I have discussed in some of the previous topics the attitude in the 1990’s that kitting was to be avoided at all costs, and replaced with a no-fuss Kanban system that was easier on the material organization and less “wasteful”. Part of the reason for this attitude was no doubt related to the definition of the term Kitting. In those days kitting was done in a separate area, often the warehouse, and delivered to the line based on an MRP schedule. The kit would sit for a while until used, and sometime get cannibalized while waiting.
An aerospace supplier that I worked with had the practice of kitting parts 30 days prior to the need date on their MRP schedule, in part to make sure that they had everything needed. The kits would be staged on the factory floor, and on average they had 2-3 weeks worth of kits waiting. Of course many of these kits would be there longer, as higher priority and emergency jobs pushed them down on the priority list. Our solution: stop doing that, and prepare kits based on the “pull signal” of an open space on a small rack. But in general, don’t do this.
JIT Kitting is something different. The concept here is to integrate the part selection work with the consuming process, as a direct extension and running at the same takt time. What we are doing is taking part selection work away from the operator and giving it to a specialist working adjacent to the line. Ideally one unit at a time, parts will be placed in a container or tray and delivered to the first station. From there the tray will be passed down the line with the product, and operators will select what is needed at their station.
The analogy here is similar to our approach to surgery: give the surgeon exactly what he/she needs, without having to do any additional effort. In a surgical suite this would be the head nurse or tech, and in a factory this would be the kitting specialist.
If parts for an entire unit don’t fit in a single container, you may need to deliver directly to individual workstations instead of being able to pass a shared container down the line. This is perfectly possible although a bit more complex. Don’t let this discourage you from applying JIT Kitting.
Since one-by-one delivery of kits involves a lot of repetitive motion, this would be a great opportunity for the use of AGVs (Automatic Guided Vehicles). The AGV would move the JIT kits to the line, without the need for human intervention. Empty containers could be passed directly to the JIT kitting portion of the line if it is directly attached, or the AGV could also be used to return the empty tray or container.
Of course you would not go through all of this effort if there was no gain or benefit. You can expect to see three main benefits from JIT Kitting:
- Space requirements will go down, especially on the line. Removing all or most of the bins at the line will allow you to compress the work areas. If space is a concern, this is a big plus. Material will be stored in the kitting cell, but this can be done more efficiently as opposed to having it spread across the line. You can also eliminate the need for an additional and separate Supermarket, since the kitting cell itself can be the supermarket.
- Quality will go up. If you give the operators just what they need, and it is correct, then part selection errors will be essentially eliminated.
- Productivity will go up, since operators are not longer required to retrieve and select parts. More of their time can be spent adding value and building the product. Toyota engineers told me that they experience a 5% overall productivity gain when they converted to JIT Kitting, and this was on a line that was already extraordinarily Lean.
Bottom line: kitting is no longer a dirty word and we see the JIT Kitting method becoming more and more prevalent.