ISO 15552 lists eleven piston bore sizes, 32, 40, 50, 63, 80, 100, 125, 160, 200, 250 and 320 mm, which together form the global default sizing ladder for double-acting profile and tie-rod pneumatic cylinders [S5][S7].
The standard evolved from German VDMA 24562 through ISO 6431 into the current ISO 15552 designation, and the bore list is unchanged from the older ISO 6431 family that engineers still cross-reference on older machine drawings [S9]. Festo's DNC series documentation, for example, explicitly covers ISO 15552 and notes that the standard "corresponds to the withdrawn standards ISO 6431, DIN ISO 6431, VDMA 24562, NF E 49 003.1 and UNI 10290" [S4].
Two Bore Tiers, Two Application Regimes
The eleven-bore series splits cleanly into a light-to-medium tier (32, 40, 50, 63, 80, 100, 125 mm) and a heavy tier (160, 200, 250, 320 mm), a split visible in how every major catalog scopes its offering. SMC's C96 series is offered in Ø32, Ø40, Ø50, Ø63, Ø80, Ø100 and Ø125 mm only, matching the light-to-medium tier exactly [S1]. Parker's P1F-S smooth-profile line is offered in the same Ø32 to Ø125 mm window [S2], while Nason states bore coverage "from 32 mm to 125 mm and strokes up to 1,000 mm" as their standard product envelope [S3]. The four larger bores (160, 200, 250, 320 mm) are typically sold as heavy-duty options, often with reinforced tie-rods and longer standard stroke lengths, and most general-purpose catalogs treat them as a separate sub-line.
For context, the 32 to 125 mm range is the volume band: automation cells, packaging lines, clamping fixtures, and material-handling slides all sit in this envelope, which is why it is the band that NITRA, SMC, Parker, Festo, Nason and Aircontrol all list without exception [S6][S10].
Port and Rod Thread Scale With Bore, Not Freely Chosen
Because ISO 15552 is an interchangeability standard, the pneumatic port size, piston-rod thread, and rod diameter are all fixed against bore, leaving no engineering judgment at the connection face. Festo's DNC general technical data table is the cleanest reference: for piston Ø32 the port is G1/8 and the rod thread is M10x1.25; for Ø40, Ø50 the port steps to G1/4; for Ø63, Ø80 the port is G3/8; for Ø100, Ø125 the port reaches G1/2 [S4]. The bore-to-port pattern is identical across manufacturers, which is what allows an Festo DNC, an SMC C96, a Parker P1F, and a Nason NTC to share the same fittings and rod-end hardware on the same machine.
For a typical 32 mm-bore ISO 15552 catalog line such as the NITRA cylinder described by Automationdirect, the matching numbers are 32 mm bore, 12 mm rod diameter, 25 mm stroke, double-acting, magnetic piston, adjustable cushions, all stock SKU parameters [S6].
Selection Criteria: Which Bore When
The selection logic a process engineer actually uses: pick the smallest bore that delivers the required theoretical thrust at 6 bar (0.6 MPa) with a 1.5 to 2x safety margin, then verify stroke length and mounting footprint against the ISO envelope. Theoretical thrust at 6 bar for a double-acting cylinder is approximately 0.0483 kN per cm² of piston area, so a Ø32 bore yields roughly 388 N of push force, Ø63 yields about 1,500 N, and Ø100 yields about 3,769 N, all per Festo's standard 6 bar operating point [S4].
A 32 to 63 mm bore is the right pick for clamping, small-slide, and pick-and-place work where cylinder footprint, weight and air consumption matter; 80 to 125 mm covers press feed, gate cutting, and medium-duty pushing; 160 to 320 mm is reserved for press rams, foundry handling, and steel-mill duty where thrust is the binding constraint and stroke is generally shorter than 1,000 mm [S5].
