Manufacturing classification: lessons from organisational systematics and biological taxonomy,


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Manufacturing classification: lessons from organisational systematics and biological taxonomy,

  1. 1. MANUFACTURING CLASSIFICATION 37Manufacturing classification:Lessons from organizational systematics and biologicaltaxonomyIan McCarthyClassifications enhance knowledge and understanding and will enable predictions to be made aboutmanufacturing system behaviourIntroduction The purpose of a manufacturing classificationIt is the belief of some scientists and statisticians that the In an amusing classification of classifications, Good[2]desire to classify objects and entities has resulted in a provided a list which suggested five purposes forvast waste of valuable scientific time. The need to performing classification.produce a scheme which will pigeon-hole an individual (1) for mental clarification and communication;entity is natural to the human brain. Goodall[1], a notedbiologist, concluded that, “a preference for classification (2) for discovering new fields of research;is developed in childhood and persists as a habitual form (3) for planning an organizational structure orof thought in adulthood”. The problem is not the desire to machine;classify, but the resultant multitude of schemes which (4) as a checklist;are based on a detailed understanding of the phenomenabut an extremely limited understanding of taxonomy. (5) for fun. Most authors of manufacturing classificationsThe ability to develop a well-defined theoretical or emphasize (1) and (2), but in the context ofempirical classification is a basic step in conducting any manufacturing change and improvement, point (3) is theform of scientific or systematic inquiry into the most valid. Generally, any change initiative will includephenomena under investigation. In this article the two stages, the ability to comprehend the situation inphenomena under examination are discrete hand (problem definition) and with this knowledge,manufacturing systems and the purpose of the produce or identify an appropriate solution. These stagesinvestigation is to identify attributes which will not only can be performed using modelling and designenable grouping, but will also help determine and predict methodologies.the laws and relationships which govern the operationalbehaviour of a manufacturing system. If a classification is linked to this change process, it is postulated that groups of manufacturing systems can beThe structure of this article is as follows: formed based on similar technological and behavioural q outline the need and usefulness of a attributes, and that there will exist an “ideal model” or manufacturing classification; solution for the group. This group reference model will then help reduce the time and costs associated with q derive taxonomic theories and rules from developing solutions for individual companies within biological taxonomy and organizational that group. systematics; q review existing manufacturing classifications to A second objective for producing a manufacturing identify essential attributes; classification is based on the process of comparative q list preliminary guidelines for the classification of study which enables the storage and retrieval of manufacturing systems. information to facilitate the application of generalizations point (4). This process enhances the investigators’ knowledge and understanding ofIntegrated Manufacturing Systems, Vol. 6 No. 6, 1995, pp. 37-48 manufacturing systems and will enable predictions© MCB University Press Limited, 0957-6061 about system behaviour.
  2. 2. 38 INTEGRATED MANUFACTURING SYSTEMS 6,6Classification science identified from the taxonomic process[4,5]). Therefore,This section provides an insight into the theories and within a manufacturing context the taxonomy stagemethods of taxonomy and classification. This is defines the manufacturing system to be classified,regarded as a necessity, as it would be improper to identifies those attributes on which the classification willdevelop a classification for manufacturing systems be performed and selects an appropriate classificationwithout understanding and applying the science of technique, such as multivariate cluster analysis[6].classification. The classification stage is concerned with identifying a sample of manufacturing companies, collecting attribute data by means of interviews and visits, and forming andVocabulary validating groups of companies using a technique suchSystematics is the label given to the “science of as cluster analysis. The relationship betweendiversity”[3]. Its application concerns the study of classification, taxonomy and systematics is shown insystems and the principles of classification and Figure 1. A classification scheme contains only onenomenclature. Systematics encompasses taxonomy and category of taxa, whereas a classification system containsclassification (Figure 1), and is the logical starting point two or more categories of taxa[7].for understanding manufacturing systems for thepurpose of classification and modelling. Taxa (taxon is the singular) exist in all classifications and can be any group of entities which are sufficientlyTaxonomy is the theory and practice of delimiting and similar to each other, while being sufficiently differentclassifying different kinds of entities[4,5]). The process from entities in other sets. For example, organizationsidentifies differences and attributes on which to base a are considered complex entities with schools,classification. Taxonomic differences within