Once your production plan has been entered (and checked) the planning calculations can be performed using the plan explosion option:


 

The way the planning process works can be altered as follows:


Reschedule early and late limits

The reschedule early and late limits will determine how late or early an existing works or purchase order must be (when compared to the corresponding suggested order) for Herschel to suggest rescheduling the existing order.  It makes sense to set these limits to the largest figure you can accept as it means that you will get fewer rescheduling recommendations.
Use your plan, outstanding sales orders or outstanding works orders

You must decide whether to use your plan, outstanding sales orders or outstanding works orders as the basis of the plan explosion. The advantage of using actual sales orders rather than your plan is that Herschel will then use the exact duedate of each sales order line to do its calculations.  In the plan all requirements are sorted into weekly buckets so some accuracy is lost.  Remember that if you want to consider forecasts you will have to use your plan as the basis of the run.
Use actual sales, forecast figures, the larger of sales and forecasts or use sales + forecasts

If you choose your plan you can use your actual sales figures, your forecast figures, the larger of sales or forecasts, or sales + forecasts.  
Ignore planned forecasts before date
 You can enter an "ignore planned forecasts before" date. This is useful if you do not want to manufacture "old" forecasts.
Explode your plan up to to date

You can enter an "explode your plan up to to" date to limit how far ahead Herschel will consider requirements.  This allows you to both limit the run time and reduce the length of the action reports as required.  You should take care to ensure that Herschel still looks far enough ahead to identify the requirements of any very long leadtime items used in your products.

 

There are various advanced settings which can usually be left at their defaults:



The advanced planning options are:



Analyse your plan on a weekly or monthly basis

You can choose whether to analyse your plan on a weekly or monthly basis. Note that if you choose monthly then all planned requirements will be brought forward to the first of the month.
Include or ignore scrap allowances
 You can choose to include or ignore scrap allowances.
Include safety stock before or after exploding requirements

You can choose whether to include safety stock before or after exploding requirements.  If you choose before then the planning process will explode any safety stock items that are assemblies and calculate the components required to make up the safety stock you have specified.  If you choose after then the planning process will not explode the safety stock items.
Ignore current purchase orders, works orders and stock on shelf figures
 You can also choose to ignore current purchase orders, works orders and stock on shelf figures.  This is sometimes useful if you are getting lots and lots of reschedule messages and it is difficult to see exactly what action is required.  Ignoring existing orders can help.
Include quarantine stock or ignore it

You can choose whether to include quarantine stock or ignore it.
Include or ignore leadtimes when calculating ROP deadlines
 You can tell the system to include or ignore leadtimes when calculating ROP deadlines. It is more accurate to include them.


The plan explosion may take some time. The time taken will depend on the size of your production plan, the complexity of your assemblies, the ordering methods used and of course the speed of your computer system. Running the planning process using actual sales orders rather than your production plan usually takes longer as more requirements have to be considered.


When calculating the date each exploded requirement will be needed, Herschel will take into account non-working days. This makes the planning process far more accurate.  When the planning process calculates suggested orders it uses the ordering details held for each partnumber in the Store module.


After the plan explosion is complete a statistical report of the process is produced. A log of errors encountered during the process is also generated: