Yes, converting fonts to outlines will prevent font substitution issues.
In the wide world of printing there are virtually thousands upon thousands of fonts to choose from, lots of which may look the same visually, but carry a different naming convention. So, if you are submitting artwork using a drawing program, such as Illustrator, CorelDraw or InDesign, we request that you convert all text to curves or outlines. Converting the font to outlines or curves actually transforms the text portions of your sign design into solid objects in lieu of actual text. The simple act of converting fonts to outlines saves everybody a headache and speeds up the print production schedule.
Even though we have hundreds of fonts in our font library, our particular fonts may not be listed by the same name as the font on your art file. Therein lies the problem of not converting fonts to outlines. When our design team pulls up your artwork on our computers and the fonts don't have the exact same naming convention, the computer will not recognize your font and substitute it with a generic font. When there is a font substitution it throws off your design, and if printed "as is" without fixing the font issue, will not look like the artwork you submitted. Nine-times-out-of-ten we have to request that you re-submit your artwork, this time with the fonts converted to outlines, to keep the integrity of your artwork intact. This leads to wasted time, which could possibly affect meeting deadlines, especially in "Rush Order" scenarios.
And for the Photoshop aficionados who don't work in Adobe Illustrator, there are steps to take before submitting your .tif or .jpg files, that will cut out the same problem we experience with Illustrator files that don't convert fonts to outlines. If you are submitting a Photoshop file that was created using "layers" you will need to "flatten all layers" before submitting your artwork. Photoshop files that are submitting without flattening the layers can create serious font issues, as well as, delay print production schedules.
NOTE: Before converting any fonts to outlines (or flattening layers in Photoshop), it is advisable to save a copy of the file first. Once fonts are converted to outlines, or Photoshop layers are flattened, the art file can no longer be edited to make future changes or corrections.