manufacturing companies and hospitals all being taxamanufacturing systems include: operational (sets of similar entities).characteristics, levels of technology and flow structures.Thus, taxonomy is a process which determines the Theoretical taxonomy is one type of methodology usedclassification scheme and the techniques used to for developing the classification. The theoretical type isconstruct it. based on knowledge of the entity characteristics and this is used to develop the classification. A shortcoming ofClassification is the development of a system or scheme this type as described by Carper and Snizek[8], is that thein order for investigators to arrange entities into taxa, application data used in theoretically constructedbased on the differences and attributes which were taxonomies have been collected primarily in support of the developed taxonomy. This means that when applying the classification, the investigators may inadvertentlyFigure 1. The concept of classification seek and collect data which support their taxonomy. Systematics Empirical taxonomy is the second type of methodology Manufacturing differences based on systems theory which collects data on the entities (empirical evidence) on Methodical approach which to develop the taxonomy. Hence, the data employed are used to actually construct the empirical Taxonomy taxonomy, instead of supporting the classification as is Theoretical/empirical approach the case with theoretical taxonomy[8]. Numerical/non-numerical Identify the manufacturing system boundaries Identify the attributes of the manufacturing system Biological taxonomy The greatest application of taxonomy has been within Classification the field of biological sciences (medicine, pharmacology, Develop the system or scheme animal and plant sciences, zoology, etc.) to establish based on taxonomic proposals names for organisms and a methodology for classifying Collect data on manufacturing attributes them. Therefore, it would seem logical to review the Apply classification and develop groups theory of classification within this discipline to establish of manufacturing systems lessons which could be useful for the development of Taxa manufacturing systems. Groups of manufacturing systems Relevant nomenclature Mayr[9] reviewed the techniques used by zoologists and in summary, four theories of classification were described:
  3. 3. MANUFACTURING CLASSIFICATION 39 (1) essentialism; reviewed were developed on the principles of cladistics, (2) nominalism; but some do have an evolutionary nature, such as the development of mass production from craft production. (3) numerical taxonomy; (4) cladistics Organizational systematics Business, management and organizational scientistsEssentialism have also been keen developers of classifications.Biologists believe that organisms have a hidden reality Developments include a business strategy classificationwhich can be defined, and that this reality dictates the system[7], a voluntary association classification[14], aorganism’s observed properties. This hidden reality is canning firm and farmers union classification[15] andconsidered so influential that it determines how a general organizational classifications[16-18]. Practitionersproduct/object can be classified. Identifying this of organizational systematics were the first to realize theessential attribute and basing a taxonomy on it is known potential benefits that biological taxonomy could offer inas “essentialism”. The benefit of essentialism is that it terms of achieving a framework for classificationsimplifies the taxonomic task because only a few development which would result in the identification ofattributes are considered. The main disadvantage is that scientifically useful groupings.the entity or object must be a totally analysable entity inwhich that essential attribute can be defined. As most Carper and Snizek[8] produced a critical review of pastobjects are not totally analysable entities, biologists theoretical and empirical efforts with the aim ofdiscarded the theory of essentialism. However, the establishing a comprehensive framework. Chrisman etimportance of identifying and selecting essential al.[7] examined business strategy classification and withattributes was recognized, as this increases the validity reference to biological taxonomy, listed objectives forof a classification. classification and necessary attributes for a clas- sification system and its taxa. McKelvey[19] argued the importance of biological taxonomy and developedNominalism guidelines for conducting multivariate classificatoryThis theory suggests that all entities, including studies.manufacturing systems, are different in some way andthat only individual entities exist. Thus, it is impossibleto classify anything truly and that belief and desire to Considerations for a manufacturingclassify is an artefact of the human mind. With biologistsdeveloping classifications for birds, trees, plants, etc. classificationthey obviously felt that natural groups could be derived The following guidelines and principles are derived fromand thus ignored this theory. the fields of biological taxonomy and organizational systematics. They have been translated into a manufacturing context with reference to attributesNumerical taxonomy which are associated with manufacturing systems.In the 1960s, the need for a more objective and scientifictaxonomy led to the development of numerical taxonomy.Developed by Sokal and Sneath[10], it is primarily an Essential attributes of the taxa (manufacturing system)empirical method based on collecting data on the This section lists five attributes