Part II: Organizational Prerequisites for Smart Materials, Automatic Identification, and Quality
Chapter 10: The Chorafas Classification/Identification System for Supply Chain Requirements
10.4 A Matter-of-Fact Example of Classification and Further Definiens
The choice of both a six-digit basic (including parity) code and a six-digit taxonomical number (two decimal digits per family, group, class) has been influenced by requirements of economy, dependability, and the assurance of a short dialing system, which comes in handy today in connection with nomadic computing. A six-digit to eight-digit number is quite similar to a telephone number in most cities, a fact giving a good hint as to the possible size of an identification or classification code, as well as to the users' ability to retain either one in memory.
Take another look at the family classification matrix shown in Exhibit 10.6. Suppose one is interested in Family 44: shaped pieces. The family is divided into groups, the 100 pigeonholes. Not all of them need to be assigned immediately. It is always good to leave room for expansion. Pigeonholes of the group matrix that are being used in the classification work are assigned to specific parts.
An example is given in Exhibit 10.9. The careful reader observes that in this case, too, more than half the positions in this group matrix are kept in reserve. Each position (pigeonhole) that is filled can be further analyzed through a class matrix, which provides greater detail.
Exhibit 10.9: A Group Matrix for Parts is the Metalayer of the Class Code
Two different examples are given in Exhibit 10.10 and Exhibit 10.11. What these examples have in common is the methodology of analysis. If one allocates the digits in the classification system — particularly its taxonomical part — in this way:
KL, for family (therefore, the original matrix)
MN, for group (a subset of the family)
PR, for class (a subset of the group)
Exhibit 10.10: Example of a Class Matrix Developed and Used by a Manufacturing Company
Exhibit 10.11: Another Example of a Class Matrix by the Same Manufacturing Firm
then one can easily see that KL is a metalayer of MN and that MN is a metalayer of PR. The existence of PR is conditioned by the MN to which it belongs, and that of MN by the KL of which it is part. That is, PR and MN have no own existence. They get meaning only within their metalayer.
With this in mind, take another look at Exhibits 10.9 through 10.11 to better understand what they represent. Exhibit 10.9 illustrates the group matrix for parts, corresponding to the KL positions in the taxonomy. Exhibits 10.10 and 10.11 provide two different examples of class matrices corresponding to MN positions. Such matrices carry forward the classification work done in the group matrix and provide a finer detail of inheritance work within a real-life environment.
Technical issues characterizing machine parts such as (primarily) shape and (secondarily) function will by norm evaluation, as explained in the following paragraph. In this particular application, the choice of shape over function was deliberately done by the engineers who implemented DCS. Functional characteristics lead to further detail that is not taxonomical. It is expressed by the first digits of the further definiens — and it can be continued by bringing more further definiens into perspective. Further definiens are elements of detail that are descriptive rather than taxonomical. In an inheritance matrix, they are weak elements, specific to the class to which they apply.
Down to its fundamentals, the concept underpinning the further definiens is primarily one of flexibility in definition and of customization. Not only two different companies but also two factories in the same company do not have exactly similar classification requirements. Accounting for this fact, a global taxonomical system should be able to handle a number of exceptions without turning the classification code on its head.
Now take a practical example. Suppose that a given manufacturing firm is faced with the problem of classifying its spare parts. After having studied the organizational prerequisites associated with this problem, the analysts establish a classification code with taxonomical structure and proceed with allocation of the first digit of further definiens. Exhibit 10.12 shows the definition of x0 in the
implementation that took place at Italcementi, a major Italian cement manufacturing company. The overall solution was:
x0, first digit of further definiens, is norm oriented
x1 identifies the part's original designer
x2x3, a two-digit field, ensures that each item file corresponds with one and only one part identification number
TAXONOMICAL CODE XX.XX.XX
KL: Family (say, mechanical parts) MN: Group, a subset of family PR: Class, a subset of group
FURTHER DEFINIENS: first digit, x0, allocated to norm evaluation
x0 = 0; ANSI-norm x0 = 1; ISO-norm
x0 = 2; ISO-norm, afterward reworked by this company x0 = 3; Catalog part without known norm
x0 = 4; Catalog part without known norm, afterward reworked by this company
x0 = 5; This company's own old product design specifications, to which cataloged parts do not correspond
x0 = 6; Reserved x0 = 7; Reserved x0 = 8; Reserved x0 = 9; Reserved
Exhibit 10.12: Allocation of Digits in the Classification Systems
This is by no means the only solution possible. Each company can choose its own approach on how to design further definiens. In fact, it can do so for each family in the matrix if this reveals itself to be necessary. For example, another company that applied DCS divided the further definiens into the following groups:
x0 is a one-digit decimal number that extends the classification capability of the taxonomical code without belonging to the latter. This gives some families the freedom to drop x0 while others may need to use it.
x1 x2 x3 x4 is a four-digit field of further definiens that helps to uniquely identify an item in terms of technical characteristics.
In this particular implementation, a basic code corresponds one-to-one to KL, MN, PR, (x0x1x2x3x4).
Hence, the <basic code>, a running number on a first-come, first-served basis necessitates 11 classification digits: six taxonomical and five descriptive.
In yet another implementation of DCS, x0x1x2 is a three-digit decimal field that identifies the company that made the original design of the machine or component. This is vital information for many parts associated with their original manufacturers. Subsequently, x3x4x5x6x7x8 is a six-digit field acting as a box able to store and retrieve, through serial numbering, the file for each machine component or part — past the x0x1x2 filter.
In practical terms, such an explanation provides considerable flexibility. This concept also applies to other further definiens (e.g., y0y1y2 that are suffix oriented). As will be remembered, the suffix was added to the ID system to permit identification of nontechnical characteristics — or, more precisely, characteristics that are of a non-core technical nature; for example, in the case of lamp manufacturing, voltage and wattage of a lamp, as well as whether it is incandescent, fluorescent, or other type, are core issues. In contrast, color, such as matte or transparent, is non-core; the same is true of the brand (this vendor was handling four different brands).
Commercial characteristics (including brand name and non-core technical issues) may also need to be classified. This is done in the further definiens through the y0y1…yn field(s). Order and flexibility are the keywords. The system just explained permits a flexible approach to classification and identification, while providing the possibility of bringing them together into a parallel code structure.