Batch, UPS and Modular (Batch pt.2)

Posted by Kathleen Fasanella on Jul 18, 2007 at 3:20 pm / Lean Manufacturing, Operations, Process Reviews / Trackback

I’d meant to get back to this but my geek vacation got in the way. As a way of restarting the conversation, I’ll address questions that had been left in the comments of the previous post. Tomorrow I plan to introduce UPS.

The first comment was from Oxanna who said in part:

I have just been considering how I would go about sewing purses as a one-woman, one-machine team. For this situation, I think a modular method would waste my time. I would have to sew, press, sew, etc., and perhaps change feet and/or thread, depending on the project. This is where batching comes in – I can cut 10 purses, sew them, press them, etc., and do it all without as much handling. So for an individual sewer *on one machine*, this is where it comes in handy. Now, if I had several machines all set up for each step, it might be different. (I’d still have to move from machine to machine and adjust my thinking to a “new” process, which might slow me down, IMHO.) In a factory, which is a multi-sewer, multi-machine operation, however, modular might be better.

Depending on your resources such as machines and bodies, modular may not be an option. It would waste more time if one did not have separate machines set up per operation. In a modular set up, there’s always more machines in a cell than there are stitchers. Still, moving from machine to machine is an adjustment but it could be less difficult to accustom yourself than you’d think. Regardless, batching would be the best solution for you now because you have limited equipment.


To which I can add nothing of salience, Krishna writes:

I feel the choice of a batching or an UPS or modular depends on the product/market which is catered to by the company. In the case of a high value/Small run orders, it makes sense to go for a modular system where each worker makes most of the garment except areas like cutting. For companies producing large runs, it makes sense to produce using batch/UPS. I feel in most countries in asia, batch system is used since it is very difficult to synchronise (balance) all operations to achieve high efficiencies. Running an UPS requires a high amount of worker training and also a great deal of delegation/empowerment…In our company, we use a hybrid system. In parts making, we use batches but when it comes to assembly, we break the bundles and move the parts on moveable hangers with each hanger carrying all the parts required for one garment. We have seen improvement in quality and efficiency levels but the true challenge is to implement this right from parts making to the last assembly operation. I agree with you that batching in unavoidable but we should strive to find better ways of improving efficiencies in batching operation. May be the advent of cost effective production tracking technologies in sewing may be of help.

A point that Krishna mentions that does bear some iteration is in regard to putting together complex products (parts making). I go round and round with others in the lean manufacturing community about it but all of our inputs have to be stacked within a cell and if it’s a complex item, there’s no room to stack it all. Toyota doesn’t do the equivalent of what we’re expected to do to be lean. While they only build one car at a time, the car is conveyed to other stations where those inputs lay in readiness for that operation. Also, the car is passed off to the next team waiting. One worker does not perform every operation on the vehicle but that’s how the process translates in apparel. Can you imagine the size of a sewing cell if the product had 50 separate pieces? You could do it if you made a really long skinny cell, all stretched out. Hence, Krishna’s observation regarding parts making or so called sub-assemblies. An example of this would be a dress that requires spaghetti straps. I’d argue that it wouldn’t be appropriate to make each strap, one by one in the cell. Rather, those would be made by batching. Once batched, the required units for each dress would be measured off, cut and set within the cell to complete the garment.

Then Carissa says:

One thing I’ve been trying to figure out is – at what point does which setup out pace the other? If you are a one woman show, it seems to me that batching is the way to go. Is modular the thing to do as soon as you get the set up and enough hands to run it? What about jobs where pressing is required during construction? Do you position irons and tables along the “work loop”? It seems to me that when you have few workers, batching is the way to go. You use the same machines for different jobs at the different stages of contruction. It seems like you would need fewer machines. Batching is what I’ve been doing. Although, I do find myself running back and forth a lot.

