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DN/DNG Series Rigid Set Screw Coupling – Zero Backlash, High Torsional Rigidity
Model Number
Check below, custom
DN-16×16
DN-16×24
DN-20×20
DN-20×30
DN-25×25
DN-25×36
DN-32×32
DN-32×41
DN-40×44
DN-50×55
DN-50×66
DN-63×71
- Phone : +86 13431039760
- Wechat : +86 13431039760
- Whatsapp : +86 13431039760
- Email : ella@apexcoupling.com
Product Description
DN/DNG Series Rigid Set Screw Coupling – Zero Backlash, High Torsional Rigidity for Servo & Stepper Motors
Factory Direct | One-Piece Integrated Structure | Zero Backlash | High Torque & High Rigidity | Low Inertia | Set Screw Fastening | Aluminum or Stainless Steel | Maintenance-Free | OEM Customizable
The Apexcoupling DN/DNG series is a high-precision rigid set screw coupling engineered for applications demanding zero backlash and maximum torsional rigidity. Featuring a one-piece integrated structure machined from a single piece of high-strength aluminum alloy (DN series) or stainless steel (DNG series), this coupling provides a solid, backlash-free connection between two shafts. The rigid design ensures perfect shaft alignment with no rotational clearance – making it the ideal choice for servo motors, stepper motors, CNC machines, 3D printers, and precision positioning systems.
⚠️ Important: Rigid couplings do not accommodate any misalignment (radial, angular, or axial). The shafts must be perfectly aligned during installation to prevent bearing damage or shaft failure.
Key Technical Specifications
| Parameter | DN Series (Aluminum) | DNG Series (Stainless Steel) |
|---|---|---|
| Brand | Apexcoupling | Apexcoupling |
| Type | Rigid / Set Screw | Rigid / Set Screw |
| Structure | One-piece integrated | One-piece integrated |
| Material | High-strength aluminum alloy | SUS304 stainless steel |
| Surface Treatment | Anodized | Polished |
| Backlash | Zero – no rotational clearance | Zero – no rotational clearance |
| Bore Tolerance | H7 | H7 |
| Outer Diameter Range | 16 – 63 mm | 16 – 63 mm |
| Length Range | 16 – 71 mm | 16 – 71 mm |
| Fastening Method | Set screw (positioning screws) | Set screw (positioning screws) |
| Screw Torque | 1.2 – 8 N·m | 1.2 – 8 N·m |
| Misalignment Compensation | None – shafts must be perfectly aligned | None – shafts must be perfectly aligned |
| Maintenance | None required – maintenance-free | None required – maintenance-free |
| Customization | OEM – custom bores and sizes | OEM – custom bores and sizes |
| Applicable Industries | Servo motors, stepper motors, CNC machines, 3D printers, robotics, automation equipment | Servo motors, stepper motors, CNC machines, 3D printers, robotics, automation equipment |
| Place of Origin | Guangdong, China | Guangdong, China |
🔧 Custom bores and sizes available. Contact us with your specifications.
DN Series – Model Range & Specifications (Aluminum)
| Model | Outer Diameter (D) mm | Length (L) mm | Bore Range (d) mm | Screw Torque (N·m) | Set Screw Size |
|---|---|---|---|---|---|
| DN-16×16 | 16 | 16 | 3,4,5,6,6.35,7,8 | 1.2 | M3 |
| DN-16×24 | 16 | 24 | 3,4,5,6,6.35,7,8 | 1.2 | M3 |
| DN-20×20 | 20 | 20 | 4,5,6,6.35,7,8,9,9.525,10 | 1.2 | M3 |
| DN-20×30 | 20 | 30 | 4,5,6,6.35,7,8,9,9.525,10 | 1.2 | M3 |
| DN-25×25 | 25 | 25 | 5,6,6.35,7,8,9,9.525,10,12 | 2.5 | M4 |
| DN-25×36 | 25 | 36 | 5,6,6.35,7,8,9,9.525,10,12 | 2.5 | M4 |
| DN-32×32 | 32 | 32 | 6,6.35,7,8,9,9.525,10,12,12.7,14,15,16 | 5 | M5 |
| DN-32×41 | 32 | 41 | 6,6.35,7,8,9,9.525,10,12,12.7,14,15,16 | 5 | M5 |
| DN-40×44 | 40 | 44 | 8,9,9.525,10,11,12,12.7,14,15,16,17,18,19,20 | 5 | M5 |
| DN-50×55 | 50 | 55 | 10,11,12,12.7,14,15,16,17,18,19,20,22,24,25 | 8 | M6 |
| DN-50×66 | 50 | 66 | 10,11,12,12.7,14,15,16,17,18,19,20,22,24,25 | 8 | M6 |
| DN-63×71 | 63 | 71 | 12,14,15,16,17,18,19,20,22,24,25,28,30,32 | 8 | M6 |
📐 Additional sizes and custom dimensions available upon request. Contact our engineering team for custom sizing.
DNG Series – Model Range & Specifications (Stainless Steel)
The DNG series offers the same dimensional specifications as the DN series but with SUS304 stainless steel construction for enhanced corrosion resistance. Standard models include DNG-16×16, DNG-16×24, DNG-20×20, DNG-20×30, DNG-25×25, DNG-25×36, DNG-32×32, DNG-32×41, DNG-40×44, DNG-50×55, DNG-50×66, and DNG-63×71.
