MRP Planner (material requirements planning)

About the MRP Planner (material requirements planning)

Runs material requirements planning (MRP) in your browser. Open your master production schedule — the finished items you plan to make, week by week — your bill of materials, your item data (stock on hand, safety stock, lead time and lot-sizing rule) and, if you have them, your open purchase and work orders. The plan explodes the schedule through every level of the BOM and works out, for each item and each week, what is needed, what is coming, what will be left and what must be ordered.

For every item you get the time-phased gross-to-net table — gross requirements, scheduled receipts, projected on hand, net requirements, planned order receipts and planned order releases — sized by its lot rule (lot-for-lot, a fixed quantity, a minimum and a multiple, or the EOQ) and offset by its lead time. Low-level coding plans a component used by several products, at several levels, once, after all its parents. Then the action list: what to buy and what to make, how much and in which week, with the late orders that should already have been released and the open orders to bring forward.

Nothing is guessed: a BOM that loops, a quantity in a unit that cannot be converted and rows that cannot be read are listed with their row. Without a pass the plan is a free preview: the counts in full, the first orders of the action list and the first items with their tables; the action list file, the workbook and the copy unlock with a Premium pass. Your files are read in your browser and never uploaded.

Common uses

• The weekly purchase and production list of a workshop or a small factory.
• Checking whether a new order can be met with the lead times you have, and what has to be expedited.
• Seeing the requirements of a shared component from every product that uses it.
• Operations management coursework on MRP records and lot sizing.

The gross-to-net logic

Each item is planned in weekly buckets, the way the gross-to-net logic of Orlicky’s Material Requirements Planning describes it:

• Gross requirements = the schedule for the item + the planned order releases of every parent × the quantity per (with the BOM’s scrap).
• Available = projected on hand of the week before + the scheduled receipts (open orders) due that week.
• Net requirement = gross requirements + safety stock − available, when that is above zero.
• Planned order receipt = the net requirement sized by the lot rule; its release = the receipt’s week − the lead time.
• Projected on hand = available + planned receipt − gross requirements.

Items are planned lowest low-level code first: a finished product (code 0) before its components, and a component used at level 1 in one product and at level 3 in another only after every parent, so its requirements are complete when it is planned.

Lot sizing

• Lot-for-lot: exactly the net requirement (whole units for pieces).
• Fixed quantity: whole lots of the lot size (250 needed, lots of 100: 300).
• Minimum and multiple: at least the minimum, rounded up to the multiple (60 needed, minimum 50, multiple 25: 75). A minimum or multiple also applies on top of the other rules.
• EOQ: at least the economic order quantity √(2 × annual demand × order cost ÷ (unit cost × holding cost %)), with the annual demand from the requirements of the plan; type the EOQ as the lot size to use your own.

Late orders and the past-due week

Week 0 is past due: demand dated before the plan starts, open orders that were due already, and releases that should have happened before week 1. A release that falls before week 1 cannot arrive in time: it is planned to release now and listed as late, with how many weeks late it is and the week it can arrive at the earliest, and its components are needed at once. The action list starts with these.

Open orders to bring forward

When a new order is planned for a week while an open order of the same item arrives later, bringing the open order forward could cover the need instead. These are listed as reschedule-in suggestions (an MRP exception message): ask the supplier or the shop floor whether the open order can come sooner, and cut the planned order if it can.

Your files

Every file is optional but the schedule: without item data, items are planned with no stock, no safety stock and no lead time (and the notes say so). Lead times are in weeks unless the column header or the setting says days (10 days plan as 2 weeks). Quantities may use a decimal point or a decimal comma: each file is read with what its own numbers show. A quantity in another unit of the same kind (500 mm of a wire kept in metres) is converted exactly; a unit that cannot be converted is reported, never guessed.

Limitations

• Infinite capacity: MRP plans materials, not machine time. Check the load on your machines with the Production Schedule Planner.
• Weekly buckets and whole-week lead times; a plan of at most 52 weeks.
• One BOM per item, no alternative components or phantom items, and no by-products.
• Lead times and lot sizes are taken as given: suppliers’ minimums and price breaks beyond the minimum and multiple are not known to it.

Privacy

On this device; its files download once

Your schedule, BOM, stock and orders are read in this browser and never uploaded; only the plan settings you choose are remembered on this device.