Manage your fuse inventory with 5S

Figure 1. Many storerooms have little order and often stock obsolete fuses.

With lean manufacturing becoming a more accepted practice at many plants, there’s a greater focus on continuous improvement and 5S. Many storerooms have little to no order and contain several similar or obsolete fuses (Figure 1). This contributes to some of the seven wastes that lean manufacturing identifies — inventory, transportation, waiting, motion, processing, defects and over-production. These wastes have a cost associated with them, and eliminating them lets you achieve cost reductions and improved efficiency.

It’s helpful to have an understanding of fuse history to better understand how the 5S process for fuse inventory works. There are four fuse classes that have the same physical size — classes H, K, RK5 and RK1, from oldest to newest — but different electrical performance and ratings. Current-limiting ability and interrupting ratings (IRs) have increased as each new fuse class emerged. There was a progression from the original Class H (10 kA IR) fuse to Class K (50 kA IR) fuse, then to Class RK5 (200 kA IR) and finally to Class RK1 (200 kA IR).

Most medium to large facilities have bins for at least two or three of these groups, in many cases all four, and some even have different bins and SKUs for different manufacturers. Lean identifies these bins as inventory waste, which can lead to excess waiting or motion while the correct replacement fuse is identified. Or worse yet, an error, or defect, in fuse selection could result in catastrophic failure if the short-circuit current is higher than the fuse interrupting rating.

Following the 5S process makes this task simple, and it works for other areas in the storeroom, as well.

Sort

Figure 2. Identifying correct replacement fuses can be a daunting task.

The first phase is to identify all old, obsolete and duplicate fuses in the storeroom and inventory management system. These old and obsolete fuses should be removed from the storeroom and quarantined to ensure they’re not able to be installed. They should be removed from installations, as well, to increase overall plant safety. Identifying the correct replacement fuses can be a difficult task, so seek expert help, if necessary (Figure 2).

Set location

Set up new bin locations once the entire old, obsolete inventory is removed. Decrease waste in motion by placing the new bins in a central location so that they’re conveniently accessible to those who need them.

Straighten

Figure 3. The diligent application of 5S techniques can yield efficiency gains.

Clearly label the new bin locations in a logical manner with product part number, type, voltage and Ampere ratings. This helps reduce waiting time to find the correct replacement fuse (Figure 3).

Standardize

Standardize on the best fuse type to better protect personnel, equipment and the plant. Typically, this can reduce inventory by 25% or more while making it easier to order replacement fuses.

Sustain

Finally, update the plant’s inventory management system data to ensure the correct parts get ordered in the future. Post a picture of the fuses in the storage area to show how they should look. Conduct annual reviews and training to keep the upgrade in place and on the path to sustaining lean initiatives.

These steps aren’t that involved; they just take time. Sustaining the work of any 5S project, however, can be a daunting. The key to sustaining a 5S fuse project is updating the ordering system and training the employees. If the ordering system isn’t updated, older parts will be reordered if they show no stock.

Whether a facility has a lean initiative in place or workers have expressed interest in implementing one, a fuse inventory 5S project is a great place to start. Standardizing your fuse inventory mitigates arc flash hazards, reduces downtime associated with electrical failures and streamlines inventory. It’s always recommended to use expert advice when changing any fuse type to ensure the replacement fuse will operate correctly.

Fuse control guides, inventory audit templates, fuse bin labels and consolidation charts are available and should be used, when appropriate.

David Komm is a technical services supervisor for Mersen (www.mersen.com). He can be reached at [email protected].