It is important to keep in mind that a tighter tolerance can result in additional cost because of increased scrap, additional fixturing, special measurement tools and/or longer cycle times because the machine may need to slow down in order to hold the tighter tolerance. Depending on the tolerance call out and the geometry associated with it, costs can be more than double of what it would be to hold the standard tolerance.
Overall geometric tolerances can also be applied to the drawing for the part. Based on the geometric tolerance and type of tolerance applied, additional cost may be the result because of increased inspection times.
The best way to apply tolerances is to only apply tight and/or geometric tolerances to critical areas when it is necessary to meet the design criteria to minimize costs.
