Dear Denis,

In my opinion, if it is not possible to reduce setup times, I think the only option is to differentiate between the batch of production and the batch of transport, similarly as proposed in OPT (TOC) way.

Thus, still producing a large batch, it may only be necessary for downstream stations a reduced quantity of products, fitting to demanded orders.

The only drawback is to correctly manage large batches upstream, to have products from all types demanded. Thus the system would be Lean.

Regards!

Embodied technological change. Improve the production process by increasing the technological level of the process?

Dear Denis,

In my opinion, if it is not possible to reduce setup times, I think the only option is to differentiate between the batch of production and the batch of transport, similarly as proposed in OPT (TOC) way.

Thus, still producing a large batch, it may only be necessary for downstream stations a reduced quantity of products, fitting to demanded orders.

The only drawback is to correctly manage large batches upstream, to have products from all types demanded. Thus the system would be Lean.

Regards!

Hello dear Raquel, thank you for answering me. What I am asking is not necessarily related to the technology level. I agree that sometimes we can improve the production by increasing the technology level. However, suppose that all suitable technology has been applied and no more reduction in setup time can be achieved. Also consider that operation times (productive time) are so small compared with setup time time. The meaning of "setup time" here is the time to change a given part to a different one (changing the tool, clean the machine, etc). Do you agree that small size of lots does not work well considering that machine efficiency will becomes so low. Machines will be performing setup times practically all day long instead of producing parts. I appreciate your comments, thank you.

Thank you dear Pedro, correct if I am wrong. You are saying that downstream will be pulled and upstream will be pushed right? and Corrections may be necessary in order to have all types of products. It makes sense, I appreciated that.

Core idea of Lean manufacturing is to create more value for customers with fewer resources using processes or practices that generate minimum waste. In this case, high change over or set-up time is surely a bottleneck and a big waste. What is important is not maximisation of machine utilization but the ability of the machine / process to cater to the customer needs as and when required by the customers. It may be worth exploring the possibility of using either a "quick tool change over" mechanism or a more undesirable "duplication of the bottleneck unit" where one unit is in use while the other is under change over. Otherwise, changing the way in which current products are produced may be the only option.

The basic technology is to take the set up out of the machine (look Shingo ; one minute change of dye) by using a flexible fixture and if possible a flexible dye. Another basic is to think the process anew as a flexible process where the variations are treated as order-variations of "standardised " work (that calls for collaboration with design and sales). One interesting possibility is also to use inserts with dyes.

Hello Denis,

Your question is tricky especially for the injection molding sector which is focused on high output numbers, so that the initial 'costs' for setup time and mold/tool making can become negligable. I think the solution to your question is also hidden in this mind set. Since people are so used to think 'long term' in this area you have to question if the requirements which come with long term process stability are necessary for your process. For example, in order to produce 500000 piece you need hardened steel molds. If you only want to produce 500 an aluminum mold or even a PEEK mold will do. These are easier to make, since the materials are softer and accordingly you can produce and change the molds much quicker than traditional steel molds. I know this is not exactly lean manufacturing but one viable way to improve the process and adapt to small scale production.

I suppose you want ideas despite they look a bit crazy, right?

I don't know the specific needs of your products nor their specifications, but it is not possible to create a mold to inject more than one model at time?

If you have two or more models that share the same material, wouldn't be possible to use one mold to inject both at the same time?

This way you reduce the setup time by reducing the mold changes.

Dear Denis,

first of all, make sure you have tried to pursue all the "options" of lean manufacturing: substitute a high productivity-long setup times machine with a smaller one that makes it possible to use smaller production batches, quick change-over tools, different production and transport batches, potential duplication of bottleneck stations (if it is not too expensive).

Once you tried all this, if the "change-over problem" still persists, you may look for the application of other production planning and control systems such as, for example, synchro-MRP. See an example of application of synchro-MRP to VSM in the paper "Extending value stream mapping: the synchro-MRP case", which is also available on Researchgate.

Regards.

In my experience, questions like this stem from a fundamental clash between the philosophies of lean manufacturing and conventional systems.

As you know, conventional systems assume that optimization of each individual part of a system will result in optimization of the system as a whole. Lean manufacturing recognizes that system-wide optimization often requires the less-than-optimal operation of individual parts of the system.

One of the reasons that it’s often so difficult to implement lean manufacturing is that the conventional approach seems so intuitively correct; every manager believes in their gut that if you just optimize the piece of the operation under their control, the entire system must improve – and this seems to be what’s happening here.

I’ve found that allowing this thinking to prevail in one part of a lean operation almost inevitably poisons the whole lean system – that allowing one exception leads to a growing cascade of other exceptions, until you end up with a wholly conventional operation.

My recommendation would be to take whatever actions you can to reduce the cost of reducing lot sizes at this operation (by investing in faster setup, by trading the current machines for multiple machines more suited to lean, or through some of the other alternatives suggested here), but to not let this operation violate the lot-size requirements you’ve imposed on the rest of the system. Increased costs at this operation will almost certainly result in much larger savings at the system level, but giving into the temptation to sub-optimize here could easily lose you the whole system.

As Bruce said, there are many elements and variables in lean manufacturing than the twos you mentioned here (a) setup time and (b) lot size.

A popular misconception is that lean is suited only for manufacturing. Not true. Lean applies in every business and every process. It is not a tactic or a cost reduction program, but a way of thinking and acting for an entire organization. The above is a quote taken from the links: http://www.lean.org/whatslean/ .

Bruce has identified a few lean means to improve the system/ organization performance. There are many other modern lean techniques.  "Knowledge Capture and Reuse" is one of them, which also provides a great benefits in reducing system costs and improving organizational productivity and quality. To that effect, you may find the following link useful.

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Conference Paper Knowledge-based Enterprising (KBE) Strategy for Lean Product...

Bruce , thank you for valuable comments. I appreciate that.

Hello Brian, I completely agree that we have several other elements in Lean Manufacturing, I appreciate your valuable comments. One of fundamentals of Lean is (Let customer pull), in this case, assuming customers make orders in small size, my question is: how to work in this environment letting customer pull the production knowing that my setup time is so high. A trade-off must be found.

Thank you for valuable comments and links, I will read those. Have a good day.

Hello Luiz, thank for your answer. I really appreciate that. I will read the link you suggested. have a good day.

Hello Denis, I keep hearing you want to optimize your operation with high set up time. Lean can be accomplished in various ways. If you are working with a standard part, one way is to look at inventory hold costs and raise your batch size. Another - that is if you want to alter the design of the part is to research commonality of parts between products. So you are really just raising your batch size again. 

Hello Chadi, what I meant by asking this kind of question is to receive feedback from experts people like you. This question for me is paradoxical. As you can see below, one of principle of Lean would be to work Just-in-Time, but in my opinion not always it is possible. Depending on production features it may not be possible. That's why, I asked that question and I have received good answers to make me understand better it.

 If we raise the batch size even considering the holding cost is really low, we are escaping somehow of lean principles. I understand what you said, it is a solution, but in my opinion it is not Lean. Thank you for answering, I appreciate that.

" Just in time - The basis behind this principle is to build what is required, when it is required and in the quantity required. Working in conjuction with levelized production, this principle works well with kanbans (a pull system). It allows for movement and production of parts only when required. This means components are not used in product that is not required and no time is wasted building unsaleable product."