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04/13/2009 10:02 AM
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Hello everyone,
In the attached file there is 4 types product, but i don't konw how to calculate the takt time for the products. Would you pls. help to see and give me some suggestions? thank you.
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04/13/2009 11:01 AM
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Quick question, what is the available production time per day (i.e. actual time associates spend working)?
You show 3 shifts, each with 40 minutes of break a day, but how long is each shift? And I would assume your available production time = Total Shift Time - 40 minutes, would I be correct?
Since process c allows for each to run through their own product specific work center, then each of those workcenter takt times would be calculated using the units/week of that product. For example, product A is 20k/week (or 3,334 per day since you work 6 days a week), so you would need to take your Available Production Time Per Day and divide that by your required Customer Demand Per Day to give you your takt time, in Time/Piece.
Just as an example, if you have 20 available production hours per day, your takt time for the process c that makes Product A, would be 20 hours / 3,334 pieces = .0059988 hours per piece = .35993 minutes per piece = 21.596 seconds per piece. If my math is correct (I did it in a hurry), you would then assume that every 21.6 seconds a customer is requesting 1 unit.
You would then do the same type of calculation for the other product lines going through their own process c workcenters.
For the other processes: You show a total of 100k/week (A,B,C,D products summed), and they all run through processes a,b,d, and e. Which would essentially give you the same takt time for those processes, and be determined the same way that you determined the takt times for process c.
In the end, you are simply looking for the answer to 'how much time do I have to produce the next piece so that I am in pace with the demand of the customer?'
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04/13/2009 11:27 AM
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Total Availiable time is (6 days x 24 hours x 60 minutes) - (6 days x 40 minutes x 3 Shifts) giving you (8,640 minutes) - (720 minutes) = 7,920 minutes.
7,920 minutes x 60 seconds = 475,200 seconds.
Demand is equal to 20k + 30k + 10k + 40k = 100k
Avialiable time 475,200 seconds divided by demand 100k units equals 4.752 seconds per unit which is your Takt time.
This is assuming that there is no change over time and that uptime for your machinery is 100%. This also assumes that the parts can be fed into the process sequentially with no interuption as well. Avialiable time for each type would be as follows:
A: 475,200 secs x .2 = 95,040 seconds per week
B: 475,200 secs x .3 = 142,560
C: 475,200 secs x .1 = 47,520
D: 475,200 secs x .4 = 190,080
Must be a very well oiled machine to handle that much variation. Maybe I am missing something?
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04/17/2009 02:41 PM
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Originally posted by: 200304
Total Availiable time is (6 days x 24 hours x 60 minutes) - (6 days x 40 minutes x 3 Shifts) giving you (8,640 minutes) - (720 minutes) = 7,920 minutes.
7,920 minutes x 60 seconds = 475,200 seconds.
Demand is equal to 20k + 30k + 10k + 40k = 100k
Avialiable time 475,200 seconds divided by demand 100k units equals 4.752 seconds per unit which is your Takt time.
This is assuming that there is no change over time and that uptime for your machinery is 100%. This also assumes that the parts can be fed into the process sequentially with no interuption as well. Avialiable time for each type would be as follows:
A: 475,200 secs x .2 = 95,040 seconds per week
B: 475,200 secs x .3 = 142,560
C: 475,200 secs x .1 = 47,520
D: 475,200 secs x .4 = 190,080
Must be a very well oiled machine to handle that much variation. Maybe I am missing something?
This calculation is right, but without information on actual wip or lead time and processing speeds of the machiens, I can't support the conclusion that it must a very well oiled machine..
Jeroen
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04/17/2009 02:41 PM
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Austin,
There is a point being missed here amidst all the calculations. Takt is product specific. Lets say your products are 4 seats in a car. Drivers side front, drivers side rear, passenger side front and rear. They are not interchangeable and you can not substitute one for the other. Second, the purpose of takt is to match your production with the customer's demand. Unless your customer is willing to accept product A as a substitute for product B, then the takt numbers are for an available time of 475,200 seconds are:
A=23.76 secs
B=15.84
C=47.50
D=11.88
If these are on the same productiion line with similar work requirements and the line is perfectly balanced with no losses then the cycle time at each station might be 475,2000/100,000 = 4.752 seconds. So at the end of the line, a good unit is produced each 4.752 seconds. If you developed an EPE Interval with a seqeuence of AABBBCDDDD, and interval of 47.52 seconds, every 47.5 second you would make 10 units. 2 of them would be As, so every 47.52 seconds you make two, or one per 23.76 seconds, likewise you will see that the rate of each product coming off the line will be at your calculated takt for that product. The cycle time of each station would be 4.752 seconds.
