How to build modular flow racks

Many people select containers according to racks and flow racks that they already have on hand—this, in fact, is contrary to lean principles. First determine the ideal material quantity and choose the suitable container size and type to transport the material. Once this is done, designing the flow rack can begin. To make the experience an easier one, read on for helpful tips on each of the flow rack’s components.

Estimated reading time: 10 minutes

  1. Choose your container/tote

    The design of your flow rack will depend on the size and weight of the container that will be moving on the roller tracks. Keep in mind that containers with a flat bottom will roll more smoothly.

    Here are the key aspects to look at when deciding which type of container to use:

    1. Dimensions (L x W x H)
    2. Weight (lb)
    3. Material (plastic, cardboard, corrugated plastic, or stand-alone parts without a container)

    Bear in mind that containers with grooved bottoms may get jammed between the rollers on the roller tracks.

  2. Define your footprint

    The footprint (i.e., space required) of your flow rack will depend on the rack’s purpose as well as the size of the area available on your plant floor.

    If you want to:

    1. Move material from point A to point B on a conveyor rack – see Step 3.
    2. Supply a workstation with material or store parts in “supermarket” style; you must define your footprint according to Kanban – see Step 4.
  3. Lay out your conveyor’s path

    Flowrack conveyor path

    This step consists of establishing the length and path of your flow rack from the containers’ starting point to their destination.

    First, you must measure the distance that the container will cover between machine A and machine B. The longer the distance between the two, the greater the slope’s incline will have to be. So the container’s starting point will be very high up and its destination, very low. Conveyor racks are often used in a shipping/receiving department where the material is loaded or unloaded onto big conveyor racks.

    It goes without saying that the location of machines and workstations already on the plant floor will have a significant influence on the length and path of your flow rack.

    With the new processes, the employees will focus mainly on reducing movement and transportation waste throughout the production floor and the warehouse. The team cut movements to a minimum by revamping the production floor’s layout and using custom-made modular gravity carts to meet employees specific needs.

  4. Define your “supermarket” or flow rack’s MIN/MAX

    Supermarket Flowracks

    Your flow rack’s fundamental purpose is to supply a workstation. That said, you need to set your Kanban according to your minimum and maximum quantities per container and number of containers. This is mostly done with regard to TAKT Time (Takt is the German word for when an orchestra conductor uses a baton to regulate the music’ tempo). In lean, it’s the rate at which a finished product needs to be completed to meet customer demand.

    In production facilities, it’s best to keep only a small lot of materials on hand, i.e., for a few hours of production, and have a material handler (The Water Spider) replenish the “supermarket” flow rack periodically to avoid overstocking the employee’s workstation and keep the production rate flowing efficiently. The supermarket gravity racks should be not too far from the assembly line to increase the efficiency of operations.

    Supermarket gravity racks help realize this approach with a continuous flow in the factory. These can be used on the assembly lines or in the storage areas. The pipe and joint system facilitate the building of these custom supermarket racks.

  5. Decide on top or bottom-level container return

    Depending on your needs, you may opt for top or bottom-level container return. The goal is to ensure optimal container flow. It’s best to keep the levels for empty containers out of the “strike zone” (a body-movement area – between the shoulders and knees – where a worker most efficiently can complete a given task with the least amount of strain).

    By adding gravity flowracks to the production area, as well as a system to avoid overstocking and unnecessary movements, operators can now carry out their tasks much more efficiently and in an ergonomic manner.

  6. Define heights and levels


    If you need more than 1 level of flow, set up ergonomic landing and loading stations for your containers that range from a minimum of 24 in. up to a maximum of 60 in. The first level will store your raw materials and the second level, the empty containers.

    Remember to factor in a 3-in. clearance to load and unload containers for easy picking.

  7. Define the slopes


    The slope should be 3 degrees, but you might need to adjust it according to the weight of the containers and length of the flow rack.

    The following load characteristics will significantly impact the flow of the gravity conveyor: the bottom’s surface, its material, rigidity, and weight.

    Take a look at the chart above for broad guidelines to help you determine what the slope should be according to the container’s weight and the distance it will travel.

    Before implementing the conveyor system, make sure to test the slope to correct any elements which may cause inferior performance.

  8. Define the container stoppers

    There are different options for container stops:

    R40-MS – Metal conveyor mount for conveyor starting point + Tube stopper


    The R40-MS is a metal conveyor mount used at the starting point of rail tracks.