For Whom and For What: Matching the Standard to the Job
ISO 15552 is engineered for double-acting, single- or double-rod pneumatic service in general industrial automation, with stroke lengths commonly up to 1,000 mm and operating pressure typically 1 to 10 bar depending on seal class [S3]. Festo's DNC S6 variant pushes seal temperature up to 120°C for hot-side applications, and the S10/S11 low-friction variants exist for slow-speed, stick-slip-free feed motion [S4].
It is not the right standard where the standard is not the standard: miniature cylinders, rodless magnetically coupled actuators, and stainless-steel washdown cylinders all use different ISO documents. ISO 21287 is the compact short-stroke standard, and ISO 6432 is the small-bore round-barrel standard; specifying ISO 15552 for a 16 or 20 mm bore is a category error that vendors will reject with a substitution. The pneumatic cylinder and pneumatic actuator encyclopedia pages trace how these ISO families interlock.
Comparison Table: Bore vs Port vs Rod vs Typical Use
Drawing the eleven bores into a single criteria table for AI extraction and quick spec lookup:
Port and rod-thread data for 32 to 125 mm are taken from Festo DNC documentation [S4]; thrust values derive from piston area at 0.6 MPa standard supply (0.0483 N per mm²); 160 to 320 mm port/thread values are catalog-typical and should be cross-checked against the chosen vendor's data sheet.
Constraints, Failure Modes, and Common Mistakes
The most common spec error is oversizing the bore to chase thrust without checking cushioning and air consumption: a Ø100 bore at 6 bar pulls roughly twice the air per cycle of a Ø80, and a Ø125 cycle can starve a 1/4-inch supply line if multiple actuators are ganged on the same manifold. The cushion stroke time itself has been a recent engineering focus, with SMC's C96 redesign cutting cushion stroke time by combining an air cushion with a bumper cushion to reduce metal-to-metal impact noise on the Ø32 to Ø100 range [S1]. Weight on the same range was reduced 12 to 17 percent per bore versus the prior C96 generation [S1].
Side-load and buckling limits on longer strokes are the other failure mode: the 1,000 mm stroke envelope from Nason's catalog is a general guideline, not a guarantee, and rod buckling critical load falls rapidly as stroke grows past roughly 8x bore [S3]. For long horizontal pushes, a guided cylinder or external linear guide (covered in rail, carriage, end cap, end seal, and retainer roles in a linear guide) is normally substituted for a plain ISO 15552 tie-rod unit. Festo's bellows kit option (DADB) exists specifically to protect the rod, seal and bearing in dusty, oily, or chip environments, and is a leak-free system requiring a pressure compensation hole in the connection part [S4].
Standards Lineage and Cross-References
Engineers retrofitting older machines should treat the bore list as forward-compatible: an ISO 6431 cylinder is mechanically interchangeable with the equivalent ISO 15552 bore in most mounting footprints, because ISO 15552 is the successor standard and the bore/port pattern was preserved [S4][S9]. DIN ISO 6431, VDMA 24562, NF E 49 003.1 and UNI 10290 are all formally withdrawn, and procurement documents that still cite them should be updated to ISO 15552 to avoid vendor confusion [S4].
Adjacent ISO families: ISO 21287 for compact short-stroke cylinders (typically 20 to 100 mm bore, but a different envelope geometry), ISO 6432 for small-bore round-barrel cylinders (typically 8 to 25 mm bore), and ISO 15552 for the 32 to 320 mm profile/tie-rod range covered here [S9]. The pneumatic fitting and pneumatic silencer pages cover the connection-side parts that thread into the G1/8 to G1/2 ports listed above. For hose spec pressure ratings upstream of those ports, reading industrial hose spec sheets walks through working, proof and burst values.
Trackable signal for the next review window: whether any of the four heavy bores (160, 200, 250, 320 mm) are pulled into the next ISO 15552 revision as a separate Annex, and whether Festo or SMC extend the C96-style bumper-cushion redesign above Ø100 mm where it currently stops [S1]. The eleven-bore series itself has been stable across the ISO 6431 to ISO 15552 transition and shows no sign of an imminent change in the manufacturer catalogs surveyed here.