Large CNC machining can be an intimidating task for any manufacturer. Even with advances in CNC technology, large-scale machining is still challenging due to the need for specialized tooling, a greater allowance for tolerances, enhanced work-holding strategies, and more extensive programming requirements.
If a complex finished part is desired, all of these considerations must be carefully evaluated and accounted for to ensure the successful production of the desired part.
Tooling
Tooling used in large CNC machining must take into account the size of the material being processed as well as the depth of cut desired. Specialized tool holders typically have integral coolant through capabilities so that proper cutting fluids can be applied during extended cuts.
Due to the large size of rough stock used in large machining operations, proper tool holders must also be chosen so as not to become deflective or vibrate on heavy cuts due to not having a tight grip on the material being processed.
Tolerances
Rigid machine construction and special bellows covers are necessary when cutting larger parts due to increasing flexibility with increased part size leading to a shorter lifespan for cutting tools and increased allowance for tolerance stacking errors.
Further consideration should also be taken into account when making decisions about heat treating and finishing operations which are affected by part size and require more control from these processes during manufacturing operations.
Workholding
Workholding fixtures designed specifically to support larger components can help reduce overhanging loads, which may adversely affect accuracy over extended cuts, vibrations, or deflection, leading to potentially causing loss of finish and shortened life spans of expensive tools; adjustments should always be accounted for during setup procedures before making any contact with the material being processed.
Programming
More complex programming techniques that include subprograms should always be listed with consideration given to their effect on productivity based upon their function when including them in long-running cycles.
Attention should also be given to memory capacity limitations within controllers prior to executing programs containing overly long repetitive cycles or extremely deep pockets that may cause premature termination of cycles due to a lack of free system memory capacity within the controller.