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What is the point of the planning time fence? Always greater than lead time?

Former Member
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    I know what the planning time fence is, but I am just wondering a little more in depth why it is so important and what its purpose is. Is there a standard on what the PTF should be? I have heard it should always be at least equal to lead time. Say I am working with only buy parts in the system. The plant is a secondary plant, meaning it is not the home plant where the parts are bought. Will the PTF even matter? Say I set the PTF to lead time + 90 days...does that mean it is a buy part that has very long lead times and has issues with the supplier meeting the necessary requirements? What does a large PTF mean?

Thank you

-Mike

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Answers (3)

Answers (3)

Former Member
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Hi

Please consult your business on their requirement. Do they actually need to firm the orders inside PTF. If Yes, then what is criteria of doing so. Is it for all material or only for specific material.

Generally PTF has impleication with proper MRP type and this is used only for MPS materials or final material in plants. Not all materials are set for PTF.

It is thumb rule that Lead time must be covered in PTF, but Lead time only for Final material.

I donot see any reason why your scenario will have PTF applicable untill some material supplied by vendor is so studious that they donot take orders in between.

Former Member
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Hi,

On top of what Dharma said, I would like to justify the relationship of lead time with PTF as follows:

PTF restricts any changes to happen automatically to the planning elements in this period.

Example: Lead time: 30 days, PTF is only 7 days.

Here, PTF can restrict any changes not to happen in the 7 days only. What if quantity required on the 10th day is increased two fold by MRP. How can we achieve it in a time which is lesser than estimated lead time?

This is why as a rule of thumb, PTF is suggested not to be lesser than lead time of the material.

Former Member
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Hi,

Planning time fence is used to prevent any automatic changes when MRP run ie, to prevent procurement or planned order creation for a material in the particular period. Basically PTF is used with Master production schedule (MPS) materials which is used for higher level assembly.

I don't find any link between PTF and material lead time.

Regards,

Dharma