which govern thephenomena under study and then applying mathematical appropriateness of the groups formed by classifications:procedures such as cluster and discriminant analysis to (1) Mutually exclusive. This means that it must not beform groupings. possible for any individual manufacturing system to be assigned membership to more than one taxon at any categorical level.Cladistics (2) Internally homogenous. Manufacturing systemsThis is defined by Fitch[11] as the process of defining within a taxon must be more similar to each otherevolutionary relationships between taxa using evidence than they are to members of other taxa iffrom extant taxa. Originally formalized by Hennig[12], generalizations are to be valid.this a natural development of Darwin’s[13] theory ofnatural selection, which stated that the natural (3) Collectively exhaustive. At each categorical level of agroupings of biological organisms were due to descent classification system, every known manufacturingwith modification from common ancestors. At present system must belong to an existing taxon.this is the dominant taxonomic method. It should be (4) Stability. The taxa of a classification should not benoted that none of the manufacturing classifications affected by empirical tests which use new or
  4. 4. 40 INTEGRATED MANUFACTURING SYSTEMS 6,6 alternative attributes. Reassignment of the period. It should be capable of enabling systematic manufacturing company should not be possible examination of both past and future manufacturing unless attributes change within the company (i.e. systems. a change in technology or a change from, make to order, too, make to stock) (5) Relevant naming. Mayr[5] suggested that the key Review of existing classifications attributes in which the classification is based To help establish taxonomic guidelines and essential should be using for naming taxa. Bock[20] stated attributes for a manufacturing classification, that if the names are also based on common investigations have been made into system classification academic and business language this would aid and manufacturing classification. This provides a effective communication. thorough understanding of the phenomena and will enable lessons to be learnt for application into a system theory based classification.Essential attributes of a manufacturing classificationThis section governs the components, construction andapplication of a classification. Classification of systems There exist two base classifications of systems (Table I).Key attributes Boulding[24] uses the criteria of complexity as theIn line with the theory of essentialism an effective principal parameter, while Lievegoed[25] uses themanufacturing classification must be based on the key concepts of static, dynamism, openness and closedness.characteristics. Existing schemes have used technology, As the levels progress from 1 to 9, there is an increase inmaterial flow, operational control, operational objectives, systems complexity. In terms of manufacturing systemsetc. there are comparisons between the Boulding and Lievegoed classification criteria and the elements andGeneral classification attributes which constitute a manufacturing system. TheFor the purpose of manufacturing systems design, a first three levels are made up of physical and mechanicalgeneral classification is more important for systems and have direct relevance to manufacturingunderstanding and predicting the laws, functions and systems types. The next three levels all deal withbehaviour which govern that system. Special purpose biological systems and the remaining three levels are ofclassifications are limited in their application for broad human, social and transcendental importance.functional studies.Parsimonious classificationA parsimonious classification is one where the mostlikely evolutionary explanation is the one requiring theleast number of evolutionary steps. Researchers will The “clockworks system” isexamine manufacturing systems and differentiate themfrom dissimilar manufacturing systems with the fewest associated with manufacturingnumber of taxa. A parsimonious classification must notinfringe other attributes such as internal system flowshomogeneity[21].Hierarchical classification Comparing the Boulding classification to Lievegoed’sThis is the arrangement of manufacturing systems into with reference to a manufacturing system there are clearan ascending series of taxa. Hierarchical classifications parallels. Boulding’s framework system can bebegin at the bottom with individuals and end up at the considered to be similar to the static element oftop with an all-embracing taxon. The different levels are Lievegoed’s typology and in terms of a manufacturingknown as taxonomic ranks and all taxa existing in a rank system relates to the static assemblage of elements suchare said to belong to the same taxonomic category[22]. A as machines. The “clockworks system” refers to thehierarchical structure facilitates information retrieval, simple dynamics and motions of a dynamic system andmakes the classification easy to use and most is associated with manufacturing system flows such asimportantly is an aid the comparative research between material and information. The “cybernetic system”manufacturing systems[23]. relates to the control and maintenance of a system which interacts with the environment beyond its boundaries.Timeless classification This is Lievegoed’s “dynamic open system” and isCladistics is based on evolution and therefore the associated with the decision control which exists in aclassification should not be specific to a certain time manufacturing system.
  5. 5. MANUFACTURING CLASSIFICATION 41Table I. Boulding’s and Lievegoed’s classification of systems System typeLevel and level DescriptionBoulding1 Frameworks Static2 Clockworks The application of predetermined motions3 Cybernetic system Self-regulating to maintain equilibrium4 Open system Self-maintaining structure at cell level5 Genetic societal system Self-maintaining structure at plant level6 Animal system Mobility, teleological behaviour and self-awareness7 Human system Self-awareness and the ability to utilize language and symbolism8 Social system Consideration and content of messages, nature and dimensions of value system, transcription of images into historical records, symbolization of human motion9 Transcendatal system Ultimate, absolute and inescapable unkowables exhibiting systematic structure and relationshipLievegoed1 Static closed systems The relationship between selected factors does not change the system. Factors outside the boundary have no influence on factors within the boundary2 Dynamic closed systems The time factor is included in this type of system and factors within the system change a certain way3 Static open systems These systems have an input and an output. The input enters the system, reacts with the system and changes, and then exits the system. The system does not change4 Dynamic open systems The same as the previous system but the system undergoes change while converting the input to the output. Every system that includes is by definition a dynamic open system5 Dynamic open systems in Same as the previous system but the environment is changing and changing environments so is the input (4) a detailed sub-classification of one of the aboveClassification of manufacturing systems (batch, flowline);Attempts to classify manufacturing systems have been (5) a combination of one of the above.developed by production engineers and manufacturing These classification headings are supported bysystems engineers. A review has been performed on Constable and New[32] who stated that allthose classifications which are regarded as having manufacturing systems can be defined by threesubstance and the taxa labels are used regularly in characteristics: product structure, organizationalengineering and common language (i.e. mass structure; (flowline, cells, functional layout, etc.); and theproduction). The review (Table II) analysed the attributeson which the taxonomy was developed. This comparison nature of customer orders (make to stock and make to(not classification) grouped the existing methods under order).five general headings, as shown below: (1) operational characteristics (job, batch, mass, Operational characteristics project, intermittent, continuous, etc.); The basis to classify by similar operating characteristics (2) operational objectives (make to stock, make to refers to the movement, logistics and control of the order, etc.); physical resources required for production. This has (3) operational flow structures (flowlines, group been comprehensively covered by Wild[26], who technology, VAT analysis, etc.); classified industry in two broad categories; continuous
  6. 6. 42 INTEGRATED MANUFACTURING SYSTEMS 6,6Table II. A summary of existing manufacturing system classificationsProtagonist Taxonomic attributes Taxa Generic attributesWild[26] Quantity and variety of product, degree 4 Operational characteristics of repetitivenessJohnson and Montgomery[27] Relationship between resources and product flow 2 Operational characteristicsDe Toni and Pannizzolo[28] Relationship between how the product is obtained 6 Operational characteristics and how the production volume is obtainedSchmitt et al.[29] Operational characteristics Operational characteristicsIngham[30]1 Observed sales and product range 8 Operational objectivesWild[31] Operational objectives 4 Operational objectivesConstable and New[32] Nature of customer orders Operational objectivesWild[33] Flowlines for mass production 6 Operational flow structuresBurbidge[34] Group technology 4 Operational flow structuresBurbidge[35] Material conversion 4 Operational flow structuresFrizelle[36] Material conversion 6 Operational flow structuresAneke and Carrie[37] Flowline classification based on products, 10 Operational flow structures sequences and flowBarber and Hollier[38] Production control complexity 6 Detailed operational characteristicsWoodward[39] Product complexity, operational objectives, 11 Combination operational characteristicsBurbidge[35] Material conversion and flow, and operational Combination characteristicsprocess and the manufacture of discrete parts. The based on operational characteristics, and stated that theymanufacture of discrete parts was further subdivided are not absolute because they are broad, have hybridsinto three broad and overlapping categories, job and exist on a linear continuum.production, batch production, mass production Anothertraditional method for classifying manufacturing A combination system was suggested based on asystems based on operational characteristics is combination of operational characteristics, rather than asuggested by Johnson and Montgomery[27] who combination of taxonomies. It is described as a generalspecified three types, project, intermittent processes and production control system (PCS) which covers thecontinuous processes. systems described and the hybrids between the systems. The PCS is based on three categories; task divisibility,The main revelation with this classification was the taxa production rate uniformity, and routing restrictions.“project” which indicates a production effort where the These categories are represented on a three-dimensionalproduct remains stationary throughout the production continuum, called a PCS cube.process and workers, equipment and material arrive atthe site to perform assembly. Civil construction work andshipbuilding are the examples of project manufacturing. Operational objectivesDe Toni and Panizzolo[28] performed a classification of Manufacturing companies and the productionproductive categories in order to overcome the management system contained within them are createdambiguities concerning manufacturing classification. for a purpose, with that purpose in mind, the system willSix classifications were distinguished (individual, function and perform in a certain way. This is the basisunique, intermittent, discontinuous, repetitive and for the next group of classification techniques, whichcontinuous), along with the respective categories of attempt to define the affect the market variable has onproductive plants (yards, laboratories, job shops and the operation of the manufacturing system and thencells, etc.). Schmitt et al.[29] reviewed the classifications categorize each system accordingly.
