It is essential that for lean manufacturing principles to be effective in a company that the management team is fully bought in and is driving the philosophy initially from a top down approach. You would hope that as the Lean philosophies are adopted, that it become tacit within the company and lean becomes a way of life that is lived and practiced by all employees. That said, the management will still need to be fully bought in and living the lean way of life.
Below is one of many interesting articles that maybe of some use and give more clarity:
The role of communication and management support in a lean manufacturing implementation
Lean Six Sigma is a very structured approach, it carefully analyzes a process before attempting or implementing any progress. This approach also helps complex processes to identify problems from the beginning to the end while maintaining sustainable processes. Furthermore, Lean Six Sigma supports an analytical approach and allows using collected data to improve processes. In addition, this method allows measuring and recording progress with quantitative scales.
I use this methodology especially when I work on processes where many similar pieces are produced. Finally, when there is a statistical approach to the project, the effectiveness of Six Sigma is significantly higher than using descriptive data.
Six sigma gives the company a framework on which they can operate and asses efficiency benchamarks. It is useful for companies that aim to improve their processes.
There is a voice of management ( define phase in DMAIC method ):-
If there are competitors : Benchmarking process by PAIAM method : Planning - Analysis - Integration - Action - Maturity.
If there are no competitors : Balanced Scorecard technique (BSC).
Also please refer to the six sigma black belt handbook by Thomas McCarty in Motorola university ( page 1 - 75) in 4 management model (Align - Mobilize - Accelerate - Govern).