Exact for Manufacturing calculator: What is the difference between “Pieces per” and “Pieces per sheet”?

Written by Pieter Hamans on . Posted in Exact Online


In the material calculator of Exact for Manufacturing we have fields named “Pieces per” and “Pieces per sheet”. How to use these fields is explained with an example. We are going to build an iconic BILLY bookcase out of MDF board.

The design of the bookcase

Our BILLY is made of two geen walls (160 cm high, 28 cm deep) with five red shelves (80 cm wide, 28 cm deep). For this example we leave out the fasteners, packaging and that wonderful instruction sheet. For the professionals: We also don’t bother to laminate the sides of the walls and shelves.



The walls and the shelves are cut out of MDF board size 3,60 x 1,80 m. Out of a sheet of green MDF we can cut 12 pieces of wall, and out of a sheet of red MDF we can cut 24 shelves.



Professional software for sheet cutting machines (a so called nesting program) could have yielded an extra piece of wall and two extra pieces of shelves by turning them 90 degrees. We will revisit this topic later.


It is required to create the items for the material (the MDF sheets) with the shape characteristic “sheet”, and to enter the trade dimensions (3,60 x 1,80 m). Don’t forget to check “Whole sheets” (the warehouse does not stock sawing rests), and “Whole pieces per sheet” (we are not mending parts of sheets together).



A flat bill-of-materials and shop order

The easiest bill-of-materials for this BILLY has two material lines for both colors of MDF.



This bill-of-materials has been created by entering the item code of the material, and clicking on the calculator icon in the line. We will then see the calculator screen:



We are now entering that one shelf measures 80 cm c 28 cm, and that we require 5 shelves per BILLY (in the field “Pieces per”. The field “Pieces per sheet” will be populated automatically by the calculator with 24 pieces. We recognize of course that this value represents the number of shelves we can cut out of a sheet. If we enter in the shop order the batch size of 28 (BILLYs), we will need 28 x 5 = 140 red shelves, and 28 x 2 = 56 green walls. These 56 green walls require 5 sheets of green MDF (5 x 12 = 60), and 6 sheets of red MDF (6 x 24 = 144). A shop paper for 28 BILLYs could look like:



A multi-level bill-of-materials and shop orders

There is a disadvantage to the above example. We may want to cut the material completely, which will yield us 4 extra shelves and 4 extra walls. We don’t need them for the 28 BILLYs, but we could stock them up in case of quality issues or for the next order. In that case we can better create the walls and shelves as items (semi-finished products). The shop orders will then show the number of shelves and walls:



The shop paper shows the quantity planned (56) and the dimensions per wall:



The first 56 walls are “Issued to parent”, the extra 4 pieces are “Put in stock”.


How to deal with nesting?

As mentioned, a nesting software could get a higher number of pieces out of your sheets. We can enter this in the field “Pieces per sheet”, thereby overwriting the calculated number.


The functionality for calculations is included in all editions of Exact for Manufacturing. The functionality for suborders is included in Exact for Manufacturing Advanced and higher.


More information with Pieter Hamans, pieter.hamans@exact.com


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