  7. 7. MANUFACTURING CLASSIFICATION 43Ingham[30] classified companies by their observed sales q sequence of operations divisible into: operationsand the product range on offer. Four types of of the same sequence, operations with variationsmanufacturing company are suggested along with their in the sequence;sub-categories. Wild[31] defined four basic types of q whether changeover is required from product tomanufacturing company according to the objective of product or operation to operation;their operating structure: q whether products are produced in batches or not; (1) from stock, to stock, to customer; q type of flow pattern. (2) from source, to stock, to customer; Burbidge[34] classified flowlines into three taxa, based on (3) from stock, direct to customer; the principles of group technology and plant layout: (4) from source, direct to customer. functional layout; group layout; and, line layout.The third criteria of the Constable and New[32]classification technique (nature of customer orders) Detailed classification of batch systemssupports this operational objective group. The technique Barber and Hollier[38] developed a method of classifyingdefines two main categories “make to customer order” manufacturing systems according to their productionand “make for stock”. The first category is further sub- control complexity. This scheme resulted in six batchdivided into jobbing production, contract work, batch manufacturing types and is based on a list of criteriaproduction and call-off schedules. which covers various aspects of production control complexity. The criteria list relates closely to the criteria suggested by Constable and New[32]:Operational flow structures q market/customer environment;All manufacturing systems have an operational q product complexity;structure which links the elements of the system(products, resources and materials) and dictates the q nature and complexity of manufacturingcharacteristics of the material flow in terms of its operations;conversion. This attribute differs from the heading q supplier environment;operational characteristics, in that it considers only the q company structure and manufacturing policies.static/framework element of the manufacturing system(i.e. the layout). This group falls into three broadheadings of classification: Combination schemes (1) flowlines; As part of a project to assess the impact of technology (2) group technology; upon the organization, Woodward[39] produced a (3) material conversion classification and VAT comprehensive classification based on a broad analysis. combination of manufacturing attributes as shown below.Aneke and Carrie[37], and Burbidge[34] have produced acomprehensive review of headings (1) and (2), while q product complexity;Frizelle[35] adequately covers heading (3). q production system (a combination of operational objectives and operational characteristics); q production classification engineering (operationalDetailed classificationThe fourth heading of classification exists due to the characteristics).desire to produce a detailed and thorough classification This resulted in a classification where eleven productiontechnique and represents the greatest level of objectivity. systems were identified.The following techniques have specialized in certainareas or characteristics of a specific classification A further development of Burbidge’s[35], materialheading. conversion classification has led to a combination technique, which includes flow type and organizationDetailed flowline classification type. The resulting classification is based on theAneke and Carrie[37] produced a comprehensive flowline following criteria:classification, more exhaustive than both the mass (1) Material conversion classification:production and group technology and flowline q process;classifications. The classification produced ten flowlinetypes and is based on the following criteria: q implosive; q number of products; q square; q number of operations required per product; q explosive.
  8. 8. 44 INTEGRATED MANUFACTURING SYSTEMS 6,6 (2) Material flow types: as Barber and Hollier[38] and Aneke and Carrie[37], q jobbing; primarily because of the narrower scope and the desire to achieve a classification for one particular type of q batch; manufacturing taxon. The stability of the taxa produced q one of a kind; by Johnson and Montgomery[27] is poor with the q continuous; manufacturing types encroaching on Wild’s[26]. This q general (where two or more flow types exist). also occurs with the De Toni and Panizzolo’s[28] classification which provides additional and overlapping (3) Type of organization: alternatives. Reassignment of manufacturing types also q process organization (process layout, not takes place among the classifications based on process industry); operational objectives[30-32]. This is expected, due to the q product organization (product layout): lack of a systematic and taxonomic approach and the continuous line flow (i.e. process industries); large level of subjectivity concerned in analysing taxa. q group technology. Also the levels of complexity play a part, with operational objectives and operational characteristics having open and dynamic complexity. Classifications based on layouts and structures (static complexity)Comments on existing schemes appear to satisfy the stability criteria of manufacturingAll of the manufacturing classifications discussed taxa.present a detailed understanding of the entity, but noclassification makes reference to, or applies the science of Finally, the naming of the manufacturing types is weakclassification. A limited exception is where Barber andHollier[38] and Aneke and Carrie[37] utilize numerical with no formal nomenclature or guidelines. Names areclustering tools. Therefore, in terms of producing a created, based on the author’s perception of the entityscientific classification, which will provide optimal and the attributes used to formulate the taxa. Thebenefits in terms of explaining and understanding the manufacturing names tend to describe the attribute,behaviour of manufacturing systems, these rather than demonstrate its evolution. For instance theclassifications have various levels of deficiency. Another taxon “mass” is a more appropriate name, thandrawback of the majority is the lack of objectivity. Some “Fordism”. Fordism reflects the inventor’s name, butreferences are made to the desire to further provides no information concerning the practices andunderstanding, but for what purpose or in what context, behaviour of this taxon.there is no reference. An assessment of themanufacturing classifications, against the taxa and Comments regarding the classification, rather than theclassification guidelines listed earlier is given. taxa produced, also have various levels of satisfaction. Many different attributes are used, with someWhen assessing the classifications against the classifications using only three attributes (productionguidelines listed for manufacturing taxa various levels of volume, degree of repetitiveness and variety of productssatisfaction are achieved. Most of the taxa produced are Wild[26] compared with the ten attributes used bymutually exclusive and internally homogenous, due to Barber and Hollier[38]. This suggests that attributes arethe thorough understanding of the entity by the authors. chosen based on the author’s perception of the hidden realities that govern manufacturing systems. “Essential” attributes must be used rather than prima facie behavioural attributes, which are not exhaustive or Most of the taxa comprehensive. Frizzelle’s[36] descriptions of system complexity are regarded as essential attributes. This is produced are mutually confirmed by Hitomi[40] who provides four essential attributes: exclusive (1) Abstract. This is the collection and assemblage of manufacturing resources.This results in a clear focus on the attributes that are (2) Structural. This is system relationship and relatedresponsible for distinguishing the manufacturingsystems. For example, make to stock and make to order to the interdependencies of the manufacturingtype companies, are definitely discerned from flow types resources. A collection of resources with noor operational types. Taxa overlap occurs with the more relationships is a group rather then a system.general classification such as Wild’s[26] job, batch and (3) Transformational. This relates to the objectivitymass types. The ability for the taxa to be mutually of the manufacturing system in terms ofexhaustive is achieved in the more detailed schemes such converting inputs into outputs.
