If ylou are looking at an ongoing process, the length of time a unit spends in processing is usually not an issue. Think of an automotive assembly line. Each vehicle may spend several hours moving down the line, but the line's "cycle time" is usually thought of as how frequently a finished vehicle comes off the end of the line. On the other hand, if one is considering a 6 position rotary table machining center, and you only run 6 pieces, the cycle time would include the time from when you loaded the first piece on, until the time you unloaded the sixth piece, which would be significantly different.
Geoff Withnell
The main point raised here is, whether the definition of cycle time given- "The time interval between start and finish of an operation"- is correct or not.
2.Time consumed on the assembly line is covered in 'Total cycle time'.
3.For making 6 pcs only, I will not prefer to load it on a 6 position rotary table machining center.
Umang,
Takt time is solely the rate of production required to meet customer demand. While your equation is technically correct, your definition of it, "minutes of work per unit produced" is incomplete. The ideal scenario would be for takt and cycle time to be equal, but this rarely the case. Cycle time is often slower or faster so adjustments would need to be made. A better definitition would perhaps be "target rate of production". Your definition as stated would basically be the same as that for cycle time.
I would also clarify the equation to support takt to be customer demand and not "total demand". If my customer only wants 100 pieces/day, but I choose to make 150, then theoretically my takt is based on 100/day. From a capacity and/or planning standpoint, I may be looking at increased demand in the near future and wish to employ some other method such as level loading in order to alleviate the need for overtime. But that doesn't change the fact that takt is customer focused.
Please don't think I'm nitpicking, I'm just trying to present the perspective based on the "purist" approach since that is what most people will have been taught or read versus what one company may or may not do. What it really comes down to is what may work for one company doesn't necessarily guarantee success for another.
Wayne
IMHO "Rate of production" relates to 'Number of units produced per minute', which in turn relates to cycle time and not to Takt time as you have suggested. There is a popular mis-concept about the Takt time, which in fact is taken as "Minutes per Unit" and not as "Units per Minute.
2.The concept of 'customer demand' is absolutely correct while catering for a single customer. In case of multiple customers, one has to consider 'Total demand' (of course of the customers). This terminology also covers the after market demand. Obviously, in the days of 'Lean manufacturing' & 'Zero inventory' ideology, no one wishes to produce without a demand! IMO, 'Total demand' is the controlling word, since the customer is automatically behind the demand! Therefore Takt is focused on 'Demand' - created by customer(s) and/or market.
'TAKT' is a German word for the 'Baton' used by orchestra conductors to make the musicians play in unison.
Umang
