One Piece Flow ( high mix low volume)| 3 November, 2011
I am being asked by management to setup one piece flow through every operation. We have SMT,DIP,RAD,AX,MANU,WAVE, Quite a bit of hand soldering, Post Inspection, AOI,CLEANING,BARCODING then out the door. We have rougly 60 different products with most having 50 to 100 piece workorders. I struggle with this idea due to the amount of changeover and idle time for mixes of components per board. I see alot less utilization of the equipment in the regard.
I presently run through TH, then cue for manual (wip) then its first in first out through the other processes. For SMT, all of our boards are DSR and then hand soldering connectors since we do not have glue capability for running a bottomside glue process.
All of these products meet in the middle at AOI.
I can give more details if someone would give me feedback if they are currently running One piece flow given these amounts of changeovers. I know we could increase WO qty' but I want to throw that out for now.
I came from a facility with High Volume/Med Mix and we converted our plant to FMS where we had 5 redundant lines SMT, TH , MAN ,etc but we always had a relative amount of wip cued between these processes SMT/TH/MAN.
One Piece Flow ( high mix low volume)| 27 April, 2012
We are in a similar situation with high mix low volume production. We are also using lean principles and the one piece flow mantra is always the target. In our plant though, we have not been able to achieve it. The guys who want one piece flow mostly come from volume thinking. The idea is elimination of the waste of waiting and inventory. But changeover is a waste and so is waiting. As a result, we ended up moving more towards controlling the WIP level at any queue locations. We have a few SKUs where we do come close to single piece flow from SMT to the end of wave, but we still needed a buffer after that so the end cell doesn't go down when the board building are runs other products. I'll close with this warning, don't let the lean guys ignore any of your costs and if your intuitions says they are asking for something wrong, challenge it but be open to a new way of looking at things.
One Piece Flow ( high mix low volume)| 30 April, 2012
JimnHky is pretty much spot on. We have a high mix low volume line of products (most anyways). We have experimented with lean quite a bit, and have achieved single piece flow on our most voluminous product. In fact, this is where I would recommend you start. Start with your highest volume product line and achieve single piece flow there. I will warn you, you may not be able to achieve this with the number of SKUs that you have. We have not gone lean on most of our lines for this reason. There are two many variances (i.e. hand soldering required on one, special programming on another, etc.), there is no way to plan for everything. Keep it simple at first. One high volume line, and go from there.