

Karakuri, like the main idea of ​​lean production, can be understood as a frugal innovation . In Latin, frugalis stands for simple and economical, but also for usable and suitable. Frugal solutions are limited to what is immediately necessary. However, it has to be flawless, durable and low-maintenance. Planned obsolescence for the artificial generation of downstream sales is excluded. Furthermore, frugal solutions are characterized by their ease of use, so that costly training can be avoided.

literature

Individual evidence

  1. ↑ Omkar Kalbhor, Tannay Neve, Omkar Pachpor, Nikhil Bhoite, Aniket Deshmukh: Study of Karakuri Kaizen . In: IJSRD - International Journal of Scientific Research & Development . 6, No. 2, April 2018, pp. 2435-2437.
  2. ↑ Adela J. McMurray, Gerrit A. de Waal (eds.): Frugal Innovation: A Global Research Companion . 1st edition. Routledge, Abingdon / New York 2019, ISBN 978-0-367-13284-2 .