Walther-Präzision: Poka-Yoke – Mistake Proofing of Quick Connection Systems

Poka-Yoke (ポカヨケ) is a Japanese term that means “mistake-proofing”. Poka-Yoke is any mechanism in a lean manufacturing process that helps an equipment operator avoid (yokeru) mistakes (poka). Its purpose is to eliminate product defects by preventing, correcting, or drawing attention to human errors as they occur. The concept is very important and broadly, the term can refer to any behavior-shaping constraint designed into a process to prevent incorrect operation by the user.

Figure 1: Mono Couplings in non-interchangeable arrangement

Process reliability and thus protection against mix-ups is a sensitive issue of increasing importance especially when dealing with aggressive and hazardous substances like those used in the chemical and pharmaceutical industries. As a technology leader in the area of industrial quick coupling systems, WALTHERPRÄZISION addressed this challenging issue early on and developed a series of pioneering locking and signal elements designed to connect media interfaces safely, flexibly and without any mix-ups. In this way, optical, mechanical, electronic and a combination of these construction elements are available today.

Mechanical Locking Elements

With Mono-Couplings, for example, various ring diameters can ensure designs on the guide parts of the locking coupling or mechanical coding so that only coupling halves which belong to each other can be connected to each other with the corresponding closure. Differently colored guide parts continue to facilitate the optical classification.

Figure 2: Mono Coupling Coding Principles

Figure 3: Poka-Yoke: UM-Series - Coded Couplings by WALTHER-PRÄZISION

Classic shapes for non-interchangeable Mono-Couplings are triangular, square or pentagonal heads. The distinctive form of closure makes an optical classification easily possible.

Figure 4: Poka-Yoke - UF-Series - Non-interchangeable couplings by WALTHER-PRÄZISION

Multi-Coupling Systems: Poka-Yoke Built-In

Multi-Coupling Systems by WALTHER PRÄZISION are non-interchangeably designed. A variety of liquid, electrical or gas lines can be process-reliably and non-interchangeably connected at the same time with customized systems for multiple media interfaces.

Figure 5: Multi-Coupling, schematic

Depending on customer requirements, the Multi-Couplings are equipped with additional sensor/signal elements. The use of these sensors allows monitoring of individual coupling conditions. This enables the integration of the Multi-Coupling into the PLC of an automatically controlled process.

Customized High-Tech Solutions

With the remote monitoring of processes, electronic safety and signal elements play a decisive role in the constant monitoring of the status of a separable connection. Especially in complex production plants, the apparent condition check is often dangerous or even impossible.

Non-contacting sensors by WALTHER-PRÄZISION are used in these cases such as e.g. initiators which are attached to a side of the coupling. The matching counter parts of these couplings are equipped with the corresponding encoders. They address the initiators in a specific, defined code pattern and document, for example, which storage tank is connected to which station. Of course, free coding or the use of data carriers in conjunction with the corresponding readers or the use of the most modern RFID identifiers is also possible.

Figure 6: RFID in the schematic layout

Here, the RFID antenna in a permanently installed coupling half (fixed half) identifies the RFID transponder located in another coupling half (free coupling) when they couple (see Fig. 6). In coupled state, all important information (including transponder data storage) is transmitted contact-free by the transponder from the free half to the fixed half. The coupling point is now clearly to identify through the RFID transponder coding. The controller can automatically start subsequent process steps. Since a lot of information can be stored on the transponder, a complex process control is possible. Equipped with such a RFID, an incorrect manual operation is virtually impossible and each coupling process can be clearly documented and each filling operation controlled. A multiple mechanical coding can also be done using an integrated pin system to mechanically exclude any mix-up. A typical application area is the loading of chemicals into mobile containers because with improper operation or control of such systems, hazardous liquids or gases can escape. Such accidents can be avoided through the use of modern process monitoring having RFID technology.

Figure 7: Sensor coded WALTHER-PRÄZISION couplings


The economically optimal use of large-scale systems is often only achieved with fluidic lines which are flexibly connected to defined coupling joints. Quick coupling systems by WALTHER-PRÄZISION offer safe, fast and comfortable solutions. Robust, reliable and upon request, noninterchangeable and fully integrated into customer processes – ideal for safety and maximum productivity.

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