    This product serves as an anchor between the conveyor and a perpendicular pipe. To stop a container, add a tube stopper.

    Buy this product online:
    R40-MS – Metal conveyor mount for conveyor starting point


    Metal tab stop conveyor mount for conveyor ending point

    R40-TS – Metal tab stop conveyor mount for conveyor ending point


    The R40-TS is a metal conveyor mount with a 1-in. tab stopper.

    Buy this product online:
    R40-TS – Metal tab stop conveyor mount for conveyor ending point


    Metal drop stop conveyor mount for conveyor ending point

    R40-DS – Metal drop stop conveyor mount for conveyor ending point


    The R40-DS is a metal mount with a 1 ¼-in. drop stop at the end of conveyor tracks.

    We recommend that you use this part when you need to stop heavy containers.

    Buy this product online:
    R40-DS – Metal drop stop conveyor mount for conveyor ending point


    R40-SLOW – Roller decelerator stainless


    The R40-SLOW is a braking device which prevents the load on the conveyor from crashing into an end-stop device.

    Buy this product online:
    R40-SLOW – Roller decelerator stainless

  9. Divide the zones

    There are different options available to separate your containers:

    R40-GUIDE – Side plastic box guide for standard conveyor


    The R40-GUIDE is a black plastic guide for containers. This Flexpipe product is handy for keeping boxes and bins on the rails and for moving on long flow racks or conveyors.

    Therefore, the R40-GUIDE is the perfect solution to make sure your containers move in the direction you intended. There is a 2-in. space between the rail and the side of the guide. Remember that this part slides under the roller track.

    Buy this product online:
    R40-GUIDE – Side plastic box guide for standard conveyor


    Central plastic box guide for standard conveyors

    R40-CGUIDE – Central plastic box guide for standard conveyors


    The R40-CGUIDE is like the R40-GUIDE, but, contrary to the latter, it is placed at the end of the rail instead of on it. Being independent of the rail means you get more flexibility and can leave as much space as you need between the guide and the rail.

    Buy this product online:
    R40-CGUIDE – Central plastic box guide for standard conveyors


    HJ-7 – Metal 90° superimposed joint set


    The HJ-7 is a metal connector set that allows you to connect two pipes perpendicularly, one above another.

    It’s a low-cost and flexible solution to create corridors.

    Buy this product online:
    HJ-7 – Metal 90° superimposed joint set


    Metal tee joint set

    HJ-1 – Metal tee joint set


    The HJ-1 is a metal tee joint set that allows you to connect two pipes in a T-shape or to create a corner. You can rotate this connector up to 360 degrees before fixing it to make 45- or 90-degree supports.

    Buy this product online:
    HJ-1 – Metal tee joint set


    HJ-6 – Metal pivoting tee joint set


    The HJ-6 is a metal joint set that lets you create a two-pipe intersection with an adjustable angle. This assembly has many applications that range from bracing, hinging, pegging, deportation and more. This part is an attractive option as it gives you a good height of separation which the other options mentioned above cannot offer.

    Buy this product online:
    HJ-6 – Metal pivoting tee joint set

  10. Increase loading capacity

    There are several ways you can increase your flow rack’s capacity:

    Add a/numerous conveyor track

    Add a/numerous conveyor track(s) to spread the load


    pipe support

    R40-TU (Metal conveyor union for standard rails) to add a pipe support and reduce the span.

    The R40-TU is a metal conveyor union used to connect two rails that are cut and interrupted by a perpendicular pipe. This product lets you keep a straight line. You would otherwise need to use two R40-MS side by side. However, this is not always ideal if you have two rails close to each other.

    Buy this product online:
    R40-TU – Metal conveyor union for standard rails


    Add pipe support under the conveyor

    Add pipe support under the conveyor track

    Such as using an R40-CS to reinforce it.


    Double front and rear tube supports


    Check out this video resume

    How to build flow racks in 8 steps


    Thorough planning for top performance

    So as you can see, each of the 10 aspects listed above has an important role to play in ensuring that your flow rack moves the containers as efficiently as possible. If one of the elements is not a perfect fit for your needs, it will negatively impact your flow rack – and your employees’ –performance.

    Ready to build your flow rack? Order the parts online.

    Need a second opinion about the design?
    Send your sketch to your project manager for validation. He will follow up with you to finalize it.

Tips from the expert
Make sure the heaviest containers are not on the highest or lowest level but in the ergonomic zone.
Sly Lejour - Chief Project Officer
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