A customer came to us with a 3D model for a custom 316L stainless steel housing and not much else to go on. No off-the-shelf part matched what they needed, and the geometry was a mix of things that needed two completely different processes — a smooth turned bore on the inside, and a pair of recessed slots with threaded holes cut into the outer wall at precise angles.

316L gets specified a lot for parts that need to hold up in corrosive or demanding environments, and this custom 316L stainless steel housing was no exception. The molybdenum content gives it better resistance to pitting and chloride exposure compared to standard 304, which matters if this housing is ever going to see moisture, chemicals, or salt exposure over its service life.

It is also a low-carbon grade, which keeps it from getting brittle around weld zones — not relevant here since the part is fully machined, but it is part of why 316L tends to be the default choice when corrosion resistance and long-term durability both matter.

Part type: Custom 316L SS Ring-Shaped Housing

Material: 316L Stainless Steel

Machining Process: CNC Turning + 5-axis CNC Machining

Surface Finish: As-Machined

Machining Approach

Once the turned profile was done, the part moved over to 5-axis milling for the two slotted recesses on the outer wall. These are not simple flat-bottom pockets — they sit at a specific angle and depth on the curved outer surface, which is exactly the kind of feature that gets difficult fast on a 3-axis machine.

5-axis machining let us tilt the tool to meet the curved surface head-on for each slot, which meant we could cut the geometry exactly as designed in a single setup. That also helped with accuracy between the two slots — since the part never had to be repositioned between operations, both slots ended up consistent with each other without any extra alignment work.

This is the kind of part that shows up when a design needs something nobody makes off the shelf — a ring that has to be turned for the bore, milled at an angle for the slots, and held to tight enough tolerances that both processes have to work together cleanly. We machine custom stainless steel parts like this regularly, in 316L and other grades, using whatever combination of turning and milling the geometry calls for. If you have a part with a similar mix of features, send us your 3D model and we will get back to you with a quote.

We provide custom CNC machining services for low-volume production and Rapid Prototyping for design verification.  Click Here to Upload Your CAD Files