Cumulative Production X Delivery X Scrap

Hi,

I'm working on a project which should show the parts in production and cross information with delivery or scraps

I work at a foundry and we need the information about how many parts are still in process based on the pouring date, delivery date or scrap date

Basically I have some orders. These production orders might have 1 or more parts in it. The orders are poured and the parts are either delivered or scraped. I need to know month by month how many parts were in process. The parts in process (WIP) should be cumulative monthly until each part of the order is scraped or delivered

This is my data model so far

Material list (1:*) Orders = Type of part to be poured in each order (each order should have only 1 type of part but may have more than 1 part)

Orders (1:1) Poured (order:order) = All the parts in the same order are poured at the same time (Date poured)

Poured (1:*) Scrap/Delivery (order:order/qty)= Each part (individually) may be scraped or delivered

*WIP = parts poured in the month and not delivered/scraped. This should cumulate all orders in the time line. There might be orders produced in the month before and parts still in process

Here is an example of a order with 10 parts poured in Jan. In jan 1 part was scraped and 9 were still in process. Feb starts with 9 parts in process, 1 part is scraped and 5 are delivered, leaving 3 parts in process. Mar starts with 3 parts in process, 2 are delivered leaving 1 part in process, which is delivered in May (leaving 0 parts in process. WIP = 0)

I need help building this up

Thanks in advance,

Thiago