DFC Aluminum Curved Jaw Coupling | Zero Backlash, 2000 N·m, 5000 RPM

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DFC Aluminum Curved Jaw Coupling – Zero Backlash, High Torque for Servo & Stepper Motors

Model Number
Check below, custom

Outer Diameter (mm)	Length (mm)	Bore Range (mm)
14	22	3 – 7
20	25	4 – 10
20	30	4 – 10
25	30	4 – 12
25	34	4 – 12
30	35	5 – 16
30	40	5 – 16
35	50	6 – 19
40	50	8 – 24
40	55	8 – 24
40	66	8 – 24
45	55	8 – 25
45	66	8 – 25
55	78	12 – 30
65	90	14 – 40
80	114	19 – 45
95	126	22 – 55

Product Description

DFC Aluminum Curved Jaw Coupling – Zero Backlash, High Torque, H6 Precision for Servo & Stepper Motors

The Apexcoupling DFC series is a high-performance aluminum curved jaw coupling (also known as a spider coupling, jaw coupling, or plum coupling) engineered for precision motion control applications. Featuring zero rotational clearance, it is ideal for servo motors, stepper motors, ball screw drives, linear modules, and CNC machinery where accurate positioning and smooth operation are critical.

Constructed from high-strength aluminum alloy with a German imported polyurethane spider element, this coupling delivers excellent wear resistance, oil resistance, and vibration damping. The clamping screw design ensures secure shaft fixation, while the anodized finish provides enhanced corrosion resistance. With H6 bore accuracy, 12.9 grade high-strength screws, and 5-axis CNC machining for superior concentricity, the DFC series offers unmatched precision and reliability for demanding automation applications.

✅ Zero backlash – suitable for positive and negative rotation. High-strength aluminum alloy – lightweight, low inertia, corrosion-resistant. German imported polyurethane spider – wear-resistant, oil-resistant, vibration damping. H6 precision bore – tighter than H7 for maximum concentricity. 5-axis CNC machined – one-piece cutting for superior accuracy. 12.9 grade screws – secure clamping without shaft damage. 3D chamfered edges – safe handling (OD ≥ 25mm). Maintenance-free – no lubrication required.

Key Technical Specifications

Parameter	Value
Brand	Apexcoupling
Model Series	DFC (Curved Jaw / Spider / Plum Coupling)
Type	Flexible / Elastomeric / Jaw / Spider
Structure	Curved jaw (spider type)
Hub Material	High-strength aluminum alloy (aerospace-grade 6061)
Spider Material	German imported polyurethane (TPU) – wear-resistant, oil-resistant, electrically insulating
Surface Treatment	Anodized (anti-oxidation) – extends service life
Bore Tolerance	H6 (higher precision than H7)
Screw Grade	12.9 high-strength clamping screws
Backlash	Zero – no rotational clearance
Rated Torque	Up to 2000 N·m (model dependent)
Maximum Speed	Up to 5000 RPM
Operating Temperature	Up to 140°C (German polyurethane spider)
Misalignment Compensation	Radial, angular, and axial
Vibration Damping	Excellent – polyurethane spider absorbs shock and vibration
Fastening Method	Clamping screw (keyway option available)
Design	Detachable – easy installation and maintenance
Machining	5-axis CNC – one-pass machining for high concentricity
Safety Feature	3D chamfered edges – no sharp edges (OD ≥ 25mm)
Customization	OEM – custom bores, keyways, spider hardness, and colors
Applicable Industries	Servo motors, stepper motors, CNC machines, linear modules, robotics, packaging machinery, automation equipment
Certification	ISO9001, BV Certificate
Warranty	1 Year
Place of Origin	Guangdong, China

