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Pick-to-Light: A Definition

One LED light, one handle, done – that’s how simple the picking process is with a pick-to-light system. Without confirming and paperwork. It’s easy to install, easy to use, and makes for a simpler, more competitive picking process all round.

What is Pick-to-Light?

The terms Pick-to-Light and Pick-by-Light are widely used in Industry 4.0. They stand for a procedure in which a worker is guided through an assembly process or a picking operation by light signals. For this purpose, light indicators directly on the material containers indicate which part of the worker needs for the next assembly step. The P2L sensor thus indicates the next work step and monitors its execution. If the worker reaches into the wrong compartment, the systems shows that and, depending on the programming, he must carry out certain actions, e.g. acknowledgement or ejecting parts for reworking. The Pick-to-Light system is thus one of the paperless systems in order picking, i.e. systems in which pick lists are replaced by more modern technology.

This system is intended as a support for the workers. The Pick-to-Light system is not a time-based clocking system, but only serves to keep the worker’s hands free and allow full concentration on the assembly process by facilitating the picking process. Workers nevertheless remain independent and self-reliant.

Installation

The installation of a Pick-to-Light system does not require much space, but  a control system within the plant in the form of software for the picking process is necessary. For this purpose, the Pick-to-Light system can be integrated into existing warehouse management systems or every manufacturer can purchase and set up new software.

Advantages

This approach offers several advantages. With P2L, for example, a high level of process reliability is achieved in manual assembly and picking processes, which is a great economic advantage, especially when a large number of variants are produced in small batch sizes. According to the Poka Yoke principle, as many error sources of a manual process as possible are eliminated. Assemblies with a large number of variants for small batch sizes are particularly prone to errors, and process reliability is of great importance, especially with safety-relevant components, and can be permanently monitored and documented with a pick-to-light system. The small design and the small minimum distance also allow very flat shelf levels, which provides for an ergonomic staging architecture with shorter gripping distances. Removal from a material compartment does not have to be acknowledged because the P2L sensor automatically detects the removal. A pick-to-light system can therefore make a decisive contribution to optimising manual assembly in terms of costs and quality and to remaining competitive in the long term.

Other systems and applications

Similar processes to Pick-to-Light include Pick-by-Voice or Pick-by-Vision, where speakers or smart glasses are used according to the same principle. There is also the Put-to-Light system, which guides workers through a picking process rather than an unloading process. Pick-to-light and put-to-light systems can be used together.

Last but not least, Pick-to-Light processes are also used in mobile applications. Typically, Pick-to-Light systems are most effective when the picking distances are short and the distances between parts to be picked are not too long. However, as this is not the case in all installations, the system can be adapted to a wider environment. For this purpose, picking vehicles are equipped with the Pick-to-Light system, which can then be transported through the plant in a mobile manner to be used at any given storage location.