Wexmar provides custom piston and cylinder machining for hydraulic and pneumatic actuators, pumps, compressors and dispensing equipment. Our Canastota, New York shop produces CNC machined pistons, cylinder bodies, glands, rod ends, piston rods and cylinder heads on Mazak and Doosan lathes, Swiss-type machines and horizontal machining centers. Seal grooves and bore fits are where these parts succeed or fail, and they are where we focus our process and inspection.
What pistons and cylinders do and who buys them
A piston seals against a cylinder bore and converts pressure into force, or the reverse in a pump. Seal groove geometry, bore finish and concentricity decide leakage, friction and seal life. Typical buyers include:
- Fluid power OEMs building hydraulic and pneumatic cylinders
- Pump, compressor and metering equipment manufacturers
- Dispensing, instrumentation and medical hardware builders with small pistons and bores
- Defense and government programs with build-to-print actuator parts
How our custom piston and cylinder machining works
Turning pistons, glands and heads
Pistons, glands and cylinder heads are turned on our Mazak and Doosan lathes. The piston OD, seal and wear ring grooves and the rod bore are finished in one chucking so the grooves stay concentric to the rod axis. The Mazak Multiplex 6300Y completes both sides in one cycle, and live tooling adds ports, bolt holes and wrench flats. See CNC turning.
Swiss machining for small pistons
Small pistons, plungers and valve spools up to 32 mm diameter run on our Maier MLK-32 Swiss-type machines, which support long, slender plungers during the cut. See Swiss machining.
Cylinder bodies and blocks
Short cylinder bodies are bored and threaded on our lathes. Block-style cylinders, compact cylinder bodies and pump blocks with multiple bores and ports are machined on our Mazak horizontal machining centers, where the 4th axis reaches ports on several faces in one setup.
Typical materials
- 1045, 1144 and 4140 steel for hydraulic pistons, glands and heads
- 6061 and 7075 aluminum for pneumatic pistons and cylinder bodies
- Bronze for glands and bearing surfaces
- 303, 316, 17-4 PH and Nitronic 50 stainless for corrosive and sanitary service
- Engineered plastics such as PEEK and acetal for pistons and wear parts
Critical features and how we hold them
- Seal groove dimensions: width, diameter and corner radii are form tooled to the seal manufacturer's specification.
- Groove surface finish: side walls and groove bottoms are finished to the seal finish callout, typically 32 Ra or finer.
- Piston OD to rod bore concentricity: cut in one chucking to keep seals evenly loaded.
- Cylinder bore size and finish: bored to size, with honing through qualified outside processors where the drawing calls for it.
- Ports and threads: SAE, ORB and NPT ports are machined and gaged, with spot faces square to the port axis.
Typical tolerances and finishes
| Feature | Typical tolerance | Tighter on request |
|---|---|---|
| Piston outside diameter | +/-0.001 in | +/-0.0005 in |
| Seal groove diameter | +/-0.001 in | +/-0.0005 in |
| Seal groove width | +0.002 / -0.000 in | +0.001 / -0.000 in |
| OD to rod bore concentricity | 0.001 in TIR | 0.0005 in TIR |
| Short cylinder bore | +/-0.0005 in | +/-0.0003 in |
| Seal groove finish | 32 Ra | 16 Ra |
Values are typical. Bore depth, diameter and material affect what is practical, and the quote confirms each callout.
Design notes
Reference the seal manufacturer and part number on the drawing so groove dimensions and finish match the seal. Lead-in chamfers on bores and rod ends protect seals during assembly, and they should be specified rather than left to the shop. For long cylinder barrels, we typically machine the ends, glands and heads, while honed tube is sourced through qualified outside processors. Piston rods can be supplied turned and centerless ground in-house, with hard chrome applied outside.
Secondary operations
Hard chrome plating of rods, bore honing, anodizing of aluminum pistons, heat treat and passivation are completed through qualified outside processors. Centerless grinding of rods and plungers is done in-house.
Quantity patterns
Orders range from prototype sets for a new actuator to production runs of hundreds or thousands of pistons and glands per year. Repeat releases run from saved programs. See also end caps and plugs.
Inspection
Groove dimensions are checked with groove gages and the Mitsubishi optical comparator, bores with bore gages, and concentricity on our Brown and Sharpe CMMs. FAI in AS9102 format, CMM reports and material certs are available.
Getting a quote
Send the drawing, seal callouts, material and quantity. You can upload a drawing for an instant estimate, and an estimator will confirm price and lead time. Call (315) 400-2654 to discuss cylinder components.