Small lot processing is one of the cornerstones of "lean manufacturing".
Traditional manufacturing economics used to focus on "minimizing labor and set-up costs" per run by maximizing the length of the production run. It might take four days to "set-up" the dies in a press line. Then the factory might run that set-up for two weeks and fill hundreds of bins or thousands of racks with parts before switching to the next part.
Sometimes the set-up was so arduous that they just left the die sets in the press line and the presses were dedicated to making just that one part.
"Lean manufacturing" stood things on their heads. Proponents saw the loss of eight shifts worth of production to set-up the dies as a monumental waste. They saw the number of specialized racks and bins needed to support production runs of that length as a waste of money and floor-space. They saw the huge inventory as a waste of liquid capital. They saw the potential for quality spills and the resulting cost of containing those spills as wasteful.
Link to video showing a quick die-change.
Once all of the costs of those huge inventories were tallied up, the goal became seamless, zero-time die changes. They never got to zero-time, but nearly all press lines can change out as many as 20 die-sets in single-digit minute times. The incoming dies are staged on roller-tables on one side of the line while empty roller table are staged on the other side of the line.
After the last part clears the line, the presses lower the upper dies onto the lower die and release them. The die-sets for the run that just finished are pushed out one side of the press line while the new die-sets are rolled in from the other side.
Everything is locked into place. A final verification is made to ensure everything is in alignment and locked into place and then the press line restarts.
Small lot canning
Small lot canning involves lots of small batches of jars as the produce comes in. It might be three jars of pickles or 5 jars of stewed tomatoes. Or it might be knocking out 7 quarts of applesauce.
I have kettles of various sizes depending on how many jars I need to process. I know how many pounds of apples I need to process to make 7 quarts (a full canner load).
This year I am messing around with pickles. I found it was very helpful to premake the pickle juice and store it in a gallon jug. Then I can add it to the jar(s) as needed.
- 1/2 gallon water (I use unchlorinated, well water)
- 3/4 cup plain, not-iodized salt
- 1/4 cup granulated sugar
- 28 grams of food-grade calcium chloride
- Fill the remainder of the gallon jug with 5% acetic acid vinegar (i.e., a little bit less than a 1/2 gallon)
I can't say this makes great pickles because the pickles need 6 to 8 weeks in a jar for the flavor to stabilize. I won't taste the first pickles until the cucumber season is over.
But I can say that it has been very streamlined to make dill pickles. Either fresh dill or dill seed gets measured into the bottom of a jar. Sliced spears of pickling cucumber goes in. Fill to within an inch with the pickle juice.
Bonus image
Quick change-over die systems was the death of many manufacturing plants because the presses they had were not compliant to the new system, i.e. mounting/locking was antiquated. Other plants bought those older presses at auction for peanuts to gain a few years of production by just "setting and forgetting" certain die sets.
ReplyDeleteThe company I retired from still had some 1930's and 1940's presses for specialized runs.
irontomflint
There are a great many general practices of lean manufacturing that are beneficial in many areas of life. For example, driving out waste (of time, materials, etc.).
ReplyDeleteThe choices were stark... modernize or die.
ReplyDeleteI did canning in small lots also. I kept notes on reduced quantities needed, how many jars, and recipes that were halved, or quartered, so I would not have to recalculate each time I made 2 jars of whatever.
ReplyDeleteI used to water bath tomato sauce or peaches or applesauce before work, getting up about 30 minutes earlier, or so, as needed. I was surprised all those little batches really filled up my storage area.
Southern NH
That is very enlightening!
Deleteirontomflint
A couple of wild grape leaves will give the pickles ~crunch~.
ReplyDeleteThe payback from reducing lot sizes is a key feature of Goldratt and Cox's book "The Goal".
ReplyDeleteI worked at a machine shop and a defense contractor later, that's where I learned abot KANBAN.
ReplyDeleteLean manufacturing allowed the end-users to accept your parts but not pay for them until use.