Product Overview
A hollow shaft is a shaft component with a through-hole bored along its axis, offering advantages including light weight, low inertia, and the ability to route cables or fluids through the bore. While maintaining adequate torsional strength and rigidity, a hollow shaft can reduce weight by 20%–40% compared to a solid shaft of the same outer diameter, significantly reducing system moment of inertia and improving acceleration response. The inner bore can also accommodate wiring, tubing, or serve as hydraulic passages, enabling structural-functional integration.
Yubao Transmission Technology produces hollow shafts with inner diameter range φ10–180mm, excellent wall thickness uniformity, inner-to-outer diameter coaxiality ≤0.03mm, and inner bore roughness Ra 0.8–3.2μm (precision grade Ra≤0.8). Made from high-strength alloy steel with tempering or carburizing heat treatment, our hollow shafts deliver high torsional strength while reducing weight, widely used in servo motors, industrial robots, reducers, and new energy drives where lightweight design is critical.
Technical Parameters
Basic Parameters (Shaft Universal)
| Parameter |
Symbol |
Unit |
Value/Range |
Tolerance |
Notes |
| Outer Diameter |
D |
mm |
21–350 |
h6–h9 |
Shaft body outer diameter |
| Total Length |
L |
mm |
≤1500 |
±0.05 |
Overall shaft length |
| Inner Bore Diameter |
d |
mm |
10–180 |
H7–H9 |
Fit bore or through hole |
| Wall Thickness |
t |
mm |
≥(D–d)/2 |
min. |
Uniform wall design |
| Straightness |
— |
mm |
0.01 |
≤ |
Full-length straightness |
| Cylindricity |
— |
mm |
0.005 |
≤ |
Measured separately for OD and ID |
| Radial Runout (OD) |
TIR |
mm |
0.008 |
≤ |
Between centers |
Hollow Shaft Specific Parameters
| Parameter |
Symbol |
Unit |
Value/Range |
Tolerance |
Notes |
| Inner Bore Roughness |
Ra |
μm |
0.8–3.2 |
≤ |
Precision grade 0.8–1.6, standard 1.6–3.2 |
| Inner-to-Outer Coaxiality |
— |
mm |
0.03 |
≤ |
Key indicator for wall uniformity |
| Inner Bore Keyway |
— |
— |
Customized |
— |
If present, 5–22mm specification |
| Inner Bore Type |
— |
— |
Through/Blind/Stepped |
— |
Per customer drawing |
| Surface Roughness (OD) |
Ra |
μm |
0.2–0.8 |
≤ |
Ground areas |
| Surface Hardness |
HRC/HV |
— |
55–62 |
— |
Post-heat treatment |
| Material Grade |
— |
— |
Customized |
— |
Common: 20CrMnTi, 40Cr, 42CrMo |
| Heat Treatment |
— |
— |
Tempering/Carburizing/Nitriding |
— |
Determined by application |
Machining Capabilities
| Process |
Equipment |
Range |
Accuracy Achieved |
| Deep Hole Drilling |
Deep Hole Drill/Gun Drill |
Bore φ10–80mm, L/D≤20:1 |
Straightness 0.05mm/1000mm |
| Boring |
CNC Lathe/Machining Center |
Bore φ50–180mm |
H7 grade tolerance |
| Internal Grinding |
Internal Grinder |
Bore φ20–150mm |
Ra≤0.4μm, roundness ≤0.005mm |
| Broaching |
CH1-1013 Broaching Machine (16T) |
Internal keyways, special bores |
Keyway tolerance JS9 |
| Outer Diameter Finishing |
Centerless/Cylindrical Grinder |
φ21–350mm |
Radial runout ≤0.003mm |
| Coaxiality Inspection |
VICI Vision Axis Tester/CMM |
Full automatic measurement |
Coaxiality ≤0.03mm |
Lightweight Design Guide
Recommended Wall Thickness Ratios
| Application Scenario |
Outer Diameter Range (mm) |
Inner/Outer Ratio (d/D) |
Wall Thickness t (mm) |
Weight Reduction |
| High Rigidity Required |
50–150 |
0.3–0.4 |
15–45 |
15%–25% |
| Lightweight Priority |
50–150 |
0.5–0.6 |
10–25 |
30%–40% |
| Fluid/Cable Routing |
80–200 |
0.5–0.7 |
15–40 |
35%–50% |
| Extreme Lightweight |
30–80 |
0.6–0.75 |
5–12 |
40%–50% |
Note: The d/D ratio should not exceed 0.75, otherwise torsional rigidity decreases significantly. Torsional strength verification is required.
Product Features
- Significant Weight Reduction: 20%–40% lighter than solid shafts, reducing system moment of inertia and improving dynamic response
- High Torsional Strength: Optimized wall thickness design ensures adequate torsional strength and fatigue life while reducing weight
- Uniform Wall Thickness: Inner-to-outer coaxiality ≤0.03mm, excellent dynamic balance at high-speed rotation
- Functional Integration: Inner bore can integrate cable channels, coolant passages, or positioning holes
- Precision Guaranteed: Inner bore roughness as low as Ra 0.8μm, meeting precision fit requirements
Typical Applications
| Application Sector |
Specific Use |
Design Features |
| Industrial Automation |
6-axis robot joint shafts |
Hollow design reduces weight 30%, inner bore for cable routing |
| Servo Motors |
High-response servo motor shaft cores |
Low inertia design for fast acceleration response |
| Reducers |
Planetary reducer sun gear shafts |
Inner bore for bearing or dowel pin mounting |
| New Energy |
Electric vehicle drive shafts |
Lightweight, high torque density |
| Machine Tool Spindles |
Machining center spindles |
Inner bore for drawbar and tool clamping mechanism |
