Stop Losing Precision and Wasting Time on Maintenance
Do you have a problem with your machine losing its position? Does the lead screw shake or vibrate when it moves fast? Are you tired of couplings that wear out too quickly or need constant greasing?If you are connecting a servo motor to a lead screw or ball screw, you need perfect movement transfer. Any small error in the connection causes bad cuts, slow response, or even machine crashes. Many cheap couplings have “backlash” (play between parts). This means when the motor stops, the load keeps moving a tiny bit. This ruins precision.You also face the problem of misalignment. It is impossible to align a motor shaft and a lead screw perfectly by hand. A rigid coupling will break if they are not aligned. A loose coupling will slip. You need a part that connects them tightly but can handle small alignment errors without adding stress to the bearings.This is why the Miki Pulley SFC-035DA2 is the best choice. It is a diaphragm flexible coupling imported directly from Japan. It solves these pain points with a smart, spring-like metal design. It offers zero backlash for instant response. It handles misalignment smoothly. It is lightweight for high-speed moves. And it requires almost zero maintenance.
What is the SFC-035DA2 Diaphragm Coupling?
The SFC-035DA2 is a high-performance “Servo Flex” coupling made by Miki Pulley in Japan. It belongs to the SFC (Servo Flex Coupling) series. The “DA2” means it uses a double-disc (diaphragm) structure. This makes it very strong in torsion (twisting) but flexible in bending.Unlike old-style jaw couplings with rubber spiders, this uses thin metal plates (diaphragms) clamped between hubs. The metal flexes instead of stretching rubber. This gives you two big benefits. First, there is no friction, so no wear and no dust. Second, it can handle much higher speeds.This specific model, the SFC-035DA2, is sized for small to medium servo motors. It is famous in the automation world for its balance of strength and weight. It is the “gold standard” for connecting encoders, small servos, and stepping motors to lead screws in CNC machines, 3D printers, and medical devices.
Technical Specifications (SFC-035DA2-10B-12B)
Here are the hard numbers for the model connecting a 10mm motor shaft to a 12mm lead screw shaft. We keep it simple so you know exactly what you are buying.
| Parameter | Value | Note |
|---|---|---|
| Model | SFC-035DA2-10B-12B | Bore: 10mm (d1) to 12mm (d2) |
| Type | Diaphragm / Disc Coupling | Double Element (DA2) |
| Rated Torque | 10 N·m | Max continuous twist force |
| Max Speed | 10,000 min⁻¹ (RPM) | Very fast for precision |
| Torsional Stiffness | 9,000 N·m/rad | Very rigid, no wind-up |
| Moment of Inertia | 26.93 × 10⁻⁶ kg·m² | Extremely low, fast response |
| Axial Misalignment | ±0.5 mm | Can handle shaft moving in/out |
| Angular Misalignment | 1° (per side) | Can handle shafts not being parallel |
| Parallel Misalignment | 0.24 mm | Can handle shafts offset slightly |
| Weight | 0.121 kg | Very light (121 grams) |
| Material | Aluminum Alloy | Light and strong |
| Clamping Screw | M4 x 1 | Standard metric socket head |
| Tightening Torque | 3.4 ~ 4.1 N·m | Do not over-tighten! |
| Shaft Tolerance | h7 / g6 | Standard precision ground shaft |
Key Dimensions:
- Outer Diameter (D): 39 mm
- Length (L): 48 mm
- Spacer Length (LP): 11 mm (This is the gap between the two hubs)
Why This Coupling Beats the Competition
You might ask, “Why buy this instead of a cheaper brand?” Here is the real-world difference on your shop floor.##### Zero Backlash for Instant ResponseWhen your CNC controller sends a signal to move 0.01mm, the motor turns. With a loose coupling, the shaft turns, but the load waits. This is backlash. The SFC-035DA2 has zero backlash. The metal diaphragms transfer force instantly. This makes your machine snappy and accurate. It is critical for high-speed picking and placing or precision cutting.##### High Rigidity with Low InertiaThis is a hard balance to achieve. Usually, a strong coupling is heavy. A light coupling is weak. Miki Pulley uses a special aluminum alloy and a hollowed-out design. The moment of inertia is tiny (0.027 g·m²). This means the motor doesn’t waste energy spinning the coupling itself. It uses all its power to move the lead screw. This allows for faster acceleration and deceleration without missing steps.##### Forgiving on MisalignmentIn real life, shafts are never perfect. The SFC-035DA2 acts like a spring. If your motor is slightly higher than the lead screw, the diaphragm flexes. It absorbs the stress. This protects your expensive motor bearings and the lead screw support bearings. You save money on bearing replacements.##### No Grease, No MessRubber couplings dry out and crack. They create black dust that gets into your linear guides. The SFC-035DA2 uses metal-to-metal flexing (with a special low-dust grease inside). It never needs re-greasing. It is clean. It is perfect for clean rooms, medical labs, or food packaging machines where oil leaks are not allowed.
