**5. Conclusions**

The present study presents the development of a cost estimation tool that calculates total operation cost based on the material requirements and machining times while applying a part complexity level as a way of standardization for the budgeting process to expedite it while considering multiple factors that affect the total operation time and thus, the total cost of part production. The cost estimation tool was successfully developed and validated for two machine types; these being milling machines capable of producing parts of different heights.


The model can be improved by conducting additional experiments and validation tests, as this tool is easily reprogrammable and adapted to different processes. Furthermore, since the estimation of manual operations can be quite difficult (resulting in deviations from the estimated to the real operation time), these operations should be minimized. Alternatively, the creation of normalized procedures for these operations can improve the accuracy of the time estimations. Despite this, the cost estimation tool can predict the manufacturing times accurately, resulting in the obtention of accurate and fast budgets. This is particularly useful for manufacturing SMEs, as this tool provides a faster and easier alternative to providing budgets for machined parts. The advantages and drawbacks of the developed tool can be observed in Table 10.

**Table 10.** Main advantages and drawbacks of the developed cost estimation tool.


Regarding further improvements to the developed tool, some other prediction methods can also be employed in conjunction with this tool, to improve prediction accuracy. The average error detected in the model can be smoothly corrected by a determining factor, and the profit yield of the manufacturer can easily accommodate this error in the first stage, being successively corrected through experiments.

**Author Contributions:** F.J.G.S.: conceptualization, work orientation, investigation, supervision, writing—reviewing; V.F.C.S.: investigation, formal analysis, writing—reviewing and editing; A.G.P.: formal analysis, visualization, writing—editing; L.P.F.: formal analysis, writing—editing; T.P.: formal analysis, visualization, writing—reviewing. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
