Actually the DMAIC methodology should be used when a product or process is in existence at your company but is not meeting customer specification or is not performing adequately.
Define - Define the project goals and customer (internal and external) deliverables
Measure - Measure the process to determine current performance
Analyze - Analyze and determine the root cause(s) of the defects
Improve - Improve the process by eliminating defects
Control - Control future process performance