Perfect Applications for the SFC-035DA2
This specific size (10mm to 12mm) is very common. You will see it used everywhere in industrial automation.##### Servo Motor to Ball Screw (CNC)This is the #1 use case. Connecting a NEMA 17 or small NEMA 23 servo motor to a ball screw on a CNC router or laser cutter. The rigidity ensures the table moves exactly when commanded.##### Medical and Lab EquipmentIn DNA sequencers, automated pipettes, or CT scanners, you need smooth, quiet, and precise motion. The SFC-035DA2 runs smoothly without vibration. It is also compact enough to fit in tight medical housings.##### 3D Printers and PrototypingHigh-end 3D printers use this to connect stepper motors to lead screws (Z-axis) or linear rails. It provides the precision needed for high-resolution prints.##### Semiconductor ManufacturingIn wafer handling robots, speed and precision are everything. The low inertia allows the robot arm to start and stop instantly without vibrating the delicate silicon wafers.##### Packaging MachineryOn a flow wrapper or labeling machine, the product moves on a belt driven by a lead screw. The coupling handles the constant start-stop cycles without wearing out.
Installation and Maintenance Tips
Installing the SFC-035DA2 is easy, but you must follow the rules to get the performance.1. Check Your ShaftsMake sure your motor shaft and lead screw shaft are clean. No scratches. The diameter must be exactly 10mm and 12mm. The tolerance should be h7 (standard for ground shafts). If the shaft is too small, it will slip. If it is too big, it won’t fit.2. Insert and TightenSlide the coupling onto the shafts. Tighten the M4 clamping screws.
- Critical: Use a torque wrench!
- Tighten to 3.4 to 4.1 N·m.
- Do not guess. If you tighten too much, you will crush the aluminum hub or warp the diaphragm. If you tighten too little, it will slip under load.
3. Alignment CheckWhile the coupling can handle some error, try to align the shafts as best as you can. Use a dial indicator if possible. Keep the angular error under 1 degree and parallel offset under 0.24mm for the best life.4. No Lubrication NeededDo not add extra grease. The coupling comes pre-lubricated with a special low-dust grease from the factory. Adding more grease might attract dust or unbalance the coupling at high speeds.
Why Buy Miki Pulley from Us?
We are a trading company specialized in industrial automation parts. We understand that for a cable production enterprise like yours, machine uptime is money. You cannot afford to buy cheap knock-offs that fail after a month.Miki Pulley is a Japanese brand with a reputation for “over-engineering” their parts. They last longer than the machines they are installed in. By choosing the SFC-035DA2, you are buying reliability.We import these directly or source them from certified distributors. We can offer you the genuine article at a competitive price. We have experience shipping to English-speaking countries (USA, UK, Canada, Australia). We handle the customs paperwork so you don’t have to.Don’t let a bad coupling ruin your product quality. If you are building machines with servo motors and lead screws, this is the heart of your drive system. Make sure it is a heart that beats strong and true.Ready to upgrade your machine performance?Send us an inquiry today. Tell us your shaft sizes (e.g., 10mm to 12mm) and your quantity. We will send you a quote within 24 hours. Let’s get your production line moving smoothly and precisely. Contact us now!