It’s more likely that batching is the way to go if machines or space limitations are your constraints rather than heads. You bring up a good point about pressing though. Most of the time, pressing isn’t needed, not the way it’s been inculcated if you’re coming from home sewing. Most pressing is done at the end of the process. In most cases, this is fine, there’s no quality compromise. Now, I know a lot of you disagree with me at this point but it’s most likely because you’re not using industrial sewing machines. Industrials meld stitching, the stitching line can be turned without pressing first because of the foot pressure. There’s a crispness afforded by pressure you’ll never know unless you use one and try it out. Still, there are exceptions. I understand this, I’m picky, I’d insist on having my collars pressed before joining them to the neckline. In this case, I don’t know what the protocol is. I’ve only seen cells at shows, not in working plants. I imagine they’d have a pressing station set up at that juncture. I mean, just because it’s a “sewing” cell doesn’t mean pressing within it is barred. There’s inspection stations in them, taggging and what not. Perhaps a cell is better described as all the equipment and set up work stations to produce the item.

6 Responses to “Batch, UPS and Modular (Batch pt.2)”

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Vesta
July 18th, 2007
5:43 PM

This is such a good line of discussion. For someone like me, who won’t ever be a one-woman shop, but who will likely start with a very small shop, what does a “beginner” lean shop look like? I imagine we’ll run one style per day, then reconfigure for something else the next day. One cell. Beyond that, I’m not sure.

Abigail
July 18th, 2007
6:36 PM

In the beginning, when I was a one woman show, I did a batching system. But it was slightly modified because I might do several seams at one time on each garment but leave all the zipper insertions to do at the same time. Or I might to the shoulder seams only to start and then do linings plus side seams together. I had a very simple pair of pants with no pockets and I would stitch all the seams except the elastic waistline and hemming. Then I would do all the waislines together and then all the hemming together.

My decisions on workflow really came down to resources (machines) available, space, manpower and skill level. Therefore, one solution that works for one person may not always work for the next person due to different work flow parameters.

In a small shop, with a couple employees, I could see the same solution occuring as a one-person show. It’s grouping different parts of the production together or not based on machines available and skill levels. The ‘floor manager’ or designer in a small shop could easily oversee the progress of their workers and adjust the situation very quickly to optimize everyone’s workflow.

Eric H
July 18th, 2007
8:52 PM

There’s a story in … Kaikaku? … in which the author is visiting a parts plant run by Ohno in his semi-retirement and notes a machine that is making multiple (6?) copies of a thing at each pass. Ohno points out that he’s not an ideologue – you batch process when that makes sense, and one-piece-flow the rest of the time.

Oxanna
July 20th, 2007
1:39 AM

Interesting food for thought. And very interesting about the pressure. I knew industrial machines had greater pressure, but I didn’t think about connecting pressing & pressure. I always wondered how they did that in factories, whipping through garments so fast, when pressing takes So. Long. in home sewing. Of course, overlock machines help simplify some of those pressing problems, too.

Theoretically, if I increased the pressure on my old domestic machine to max pressure, would it come close to reaching an industrial machine’s pressure? (AKA, for normal medium-weight garment fabrics, should I be using the heaviest pressure instead of the lighter pressures like I’ve been doing. It has a 0-1-2-3 range.)

Babette
July 22nd, 2007
4:50 PM

The pressure on an industrial machine is suprisingly strong. Having been the tech officer in a fashion school it was always interesting to watch the new students coming off domestic machines into an industrial world. They were always trying to back off the intensity of the industrials – both speed and pressure.

You need the level of pressure to keep up smooth feed at the sewing speed which is achieved on industrials.

If you back off the pressure on an industrial to the lowest level and don’t adequately tighten the holding nut, after a short period of sewing it will jolt loose and the spring will fire out the top of the head with amazing force. It’s a large spring and quite thick which means it can hold a lot of pressure. It was my job to find them where they had flung and fit them back in. No mean feat.

J C Sprowls
July 23rd, 2007
10:24 AM

Oxanna,

The answer is no. As Babbette points out, the springs are incredibly strong on an industrial sewing machine – they need to be. Originally, they were designed with such force to compensate for vibration. But, as technology advanced, it was soon uncovered that the pressure also melds the seams, as Kathleen points out.

Even though they are making machines with less vibration, the pressure is still needed for other reasons.

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