Critical evaluation of the theory of constraints lean six sigma continuous improvement management approach / Rojanette van Tonder.

Three methodologies are associated with production optimisation, namely, Theory of Constraints(TOC), Lean and Six Sigma – and each boasts with a number of success stories. This dissertationaddresses the possibility of implementing all three these methodologies in a specific sequence atan organisation and also sets out to determine the impact of this implementation.A literature survey was conducted on all three stand-alone methodologies as well as on thecombined methodology, which is called the Theory of Constrains Lean Six Sigma (TLS). TLSliterature suggests that TOC should be implemented first with a view to identify the constraint inan organisation. Lean implementation should follow in order to eliminate any waste in theorganisation. Lastly, Six Sigma should be implemented to optimise the process variability.TOC literature explains that The Goal of any organisation is to make money. All other objectivesare only the means of achieving The Goal. The literature further indicates that the constraint inany organisation determines the drumbeat, and that this constraint should be managed by meansof the Drum-Buffer-Rope methodology.Lean literature points towards 14 Management Principles by means of which an organisationshould be managed in order to become a Lean organisation, while Six Sigma literature isconcerned with the DMAIC (Define-Measure-Analyse-Improve-Control) methodology used forimprovement projects and the belt system that is used to manage these improvement projects.Jonker Sailplanes, a sailplanes manufacturer in Potchefstroom, South Africa, was used as a casestudy for the implementation of TLS. A description is given of the processes and procedures thatwere followed before and after the implementation of TLS. The TLS methodology had to be adapted in order to meet the specific needs of Jonker Sailplanesinto an adapted 14-step TLS implementation plan. After implementing TOC and Lean at JonkerSailplanes, it was found that the organisation was not ready for the transition from Lean projectsto Six Sigma projects. The implementation of Six Sigma was therefore referred for futureresearch.One of the most significant findings of the current study was the very positive impact that theimplementation of TLS had on the organisation: the production tempo (throughput) of theorganisation has increased while the operating expenses per aircraft have decreased. Thisconfirms that the profit per aircraft has increased. A critical evaluation of the implementation ofthe TLS methodology can therefore maintain that the implementation of TLS at Jonker Sailplaneswas a success since the production tempo (throughput) and the organisational profit wereincreased and the implementation of the methodology was done with relative ease.In terms of interpreting results it was also necessary to set out how Jonker Sailplanes proceededfrom a prototyping environment to a production setup, and how specifically identifying theconstraint helped to achieve this transition. Furthermore, is it argued that when Lean isimplemented before TOC, this could move the organisation away from The Goal, which is to makemoney. The interpretation of findings suggests that the procedure followed at Jonker Sailplaneswas the most appropriate one.Finally, recommendations are made for future studies in terms of how to further improve theimpact of the TLS implementation at Jonker Sailplanes.