Stop Losing Precision and Money on Your Production Line
You know the feeling. You set up a new CNC machine or an automated assembly line. Everything looks perfect on paper. But when you start running the program, the parts are not where they should be. You see tiny vibrations on the camera feed. The surface finish is rough. You check the ball screw, and it is fine. You check the motor, and it is brand new. So, what is wrong?The problem is often the hidden connection between the motor and the lead screw. A cheap or low-quality coupling acts like a spring. It absorbs the power meant for cutting or moving. It creates a “dead zone” where the motor turns, but the table does not move. This is called backlash. In high-speed applications, this causes heat, noise, and lost steps. For a cable production line or a precision sliding table, this means scrap parts and wasted time. You need a connection that is rigid, instant, and precise. You need the Miki Pulley SFC-020DA2.
What Makes the SFC-020DA2 Special?
This is not just a piece of metal. It is a precision tool made in Japan by MIKIPULLEY. The “SFC” stands for Servo Flexible Coupling, but do not let the word “flexible” fool you. It is rigid where it counts.
Aluminum Alloy Body for Speed
The main body uses a special high-strength aluminum alloy. This is not soft pot metal. It is strong but very light. Why does weight matter? Because when your linear slide table moves back and forth fast, heavy parts want to keep moving due to inertia. A heavy coupling fights the motor. This lightweight design lets the motor start and stop instantly. It improves the “response” of your machine. You get faster cycle times.
The Double Diaphragm (DA2) Design
The “DA2” in the name means Double Diaphragm. This model has two sets of spring plates (diaphragms) separated by a spacer.
- Single Diaphragm (SA2): Very stiff, for when you need absolute zero give.
- Double Diaphragm (DA2): This is the SFC-020DA2. It handles more misalignment. If your motor shaft and the lead screw are not perfectly aligned (and they never are), this coupling absorbs the error without transmitting vibration to the screw. It protects your expensive linear guides and ball screws.
Zero Backlash is Real
Backlash is the gap between teeth in a gear. In a diaphragm coupling, there are no teeth. The diaphragms are clamped tight. When you reverse the motor direction, the table moves immediately. There is no “dead time” waiting for the gap to close. This is critical for 3D printing, laser cutting, and CNC routing where direction changes happen thousands of times a minute.
Technical Specifications You Can Trust
We do not guess. We look at the real data from the factory catalogs. Here is what you get with the SFC-020DA2 series specifically for your setup:
- Model: SFC-020DA2
- Bore Diameter (Shaft Side): 6mm to 8mm (This fits many small servo motors like Panasonic or Yaskawa)
- Bore Diameter (Screw Side): 6mm to 8mm (Perfect for small ball screws on linear stages)
- Max Torque: Up to 15 N·m (Depending on the specific bore size, usually around 10-15 Nm for this size)
- Max RPM: Up to 10,000 RPM (Safe for high-speed spindles)
- Moment of Inertia: Extremely low (Approx. 0.00002 kg·m²)
- Material: Aluminum Alloy (A7075 equivalent) and Stainless Steel diaphragms
- Clamping Method: Keyless clamping screws (No keyways to weaken the shaft)
- Backlash: Zero
- Temperature Range: -20°C to +80°C
Dimensions (Approximate for reference):
- Outer Diameter: 20mm – 26mm (Compact size saves space)
- Length: 30mm – 35mm
Note: When you inquire, please tell us your exact shaft sizes (e.g., Motor 8mm, Screw 6mm). We can supply the specific part number like SFC-020DA2-6B-8B.
Perfect Fit for These Applications
You might ask, “Is this right for my machine?” If you are building or repairing equipment that needs precision, the answer is yes.
Linear Motion and Slide Tables
This is the #1 use case. Imagine a linear actuator moving a welding head or a camera. The SFC-020DA2 connects the servo motor to the ball screw. Because it is stiff, the table stops exactly where the code says. No overshoot. No ringing.
Semiconductor and Electronics Manufacturing
In pick-and-place machines, speed is everything. The low inertia of the SFC-020DA2 allows the head to accelerate at 2G or more without missing a component. The zero backlash ensures the chip lands perfectly on the pad.
Medical and Lab Automation
Lab analyzers use small lead screws to move pipettes. These need to be smooth and quiet. The diaphragm design dampens any motor noise. It also prevents metal particles (from wear) from contaminating the lab environment because there are no rubbing parts like in jaw couplings.
3D Printers and CNC Routers
Hobbyists and pros use these. If you are upgrading a 3D printer from a rubber spider coupling to this, you will see a huge drop in “ghosting” (echoes on the print walls). The print corners will be sharp.
Why Buy Japanese Imported vs. Cheap Copies?
You will see many “compatible” couplings on Alibaba or eBay for $10. They look the same. But they are not the same.
- Material Quality: Cheap copies use soft aluminum or zinc alloy. They deform under torque, causing the bore to slip on the shaft.
- Balance: The Miki Pulley parts are dynamically balanced. A cheap copy will vibrate at 3000 RPM. This vibration ruins your linear bearings.
- Clamping Screws: The imported version uses high-grade alloy steel screws that do not strip. Cheap ones use soft steel that rounds off when you tighten them.
- RoHS Compliance: If you export to Europe or the US, you need lead-free components. Miki Pulley is strictly RoHS compliant.
Installation is Fast and Easy
You do not need a machinist to install this.
- Clean the motor shaft and the screw shaft.
- Loosen the clamping screws on the coupling hubs.
- Slide the coupling onto the shafts.
- Tighten the hex socket screws with a standard Allen wrench.
- Important: Check that the shafts are not bottoming out in the hub. Leave a tiny gap (0.5mm) for thermal expansion.
It takes 5 minutes. No special tools. No heating. No keyways to file.
Ready to Upgrade Your Machine Precision?
Do not let a bad coupling ruin your product quality. The Miki Pulley SFC-020DA2 is the industry standard for a reason. It is reliable, precise, and built to last 10 years in a factory environment.We have access to the full MIKIPULLEY catalog. Whether you need the SFC-020DA2 for a 6mm lead screw, an 8mm motor shaft, or a custom configuration, we can source it. We also have stock of similar models like the SFS series (steel body) if you need even higher torque.Contact us today for a free quote. Send us your shaft diameters and the quantity you need. We will check the stock in Japan or our local warehouse and give you the best price and delivery time. Let’s make your machines run smoother.