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Nowadays, it is paramount for manufacturers to strive to improve the quality of the goods that they produce, not only to reduce the waste involved in the production process but also to be able to better satisfy their customers, which is pivotal if an organization is to gain the trust of consumers and to be able to survive in the competitive modern world of business. To do so, it is possible to utilize some quality control and improvement instruments. The current paper proposes a project aimed at reducing the defect rate in the casting process by implementing the DMAIC tool, which is a part of the Six Sigma set of quality control and improvement methodologies.
On the whole, the main idea of the proposed project is to increase the effectiveness and efficacy of an organization that employs a casting process for manufacturing products, by using certain tools and techniques that were specifically designed for such a purpose and successfully employed in several companies (Jirasukprasert, Garza-Reyes, Soriano-Meier, & Rocha-Lona, 2012; Rahman & Talapatra, 2015). The current project offers to implement the methodology that is called Six Sigma. In particular, this aim will be achieved via using the DMAIC technique; it should be highlighted that the abbreviation DMAIC stands for Define, Measure, Analyze, Improve, and Control (Jirasukprasert et al., 2012).
It is expected that system using the DMAIC technique to improve the quality of the manufactured products by finding out the causes of the most frequently occurring defects will allow for considerably reducing the ratio of defective products to the total amounts of production. It is highly unlikely that implementing this method once will permit for lowering the rate of defects occurrence to 3.4 or fewer defects per one million opportunities (which is a goal set by Six Sigma) unless the rate of defects in the targeted organization already approximates this rate closely enough. However, it should be clear that one-time use of the DMAIC technique cannot solve all the problems in manufacturing at the same time, and, if its use has been successful, it should further be implemented repeatedly until the desired rate of defects in production is achieved.
Thus, the proposed project will test the effectiveness of the DMAIC method in reducing the percentage of defected production to ultimately achieve the desired ratio of 3.4 or fewer defects per one million opportunities as set by the Six Sigma system, and will also help improve the production in the chosen company and teach its employees to efficaciously use the DMAIC instrument in practice.
Methods to Be Used
As has been noted, the DMAIC tool, which is a part of the Six Sigma system, will be used for quality improvement. The key principle of QFD (quality function deployment), the point of which is to transform the Voice of the Customer (VOC) into a characteristic of a product, will also be employed by taking into account the desire of the customer to purchase goods that include details made using the casting process without the defects such as the roughness of the surface, porosity, shrinkage, and so on (Rahman & Talapatra, 2015). The statistical process control (SPC) methods will also be utilized to assess the defect rate of the production.
It should be stressed that the casting process often consists of six main phases, namely: a) mold-making (expendable molds are made for each instance of the casting), b) clamping (the halves of the mold are closed and clamped together to prevent the loss of metal), c) pouring (molten metal is poured from its container in the furnace into the mold; this should be done quickly before the metal starts solidifying), d) cooling (the metal is cooled, and the shape of the casting is created; many defects can emerge at this stage); e) removal (after the metal solidifies over the time that was identified for the previous step, the mold is broken and removed); f) trimming (the excess material from the channels in the mold through which the metal was is removed) (Rahman & Talapatra, 2015).
It is also critical to elaborate on the nature of the DMAIC tool in greater detail, and explain how it will be used during the process of casting. As has been noted, DMAIC stands for Define, Measure, Analyze, Improve, and Control (Jirasukprasert et al., 2012). These five phases of this quality enhancement instrument involve the following actions (Jirasukprasert et al., 2012; Rahman & Talapatra, 2015):
- Define – the team that is to be responsible for the improvement process is formed, and its role, as well as the roles of individual members, are identified. It is also paramount to understand what VOC demands, and set the goals of the whole incentive accordingly;
- Measure – by the aspects identified during the previous phase, the factors which are to be measured are selected, and assessment procedures are chosen.
- Analyze – at this step, the factors selected during the previous phase are analyzed, and the causes of the defects in the manufactured product are identified. Besides, the ways to address these causes are compared and prioritized.
- Improve – at this stage, experiments and SPC tools are used to identify the best methods for improving the quality of the manufactured products.
- Control – at this last phase of the DMAIC tool, the team makes sure that the improvements identified during the previous phase are sustained and used in further production. These improvements are documented and further institutionalized in the organization.
