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Flow racks are also known as first-in-first-out (“FIFO”) racks, gravity racks, cartons flow, or gravity-fed rack (“GFR”). They enable containers, plastic bins or loose parts to flow from back to front thanks to inclined racks where gravity naturally forces parts to be consumed on a first-in-first-out basis. Flexpipe’s five types of flow racking system can increase your production line’s efficiency and reduce production costs in several ways. How? Read on for detailed descriptions of each type of structure and how they can solve specific production problems.
Flow racks are very easy to implement in any given facility as part of the FIFO method. Here’s how it works, on one side, the employee tasked with keeping materials in stock at the point of use in production areas (sometimes referred to as a “water spider”—‘mizusumashi’ in Japanese) will supply containers of new parts to the production side on inclined tracks. They will then unload the empty containers from return lines.
On the production side, workers will always pick the oldest components available first, then channel the empty component containers back to the supply side. The structures are designed and built to bring parts as close as possible to the work zone, thus ensuring that employees work ergonomically.
Flow racking structures are ideally suited to a Kanban system. The structures are also essential in Lean Manufacturing as production lines can operate without the stoppages that would typically occur when restocking employee workstations. Implementing gravity racks can therefore substantially increase productivity.
For more information on how to build a flow rack, please read our
How to build flow racks and part presentations article.
Let’s start with return lines for empty containers: these are tracks which move empty containers from the production side to the supply side where an employee can replenish necessary parts. That way, they do not have to step into the production zone to load or unload containers.
Now, while return lines are not a type of gravity flow rack, we highly recommend implementing them for these reasons: to make part replenishment faster, to reduce work interruptions so the production line can maintain its pace, and to free up employee workspace. For ergonomic reasons, return lines are always located at the bottom or the top of the structures.
Supermarket racks, or marketplace racks, are higher density flow racks strategically located on the production floor to create mini stockrooms. They reduce transportation time—one of Lean Manufacturing’s eight wastes—between the production line and the storage area, in addition to cutting down on forklift traffic. The stock level in a marketplace rack will be higher than the point-of-use racking, but lower than the central warehouse.
While most flow racks are designed to be in a straight line, some of them are built in an L-shape. This configuration saves workers from making unnecessary, repetitive movements. L-shaped gravity racking are used widely in the automotive industry to bring parts as close as possible to the operator’s machine. However, these structures are not intended for this industry only; they can be used in any environment to make workers’ tasks safer and more efficient. check out the photo gallery to see how we create it.
Depending on the size and weight of your containers, it is best to test and rework your prototype, so it accurately meets your requirements. Once you have mastered this type of structure, you will be able to create a Z-shaped flow rack with two angles.
These structures incorporate the concept of gravity racks by its eight-foot roller tracks. The one-piece flow concept is a core element of Lean Manufacturing, widely used in the Toyota Production System (TPS), where each operation only builds what the next operation needs. Subway restaurants also use single-piece flow to custom-make one sandwich at a time on a long—but not deep—counter.
The stations are built in such a way that employees can work on only one product at a time. By creating a workspace restricted to the bare minimum, workers naturally carry out their tasks according to the one-piece flow concept. Also, as roller tracks also move products more efficiently from one location to the next, employees are less inclined to make unnecessary movements.
Flow tracks are integrated into workstations to feed workers with parts, raw material, hardware, fasteners, or for sub-assemblies. They are used for small-density bins such as fasteners, whereas portable flow racks units will store bigger parts. Additionally, embedding gravity racks into workstations saves floor space and reduces costs. When designing return tracks for empty containers under a workstation, remember to make them short enough so as to leave enough room for the workers’ feet.
Julien is one of the co-founders of Flexpipe. He has been working in the material handling industry since 2006 building custom-made steel racks, carts, and workstations. He has a large experience in implementing tugger carts for lean manufacturers trying to improve material flow. He started Flexpipe in 2011 and since then, he made his mission to grow Flexpipe and deliver the modular system to new markets by making it more affordable.