  9. 9. MANUFACTURING CLASSIFICATION 45 (4) Procedural. This is the operational and dynamic The resulting 14 classistic guidelines are: aspect of manufacturing systems. The steps and (1) Focus on attributes central to manufacturing controls required to achieve the transformational system complexity. aspect. (2) Manufacturing systems having the greatestThe number of classifications represented as a hierarchy overall similarity among their complexities willare limited. A variety of representations are used from be grouped together.the PCS cube produced by Schmitt et al.[29], to the (3) Arrange the higher categories so that the familyrelationship tables produced by De Toni and tree of manufacturing systems reflects theirPanizzolo[28] and Ingham[30], through to simple lists by evolution from past to present.Barber and Hollier[38] and Constable and New[32]. A (4) Avoid too small or too large an aggregation oftrue hierarchy representation is produced by Wild[26] groupings at the higher levels, unless theand his classification of mass production systems. evidence clearly indicates an extreme. (5) Grouping within a category level (e.g. family, order, etc.) of the classification should be roughly equivalent in overall similarity.Guidelines for the classification ofmanufacturing systems (6) Formal recognition of a group of manufacturing systems should be accompanied by theEssential attribute selection description of its internal (operations) andThe attributes used in previous classifications are external (market) environments.varied, broad, sometimes personal to the author and havea large degree of overlap. If a manufacturing system is (7) For each recognized branching of a newtreated as an open and dynamic operational system all of manufacturing system away from an old one,the attributes used have direct relevance to difference identify at least one dominant environmentaltypes of system complexity. Therefore, in terms of force that, when adapted to, would result in theselecting essential attributes which satisfy taxonomic attributes of the new form.guidelines, the following variants of complexity are (8) Begin with the lineage’s which are most apparentrecommended. and satisfy the objectives of the classification. (9) Arrange the dendrogram (family tree) so thatProduct complex ity. An indicator of the degree of similar manufacturing systems are adjacent tomanufacturing difficulty associated with the product each other.(number of parts, number of connections, product variety (10) Give each manufacturing category a label,and volumes, etc.). A primary influence on structural and leaving room for future elaboration.dynamic complexity. (11) Recognize that some forms of manufacturingOpen complexity. The complexity of the environment that systems have evolved faster than others. Thus,the manufacturing system must interact with more levels will be needed to in these lines to(customers, suppliers, legislation, etc.). Also, a primary account for the increased levels of specialization and diversity.influence on structural and dynamic complexity. (12) Use an italicized, hyphenated binominal name,Structural complexity. An internal complexity relating to with the genus name coming first and capitalizedthe static/structural aspect of the manufacturing system. and the species name second.It is associated with hierarchy, size, flow structures, etc. (13) All genus species labels will be in the singularDynamic complexity. Related to structural complexity, and all higher category labels will be italicized,but deals with the activity and time aspects (operational) capitalized and given in the plural.of the manufacturing system. Describes the interaction (14) Label a higher manufacturing class after abetween resources (material, machines, labour). dominant attribute differentiating that class from others at the same category rank.Classification development In accordance with taxonomic hierarchy a preliminaryThe wide application of cladistics has resulted in the dendrogram (Figure 2) has been produced to representdevelopment of rules and principles. These rules concern manufacturing category levels. The dendrogram doesthe operational principles of cladistics such as branching not suggest a correct or valid classification, but simplyand labelling. The rules are listed by Ross[41], and have provides an illustration of how biological taxonomy canbeen translated into a manufacturing system context, be applied to manufacturing systems. The sub-tribe,using system complexity as the core attribute. genus and species level are a development of Wild’s[26]
