one approach to creating engineering bill of materials

SRMA 2011

ISBN 978-86-82631-59-0

*Faculty of Mechanical Engineering, Belgrade, Serbia, miroslavgojic@gmail.com

One approach to creating engineering bill of materials

Miroslav Gojić, Faculty of Mechanical Engineering, Belgrade

Mentor: prof. dr Slobodan Radojević, Faculty of Mechanical Engineering, Belgrade

Bill of Materials (BOM) is a list of materials and components of a product. BOM is a basis for production planning in a company. BOM in various forms can be applied to companies which are not

related with production. Good design and optimizing BOM directly affects to the productivity of

companies with no change in capacity of production facilities. The BOM can be roughly divided into

generic bill of materials (GBOM) and engineering bill of materials (EBOM). BOM is basis for advanced

lists of materials. GBOM is BOM adjusted for data analytical and EBOM is BOM adjusted for engineers.

This paper presents the basis of the methodology for creation GBOM and influence EBOM on the

functioning of BOM trough their implementation through the database.

Keywords: bill of material, generic bill of material, engineering bill of material, database,

production planning.

I. INTRODUCTION

BOM includes all the elements of structural,

technological and operational production data,

which define the product structure and

technological process of production. BOM task

is to control and manage of complex ways for

obtaining assemblies from sub-assemblies,

while is the calculations of required quantities

for launch of the work order less important.

BOM development is significantly influenced

by computer science that allow quickly

obtaining BOM of final product in the most

diverse variants, with a large number of

connections between data that are incurred in

the production. Instead of requests for materials,

BOM has become the basis for planning and

managing resource in production.

Engineers based on the BOM can analytically

evaluate the quality of the product, and directly

affect on the speed for getting new product. The

study of BOM is a complex problem because it

is a multidisciplinary field in which, with the

computer is applied a simple tree data structure

and easy calculation, and with engineers the

problem is expressed by large amount of data

that has been developed by the creation of new

BOM for new products.

Design of the basic BOM is a key activity in the

definition of data for design and realization of

the production process. The lowest element of

the BOM, known as leaf, is material, while the

highest element, known as root, is the finished

product, and between them are materials, parts,

subassemblies and assemblies that make up a

product.

Presentation of the actual data in databases is

done through entities and relations. The data

what are stored in a database, first must be

processed (normalized) in order to save more

effectively.

By properly defining the database tables and

relationships between tables, we can get a very

efficient system what can accept the BOM in a

modified form suitable for storing in the

database. BOM stored in the database is not

acceptable for use by the human; we must have

a mediator, like query, who will create BOM list

of product that can be readable by human.

In this paper, it is shown on way of forming

GBOM through the arranged couples, parent

and child Fig.4.

Adding attributes important for engineers we

get an engineering bill of materials. Through the

examples it is presented the work of pseudo-

functions for formation EBOM on the base of

defined GBOM.

I. BOM ADDOPTION FOR DATA-

BASE

For example on Fig.1 it is shown Bill of

Materials (BOM) with one root and five levels.

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First international symposium for students with papers from mechanical engineering

One approach to creating engineering bill of materials

Fig. 1 Bill of Materials (BOM)

This BOM it show's set of leafs {3, 6, 7, 8, 9}

and a, leaf three one time, leaf six two times,

leaf seven three times, leaf eight three times and

a leaf nine one time. Analyzing the given BOM

we can see that is made from a leaf three {3}

and two sub-BOM (sBOM).

Fig. 2 Example of two sBOM, each sBOM is

new BOM

In Fig.2 we show that there are sBOM which

are part of both, the now BOM. In complex

BOM, finding common sBOM is very difficult;

in more complex BOM it is practically

impossible.

Each BOM it is represent of finish product, an

each sBOM in BOM as complex sub-assemble.

Seeking for com's sBOM is primary task in

Material Requirements Planning (MRP).

Using computers it makes ease to improve

BOM and lead to more developed finish

products. This is achieved when the BOM is

based on two level bill of materials or Modular

Bill of Materials (MBOM).

MBOM is sBOM based on two levels, which

according to Fig.1 and Fig.2 have the form

shown in Fig.3.

Fig. 3 MBOM as sBOM

For the realization of a BOM which can be

observed by computer is necessary to define a

Generic Bill of Materials (GBOM), Fig.4.

Fig. 4 Basic table field

Fig.4 also defined tree structure, which is

assumed that is acyclic. In this definition we can

simply add all the other attributes that

characterize the Engineering Bill of Materials

(EBOM). Fig.5 presents the Fig.1 through

GBOM definition.

Fig. 5 BOM in data structure notation

Given data in Fig.5 we can pass through the self

recursion pseudo-function r( ) defined in Fig.6.

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First international symposium for students with papers from mechanical engineering

One approach to creating engineering bill of materials

Fig. 6 Self recursion pseudo-function r( )

As we see the function seek (arg1, arg2) has

two arguments. The first argument arg1 is the

name of the table with MBOM. The second

argument arg2 is a value that is found by index

in MBOM table. The results of function seek( )

is a list, which is a subset of EBOM.

If the function r( ) has already been called, the

result of the last call is added to previous result.

The pointer is set on the list, by default at first

element of a list that was last added. Also the

result of function r( ) may be an empty list

(NILL).

For example, Fig.7,

EXAMPLE(t) = seek (EBOM (t), 5)

is assuming it has been invited by arguments

seek(EBOM (t), 4).

Fig. 7 Results from execution

EXAPMLE(t) = seek(EBOM(t),5)

If on the result from Fig.7 we apply function

EXAMPLE(t) = seek (EBOM (t), 7) the result is

NILL, Fig.8.

Fig. 8 Results from execution

EXAPMLE(t) = seek(EBOM(t),7)

Fig.9 is a transformation of Fig.8, using the

function EXAMPLE(t) = seek (EBOM(t), 7).

Fig. 9 Results from execution

EXAPMLE(t) = seek(EBOM(t),7)

Function skip(arg1, arg2) has two arguments.

The first argument arg1 is the name of the list,

while the second argument arg2 is the integer

value. The result of this function is the same

list, but the pointer is moved for arg2.

Let's give an example, Fig.9, in which we use

skip(EXAMPLE(t), 1), then the result is given in

Fig.10.

Fig. 10 Results from execution

skip(EXAMPLE(t), 1)

II. CONCLUSION

GBOM it is introduced through a

database on the basis of ordered pairs

and represents the most general BOM.

By adding different attributes,

arrangement, we get the different types

of EBOM. For each of the obtained

EBOM it is necessary to make a

pseudo-function r( ) which generates

the appropriate database list, BOM.

Future studies are aimed at finding the

"standard" pseudo-function r( ) and

special functions required by the

engineer. One such function is the one

that gives results in probability of

making the product.

III. REFERENCES

[1] C. Todman, Design a Data

Warehouse, Cet Beograd, 2001.

[2] L. Welling and L. Thomson,

MySQL Tutorial, Mikro knjiga

Beograd, 2005.

[3] B. Meyer, Object-oriented Software

Construction, Cet Beograd, 2003.

[4] mr. S. Radojevic, Algorithms for

formation BOM in relations database,

Mechanical Faculty Belgrade, 1989.

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First international symposium for students with papers from mechanical engineering

One approach to creating engineering bill of materials

[5] mr. S. Radojevic, Forming BOM of

products by simulated recursion and

pointers in relations database,

Mechanical Faculty Belgrade, 1990.

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