Beskrivning
EP6-16 Miniature Set Screw Oldham Coupling — Compact Three-Piece Flexible Connector for Precision Motion
De EP6-16 miniature Oldham coupling is the smallest member of the EP6 set-screw family — a 16 mm outside-diameter, three-piece flexible shaft coupling built for sub-newton-meter precision drives where parallel misalignment must be absorbed without introducing rotational backlash. Two anodised aluminum-alloy hubs sandwich a self-lubricating polyacetal (Delrin/POM) slider; the slider’s two orthogonal tongues engage matching slots in each hub, allowing the hubs to glide laterally while preserving an exact 1:1 angular relationship. The result is a constant-velocity transmission that tolerates up to 1.0 mm of radial offset, all in a package light enough (about 6 g) that the host motor barely notices it.
Engineers selecting the EP6-16 typically need to mate a small DC, brushless, or stepper motor — NEMA 8 / NEMA 11 frame, or a 13 mm encoder shaft — to a downstream load such as a leadscrew, optical chopper, or rotary indexer. In those situations a rigid coupling would translate every micron of mounting eccentricity into bearing side-load, shortening service life and degrading positioning repeatability. A bellows or beam coupling, on the other hand, would react against misalignment with a spring force that pulses through the loop and excites resonance. The Oldham architecture sidesteps both failure modes: the centre disc slides instead of flexing, so there is no restoring force and no reflected torsional spring.
Specifikationer
| Parameter | Värde |
|---|---|
| Modell | EP6-16 |
| Ytterdiameter (ΦD) | 16 mm |
| Total längd (L) | 18 mm |
| Borrningsområde (d1 / d2) | 4, 5, 6 mm |
| Nominellt vridmoment | 0.7 N·m |
| Maximalt vridmoment | 1.4 N·m |
| Maximal rotationshastighet | 9 000 rpm |
| Tröghetsmoment | 3.0 × 10⁻⁷ kg·m² |
| Statisk vridstyvhet | 29 N·m/rad |
| Parallell feljustering | 1.0 mm |
| Vinkelfeljustering | 3,0° |
| Gänga för ställskruv | M3 |
| Åtdragningsmoment för skiftnyckel | 0.7 N·m |
| Massa (max borrning) | 6 g |
| Glapp | Noll |
Material
Aluminum-Alloy Hub (A2017)
The two outer hubs are CNC-machined from anodised aluminum 2017, an aerospace-grade alloy that combines high specific strength with low rotational inertia. For a 0.7 N·m duty rating this is the optimal hub material: it keeps the reflected inertia at the motor shaft low (3.0 × 10⁻⁷ kg·m²), accelerates with the servo, and remains dimensionally stable across the −20 °C to +80 °C range typical of indoor automation.
Polyacetal (POM) Centre Disc
The sliding disc is moulded from engineering polyacetal — known commercially as Delrin or POM. POM offers a self-lubricating sliding interface, electrical insulation between the two shafts, oil resistance, and a fatigue endurance that easily covers tens of millions of cycles at the EP6-16’s rated load. Two hardness grades are available on request when the application requires extra damping or, conversely, higher torsional rigidity.
Stainless Hardware
Set screws are SUS304 stainless steel, hex-socket M3. The stainless grade is specified to prevent galvanic interaction with the aluminum hub and to survive light condensation in semi-conditioned enclosures — a small detail that pays dividends in field reliability.
Working Principle of the Three-Piece Oldham Structure
An Oldham-koppling is, in essence, a planar four-bar linkage compressed into three concentric discs. Hub A locks to the driving shaft via two opposed M3 set screws at 90°. Hub B locks to the driven shaft in the same manner. Between them sits the polyacetal slider, whose front face carries a tongue that engages a slot in Hub A, and whose back face carries a second tongue, rotated 90° from the first, that engages a slot in Hub B.
