THE PROCESS MANAGEMENT IMPACT ON THE NONCONFORMITIES LEVEL REDUCTION IN THE COURSE OF CASTING PRODUCTION. Krzysztof Siekański a

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1 THE PROCESS MANAGEMENT IMPACT ON THE NONCONFORMITIES LEVEL REDUCTION IN THE COURSE OF CASTING PRODUCTION Krzysztof Siekański a a Częstochowa University of Technology, Department of Management, Division of Production Engineering, Armii Krajowej St. 19 B, - Częstochowa, Poland, ksiekanski@op.pl Abstract The variety of the influencing on the quality of castings mutual dependent actions causes that the founding requires the analysis of the every single sub-processes. Afterwards it requires also synthesis of all sub-processes in the aim of the elaboration of the technological as well as management decisions for the quality improvement. The production is connected with the realizations of the series of special processes and could be conducted with implementation of the many different kinds of the technological solutions. The usage of the process approach was proposed in the ISO 91: standard and was applied to the processes as well as products quality improvement. The process approach implementation is the ideal solution fully matched to the specific condition of the foundry work. In this paper the process management as well as possibility of the utilization of its principles to the nonconformities level reduction in the course of casting production were presented. In the area of investigation the very significant level of the improvement (the lowering nonconformities level) about 5% was acquired. It was simply the effect of the development in the basic foundry processes: mould preparation, mould execution and flooding process. 1. INTRODUCTION One of the most common gauge of quality is the level of so called the lack of quality. It is a simple and measurable criterium of assessment as well as a credible carrier of information. The application of such kind of measurement in case of a casting product is a result of the practical management. One of its functions is a control that enables an access to sterling research material on the base of which we can presume that the reguirements will not be come up to. Therefore, instead of measuring the quality level (which presumably contains mistakes in the selection of indices and is methodically difficult because of many not very objective factors) we can measure its lack. The reflection of the lack are inconsistencies methodically classified and described in Polish standards [, s. 7-71]. Additional complement to the information about the mistakes connected with manufacturing a product is the analysis of complaints. The lack of quality determined and planned has to create further correcting and preventing actions that may lead to a situation in which the level of mistakes in a factory will lower. The article presents the analysis of casting inconsistencies. There are also suggested actions that aim at eliminating them.. THE APPLICATION OF QUALITY TOOLS IN THE ANALYSIS OF THE PROBLEM CONNECTED WITH APPEARING INCONSISTENCIES The basic presumption of quality improvemnet in the process management of the casting house is identifying the inconsistencies in a given area (time and place) of doing the work. Some proposals that make a full deduction easier are as follows [5, s. 7]: continuous keeping track of the s in the production process and a current registration of the inconsistencies (in the daily, weekly, quarterly, yearly sections), keeping the books covering a sort of an inconsistency,

2 conducting researches in the sections of the places where the inconsistencies form [, s. 57], keeping up with changable trends of unfavourable phenomena, adjusting the researches to the specifity and a kind of production, researching how the inconsistencies appear depending on a sort of material and a product s features [, s. 1]. The casting production can concentrate on a serial or an unitary product, additionaly the tonnage of production can be limited to specific small amounts, it may also cover a wide production spectrum. In the researched case the object the casting house - produces goods of very different shapes, applications and the tonnage (.1 5 kgs). The first stage of researching the processes of the cast iron foundry is verifying the documentation of the quality management system as well as the data collected during the current process control [1, s. 7; 3. s. 171]. The analysis can be started by the Pareto Lorenz diagram, which segregates the inconsistencies lucidly, from the most significant ones to the least important fig. number 1. Share of the nonconformities of every type in the all nonconformities [%] 1 59,7% 1,1% Casting nonconformities 11 mechanical demage inner demage 3 cold cracks sand holes misrun casting 11 indent 15 mould shift 1 breach of dimension 1 porosity 5 pinhole porosity 1 fash 7 fold external blister 31 hot cracks 19 effluent shrinkage depresion 9 segregation veining Fig. 1. The Pareto Lorenz diagram for the problem of appearing casting nonconformities from to 3 yr. Source: own compilation based on the data regarding the researched object The article presents an example of an analysis connected with the production of two assortments which constitutes about 11,5% of the production in all. The analysis was based on the verification of effectiveness regarding the quality improvement ensuing from the acceptance of guidelines of the process attitude [5, p. 7]. The production process of casting was divided into the following stages: P1 preparing mass, P melt, P3 making moulds, P mould assembly, P5 pouring into moulds, P purify machining, P7 heat treatment, P mechanical working, P9 coating, P1 special researches, P11 final control, P control before giving a product to a customer [see 5, p. 15-1]. The analysis regarded the effectiveness of acting connected with quality improvement ensuing from the process attitude. The level of inconsistencies on the assemblies (X) where a chosen assortment is producted - was analysed. The level was measured before starting the quality improvement actions () and after the implementation of them (X) in the strictly casting processes (P1-P5) and processes in all. Because of the fact that these are values formulated in the per cent shares, we can only compare their structural shares. The most important are inclusions - 11, cracks in cold 3, inside defects and dusted areas. After the analysis of the results of the quality control and a cumulative compilation it was suggested to implement a lot of actions that would aim at lowering the inconsistency level. Before that all preliminary data connected with the production quality of assortments I and II on the lot of castings had been collected (the probe was marked symbolically as XI). The recommendations concerning the quality improvement in case of particular processes are:

