Hi Ron,

If a user needs to maintain the Safety stock from MRP run date, user can enable the ‘Plan Safety Stock Receipt on MRP run date’ check in Perform MRP dialog. 

This would basically check the safety stock you have set for your parts and consider it when creating supplies for the demands. However, It's not possible to execute MRP for only safety stock. You can set up the safety stock for a part in Inventory Part > Planning Data tab > General sub tab> Safety stock field.

Hope this helps.

/Pabasara

@Pabasara Kalahe  thank you very much.

@Pabasara Kalahe 

i have one more question, 

safety stock is calculated via Calculate Planning Data this program, if i check the option i mentioned above, MRP will not recalculate the safety stock, right? instead, MRP will check whether there is enough safety stock available, if not, it will do the replenishment, am I understanding correct?

Thank you.

Hi,

Yes, since Safety Stock is a user defined value, MRP will only consider the value for inventory replenishment based on the demands that are available.

/Pabasara

@Pabasara Kalahe thank you for your time.

Hi Ronhu,

If you select the checkbox ‘Plan Safety Stock Receipt on MRP run date’", MRP will generate supply for safety stock value on run date if there is no enough supplies to cover the safety stock.

If the check box is cleared, safety stock receipts will be planned in conjunction with the first event for the part.

example, if the ss=10 and there is no any event(demand/supply) in the system for this site, if you still need to generate supplies for SS, you need to select the above checkbox. MRP will create a supply for ss on run date. This can be used to generate supplies for ss only.

if the ss=10 and  there are some events(demand/supply), first event on date xxxx , then you can run MRP without selecting this check box, MRP will generate supply for the SS on first event date xxxx.

You can still run MRP by selecting this check box, then MRP generate supply for SS on run date , not on first event date.

The Calculate Planning Data dialog box can be used to automatically calculate and update the planning parameters for selected parts, if the safety stock check box is selected.

If not safety stock value can be manually updated. MRP will consider this value when generating supplies for ss depending on the selection of the check box in the Perform site MRP.

MRP will not calculate safety stock, instead it generate supplies according to the value given in the safety stock field.

Hope this helps you.

BR

ANMASL

@ANMASL appreciated your reply. it does help.

 by the way, if you would like system calculate the SS, you have to work with demand server? as i learnt, SS is calculated base on the Standard Deviation.

Thank you.

Hi Ron Hu,

You need standard deviation for the demand as one factor. Below is the equation to calculate SS, taken from IFS documentation.

Calculation of Safety Stock

The safety stock is calculated for all planning methods.

Safety stock (pieces) = Safety factor -] * standard deviation for demand (pieces/period) * square root of part lead time (period)

• The lead time is retrieved from the inventory part record, purchase or manufacturing lead time depending on part type.
• The safety factor is retrieved from the service rate connected to the inventory part. Here the normal standard distribution is used to define the service rate and the safety factor. The service rate is considered as the probability and the safety factor is considered as the standard score of normal standard distribution. It is also possible to retrieve the safety factor for a given service rate by using the standard Excel function NORMSINV(Probability).

Note: The safety stock will not be updated if the predicted yearly demand is used, as standard deviation is zero because of constant demand. Also note that if lead time is zero, the safety stock will be zero.

Best regards.
Anju

@ANMASL  Thank you.