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Process

Does a Metal 3D Printed Part Need CNC Machining?

When printed components need machining, which features are usually machined, and how to plan machining allowance into the design.

Process5 min read

Often, yes — but usually only in specific places. Most industrial additive components are hybrid: the complex form is built additively, and the features that carry tolerance, sealing or assembly function are machined afterwards.

Features that are normally machined

  • Bearing and dowel bores requiring close fit.
  • Sealing and mating faces requiring flatness and finish.
  • Threads, particularly load-bearing or repeatedly assembled threads.
  • Datum surfaces used for assembly or inspection.
  • Interfaces where position must be held relative to other features.

Features that are often left as-built

  • External aerodynamic or organic surfaces.
  • Internal channels and lattice structures.
  • Non-critical webs, ribs and clearance features.
  • Cosmetic surfaces where a blasted or tumbled finish is acceptable.

Plan the allowance, not the rework

Adding stock to critical features at the design stage is inexpensive. Discovering after the build that a bore cannot be finished because there is no material to cut is not. Machining allowance, fixturing access and a workable datum structure should all be decided before the part is built.

Capability

Design, manufacture, finish and inspect — from one supplier.