Product Structure File Maintenance

Application Overview

This application enables the user to maintain the Product Structure File.  Numbers of related records from this file make up the various bills of material and so the Product Structure File is the main file in the BOMP package.

This file and the bills of material, which can be stored in it, become a very important tool in the manufacturing environment.  In addition to containing design and manufacturing specifications, it can also be used for forecasting and product scheduling.

The following is a brief explanation of the contents of the records stored in this file with some hints as to how this file might be utilized.

Product Structure Maintenance

A product structure is created by specifying relationships between pairs of items where the lower one is a component that is assembled with other components to create the higher item which is called a parent.  A parent will usually have relationships with two or more component items.  However, it is allowed for a parent to have a single component.  A component may be used in many different assemblies, each of which would be considered a parent.  Each of these component-parent relationships needs to be specified in the Product Structure File.  See Product Structure example below.

In addition to the parent and component numbers, the Product Structure record includes the following fields:

a)   The sequence number of the component within this structure.  Components will display and print according to this sequence number, which is entered by the user.

b)   The quantity per assembly.  This field assigns the quantity of components per parent item.  The magnitude of the quantity can be expressed in either integer or decimal form and can be either positive or negative. This wide choice makes the file useful for different types of bills.

c)   Where the component attaches to the operation.  One of the important considerations of the capability to specify this operation is that the user can now see if any of his shortages are, in fact, not crucial until later in the assembly if Shop Floor Control is being used.  

d)   Shrink/scrap factor.  This gives the user the capability of being more accurate in estimating component usage.

e)   The activity code indicating whether this parent-component relationship is currently active, planned for future, or obsolete.  The capability of noting obsolete items allows the user to maintain structures he no longer wants to use but, for whatever reason, does not want to delete.  He can leave them on file to be reviewed later to then determine if they should be modified or deleted.

f)    The effectivity date indicates the date that a forecasted item should become active. For a more detailed explanation of the effectivity date, refer to the Package Overview document.

g)   The obsolete date indicates the date that an active item should become obsolete.  For a more detailed explanation of the obsolete date, refer to the Package Overview document.

h)    User-Information field.  This can be a date or any user-defined code.

i)    The reference designator can be used to show a routing of a component item.  It may contain information pertinent to this component for this parent.  For example, it may describe additional processing procedures, replacement parts, references to schematics or blueprints, machining tolerances, or inspections to be performed.

Types Of Bills

In addition to the Bill Of Material designed by engineering and used by manufacturing, there are other bills, which are used in planning and scheduling.  These so-called pseudo-bills differ most from the Bill Of Material where there is a product with many different options.

Forecasted bills (pseudo-bills) are an artificial grouping of items, in bill of material format, used to facilitate master scheduling and/or material planning.  For example, forecasted bills can be used in master scheduling to explode requirements properly for optional components.  These bills are also called planning bills.

A modular bill is a type of planning bill, which is arranged in product modules.  It is often used in companies where the product has many optional features, e.g. automobiles.  This type of bill is designed and maintained in the Feature/Option Configuration File Maintenance application.

Copy Structure

The copy structure feature provides the ability to copy the structure of an existing bill to a new item number.  Then modifications can be made to create a new assembly without starting from scratch.  A new activity code, a new effectivity date, a new obsolete date, and a new user-defined field can be specified for the new bill.

Mass Replace

Replacing an obsolete part with another is simple with the mass replace feature.  After the user specifies the obsolete and replacement item numbers the old part, wherever it occurs in all bills, is replaced by the new part.  This feature can also be used to phase out obsolete items by making the replacement item the sole component of the obsolete item in the bill.

Product Structure Example

Structuring bills of material can be confusing until you do some, and then it becomes much easier.  A bill of material is, by definition, a parts list.  By structuring a bill of material you get a product structure i.e., a breakdown of the parts list in a manner resembling the stages in which the product is built.  A good example is a motherboard for a personal computer.  This motherboard has the following components:

           1.  1 CPU (CPU)

           2.  1 Video-CD (VID)

           3.  1 Input/Output (I/O)

The motherboard (MB) structure would be shown as:

NOTE:  The numbers in ( ) in the diagram indicate the quantity-per.

