Cycle time for batch process

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Cycle time for batch process

Postby BenjaminRogiers » 05 Apr 2012, 20:13

Hello,

the following image show the situation I'm dealing with:
Image

The coating machine processes products in a batch of 6, which takes 60 minutes. Afterworths the products go to the inspection machine, where the products are inspected for any malfunctions. (20% of the products are not ok and go to in a rework queue)
These products have to be re-coated, which takes only 40 minutes if the whole batch of 6 consists of re-coating products only (so no mixing of both re-coating and coating products).

I assign a label on the product when they exit the conveyor:
Code: Select all
Label([servicetime], i) := mins(60)

When a product leaves the rework queue a label is also assigned:
Code: Select all
Label([servicetime], i) := mins(40)


The cycletime for the coating machine is then determined as followed:
Code: Select all
Label([servicetime], first(c))


The problem is that I don't know how to link the batch size in the coating machine and the type of product (first time coating or re-coating). How do I prevent the products from getting mixed up?

Thanks in advance,

Benjamin
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Re: Cycle time for batch process

Postby BenjaminRogiers » 05 Apr 2012, 20:20

Looks like the image is not working and I don't have the option to edit my post.

http://i.imgur.com/6YILw.png
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Re: Cycle time for batch process

Postby Josie » 06 Apr 2012, 11:02

Dear Banjamin,
One solution is:
put "i.input := ic(c)" in the trigger on entry of the Coating Machine,
and "If( Content(c) > 0, OpenIC(Label([Input],First(c)),c), OpenAllIC(c))" in its Input Strategy.

hope these will help.

KR,
Josie
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Re: Cycle time for batch process

Postby BenjaminRogiers » 09 Apr 2012, 17:45

I'm afraid your suggestion is not working, the queue fills up to the maximum and the coating machine is not processing products from the rework queue.

Benjamin
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Re: Cycle time for batch process

Postby Josie » 10 Apr 2012, 10:23

Dear Banjamin,
It is because the batch rule for the coating machine is 6, and the rechecked product once enter the coating machine, will still wait for other products coming from the queue, using the same batching rule as normal products. As there might not be 6 products from the rechecked queue, the server of coating machine will be blocked.

Solution: just add these codes in the batch rule in your coating machine:
if( ic(c) = 2, 6, 1 )

the 2 refers to the input channel of normal products which need to be resembled. If you use channel 1 as the input channel of normal products, then replace the 2 with 1.

Another thing is that if you want to handle the rechecked product first, which has a higher priority to normal products, you need to let rechecked products in first by using channel 1 for their input.

Anything more, welcome to ask.

Best regards,
Josie
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Re: Cycle time for batch process

Postby BenjaminRogiers » 10 Apr 2012, 13:47

Hello Josie,

I have implemented the suggestions in the model, but the queue still fills up and blocks the throughput. I have tried to mess around with your solution, but I can't seem to get it working correctly. I have included my .mod file as an attachment, maybe this will help.

Thank you for your help so far!

Benjamin
Attachments
model.mod
(63.65 KiB) Downloaded 122 times
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Re: Cycle time for batch process

Postby Josie » 10 Apr 2012, 14:14

Dear Benjamin,
With the connections in your current model and using "if( ic(c) = 2, 6, 1 )" in batch, you intend to batch 6 products that come from channel 2, which is the same as "batching 6 rechecked products"!
Solution:
You need to switch the two input channels of coating machine...

Let me know whether it works.

KR,
Josie
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Re: Cycle time for batch process

Postby BenjaminRogiers » 10 Apr 2012, 14:32

Dear Josie,

the coating machine always has to work in batches of 6, so 6 new products or 6 products that need rework. Switching channels didn't work, as it doesn't fill the queue up to 6 (I think it mixes both new and rework products). The new products and rework are not allowed to be mixed. A batch of 6 new products take 60 minutes in the coating machine and a batch of 6 rework products takes 40 minutes.

Hope this helps, thank you!

Benjamin
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Re: Cycle time for batch process

Postby Josie » 10 Apr 2012, 14:51

Hi,
Please find attachment the model in which the coating machine will not mix up new products and reworked products.

Changes: "Input Strategies", "batch" in "Coating Machine"

KR
Josie
Attachments
model.mod
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Re: Cycle time for batch process

Postby BenjaminRogiers » 10 Apr 2012, 15:36

Dear Josie,

Thank you for your help! Works perfectly.

Benjamin
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