📐 Custom bores and sizes available. Contact us for stainless steel options.
Product Structure
One-Piece Integrated Body – Precision-machined from a single piece of high-strength aluminum alloy or stainless steel for maximum rigidity.
Set Screws – Positioning screws provide secure shaft fixation.
Smooth Bore – Precision-machined bore with H7 tolerance for accurate shaft fit.
💡 How it works: The DN/DNG rigid coupling is a one-piece clamping-type coupling that creates a solid, backlash-free connection between two perfectly aligned shafts. The set screws are tightened evenly to secure the coupling to both shafts, creating a single rigid unit that transmits torque with zero lost motion. Unlike flexible couplings, rigid couplings have no element to absorb misalignment – they rely on perfect shaft alignment for proper operation.
Rigid Coupling vs Flexible Coupling – Key Differences
| Feature | Rigid Coupling (DN/DNG) | Flexible Coupling |
|---|---|---|
| Backlash | Zero – no rotational clearance | Zero (some types) |
| Torsional rigidity | Ultra-high | Moderate to high |
| Misalignment compensation | None – shafts must be perfectly aligned | Angular, radial, axial |
| Inertia | Low | Moderate to high |
| Best for | Perfectly aligned shafts, high precision, high torque | Applications with misalignment, vibration damping |
Product Features & Advantages
| Advantage | Benefit |
|---|---|
| Zero Backlash | No rotational clearance – precise positioning for servo and stepper motors |
| One-Piece Integrated Structure | Maximum rigidity – no moving parts, no wear, long service life |
| High Torsional Rigidity | No angular deflection under load – maintains system accuracy |
| Low Inertia | Lightweight design enables high-speed operation and quick starts/stops |
| High-Strength Material | Aluminum alloy (DN) or stainless steel (DNG) – durable and reliable |
| Set Screw Fastening | Simple and secure shaft fixation |
| H7 Precision Bore | High concentricity and accurate shaft fit – reduces vibration |
| Maintenance-Free | No lubrication required – reduces operating costs |
| Oil & Corrosion Resistant | Anodized aluminum or stainless steel – suitable for various environments |
| OEM Customization | Custom bores and sizes available |
Applications
Servo Motors – High-precision motion control, zero backlash requirement
Stepper Motors – Accurate positioning, no lost motion
CNC Machines – Feed drives, positioning systems
3D Printers – Precision shaft connections
Robotics – Joint drives, precision motion
Encoders – Precision position feedback systems
Automation Equipment – Pick-and-place systems, indexing tables
Precision Positioning Systems – XY tables, linear stages
Important Installation Note – Perfect Alignment Required
⚠️ Rigid couplings do NOT accommodate any misalignment. The shafts must be perfectly aligned during installation.
| Misalignment Type | Allowable Tolerance |
|---|---|
| Radial (eccentricity) | 0 mm – must be fully adjusted |
| Angular | 0° – shafts must be collinear |
| Axial | 0 mm – no end play allowed |
💡 Installation tip: Use a dial indicator or laser alignment tool to ensure perfect shaft alignment before tightening the set screws. Improper alignment will cause premature bearing failure and shaft damage.
Why Choose Apex Coupling for DN/DNG Rigid Couplings?
| Advantage | Description |
|---|---|
| Factory Direct | Competitive B2B pricing – no middlemen |
| Premium Materials | High-strength aluminum alloy or SUS304 stainless steel |
| Zero Backlash | Precise positioning for servo and stepper motors |
| High Torsional Rigidity | No angular deflection – maintains system accuracy |
| Low Inertia | High-speed capability – quick starts and stops |
| One-Piece Construction | Maximum rigidity – no wear parts |
| Set Screw Fastening | Simple and secure shaft fixation |
| H7 Precision Bore | High concentricity and accurate shaft fit |
| Maintenance-Free | No lubrication required – reduces operating costs |
| OEM Customization | Custom bores and sizes available |
FAQ
Q: What is a rigid set screw coupling?
A: A rigid set screw coupling is a one-piece coupling that creates a solid, backlash-free connection between two perfectly aligned shafts. It uses set screws to secure the coupling to both shafts, transmitting torque with zero lost motion.
Q: What is the difference between DN and DNG series?
A: DN series features high-strength aluminum alloy construction with anodized finish. DNG series features SUS304 stainless steel construction for enhanced corrosion resistance.
Q: Does the coupling have backlash?
A: No. The DN/DNG series features zero backlash – no rotational clearance, ensuring precise positioning for servo and stepper motors.
Q: Can the coupling compensate for misalignment?
A: No. Rigid couplings do not accommodate any misalignment (radial, angular, or axial). The shafts must be perfectly aligned during installation.
Q: Is the coupling maintenance-free?
A: Yes. The one-piece integrated structure has no moving parts or wear items – maintenance-free operation.
Q: What are the common applications?
A: Servo motors, stepper motors, CNC machines, 3D printers, robotics, encoders, and precision positioning systems.
Q: Can I get a custom coupling?
A: Yes. We offer OEM customization – custom bores and sizes available.
Request a Quote
Send us your model (e.g., DN-25×25), bore size, material preference (aluminum or stainless steel), and application details. Our engineers will recommend the optimal model and provide a quotation within 24 hours.
DN rigid coupling
DNG rigid coupling
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DN-16×16 DN-20×20 DN-25×25 DN-32×32 DN-40×44 DN-50×55 DN-63×71
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