How DMAIC will be used is explained below, after the firm where it will be utilized is described.
From what has been described above, it should be clear that the instrument of DMAIC is planned to be employed in a company which manufactures metal shapes using the molding process, and fails to meet the goal established by Six Sigma principles, namely, that there should be no more than 3.4 defective products per million products created. Of course, the product the attempt to improve the quality of which will be made will be these metal shapes. It is stressed that the main defects that can be encountered in molded products include porosity, shrinkage, and defects on the surface of the shape (Rahman & Talapatra, 2015); consequently, the proposed project will be focused on finding the reasons why such defects appear in the product and creating and implementing methods aimed at the elimination of these defects in the metal shapes. This should permit for enhancing the overall quality of production, for improving customer satisfaction, and for lowering the expenses of the firm and the amount of waster which is produced in the casting process due to defected molds.
The DMAIC process will be implemented as per the step-by-step procedure described above. The actions taken during each step will be informed by the recommendations made by Jirasukprasert et al. (2012) and Rahman and Talapatra (2015). These are as follows:
- Define: At this stage, VOC should be identified, the team should be formed, and its responsibilities should be defined. As has been previously stressed, VOC demands that the metal shapes produced contain no defects such as porosity, shrinkage, etc.; however, other demands may exist as well (Rahman & Talapatra, 2015). Thus, a team comprised of appropriate professionals in the field of casting process will be created to identify and eliminate the reasons behind the most commonly occurring defects; it will be possible to include a production manager and an experienced operator in the team. The type of the product to be inspected will also be selected; it will be needed to choose the product which is characterized by the highest rates of defects per number of produced units (e.g., per million). The specifics of the chosen manufacturer will probably dictate what metal shape’s production to investigate to find out the causes for the most commonly occurring defects.
- Measure: It will be necessary to create reliable measurement tools for assessing the number of defects in the produced goods, and for monitoring the progress resulting from the implementation of DMAIC. It will also be pivotal to identify the main defects in the product that will need to be dealt with, and measure the frequency of their occurrence; the specifics of these defects may vary from factory to factory.
- Analyze: At this point, exploring the previously collected data and using the obtained results to determine the roots of the identified defects in the manufactured metal shapes will be needed. While doing so, it might be required to utilize the method of brainstorming for the team to identify the potential causes of the defects in the shapes. After that, it will be needed to use SPC and other statistical tools to understand which aspects of the manufacturing process indeed have a significant impact on the frequency of the named defects in the products.
- Improve: This phase will involve determining which methods may allow for reducing the adverse impact of the factors identified at the previous step of the DMAIC procedure on the quality of the produced metal shapes and the frequency of defects in them. It will be required to identify the potential methods for dealing with the named factors, and to use them, at the same time collecting the data of the results of their utilization in the production process. This data will need to be analyzed to determine which improvements in the manufacturing process indeed do have a significant positive influence on the frequency of defects in the manufactured shapes.
- Control: At this step, it will be required to make sure that the improvements in the production process which have been identified during the previous phase as having a significantly positive impact on the frequency of the defects in the created shapes are documented, and that their utilization is appropriately institutionalized in the given organization, for instance, by creating specific protocols and designing new routines aimed at the appropriate use of these improvements in the metal shapes casting process.
Therefore, using DMAIC in a company that utilizes the casting process to manufacture metal shapes may permit for significantly reducing the defect rates in the product. Noteworthy, although Jirasukprasert et al. (2012) provide detailed guidelines about the implementation of DMAIC in the gloves manufacturing industry, whereas Rahman and Talapatra(2015) supply such guidelines for the casting process, the team members will still be required to carry out their analysis, as the causes of defects in metal shapes may vary from one factory to another.
Jirasukprasert, P., Garza-Reyes, J. A., Soriano-Meier, H., & Rocha-Lona, L. (2012). A case study of defects reduction in a rubber gloves manufacturing process by applying Six Sigma principles and DMAIC problem solving methodology. Web.
Rahman, A., & Talapatra, S. (2015). Defects reduction in casting process by applying Six Sigma principles and DMAIC problem solving methodology (a case study). International Conference on Mechanical, Industrial and Materials Engineering, 2015, 1-6.