Effects of Increased quantity on cycle time

[JDK1]

I'm attempting to quantify the effect of multiple orders for the same product on cycle time.
As an example;
1st order is for 50 items and cycle time is 100hrs, if we are to complete for 3 additional orders of 50 items at the same time (4 individual orders of the same product for 4 different customers)
How will can I quantify the reduction in cycle time on each of the three additional orders?

Thanks in advance

 

[ajack1]

If I am understanding you correctly all you will save is the downtime involved in getting the machine, assembly line or whatever set up to produce a certain item.

 

[tomwalz]

We separate downtime into downtime to start up a line and downtime to shut down a line. In operations which are operator controlled, such as hand assembly, we find that the time per part, not counting downtime, can decrease as the batch size increases.

Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

 

[JDK1]

Thank you for the replies,
We will save machine setup and change over time but,
I think I'm looking for the quantifiable portion to the machine downtime and the decrease in time per part,

Is there a formula to calculate the reduction based on parameters such as utilization, cycle time etc??

Thanks again

 

[ajack1]

Again I might be misunderstanding you but isn’t that just A + (B/N) ?

Where A is the time to produce a part, B is the time to set up and disassemble the machine/ production line and N is the number of components.

I am sure other factors come into play as Tom says time will decrease as operators “get in the swing”, I would however guess this reaches a point where fatigue, boredom or the need to use the rest room come in and the opposite is true.

 

[tomwalz]

ajack1

Yup, you're correct.

We take all the time we pay for and divide it by all the parts we get. This includes breaks, downtime, repairs, etc.

My favorite has always been the boss, engineer, etc. who comes out; works like crazy for ten minutes to set "the standard" and then goes back to his office.

To get meaningful answers we need many samples as changeover time varies as does everything else.

I guess we use (A*N) + B/N

However I think yours is a better answer to the question as given. We look at the question somewhat differently.

Have good weekend,
Tom


Thomas J. Walz
Carbide Processors, Inc.

http://www.carbideprocessors.com

 

[griffengm]

JDK1,
In my experience there is X amount of time for set-up regardless of quantity. Then there is an amount that varies according to product features. If you can only fit 10 parts on a skid and your usual lot size is 50 then you need to include handling time for the four skids in your calculations. OTH, if 30 fit on a skid you need to figure in two handlings even though one skid has only 20 pieces on it. Sometimes refered to as "stepwise" incrementals.
I believe Maynard's Handbook covers some of this topic in better detail than we can here. Locate a copy.
This is one reason that diferent companies approach your question somewhat differently.
Griffy