Takt Time & Cycle Time Calculations

P

paxbritannia

#1
Hello. My name is Daniel from the UK. I am unemployed and decided to do a lean course to improve my chances. I've come across 2 questions that I am not sure how to start making calculations. I'd be grateful if someone can show me the calculation process. The questions are:

1. What should you do if the takt time is 6.0 mins/part and the cycle time is 5.0 mins/part?

2. If 4 operators have cycle times of 17, 16, 15, and 18 minutes with a known takt time of 15 minutes, what is the output of the line?

Thank you and God Bless.

Daniel
 

Stijloor

Staff member
Super Moderator
#2
Welcome to The Cove Forums Daniel!! :bigwave: :bigwave:

Very good questions! Glad you found us.

It is weekend + Super Bowl Sunday, but responses will come.

Stijloor, Forum Moderator.
 

somashekar

Staff member
Super Moderator
#3
Hello. My name is Daniel from the UK. I am unemployed and decided to do a lean course to improve my chances. I've come across 2 questions that I am not sure how to start making calculations. I'd be grateful if someone can show me the calculation process. The questions are:

1. What should you do if the takt time is 6.0 mins/part and the cycle time is 5.0 mins/part?

2. If 4 operators have cycle times of 17, 16, 15, and 18 minutes with a known takt time of 15 minutes, what is the output of the line?

Thank you and God Bless.

Daniel
Takt time comes from a german word which translates to cycle time. Takt time concept aims to match the pace of production with customer's demand.
Takt time can be determined with the formula:
T=Ta/Td
Where
T = Takt time, e.g. [minutes of work / unit produced]
Ta = Net time available to work, e.g. [minutes of work / day]
Td = Time demand (customer demand), e.g. [units required / day]
(courtesy wikipedia)
So
In your case 1.,
Be happy that the cycle time can meet the demand and have some surplus stock.
In your case 2.,
If the 4 operators are working in a line one feeding the other, then the cycle time is 18, (the weakest link) and requires a line balancing to improve so as to meet the demand of takt time 15.
 

AdamP

Inactive Registered Visitor
#5
HI and thanks for asking your question here at the forum!

The posts so far have provided correct math, so:

1. Your process (cycle time = 5 min.) can not only keep up with current customer demand (takt = 6 min.), but will begin to build up inventory - either somewhere mid-process as WIP (work in proces) or at the end as finished goods. Either way, in lean terms, that's waste, as you will be making more than demand called for. From an accounting perspective, it's costing you more to sit there too!

There are follow on exercises and tools which would allow you to arrive at a more optimal match between cycle and takt. This involves load balancing and perhaps reconfiguring your staffing, but those would be "other" questions for the classes you're taking.

2. In this case the math works nicely (that means is easy for me!) For your overall process, the total cycle time, or completion time, is determined by the slowest step. So in this case, it's 18 minutes. Take that against a takt time of 15 minutes, and you find you cannot keep up with demand. At this point, you would need to conduct a value add/non-vlaue add analysis and then probably a line (load) balancing exercise to improve your cycle times so you can meet takt. Given that none of the 4 operators has a cycle time less than takt, probably not an easy puzzle.

Hope this helps.

Cheers!
 
M

megahertz

#6
The slowest process will determine the line cycle time or in engineering term called the "bottle-neck" process. Line balancing would be the best method in this issue. Anyway, as mentioned by AdamP, considering that none of the process are below takt time, it would be a hard task to re-balance.
 

wmarhel

Quite Involved in Discussions
#7
[/B]

1. What should you do if the takt time is 6.0 mins/part and the cycle time is 5.0 mins/part?
First, thank the heavens since the issue is usually a longer cycle time than takt.

You could look at using the additional or free minute of the operator/s to perform some additional value-added activities such as preventative maintenance, problem solving and possibly even fulfilling kanban/s for other areas of the plant.

Another alternative could be to change the process to remove one person with a cycle time that is nearer to takt.

[/B]

2. If 4 operators have cycle times of 17, 16, 15, and 18 minutes with a known takt time of 15 minutes, what is the output of the line?
I'm going to disagree with somashekar's post slightly, although not because he's wrong, since on the surface a line only produces at the slowest rate. Based on the times you provided though, the slowest cycle time (18 minutes) at a station would yield 3.33 units per hour. If you take the average of those stations, which equals 16.5 minutes, you could actually get 3.6 units per hour. Assuming of course that the work could be distributed evenly across all operators.

A simple calculation to determine manning is to divide the cycle time of a process by the desired takt. This will yield the manning that should be necessary to meet takt. The particular process might requires some additional effort on processes, standardized work, etc; but that is one of the many reasons for kaizen events.

Regards,

Wayne
 

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