Advances in Conveyance Methods
If the quantities of material stored at the Points of Use has been reduced over the years, as discussed in this series, then it would be reasonable to expect that the modes of conveyance have also evolved. Let’s go through the main modes of material conveyance, and take a look at what has shifted since the 1990’s. Keep in mind that these comments are based on our personal observations, and don’t represent a formal industry study.
One can easily envision the use of simple hand carts to move material to the Points of Use if the quantities are small enough and the distance is short enough. This mode of conveyance has the advantage of very low cost, and high flexibility of access. A case can be made that this is your first choice if conditions are right. Motorized carts can extend the range and weight limitations of a hand cart.
In 2017 fork truck sales grow over 8%, so clearly they are still in use. Many materials, due to their weight and size, require the use of a fork truck. Shipping containers and large totes also require their use. The data does not show use going down, at least in terms of overall units sold.
Where we do see a policy shift is in their use on the factory floor or in work areas, as opposed to the shipping dock or warehouse areas. Many companies strive to reduce or eliminate their use inside the factory. Dell Computer was an early pioneer in designing a fork-lift free factory in Austin many years ago. Certainly for a high-mix production environment with lots of different components, a fork truck is highly inefficient, and in a Mixed Model environment the shift away from fork lifts on the factory floor has been highly noticeable.
Use of Tuggers
A tugger pulling a set of carts seems to be the conveyance method of choice today, especially for larger factories, longer distances, and a larger number of items. It is possible to deliver a very large number of containers in a single replenishment cycle, and the tugger is an ideal mode of conveyance for a formal Kanban system. This shift to tuggers is still taking place, and we have worked with factories this year (2018) that are in the process of making the change from fork lift delivery.
Automated Guided Vehicles (AGVs)
AGVs is a growth area for material conveyance, especially with the introduction of JIT Kitting methods. A kit of parts for a single unit will need to be delivered every takt time, and to have a human being perform these repetitive deliveries would be highly inefficient, not to mention boring. AGVs can automatically follow a delivery path to deliver these kits with no human intervention, and return for restocking automatically.
An indicator of the growth of the AGV market is the recent formation of a separate business unit within Toyota in the US, focused exclusively on these products.