Continuing to the next level, the CPU is made of:

               1.  1 Clock (C)

               2.  1 Data-Bus/Buffer (DB)

               3.  1 Memory Manager (MM)

               4.  1 Monitor-ROM (M)

               5.  1 2 Meg. Ram (MR)

               6.  1 Ram Address Multiplexer (RM)

               7.  1 CPU Reset (CR)

               8.  1 280 Micro Processor (MP)

The (CPU) structure would be shown as:

You should know a few things here.

1)   There generally is a lower level for any part unless that part is purchased.  If you buy or purchase a part, that means you are not manufacturing it yourself.  If you are not manufacturing it yourself, there is no need here for its components, since you will not use them for this part.

2)   You must have unique item numbers for all items (parents, sub-assemblies, and components) used in Product Structure.

3)   As you can see, the use of significant item numbers (i.e., the number tells you something significant about the item) can quickly become limiting and therefore is not recommended; i.e., non-significant item numbers.

4)   Load the Product Structure (P/S) File via the Product Structure File Maintenance application.  Notice that each P/S record has one field for parent item and one for component item.  Each P/S record shows one relationship, and one way to load the P/S File is one product line at a time, one level at a time.  For example, the above Mother Board may be entered as follows:

        P/S File

        Maintenance     Parent     Component     Quantity-Per

        1st Entry        PC           CPU            1

        2nd Entry        PC           VID            1

        3rd Entry        PC           I/O            1

And then the CPU's structure may be entered as:

        1st Entry       CPU           C              1

        2nd Entry       CPU           DB             1

        3rd Entry       CPU           MM             1

        4th Entry       CPU           M              1

        5th Entry       CPU           MR             1

        6th Entry       CPU           RM             1

        7th Entry       CPU           CR             1

        8th Entry       CPU           MP             1

Note:  All the reports and inquiries will show components in the sequence they were entered.  The only way to alter this sequence is to use the field labeled Sequence Number.  The sort for bills of material is by sequence number within parent item number.  This is important not only because it allows components in alternating sequences, but also because you can now specify the same components several times on the same level for a common parent.  This circumstance does arise once in a while e.g., left and right-handed knobs where the right-handed one is used in operation 20, but the left-handed one is not used until operation 50.

The key to becoming good at handling product structures is practice.  If it seems confusing, start by entering a non-complex structure of anything you want and look at the reports.  Once you have the basic understanding, then you may want to analyze some of the evolutionary terms like planning bills, pseudo bills, super bills, modular bills, etc.   However, you must understand the simple bill of material relationship.

One concern that frequently seems to arise is the situation where one large piece of material is used for smaller pieces of various sizes; when the various sizes are not consistent, and all go with different products.  Examples are:

BOMP does not handle the above directly.  A way it can be handled is with a two-pronged approach.  First, all such product structures are set up so the components (that come from the larger pieces) indicate a specific size i.e., a 2' x 5' metal piece, 2' x 4' wood piece or 10' of a certain cross-section tubing, wire, cable, etc.  It disregards the larger piece, per se.  An optional way is to determine which type of order will first cut into the larger piece.  Then, you can discern what non-related components are by-products of the extracting operation, set up the structure including all components to be extracted, but use a negative quantity-per on the non-related by-products.

Second, regardless of the above method, the size of by-product issues are handled more directly through a combination of more efficient manufacturing processes, statistical process control and a scrap/rework department charged with getting scrapped material back in production.

Bill of Material Product Structure Import

This is an add-on feature.  This utility can be used to either import a new product structure or modify an existing product structure.  Modifying an existing product structure may cause a quantity allocation integrity issue, if the parent item already has activity.  Since this problem can be easily resolved through the Reset Qty Allocation utility, the import utility will only give a warning message when this happens.  Contact Netcellent or your Elliott reseller for more information about this utility.

Run Instructions

Select Product Structure File from the pull down BOMP Maintenance window.  The following screen will then be displayed:

Product Structure File Maintenance Entry Screen

 The following options are available:

                        Add New Product Structure Items

                        Change Product Structure Items

                        Delete Product Structure Items

                        Copy Product Structures

                        Mass Replace Items in Product Structure File

      To return to the menu bar, press the ESC or F10 key. To leave this application, press X for EXIT when positioned at the menu bar.

Entry Field Descriptions

Add, Change, Delete

Copy Structure

Mass Replace

Product Structure File Maintenance

Reference Designator

Product Structure File (Copy Structure)

Product Structure File (Mass Replace)