From CAD to part: choosing a process

Start with the finished requirements

Process selection begins with material, quantity, tolerances, surface quality, geometry, and inspection—not with whatever machine is most exciting. A flat profile and a three-dimensional bearing housing are fundamentally different manufacturing problems.

Make a short process matrix before detailed design. Record which operations each candidate can accomplish, which are secondary operations, and which require a different supplier.

What each process tends to do well

• Laser and waterjet cutting: efficient planar profiles; edge quality, kerf, thickness, and material compatibility require review.
• CNC machining: precise three-dimensional features and repeatable locating surfaces, subject to access and fixturing limits.
• Sheet forming: inexpensive repeatable bends after tooling and springback are accounted for.
• Casting: useful near-net-shape methods that may need finish machining and defect inspection.
• Additive manufacturing: complex geometry and rapid iteration, with process-specific property and finish constraints.

Prototype versus production

A one-off price includes different overhead from a batch price. Record quotations at several quantities, but keep material quantity, manufacturing effort, and setup discounts separate. A unit-price reduction does not imply that the part consumes less stock.