DFC Series – Model Range & Dimensional Matrix

Model	Outer Diameter (D) mm	Length (L) mm	Bore Range (d1,d2) mm	Clamp Screw Size	Rated Torque (N·m)	Max Speed (RPM)
DFC-20×25	20	25	4 – 10	M3	10	19000
DFC-25×34	25	34	4 – 12	M4	20	16000
DFC-30×35	30	35	5 – 16	M4	40	12000
DFC-40×55	40	55	8 – 24	M5	80	10000
DFC-40×66	40	66	8 – 24	M5	80	10000
DFC-55×78	55	78	12 – 30	M6	46	6000
DFC-65×90	65	90	14 – 38	M8	200	5000

📐 Custom bore sizes available. Input (d1) and output (d2) bore diameters can be customized independently (e.g., 12mm × 20mm bore combination). Keyway, hexagon, and square hole options available.

Product Structure

Two Aluminum Hubs – High-strength aerospace-grade 6061 aluminum alloy, precision-machined with curved jaws, anodized finish.
German Imported Polyurethane Spider – The elastic insert that transmits torque, absorbs shock, and compensates for misalignment. Available in multiple hardness grades.
Clamping Screws (12.9 Grade) – Secure shaft fixation with even clamping force – no shaft damage.
5-Axis CNC Machining – Hubs are turned and bored in a single chucking operation, guaranteeing strict H6 inner bore tolerance and high concentricity.
3D Chamfered Edges – Models with outer diameters over 25mm undergo full 3D edge chamfering, removing sharp edges for safe handling.

💡 How it works: The DFC coupling consists of two aluminum hubs with curved jaws and a polyurethane spider. The curved jaw design creates a press-fit with the spider, eliminating backlash and providing smooth, precise torque transmission. The polyurethane spider flexes to absorb shock, dampen vibration, and compensate for radial, angular, and axial misalignment. The clamping screw design provides even clamping force without damaging the shaft surface. The 5-axis CNC machining ensures high concentricity and surface finish for reduced vibration at high speeds.

Spider Insert Options – Choose the Right Hardness

The DFC series uses German imported polyurethane spiders available in multiple hardness grades to optimize torsional stiffness and damping:

Hardness (Shore A)	Color	Torsional Stiffness	Damping	Best For
98A	Yellow	High	Moderate	High torque, low damping
95A	Red	Moderate-High	Moderate	Balanced performance, general purpose
92A	Blue	Moderate	Good	Standard applications, good damping
85A	Orange	Low	Excellent	High damping, vibration isolation
64D	White	Very High	Low	Extreme high torque (stiff)

💡 Selection tip: For most servo motor and general industrial applications, 95A (Red) offers the best balance of torque capacity and damping. For high-vibration applications, choose 85A (Orange) . For maximum torque transmission, choose 64D (White) or 98A (Yellow) .

Product Features & Advantages

Advantage	Benefit
Zero Backlash	No rotational clearance – precise positioning for servo and stepper motors
H6 Precision Bore	Tighter tolerance than H7 – maximum concentricity, reduced vibration
5-Axis CNC Machining	One-pass machining – superior concentricity and surface finish
German Imported Polyurethane Spider	Excellent wear resistance, oil resistance, and electrical insulation – operating temperature up to 140°C
High-Strength Aluminum Alloy	Lightweight, low inertia, corrosion-resistant – enables rapid acceleration
12.9 Grade Screws	High-strength clamping – secure shaft fixation, no loosening under vibration
Anodized Finish	Enhanced corrosion resistance and professional appearance
3D Chamfered Edges	Safe handling – no sharp edges (OD ≥ 25mm)
Misalignment Compensation	Compensates for radial, angular, and axial deviations – protects bearings and seals
Vibration Damping	Reduces settling time and improves system stability
Detachable Design	Easy installation and maintenance – replace spider without moving hubs
OEM Customization	Custom bores, keyways, spider hardness, and anodizing colors available
Maintenance-Free	No lubrication required – reduces operating costs

Why Choose DFC for Servo & Stepper Motor Applications?

Zero Backlash for Precision Positioning
The curved jaw design creates a press-fit with the polyurethane spider, eliminating rotational clearance. This ensures that every motor step translates directly to load movement – no lost motion, no positioning errors.