  10. 10. 46 INTEGRATED MANUFACTURING SYSTEMS 6,6Figure 2. Preliminary manufacturing dendrogram Kingdom Organization Industrial Class organization Manufacturing Order organization Process Discrete Project production production production Family Mass production Batch production Job production Tribe Quantity Genus production Flow production Large labour force Mechanization Flow process Discrete flow line Species Transfer line Assembly line Sub-speciesclassification. Each level is labelled and the terms used would be: Fabricator plurimi Ford. The citation includesare those usually employed in zoology. The dendrogram “Ford” who is the “authority”, i.e. the first person toprovides a visual interpretation of the evolution of validly publish the name. Previous citations for this typemanufacturing systems with the vertical distance of manufacturing company were termed “Fordistbetween levels representing time and the horizontal companies” and “Fordism production”. Ford firstdistance between taxa representing the degree of proposed this term in his 1926 article for thedifference. Encyclopaedia Britannica, Ford[42].The citation given to a taxa must act as a means ofreference and act as a vehicle for communication, itshould also indicate the rank of a taxon item (12) in the Summarylist of cladistic guidelines. The codes of nomenclature Previous research into developing manufacturingused by biologists, botanists and zoologists, require that classifications has been based on a comprehensiveall scientific names be written in the Latin form. understanding of manufacturing companies, but with noNomenclature codes provide one form of regulation for reference to or application of the science of biologicalnames of taxa above the rank of genus and another form taxonomy. This would be appear to be a majorof regulation for names of taxa below the rank of genus. shortcoming, which reduces the usefulness, stability and accuracy of the classifications. Lessons have been drawnA preliminary example of a possible manufacturing from biological taxonomy in an attempt to stimulateclassification conforming to the codes of nomenclature further investigations into this established problem
  11. 11. MANUFACTURING CLASSIFICATION 47based on the disciplines and rules regularly used by 10. Sokal, R. and Sneath, P., Numerical Taxonomy, thebiological scientists. Principles and Practices of Numerical Classification, Freeman, San Francisco, CA, 1973.Classifications are based on knowledge, and as 11. Fitch, W.M., Cladistic and Other Methods: Problems,knowledge increases so will the validity of the Pitfalls and Potentials. Cladistics: Perspectives on theclassification. As an investigator’s knowledge evolves, so Reconstruction of Evolutionar y History, Columbiawill the entities under study. In fact, a common statement University Press, New York, NY, 1984, pp. 221-52.within manufacturing is “the only constant is change”, 12. Hennig, W., “Grundzuge einer Theorie derderived from the need for continuous improvement. This phylogenetischen Systematik”, Deutscher Zentraverlag,leads to an inherent conflict between the need for a Berlin, 1950.classification which has stability and accuracy, versus 13. Darwin, C., The Origin of Species, Murray, London, 1859.the inevitable evolution and change that manufacturingsystems are subjected to. Nevertheless, classification is 14. Gordon, C.W and Babchuk, N., “A typology of voluntarythe only generally accepted system available for forming organizations”, American Sociological Review, Vol. 24, 1959, pp. 22-3.groups. 15. Emery, F.E. and Trist, E.L., “The casual texture ofFinally, the ability to undertake such research could organizational environments”, Human Relations, Vol. 18,result in a classification which is relatively accurate, 1965, pp. 21-32.stable, timeless and general. This scheme would greatly 16. Thompson, J.D., Organizations in Action, McGraw-Hill,enhance an investigator’s understanding of New York, NY, 1967.manufacturing systems and would increase the value 17. Perrow, C., Organizational Analysis: A Sociologicaland accuracy of any predictions. An example of the Review, Brooks-Cole, Belmont, CA, 1970.benefits that an appropriate classification could offer is 18. Van Ripper, P.P,. “Organizations: basic issues andthat, if accurate groups of manufacturing systems were proposed typology”, in Bowers, R.V. (Ed.), Studies onformed, an “ideal” model or solution for the group could Behaviour in Organizations, University of Georgia Press,be developed. This reference model would reduce the Athens, GA, 1966.time and costs needed to produce individual models or 19. McKelvey, B., “Organizational systematics: taxonomicsolutions for manufacturing systems within that group. lessons from biology”, Management Science, Vol. 24 No. 13, September 1978.References 20. Bock, W., “Philosophical foundations of classical evolutionary classification”, Systematic Zoology, Vol. 22, 1. Goodall, D.W,. “Vegetational classification and 1973, pp. 375-92. Vegetational continua”, Angew. Pflanz (Wien) Festsch. 