Hence, it was necessary to support the process of identifying causes of incompatibilities in products. The NDT identifies incompatibility but does not determine the cause of its occurrence. The popular method for this is using the non-destructive testing (NDT). The tests of product quality can stabilize the quality of industrial product materials. This applies mainly to new or significantly modified materials. Stabilizing the quality of industrial product materials remains a challenge. We opted for a new model of Ishikawa diagram, resulting from the composition of three fish skeletons corresponding to the main categories of parts accuracy. For each of the three categories of causes there were distributed potential secondary causes on groups of M (man, methods, machines, materials, environment/ medio ambiente-sp.). We took into account the main components of parts precision in the machine construction field. The paper shows the potential causes of the studied problem, which were firstly grouped in three categories, as follows: causes that lead to errors in assessing the dimensional accuracy, causes that determine errors in the evaluation of shape and position abnormalities and causes for errors in roughness evaluation. The most known Ishikawa models are 4M, 5M, 6M, the initials being in order: materials, methods, man, machines, mother nature, measurement. The studied problem was'errors in the evaluation of partsprecision' and this constitutes the head of the Ishikawa diagram skeleton.All the possible, main and secondary causes that could generate the studied problem were identified. The following tree diagram shows the difference between categorization (grouping of causes) and causality (the tree).The paper presents the results of a study concerning the use of the Ishikawa diagram in analyzing the causes that determine errors in the evaluation of theparts precision in the machine construction field. Just as the main categories (Equipment, People, etc.) are highlighted by placing a circle or box around them, if you include sub-categories in your cause-and-effect diagram, circle the sub-category so you can distinguish between categorization vs. Using the fish bone diagram loosely may result in a combination of the two approaches as the group oscillates between categorizing different causes and asking 'Why?' or 'Why else?'.Īlthough I've never seen any reference for this technique, I use the following rule to distinguish between categorization vs. Investigate: Now that you've come up with possible causes, it is time to go gather data to confirm which causes are real or not.Ĭommon Categories in a Fishbone Diagram The M'sĮffect: Light Bulb Burning Out PrematurelyĪ tree diagram, probability tree, or root cause analysis is geared more towards thinking in terms of causality, while using a fishbone diagram tends to make people think in terms of categorization.But, you could still ask 'Why was he/she not wearing gloves?' with the possible response 'There were none available.' It is a lot easier to take action against the inventory problem than just the generic 'improper handling'.

'Improper handling' is not a root cause, while 'Failing to wear Latex gloves' might be closer to a root cause. Ask Why?: You really want to find the root causes, and one way to help do that is to use the 5 Whys technique: asking 'Why?' or 'Why else?' over and over until you come up with possible root causes.Brainstorm Possible Causes: Using the diagram while brainstorming can both broaden and focus your thinking as you consider the various categories in turn.Choose Categories: The template is set up with the most common set of categories, but you can add or remove categories based on your specific case.Steps to Using a Cause and Effect Diagram

Models like ishikawa diagram