This is part three in the sewing organization process systems entries. Parts one and two discussed bundling. Today I’ll start with UPS or Unit Production System. You can desribe UPS as a hybrid system of lean (modular) and standard bundling (which is often called PBS or progressive bundle system these days). UPS is a hybrid system in that only one unit is made at a time, and it is bundled singly with all the inputs to make one unit. However, unlike modular, it is constructed by different operators in the same way as bundling. A practical example means that all the collar pieces, sleeves, cuffs, bodice pieces, pockets etc to make a single unit, are bundled together. This single unit will move to each operator in the process. The collar maker would form the collar, rebundle the unit, passing it along to the pocket stitcher etc. An advantage of this method over the traditional bundling method is that a collar (for example) from one lot wouldn’t mistakenly be sewn to bodices of another lot. It couldn’t happen as each bundle only consists of inputs needed to make the one unit. Reread the section in my book starting on pg 118 for more explanation on how to control pieces from being misbundled. Perhaps the best way to describe UPS is as a WIP (work in progress) material handling solution.
Here is a chart called Comparison of UPS vs. Progressive Bundle System on the web. The document shows a comparative of bundling system vs UPS. Caveat lector: this paper was prepared by a consulting group promulgating their SMRT system (a derivative of UPS) which isn’t a bad thing but consider the source. By this I mean that the disadvantages of bundling are exaggerated. I find it very hard to believe that a bundling system will be staggered in such a fashion that one worker’s productivity will outstrip other operators by 120-150 dozen per day, much less 250-350 dozen per week. While production management of sewing plants are not noted to be the most progressive lot, I find it difficult to believe they are this stupid either; financially it wouldn’t make sense. Somebody would notice if the line balancing was this much out of whack so read this document comparing systems with a critical eye. There was an article courtesy of Cal Tech at Pomona which had more exaggerated claims than that but the link is dead.a
Speaking of the above referenced article, it occurs to me that this would be a good time to remind you that the term S.A.M means Standard Allowable Minutes. Another useful phrase to know is “Through Put Time”. This refers to the total amount of time it takes to move a product through all phases of operation to completion. For example, the SAMS of a product might only be 12 minutes (aggregate of all sewing time) but the through put time may be a week to organize and process all of those lots into finished units.
As a method, in it’s traditional application, UPS isn’t feasible for most DEs. UPS systems require high capital costs to move stuff around because it means an installed overhead conveyor system. Most of you aren’t likely to have seen something like this but a theoretically similar system would be at a dry cleaners but much more specialized and technologically advanced. In a smaller shop, one person could schlepp each bundle around.
The leading supplier of UPS systems is a Swedish firm called Eton. I wrote about them before and we were very surprised at how nice they were to us even though we couldn’t possibly be a customer. To save you a click, I wrote:
Eric and I visited the Eton booth, I was very very surprised at how cordially we were received there. Honestly, I was looking at it from afar because Eton is a huge company, with complex handling systems that I don’t think would interest many of you -and I told them so as to spare their effort- but James Hoerig (VP of sales) didn’t care that we were piddley sized and gave us the spiel anyway. Eton is a class act. Basically, Eton is an overhead conveyor system, conveyor in the sense it conveys, moves parts and finished goods from place to place. They had an operational system running in the booth with accompanying video. There’s video on their site too (very cool). Their system moves WIP from operator to operator; I’d only thought of these conveyance systems as being useful in inventory and distribution. James explained that in certain types of manufacturing -parachutes for instance- conveyance systems are obligatory and it makes sense if you think about it although I never had. The conveyors have to be installed over 20 feet up (or did he say 30 feet?) for big products like that. These systems are very useful when making over sized products to include items like comforters and blankets.
When I did later research, I found that Eton started out as a shirt manufacturing company. The UPS system they developed was something they did in house to facilitate their own process. Interestingly enough, the only automaker who uses a UPS system is Saab, another Swedish company.
In summary, a DE could employ a UPS system if they bundled inputs according to each unit. Each unit would still have to move through the system being processed by different operators. I don’t see how this would be of much benefit to you except if your products were highly individualized. I have no idea as to how much of an increase in productivity and cost reduction this could represent. I don’t know of any case studies using UPS sans the conveyor system. The conveyor system seems to be part and parcel with UPS making it only within reach of larger firms. Can any of you think of reasons a modified UPS system (non mechanized) would be of benefit to smaller firms?
I think the hat & accessories maker I worked for essentially used semi-UPS system. She made hand-felted items like scarves, hats and bags, with a limited number of bodies, but a mindboggling variety of colors and decorations. She would cut all the wool pieces and stack them in piles-one pile for each item. Each item was prepared individually at a prep station– spreading & arranging the wool, and placing the decorations on top. These preps were stacked & the prepared pieces were taken to the felting station. After felting, the hats were finished in something much more like a batching system.
To generalize, it seems a UPS system is appropriate for simple items (not many pieces) that have a number of processes applied to them to make a large variety of customized items.
I have been involved with a number of sewing bag and luggage factories who have used variations of the UPS system without complicated conveyor systems. Most have used what I would call a manual conveyor belt. The factory utilized a long stainless steel table that ran along side of all the machines in the line. When an operation was completed at one work station the work was placed in a basket and pushed toward the next work station. Typically there would be only 2 to 3 pieces of work in progress waiting at each station. This system was successfully applied to very complex products with hundreds of operations and 30 to 40 panels. I am looking at a wheeled duffel bag right now that has over 50 individual panels and dozens of trim items as well. This bag is being successfully produced using a manual UPS system.