3 - organizing a series of training (the staff of the moulding shop department and the one that takes a direct part in the process of pouring into moulds), - basic s in the production technology (projecting gating systems), - the need of verifying a deliver of moulding materials used in production, - the modernization of the assembly line of manufacturing forms and cores and an additianal control over the pouring workers actions, - the modification of the procedures of acting concerning a product before giving it to the heat treatment. The next stage is the analysis of the inconsistency level and researching the effectiveness of the taken actions regarding the quality improvement that result from applying the rules of the process management for assortments I and II (probe X). The Pareto diagram presents the preliminary stage of the analysis of the current state of affairs whereas using the histogram enables us to assess the taken actions concerning the quality improvement. They are connected with the production of chosen assortments I and II of the cast iron foundry pictures and 3. Comparing the results for assortment I we can tell the difference between them. Hence, counting: X 1 X,9,7 X 1 =,9% and X =,7% ). Hence, counting: 1% = 1% =,397% we X 1,9 obtain a situation in which the inconsistency level lowers by,% during the production of assortment I. The results for assortment II equalled adequately: X 1 = 9,53% i X = 7,9%. Hence, X X 9,53 7,9 9,53 1 counting: 1% = 1% = 3,55% we obtain 3,51% a situation in which the X 1 nonconformities level lowers by 3,51% for assortment II. Fig. and 3 - show a better tendency. a) of X sample -,1 % X of sample -, % measurement probe of the lots of goods s X measurement after implementing the s b) of X sample - 5,39 % X of sample -,9 % measurement probe of the lots of goods s X measurement after implementing the s Fig.. Histograms and normal distributions based on the results connected with improving the quality of the chosen assortment I (I guarter ): a) results for all processes, b) results for basic casting processes. Source: own compilation

4 a) Liczba obserwacji 1 X of X sample - 7,9 of sample - 9,53 measurement probe of the lots of goods s X measurement after implementing the s b) 1 of X sample -, X of sample - 5,79 measurement probe of the lots of goods s X measurement after implementing the s Fig. 3. Histograms and normal distributions based on the results connected with improving the quality of the chosen assortment II (I guarter ): a) results for all processes, b) results for basic casting processes. Source: own compilation The positive tendency of lowering the inconsistency level for chosen assortments is a signal that indicates the quality improvements of the production in all and is a result of innovations and preventing actions taken at the beginning of. 3. CONCLUSIONS Improving the production is a great challenge to factories and is an important problem in the situation of management of many complex processes. On the base of the conducted research, presented in the article, we showed the effectiveness of quality improvement actions that had been taken as a result of implementing the rules of the process management in the given casting house. The quality state in the factory and the problem of appearing mistakes in the production while applying the Pareto Lorenz diagram were also characterised and illustrated. Then, a full analysis of quality was conducted in two stages. The first one concentrated on the research on the preliminary probe of the two assortments I and II. On the base of the obtained data we prepared histograms and presented basic parametres that characterize the inconsistency level. Having researched the structure of the inconsistencies, some s were suggested, for example: in the areas of producing forms, pouring into moulds and staff training. The repeated research of the probe of products confirmed the effectiveness of quality improvement actions that aim at reducing the inconsistency level by 5% in comparison with the assortments I and II. Hence, the inconsistency level obtained in each of X probes was significantly lower than the one in probe. The analysis suggested in the article can be adopted directly in case of other production assortments of the factory.

5 REFERENCES: 1. BORKOWSKI, S., SIEKAŃSKI, K., Analiza zmian w strukturze niezgodności wyrobów odlewniczych po wdrożeniu zarządzania procesowego, Archiwum Odlewnictwa, Vol.., nr 1, pages BORKOWSKI, S., ČOREJOWÁ, T., Instrumenty rozwiązywania problemów w zarządzaniu, Wyd. Wyższej Szkoły Zarządzania i Marketingu w Sosnowcu, Sosnowiec. 3. RYCHTER, A., SIKORA, R., Technologies Influencing the Cast Quality, In: TRANSCOM 3. 5-the European Conference of Young Research and Science Workers in Transport and Telecommunications, Żilina 3, pages SIEKAŃSKI, K., BORKOWSKI, S., Kształtowanie jakości wyrobu odlewanego na wszystkich etapach procesu produkcji, In: XI Konferencja Naukowo-Techniczna. Produkcja i Zarządzanie w Hutnictwie, Częstochowa 3, pages SIEKAŃSKI, K., Wpływ zarządzania procesowego na jakość wyrobów odlewanych, Praca doktorska napisana pod kierunkiem S. Borkowskiego, Częstochowa.. ULEWICZ, R., SELEJDAK, J., System kontroli jakości wytwarzania odlewów z żeliwa sferoidalnego, In: Zakopane, IV Warsztaty z nauk o zarządzaniu, 3, pages