Actuator housings
Broader housing RFQ scope for linear, rotary, hydraulic, pneumatic, and electric actuator assemblies.
Interactive housing screening tool
Start with a first-pass pressure and material comparison, then use the engineering report to decide whether 304 stainless steel is the right actuator housing choice for your environment.
For actuator housings requiring an optimal balance of strength, machinability, and corrosion resistance in non-marine environments, 304 stainless steel is the industry standard.
Housings can be machined from solid bar or thick-walled tubing. Tubing saves rough boring time and material cost, but may have broader dimensional tolerances on the raw stock that require careful setup.
| Property | Metric Value | Imperial Value |
|---|---|---|
| Yield Strength | ~215 MPa | ~31,200 psi |
| Tensile Strength | ~505 MPa | ~73,200 psi |
| Young's Modulus | 193 GPa | 28,000 ksi |
| Hardness | ~201 HB | ~92 HRB |
| Machinability (vs B1112) | 45% | Slower than 303, faster than 316. Prone to work-hardening. |
Values are planning references verified on June 27, 2026; final purchasing should use the mill certificate and customer specifications.
| Decision point | 304 SS | 316 SS | 6061-T6 Alum |
|---|---|---|---|
| Primary reason to specify | Balanced cost and excellent general corrosion resistance | High chloride or marine environment resistance | Lightweight and lowest machining cost |
| Machining behavior | Prone to work-hardening; requires conservative tool-vendor cutting data, heavier feeds, and rigid tooling | Slightly tougher to machine than 304 due to molybdenum addition | Highly machinable (600+ SFM), excellent chip formation |
| Actuator housing fit | Good fit for washdown, food-grade, and low-chloride environments after chemistry review | Preferred for marine, chemical processing, coastal, or chloride-cleaning exposure | Best for standard pneumatics (4-8 bar), robotics, and weight-sensitive applications |
| Main risk | Pitting in chloride environments and slower cycle times vs aluminum | Higher material cost than 304 and slightly slower cycle times | Poor corrosion resistance without anodizing; lower strength |
The calculator uses Barlow's formula for hoop stress in thin-walled cylinders where internal diameter divided by wall thickness is at least 10:1. It estimates safety factor against static internal pressure yielding only.
Environmental ratings are generalized. Actual corrosion rates depend on temperature, concentration, and exposure duration.
Cyclic fatigue (pressure pulsations), port threading stress concentrations, thermal derating, and seal wear mechanics need drawing-level engineering review.
| Risk | When it appears | Minimum mitigation |
|---|---|---|
| Chloride Pitting & Stress Corrosion | Exposure to saltwater, de-icing salts, chloride cleaning agents, or warm chloride-bearing process fluids. | Upgrade to 316 stainless steel (which adds molybdenum) or use a protective coating/barrier. |
| Work-Hardening & Tool Glazing | Light cuts (< 0.010" DOC) or dwelling tools during deep hole boring for the cylinder. | Use rigid setups, sharp carbide tooling, flood or through-tool coolant, and a tool-vendor feed/speed window that avoids rubbing. |
| Thread Galling | Repeated assembly of stainless steel fittings into the housing ports under pressure. | Use dissimilar thread materials, anti-seize compounds, or thread rolling instead of cutting. |
| High Manufacturing Cost | Specifying tight tolerances (e.g., < 0.01mm) on non-critical exterior features. | Apply tight tolerances only to the bore, seal grooves, and mounting faces (DFM). |
304 stainless steel provides vastly superior corrosion resistance, higher strength, and better temperature resistance than aluminum. It is standard for food processing, medical, and washdown environments where aluminum would degrade or require specialized plating.
In its annealed state, 304 is practically non-magnetic. However, cold working (like drawing or severe machining) can induce slight magnetism. If zero magnetic permeability is critical (e.g., for certain sensors), specific processing or a different alloy might be needed.
While bare 304 stainless steel can withstand oxidation up to 925°C (1700°F), the practical limit of an actuator assembly is entirely dictated by the internal seals. Standard NBR seals limit operation to ~80°C, while Viton/FKM seals extend this to ~150°C. Note that continuous exposure between 425°C–860°C can cause carbide precipitation (sensitization), reducing the housing's corrosion resistance.
The internal cylinder bore often requires a very smooth finish (e.g., Ra 0.4 µm) for seal longevity. This is typically achieved by precision boring followed by roller burnishing or honing. 304 responds well to burnishing due to its work-hardening properties.
Yes, 304 has excellent weldability. However, if the housing is heavily machined first, welding can introduce distortion that ruins bore tolerances. It is usually better to machine the housing from a solid block or weld a 304L blank before final precision machining.
No. The calculator is a screening tool for early RFQ discussion. Final rating needs drawing-level review of ports, threads, fatigue, temperature, seal limits, inspection method, and any applicable pressure-vessel or customer standard.
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