H6 Bore Accuracy for High Concentricity
With H6 bore tolerance (tighter than H7), the DFC coupling provides exceptional shaft fit and concentricity, reducing vibration and improving system stability at high speeds.

Lightweight Aluminum for Low Inertia
The high-strength aluminum alloy hubs reduce overall system inertia, enabling faster acceleration, deceleration, and shorter cycle times.

German Polyurethane for Durability
The imported polyurethane spider offers excellent wear resistance, oil resistance, and electrical insulation, with an operating temperature up to 140°C – ensuring long service life in demanding environments.

Vibration Damping for System Stability
The elastic spider absorbs shock and dampens vibration, reducing settling time and improving overall system stability – critical for CNC machining, robotics, and automation.

Applications

Servo Motors – High-precision motion control, zero backlash requirement
Stepper Motors – Accurate positioning, no lost motion
Ball Screw Drives – Smooth, accurate linear motion
Linear Modules – Precision linear positioning systems
CNC Machines – Feed drives, spindle drives, positioning systems
Robotics – Joint drives, precision motion control
Packaging Machinery – Registration and indexing systems
Printing Equipment – Register control, high-speed operation
Automation Equipment – Pick-and-place systems, indexing tables
Medical Devices – Precision motion systems
3D Printers – Lightweight, precise shaft connections

Why Choose Apex Coupling for DFC Curved Jaw Couplings?

Advantage	Description
Factory Direct	Competitive B2B pricing – no middlemen
Premium Materials	Aerospace-grade 6061 aluminum + German imported polyurethane
Zero Backlash	Precision performance for servo and stepper motors
H6 Precision Bore	Tighter than H7 – maximum concentricity
5-Axis CNC Machining	Superior accuracy and surface finish
12.9 Grade Screws	Secure clamping – no shaft damage
Anodized Finish	Corrosion-resistant and professional
OEM Customization	Custom bores, keyways, spider hardness, and colors
ISO9001 & BV Certified	Quality assured manufacturing
Fast Delivery	Large semi-finished stock – quick turnaround for custom orders

FAQ

Q: What is a curved jaw coupling?
A: A curved jaw coupling (also called a spider coupling, jaw coupling, or plum coupling) consists of two aluminum hubs with curved jaws and a polyurethane spider element. The curved jaw profile ensures zero backlash operation.

Q: What does “zero backlash” mean?
A: Zero backlash means there is no rotational clearance between the hubs and the spider. This ensures precise torque transmission with no lost motion – critical for servo motors, stepper motors, and CNC machines.

Q: What is the advantage of H6 bore tolerance?
A: H6 is tighter than H7, providing higher concentricity and more accurate shaft fit – reducing vibration and improving system stability at high speeds.

Q: What spider materials are available?
A: Standard is German imported polyurethane – available in multiple hardness grades: 98A (Yellow), 95A (Red), 92A (Blue), 85A (Orange), and 64D (White). Different hardnesses offer different torque and damping characteristics.

Q: What is the torque and speed rating?
A: Rated torque is up to 2000 N·m and maximum speed is up to 5000 RPM (model dependent).

Q: Can the coupling compensate for misalignment?
A: Yes. The polyurethane spider compensates for radial, angular, and axial deviations.

Q: Is the coupling easy to install?
A: Yes. The detachable design and clamping screw fastening allow for easy installation and maintenance without moving connected shafts.

Q: Does the coupling require lubrication?
A: No. The DFC series is maintenance-free – no lubrication required.

Q: Can I get a custom coupling?
A: Yes. We offer OEM customization – custom bores, keyways, spider hardness, anodizing colors, and special materials available.

Q: What is the maximum operating temperature?
A: The German imported polyurethane spider operates at temperatures up to 140°C.

Request a Quote

Send us your model (e.g., DFC-55×78), bore size(s), keyway requirement, and application details. Our engineers will recommend the optimal model and provide a quotation within 24 hours.