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SMT Line Performance Measurement

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SMT Line Performance Measurement | 27 October, 2020

Hello, How do peoples measure SMT line performance. Do you have preferred methods?

We measure utilisation of equipment by time the head on P&P machine is moving. Is this normal ? Company is medium volume, high mix manufacturer. Do anyone do similar ? or is OEE preferred or maybe other measurement form ?

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SMT Line Performance Measurement | 27 October, 2020

Hi Processman,

Where I worked before, as an SMT Department Leader, there were two more departments who ran SMT lines, and we had a task from the CEO to decide to how we measure our performances. The result was like this:

- first of all, you will have a changeover time for every product. Depending on your business, machines and complexity of the machines, you should define a 'legal' average changeover time which is not considered as downtime. We all worked in the 3 SMT departments with ASM Siplace machines, so we decided this legal changeover time to be 30 mins (interval of measurement of this time was last board at entrance of oven from one job, to the first board at entrance of the oven of the next job);

- second, there will always occur small/big problems on the line, so we said that only those downtimes will be investigated first, which are bigger then 10 minutes (same measurement point, oven entrance; time difference between 2 boards);

- third, we defined together that time spent on new products (sample production), which run on the line for the very first time, not to be considered downtimes, as we carried out process optimizations, case studies of new components/tooling and preparing production procedures for serial production;

- fourth, planned maintenances are not downtimes (our decision) because they are planned, and if carried out in the given timeframe (our case, 1 shift) then it is legal. All the time which was more then 480 minutes over maintenance, was considered as downtime.

Add all the illegal downtimes together, and take it out of your available production time (between 15-19 shifts) and you can calculate a percentage.

We used traceability system, so behind all this, there was a massive amount of automatically gathered data, but it worth it. It made us more competitive, and more attentive to details.

If you want more information regarding this, you can contact me.

BR, Tom

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SMT Line Performance Measurement | 28 October, 2020

Words of advice:

There needs to be an audit of downtime data being logged by operators. Everybody has to be on the same page and understand how and when to log specific reasons.

It makes the boss feel better that you are measuring something BUT you have to be realistic..... Taking the resource to collect massive amounts of data that you really don't do anything with is of no value and needlessly saps resource.

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SMT Line Performance Measurement | 28 October, 2020

Back in the old days, based on "The Goal" by Eliyahu Goldratt, we wanted to optimize throughput. In this ...

* THE GOAL: Make more money. Increase throughput. Make more money.

* Throughput is gated by the bottleneck.

* Bottleneck is where the material is converted more slowly than other parts of the process. Bottlenecks have buffers in front of them.

* Spending money on improving things in areas other than the bottleneck will not improve throughput.

More recently, Ron Lasky [ 603-646-9197] wrote "The Adventures of Patty and the Professor." It is similar to "The Goal." Where "The Goal" has no industry focus, "The Adventures of Patty ..." focuses on specific electronics assembly process improvement tools and is excerpted from Dr. Lasky's blog. Both are good books.

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SMT Line Performance Measurement | 29 October, 2020

The best way to measure is by money made(quality product and minimal rework). I worked for a company that asked me to achieve building 100 boards/week for an assembly. A year later they were unhappy that we don't hit 150 boards/day of the same board consistently everyday. Most of the monitoring nowadays is useless. Managers place goals on engineers without understanding the goals. Then goals are not met and requirement will be shifted to meet the goal. It is all made up charts and graph, but this is all corporate America understands nowadays. "Ohhh the DPMO graph goes up and this is great". My point is figure out what you want to measure and what is important to measure. Your machine might be moving 80% of the time and you can still build crap.

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SMT Line Performance Measurement | 29 October, 2020

The other problem with managing by spread sheets is people learn to play the game. Engineers and Mangers will fudge the numbers to make the graphs looks good to their bosses. Considerable time and money is spent to create absolutely useless information and everyone is happy to receive it.

Sometimes I think I should get into the MES/ERP business. I can write software that does nothing useful and I can do it much cheaper than the competition!

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SMT Line Performance Measurement | 29 October, 2020

The software is crazy expensive for some of this stuff and in many cases you could develop the bits of it you actually use in-house for a fraction of the cost.

Unless you are a company who really like this level of process control and you run multiple lines and understand the differences between them (your prototype/NPI line can't be measured the same way as your production one after all) all this stuff is completely useless data.

We run a single line, I could give you a pretty good idea of its utilization rate without even referring to its own log data, user timesheets and I know what I would need to improve that number. I'd wager outside of new product most time loss on any line is down to picking and feeder loading & feeder inventory and a little stock control (because who doesn't unexpectedly run out of something or find wrong parts in their shipments?)

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SMT Line Performance Measurement | 29 October, 2020

He has posted the individual episodes online. The most relevant one is here

In it Pete estimates his line has 95% up-time and everyone agrees. The Professor estimates that it is closer to 10%. Pete is not a happy camper.

I read the posts quite a while ago but don't have the link for the next installment to find out what % they ended up finding.

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SMT Line Performance Measurement | 2 November, 2020

Yup some people are pretty deluded ;).

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SMT Line Performance Measurement | 3 November, 2020

Stephen ... The article that you missed could be "The Professor Returns to ACME" [ ]

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SMT Line Performance Measurement | 12 January, 2021

Hello all Tommy you are very close to how we measure. Also other replays and info very interesting to read as I too see these problems with playing with numbers and wasting time on issues of no concern. We record all data on ASM siplace explorer software. We attempt to category every reason of head stopping moving. Category includes, reel change, changeover, start up, clean down, machine problem etc and then we analyse. Really we measuring availability of smt line. Managers expect target of 92% to be met. Is this realistic ?


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SMT Line Performance Measurement | 19 January, 2021

Hi Processman,

I would say that 92% is realistic if you have low mix - high volume manufacturing.

In this case, the only reason for the machines to stop is to:

- change reel (on ASM machines you can splice them together, so theoretically with ASM you should not even stop to change reel, but let's say in certain cases you would);

- changeover (has to be a set a target, again, depending mostly on how old the machines are, how many operators work on the line, how many more people can you get involved to help with changeover only - SMT technicians / maintainers / kitting operators);

- breakdown - where you must have an action plan I believe, and 1 responsible person who manages the resources (people, parts, time, etc).

Start up should happen within 10 minutes before the shift start, so by the time you enter 'production time' you will have all machines up and running (not your oven though, but while you prepare the first off, it should be heated just enough). Cleaning and maintenance should be regarded as productive time, as they are preventative and planned maintenances, to avoid future breakdowns.

Our target was 90%, and with the machines and people I've been responsible for, we achieved around 85 % at most.

If you want to discuss more about this, you can find my contacts on profile.

Kind regards, Tom


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