Just in time with radio

“Wireless Kanban” simplifies reconstitution of consumption in production systems

How can more than a thousand switching devices be integrated in an electronic Kanban system? Identytec GmbH & Co. KG in Hanover has found a solution which is as logical as it is innovative: by eliminating cables and using wireless position switches.

In 1947, Toyota Executive Taiichi Ohno attached cardboard cards to warehouse stock and instructed production staff to remove the cards and put them into a Kanban box as soon as containers became empty. In this way the planning staff at the factory had constant feedback regarding the articles which needed to be re-ordered or re-produced, allowing them to reduce warehouse stock to a minimum without ever being in danger of running out.

E-Kanban: material ordering at the touch of a button via ERP
Today the flow of information no longer requires cards because the “container empty” feedback takes place via computer. This kind of electronic reconstitution according to the “pull” principle is known as e-Kanban.
Identytec GmbH & Co. KG has developed intelligent hard and software solutions for precisely this task. One of the hardware components is the “ID Tag”: a mobile call button which enables assembly staff to request goods or parts. At the touch of a button the ERP system knows to re-supply the assembly point in question with a desired product.

Using the “ID Shell” developed by Identytec, reconstitution of a shelf occurs completely automatically, without even requiring the pushing of a button. Here a roller conveyor shelf is fitted with a position switch module. Via a rocker, the position switch detects whether the shelf is full or empty. As soon as production or assembly staff remove a container, the position switch automatically sends a signal to a Wi-Fi communication unit, which in turn triggers an order in the ERP system.


Wanted: signal generation from over 1000 transmitters
The software which Identytec has developed for these e-Kanban systems is called “ID Connector” and links the terminal devices such as the roller conveyor shelf to a control station, and thus also to the ERP system. Other devices, e.g. label printers or mobile control terminals on forklifts, can also be integrated in the IT structure in the same way.

Users of the e-Kanban system include car manufacturers choosing to equip numerous assembly points with this efficient method of material supply. The method facilitates simultaneous management of more than 1000 articles along a production line or in a production hall.

In its choice of switchgear Identytec decided to opt for an innovative technology in order to save assembly costs and remain flexible. As transmitters for the individual shelf compartments, RF 96 TK position switches sending wireless signals were selected. These switching devices use a stable and yet low-energy wireless protocol reaching the receiver unit in question extremely reliably and with high transmission quality.

When the warehouse stock is lightweight, or when the shelf design is so compact that updating to wireless rockers is impossible, an RF 96 LT wireless light scanner is used instead. This light scanner uses the same wireless standard as the electromechanical wireless switchgear.
High transmission reliability, long battery life
All of the abovementioned wireless switching devices are to be found in the steute Schaltgeräte GmbH & Co. KG product portfolio. The energy required to send the signals is generated either via “energy harvesting” from the surroundings or – as in this case – via long life batteries. Transmission of the radio signals requires only small amounts of energy, meaning an advantageous battery life of more than 4 years.
By assigning transmitters to receivers, set up in just a few steps prior to initial use using the teach-in method, numerous wireless switching devices can be used in parallel. Previous experience in various application fields has shown that the function of the devices is not interfered with by other wireless networks (e.g. Wi-Fi).

In the electronic Kanban system a wireless rocker switch detects when a user removes a container and transmits a corresponding signal to the ERP system

Self-sufficient pull wire switch working according to the “energy harvesting” principle

For evaluation of the radio signals users can choose between different single- and multi-channel receiver units, installed inside the control cabinet. A practical, simple-to-install, complete solution for wireless communication is therefore available which can be adapted by steute to suit individual user requirements and wishes if so desired.

The electronic Kanban systems from Identytec are not the only example of steute wireless switchgear in material flow and production technology, however. Pull wire switches from steute have also proven successful with many users for opening warehouse gates from the seat of a forklift. These devices are usually fitted high up under ceilings, and laying cables at that height is several times more expensive than the cost of the switches themselves. Wireless pull wire switches enable these costs to be saved.
Another application example is the self-sufficient pull wire switch (see photo) used by a car manufacturer along its production lines. As soon as a worker discovers a quality fault, he pulls the wire and in this way halts the entire line.Pulling the wire also sends a signal to the control centre, which can then immediately remove the cause of the fault in order to prevent quality from suffering along the entire serial production line.
Andreas Schenk is Product Manager of the Wireless business division at steute Schaltgeräte GmbH & Co. KG in Loehne, Germany

  Ask For More Information…