Range limitation rejections

Very often claims include specific ranges. For example, an electronic device claim may recite a specific amount of certain chemicals such as, 5-10 weight percentage of Titanium, 5-10 weight percentage of Silicon and 10-20 weight percentage of Iron.
During prosecution, very often an Examiner may find a reference in which a similar electronic device includes the same chemicals, but not having a weight percentage with the recited range. In this situation we may likely receive a rejection from the examiner under 35 U.S.C. 103 with a form paragraph stating that because the range was generally known it would be obvious to merely optimize the range.
The best way to deal with this rejection in my experience is to (1) argue that the examiner has not established that the range (such as weight percentage) is a result-effective variable (a variable which achieves a recognized result); and (2) presenting evidence that the particular range is critical (achieves an unexpected result).
Presenting evidence of the critical nature of the range is easiest when the application includes experimental results showing the benefits of the recited range. If such results are not included in the specification, a declaration under rule 132 will likely need to be included to make these technical arguments.
Summary: An obvious rejection based upon optimization of a range can be overcome by successfully arguing the criticality of the range and that the examiner has not established that the variable of the range is a result effective variable.