The experiment aims to analyze the causes of each problem (effect) identified in raw eggs and mayonnaise products during manufacturing and processing through the use of fish-bone diagrams or Ishikawa diagrams (cause and effect diagrams).Additionally, dispersion analysis and process classification type fish-bone diagrams were used. The result of the experiment showed that process classification diagram is more effective in pinpointing specific causes of error/ problems thus help more in formulation of corrective actions to be taken. However, dispersion analysis concentrates more in analyzing the general root causes of the errors/ problems, thus fails to identify minor causes of the problems.
A fish-bone diagram, also known as Ishikawa diagram or a cause-and-effect diagram, is an organized tool that helps manufacturers in identifying the possible causes of quality problems (Forman, 2001). This visual tool is also used for organizing possible causes of defect in different categories. It has angled lines, or the ‘bones’, which represents a possible cause of error. Each bone can have ‘sub-bones’ which contains further details about a possible cause of error. The ‘bones’ are joined together in a singular straight line that describes the main defect. This outline gives a shape similar to the bones of a fish, hence the name fishbone chart as seen in Figure 1.
Figure 1. Fishbone Diagram (Cinergix Ltd, undated)
There are three main types of fishbone diagrams namely, the dispersion analysis type, product process classification type, and the cause enumeration type. The dispersion analysis type organizes and relates the factors that result in the difference among the product and other process outcomes. The production process classification type is made by making the steps in the production process be the major ribs of the fishbone diagram. It focuses on each step of the process to determine all possible causes of the error. In the cause enumeration type, all possible causes that results to the defect is determined and then organized to show the relationships to the aspect of product of process quality that is being examined (Florac, 1999).
Prior to the exercise, the group identified and listed possible defects in both eggs and mayonnaise. One possible defect was then chosen for each the raw material (eggs) and the finished product (mayonnaise). The possible defects chosen were cracked eggshells and unstable emulsion for the raw material and finished product, respectively. The group then constructed two types of fishbone diagrams (Dispersion Analysis and Process Classification) for each of the chosen possible defects by identifying and writing its main causes and further causes in the diagram. The diagrams were then analyzed by the group to determine the root cause of the defects and to identify and suggest corrective actions to eliminate it. The effectiveness and efficiency of the corrective actions were also considered and analyzed. The group then presented the diagrams to the class.
III. SUMMARY OF RESULTS
IV. INTERPRETATION OF RESULTS
Dispersion analysis and process classification type of fishbone diagrams are used in the analyzation of the causes of the problems identified. Dispersion analysis cause and effect diagrams are structured in such a way that the factors contributing to the problem under study are classified into the “standard six” which are manpower, methods, materials, measurement, operators, and environments. Process classification diagrams on the other hand are structured in such a way that the factors are classified according to steps involved in the process (Brassard and Ritter, 1994). In the case of mayonnaise, some of the steps are sifting, mixing and filling. In terms of emphasis, dispersion analysis CE diagrams are advantageous in such a way that it helps organize and relate the factors that lead up to the problem.
However its drawback is that it may fail to identify minor causes that may be overlooked (Omachonu & Ross, 2005). On the other hand, the advantage of process classification CE diagrams is that is easier to create because it follows the process in a product. However, redundancy may occur. Process classification is often used when the problem encountered cannot be isolated into a single department (Basu, 2011). An example of which is faulty factory workers which may be a reoccurring problem in all steps.
This makes it hard to pin point what corrective action should be performed (Omachonu & Ross, 2005). Based on the exercise, it was observed that the use of process classification CE diagrams are more effective in being able to identify the specific causes of errors within a process however; dispersion analysis CE diagrams were able to pinpoint general root causes of the problem by narrowing down the sources of errors into the “standard six”. General corrective actions can be generated using dispersion analysis CE diagrams but process specific corrective actions can be generated from process classification CE diagrams
Basu, R. (2011). Fit sigma: A lean approac to building stustaiable quality beyond six sigma. (1st ed., p. 71). UK: John WIley and Sons Ltd.
Brassard, M. and D. Ritter. (1994) The Memory Jogger II: A Pocket Guide of Tools for Continuous Improvement & Effective Planning ,Methuen, MA: Goal/QPC. Accessed via: http://www.goalqpc.com
Cinergix Ltd. (n.d.). Graphic Organizer Templates. Retrieved January 3, 2012, from Creately: http://creately.com/examples/Graphic-Organizer-Templates
Florac, W. C. (1999). Measuring the Software Process: Statistical Process Control for Software Process Improvement. Indianopolis: Addison-Wesley Professional.
Forman, E. S. (2001). Decision by Objectives: How to Convince Others That You Are Right. Washington: World Scientific. Omachonu, V. K., & Ross , J. E. (2005). Principles of totaly quality. (3rd ed., p. 265). New York: CRC PRess.