One of our key phrases at Geolean is “Get the fork outta here!” When we work with clients to create their lean system, removing forklifts from the manufacturing area is often one of the first initiatives. Getting rid of forklifts makes sense, but it’s not always an easy change because they are commonly the main way materials are moved and the change requires a new approach to systems, processes, and things. One of the main “things” to change in material flow is made by introducing tugger cart systems, of which there are many options.
What are tugger cart systems?
Tugger cart systems work almost identically to a real train, but on a small, focused scale just right for your operation. The train itself has a powered tugger operated by a person (like a locomotive) that tows a connected train of several non-powered carts.
Train systems are one of the first improvement steps to get away from using forklifts for lineside material movement. They work as a part of a system to exchange materials and information between the production area and the warehouse area.
Different cart styles can be used in a train system – standard carts, mother-daughter cart systems, corral cart systems, and automatic exchange systems – but they all fulfill the same basic function.
Critical parts to pay attention to in a train system are the tow package (tow arm and connecting hitch), cart base (designed for towing, with aisle width and weight capacity in mind), cart top hat (when moving totes, boxes, and / or parts), and casters (specified for high speed towing).
How do they work?
Both tugger cart and forklift deliveries move materials and information. The differences in how often, how much, and the movement direction create a clear distinction between the two approaches.
Forklift delivery moves a large quantity of a single part, very infrequently (because the quantities moved each time are large), usually in a “push” direction from the warehouse to production.
Tugger cart delivery moves small quantities of many parts, very often (because the quantities moved each time are small), usually in a “pull” direction between the warehouse and production.
The tugger follows a standard path with stops along the way to exchange material, then proceeds to a replenishment area to then make the same route again. This standardization of material flow follows the same idea as the standardization of the production process.
Where can tugger cart systems be used?
Tugger cart systems are used successfully in almost any manufacturing, distribution, or logistics environment. The three key areas for a train system to function (replenishment, delivery, and lineside) will look different in each of those operations but the principle is the same.
There are three critical areas for a cart system to work well:
- Replenishment area
This can be called the warehouse, supermarket, kitting area, or anywhere else product is prepared to be delivered to operators. There needs to be a very clear and strong information link between the lineside area and the replenishment area so that the tugger cart is loaded with the right materials to supply production.
- Delivery aisle
The delivery aisle itself forms the path that the train will follow on its route, but is often a traffic area shared by trains and people and needs to be well planned. People have thousands of years designing standard traffic intersections and still do it poorly, so don’t take well-planned delivery aisles for granted.Understand the area needed for vehicle traffic and people. Force delivery traffic into a single lane traveling one way only. Create visual, bright signage visible for tugger drivers and walking pedestrians.
- Lineside staging
The lineside staging area is a zone between the operator’s workspace and the delivery aisle. It’s not always a simple rectangle, but there should be a buffer zone between the operator and the train route. This is for practical purposes for standard work in process quantities and material presentation, but also to provide safety for the operator so they are not disturbed by the traffic. Lineside staging usually takes the form of flow racks or flow chutes, but cart staging lanes are also used for large parts or kit carts.
Why should you care?
Tugger carts connect and integrate the physical components of material flow together with the exchange of information. They are required equipment for any company integrating a lean system. If you say you’re “doing lean”, but you move materials with forklifts – you need to change your approach.
The systems part of “tugger cart systems” is important, and even operations that use tugger carts can see a big impact by focusing on the connection of the system. Are you using tugger carts but still stuck with a push/pull hybrid delivery? Are you using tugger carts and forklifts for material delivery? Do you use tugger carts but still have frequent material outages? All of these instances are symptoms of a “system” that needs work.
What do you get out of these systems?
- Flow and pull. Know train systems, know flow and pull. No train systems, no flow or pull.
- Productivity. The initial productivity improvement in moving from forklift delivery to tugger cart delivery is obvious, but the second one that comes from right-sized packaging in the warehouse and at the line side is not always as easy to see. Each improvement is connected and builds on the others.
- Flexibility. Forklifts move a single unit of a large container. tugger carts can be designed to move any size container with a combination of carts – one cart with a large container, two carts with shelves for small boxes, and a last cart for consumables or hardware replenishment. The options are endless.
- Safety. By their nature, tugger carts support the separation between the delivery aisle and the line side. This separation creates a safer environment for production operators. Well, designed cart routes also make part delivery predictable, reducing the rushing and excess speed you see with an unpredictable, push delivery system that can lead to accidents.
Types of Tugger Cart Systems
- Mother Daughter Cart Systems – Mother-daughter cart systems use a tugger with base carts (the mothers) from which various insert carts (the daughters) can attach and detach. The specific design and style of the mother and daughter carts vary, but the general function is the same.
Tugger cart systems provide many benefits to your operation, and not all of them are obvious. The important thing is to not get stalled by choosing what type of train but to try something so you can learn from the experience. Get your lean manufacturing and lean logistics system moving today!