21. Quicke, D.J.L., Principles and Techniques of Aich, Vol. 1, 1954, pp. 168-82. Contemporary Taxonomy, Chapman & Hall, London, 2. Good, I.J., “Categorisation of classification”, 1993. Mathematics and Computer Science in Medicine and 22. Jeffrey, C., Biological Nomenclature, 3rd ed., Systematics’ Biology, HMSO, London, 1965, pp. 115-28 Association, Chapman & Hall, London, 1977 3. Simpson, G.G., Principles of Animal Taxonomy, 23. Ashlock, P., “An evolutionary’s systematists’ view of Columbia University Press, New York, NY, 1961, p. 7. classification”, Systematic Zoology, Vol. 28, 1979, 4. Mayr, E., The Growth of Biological Thought: Diversity pp. 441-50. Evolution and Inheritance, Harvard University Press, 24. Boulding, K.E., “General system thinking: the skeleton of Cambridge, MA, 1982. science”, Management Science, 1956, pp. 197-208. 5. McKelvey, B., Organizational Systematics: Taxonomy 25. Lievegoed, B.C., Managing the Developing Organization, Evolution, Classification, University of California Press, Basil Blackwell, Oxford, 1991, Ch. 2. Berkeley, CA, 1982. 26. Wild, R., The Techniques of Production Management, 6. Everitt, B., Cluster Analysis, Gower, Aldershot, 1986. Holt, Reinhart and Winston, London, 1971. 7. Chrisman, J., Hofer, C. and Boulton, W., “Toward a 27. Johnson, L.A. and Montgomery, D.C., Operation system for classifying business strategies”, Academy of Research in Production Planning, Schedul ing and Management Review, Vol. 13 No. 3, 1988, pp. 413-28. Inventory Control, John Wiley & Sons, New York, NY, 8. Carper, W.B. and Snizek, W.E., “The nature and types of 1974. organizational taxonomies: an overview”, Academy of 28. De Toni, A. and Panizzolo, R., “Repetitive and Management Review, Vol. 5 No. 1, 1980, pp. 66-75. intermittent manufacturing: comparison of 9. Mayr, E., Principles of Systematic Zoology, McGraw-Hill, characteristics”, Integrated Manufacturing Systems, New York, NY, 1969. Vol. 3 No 4, 1992, pp. 23-37.
  12. 12. 48 INTEGRATED MANUFACTURING SYSTEMS 6,6 29. Schmitt, T.G., Klastorin, T. and Shtub, A., “Production 36. Frizelle, G.D.M., “OPT in perspective”, Advanced classification system: concepts, models and strategies”, Manufacturing Engineering, Vol. 1, January 1989. International Journal of Production Research, Vol. 23 37. Aneke, N.A.G. and Carrie, A.S., “A comprehensive No. 3, 1985, pp. 563-78. flowline classification scheme”, International Journal of 30. Ingham H, Balancing Sales and Production: Models of Production Research, Vol. 22 No 2, 1984, pp. 282-97. Typical Business Policies, Management Publications, 1971, Chs 1-2. 38. Barber, K.D. and Hollier, R.H., “The use of numerical analysis to classify companies according to production 31. Wild, R., Production and Operations Management, control complexity”, International Journal of Production Cassel, London, 1989, Ch. 1. Research, Vol. 24 No 1, 1986, pp. 203-22. 32. Constable, C.J. and New, C.C., Operations Management: 39. Woodward, J., Industrial Organization, Theory and A Systems Approach through Text and Cases, John Practice, Oxford University Press, 1980, pp. 22-49. Wiley & Sons, New York, NY, 1976. 33. Wild, R., Mass Production Management, the Design and 40. Hitomi, K., Manufacturing Systems Engineering (a Operation of Production Flowline Systems, John Wiley & Unified Approach to Manufacturing Technology and Sons, New York, NY, 1972. Production Management), Taylor & Francis, Chichester, 1979. 34. Burbidge, J.L., “Final report”, International Seminar on Group Technology, Turin International Centre, Turin, 41. Ross, H., Biological Systematics, Addison-Wesley, 1970. Reading, MA, 1974. 35. Burbidge, J.L., The Principles Of Production Control, 4th 42. Ford, H., “Mass production”, Encyclopaedia Britannica, Ed, MacDonald & Evans, Plymouth, 1962. 13th ed., suppl., Vol. 2, 1926, pp. 821-3.Ian McCarthy is a member of the Manufacturing Systems and Management Unit (MSMU) at the University of Sheffield.