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Using FIFO to Achieve Flow
If You Can’t Flow – FIFO – The Simplest Way to Keep Product Moving.
In very many processes, it is not practical to achieve “one piece flow” (where products move one by one at the rate of customer demand). Perhaps one process in the chain will need to stop periodically (for cleaning for example). Perhaps there are variations in output from one product to the next or perhaps production cycle times vary. In these cases a first in first out (FIFO) lane will help keep the product moving
The Rules of FIFO
The purpose of FIFO lanes is to control both the sequence of work and the quantity of work between processes. Therefore the two key rules are that the first product to enter the lane from the upstream process is the first product to taken by the downstream process. This ensures that lead times between the processes are consistent. The other key rule is that the FIFO lane only accommodates a limited amount of product. Once the FIFO lane is full, then the upstream process must stop production until the downstream process has used up some of the product in the lane and created space. As a general rule the length of time that products sit in a FIFO lane should be measured in minutes or hours, not days. FIFO lanes are particularly useful in make to order processes where products are unique and it is not possible to make stock for a supermarket.
Types of FIFO Lanes
In their most simple form, a FIFO lane can simply be a rectangle on the factory floor with an arrow showing the direction that the product must flow and clearly labelled with the maximum stock allowed in the FIFO lane. Gravity roller conveyors are the most effective way to maintain FIFO as they ensure that batches are loaded at one end and taken out the other in FIFO sequence. Sometimes roller conveyors are not available and the nature of the product does not lend itself to being moved along in first in first out sequence (bulky products for example). In this case what TXM refer to as “job sheet FIFO” can be effective. In this way it is the flow of kanban cards or job sheets that follow a FIFO sequence and therefore control the physical flow of the product.
In many processes (such as the batch process industries mentioned above), the FIFO flow is not of products, but batches. This can also apply in some “batching” discrete processes such as machining, packaging plastic moulding and sheet metal fabrication. In this case the principles are exactly the same, but it is batches that are queued using physical or “job sheet” FIFO.
There are many tricks of the trade and variations on the FIFO theme, but for keeping your product flowing, using a FIFO lane will provide a simple, cheap and effective solution. Contact the TXM team to find out.