Don't confuse takt with cycle time......takt is product specific
It makes no difference if it is a 2 step process, or a 10 step process and it make no difference if the work stations are a flow line or cells or in series or parrallel, Takt is based on two end conditons, available time and customer demand.
Takt is the concept that we want to synchronize externally with our cusomter and of course our customer wants a specific product mix, he does not care, that we can, on average produce this product he wants a specific volume of A, B C and D.
Then you synchronize the steps internally to balance flow and reduce wastes. In this case , if cells a, b, d and e each have one work station, then the work performed, the cycle time would be 4.75 seconds per station but cell c with 4 parallel paths would have about 19 seconds of work per path but since there are four paths they still feed cell d, at a rate of 4.75 seconds.
Amid all of this design of the processing line, the takt has not changed.
The use of takt goes beyond the numerical calculations and feeds into other lean concepts and visual management techniques so it is wise to know the difference between the concepts of takt and cycle time.
Stay in touch,
Lonnie Wilson
law@qc-ep.com
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04/19/2009 10:04 PM
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thank you all for reply, i am much more clear now.
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04/24/2009 01:21 PM
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"This is assuming that there is no change over time and that uptime for your machinery is 100%. This also assumes that the parts can be fed into the process sequentially with no interuption as well."
No assumptions. Takt time is the average pace of customer demand within the available time to produce it.
Machine uptime, cycle times, changeover, etc. do not affect customer demand or the available time and are not used in the takt calculation.
Use a percentage of takt to calculate target cycle time. Target cycle time is where all your ineffeciencies go not takt.
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04/26/2011 11:34 PM
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Hi Robert,
You had mentioned that "Machine uptime, cycle times, changeover, etc. do not affect customer demand or the available time and are not used in the takt calculation."
Does the available production time vary when you consider setup time? I mean we all know that takt time = rate of customer demand per time frame/ available production time for the same time frame. So if I have setup time for each and every machine in my production line, will that not reduce the available time per shift on my hands? I am not really certain whether set up times are included in the takt equation becoz some literature says that you should not while others like Toyota subtracts changeover time in calculating the planned cycle time of a process (unplanned downtime is not calculated becoz Toyota makes it up with overtime in order to keep problems visible). Im not certain about consider setup time in the takt equation so please help out.
Thank you,
Allan
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04/27/2011 10:51 PM
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Hi, I am vipin kumar.Takt Time is the pace of production that aligns production with customer demand. In other words, it is how fast you need to manufacture product in order to fill your customer orders.
========================================
Agricultural Implements Manufacturer
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04/27/2011 10:51 PM
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If you take the approach that your available time is reduced by your setups, then you risk locking in those setup times as you plan to meet takt. I prefer to keep takt time purely based on available working time and customer demand and then look at all of the factors that cut into capacity. These would be setups, downtime, yield loss, rework, etc.
If you have lots of setups, a far better metric is to look at Every Part Every Interval (EPEI) which gives you an excellent sense of the impact of setups, downtime, yeild, etc on your capacity and ability to meet takt time.
Phil
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04/27/2011 10:51 PM
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Machine uptime and changeover time does not come into play in Takt time calc.
eg
available time after mandatory breaks=450 shift-vol per shift 450=takt time 1min(60 seconds)
assume machine uptime after changeovers 350 min/450=.78 minutes(47 seconds).
47 seconds is what cycle time you have to hit to meet customer demand.The customer still theoritically wants his product every 60 seconds.
so you have several options-run at 47 seconds if you can,if you cannot-increase uptime,work overtime,purchase new equipment-the Lean and cheapest way is to reuce changeovers,
I hope this gives you some clarification.
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04/29/2011 05:25 PM
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Allan,
Takt time is perfect world without consideration for downtime or changeover time or other "losses".
Takt only considers scheduled time - if preventive maintenance is scheduled one hour per shift, then that time is not available. Scheduled breaks, lunch, safety meetings, clean up, etc that are scheduled, are not available time.
To account for all the unscheduled time (unplanned maintenance, late return from lunch, material shortages, changeover, etc) multiply takt time by a factor to arrive at a target cycle time (some people use different names for this calculation but I could not find a standard term in the Lean Lexicon).
Some people use OEE as the factor, others use "efficiency", or some other fudge factor. I often find a factor in the customer quote assumes 85% efficiency so I have to use that number or higher when designing processes. What is important is that people understand the delta from takt to target is waste and that we should seek to improve it, not just accept it.
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05/18/2011 01:19 PM
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Hallo everybody,
maybe I miss something, but what I see here are calculations that have nothing to do with takt time. Takt time is the rate at which customers demand products. It is NOT the rate at which you manufacture products. So in order to compute takt time, you need info about sales, not about factory.
As a second step you must align your factory. So the question is, what are your sales?
Kind regards,
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