PEEK Reaction Cylinder Body, CNC Turned and Milled from 97 mm Solid Bar

About This Part

This reaction cylinder body is machined from solid PEEK bar rather than molded, and that choice is what makes the part work. Molding PEEK in a section this thick traps residual stress and sink, and the bore drifts once the material relaxes. Cutting it out of annealed bar removes that variable, so the 36.5 mm bore, the square slot, and the small outside diameters all come out of one piece that is already dimensionally stable.

The geometry is a typical precision chamber body. A 36.5 mm bore runs along the axis, opened in two stages. Roughing leaves 2.5 mm per side, then the bore is finished after the part has had its chance to move, so the final cut removes the distortion instead of chasing it. A square slot is milled across one face, and the large outside diameter is faced first so every later feature has one clean reference for orientation.

Turning handles the small end. All of the mating diameters there are cut in a single clamping together with the 60 degree center hole, so concentricity between them comes from the machine instead of from a fixture. A second turning operation forms the outer end profile. The last milling pass picks up the auxiliary holes in the side, and because those holes have a defined direction relative to the square slot, they are cut only after the slot is finished and checked.

Bench work closes the route: chamfers on every hole mouth, tapping of the threaded holes, then dimensional and visual inspection before cleaning and packing. Parts run in 40 piece lots from 97 mm diameter by 125 mm long bar.

PEEK is specified here because the body sees product, cleaning agents, and elevated temperature in service. It self lubricates, it resists the chemicals used to wash equipment down, and it insulates electrically, which matters when the vessel carries instrumentation. Nothing is done to the part after the last cut.