When the two shafts are perfectly concentric, the slider does nothing — it spins with the assembly as a rigid body. When the shafts are offset by, say, 0.4 mm radially, the slider’s centre traces a small circle once per shaft revolution: it slides one way against Hub A in the first half-turn, then the other way against Hub B in the second half-turn. Because the slot orientations are exactly orthogonal, the angular velocity transmitted from Hub A to Hub B is identical to the input — there is no second-harmonic ripple of the kind a universal joint introduces, no torsional wind-up of the kind a bellows produces.
For an EP6-16 in a typical encoder feedback loop, this matters in three concrete ways. First, position accuracy is preserved: a 0.5 mm parallel offset does not corrupt the angular reading at the load. Second, motor side-loads are eliminated: the slider absorbs the lateral force component, so the upstream bearing is not preloaded by the misalignment. Third, the absence of an elastic restoring element means the closed-loop controller does not have to fight a parasitic torsional spring — a major advantage in high-bandwidth servo tuning.
Industritillämpningar
Laboratory & Analytical Instruments
Driving optical choppers, filter wheels, and sample carousels in spectrometers and microplate readers. The EP6-16’s zero backlash protects the angular registration that determines wavelength accuracy.
Medical & Diagnostic Equipment
Pipette positioning heads, blood-analyser rotors and centrifuge indexers benefit from the coupling’s electrical insulation between drive and load — relevant when patient-contact circuits must be galvanically isolated from chassis ground.
Encoder & Resolver Feedback Lines
Linking incremental encoders (typically 13 mm or 16 mm housings) to motor shafts in stepper-based positioning stages. The 3.0 × 10⁻⁷ kg·m² inertia is negligible against typical encoder rotors.
️ Desktop 3D Printers & Engravers
Connecting NEMA 11 / NEMA 14 steppers to lead-screws on Z-axes. The Oldham architecture forgives the parallel misalignment that comes from low-cost extruded-frame assemblies.
Optical & Imaging Systems
Focus-drive motors in microscopy, motorised iris assemblies and small-format cinema lenses. The slider acts as an electrical insulator, preventing ground loops between camera body and motor driver.
⚙️ Miniature Linear Stages
Coupling stepper motors to 6 mm and 8 mm ball-screws in research-grade XY tables. Position repeatability of ±2 µm is achievable when the EP6-16 replaces a rigid hub-and-collar joint.
Why Choose Ever-power for Your EP6-16 Couplings
Quality Certifications
Every EP6-16 leaving our line is inspected against drawings traceable to an ISO 9001:2015–certified quality system. The aluminum and POM raw materials carry RoHS-riktlinjer and NÅ declarations of conformity, and finished couplings can be supplied with CE declarations for inclusion in machinery destined for the European Economic Area.
Anpassning
Standard bore set is 4 / 5 / 6 mm, but the EP6-16 is regularly produced with custom bore tolerances (H7, F7), keyway slots, flats, set-screw points (cup, flat, or oval), and alternative anodising colours for visual line identification. POM hardness can be swapped to a glass-filled grade when the load is closer to the upper end of the torque envelope.
Engineering & After-sales Support
Our English-speaking technical team responds to selection and CAD-model requests within 24 timmar. STEP files, 2D PDFs, and torque-de-rating curves at elevated temperature are available on request. For volume programmes we maintain a buffer inventory of standard bores to keep MRP-line replenishment under two weeks.
Kundrecensioner och fallstudier
★★★★★
Germany — Bio-analyser Manufacturer
Används i: Filter-wheel drive of a benchtop fluorescence reader, 6 000 rpm continuous.
Feed-back: “We replaced an in-house bellows coupling with the EP6-16 to remove the 1.7 kHz resonance peak we were chasing in our control loop. The Oldham architecture flat-lined our spectrogram in that band. Mechanical assembly time also dropped because the M3 set-screws are accessible without dismounting the encoder.”
★★★★★
South Korea — Semiconductor Test Equipment
Används i: Probe-station Z-axis of a wafer-level test cell, 0.4 N·m peak duty.
Feed-back: “The 1 mm of allowable parallel misalignment matched the worst case from our motor-mount stack-up perfectly. Two years and tens of millions of dwell cycles later, no measurable change in position repeatability.”
★★★★☆
United States — Desktop 3D Printer OEM
Används i: Z-axis lead-screw to NEMA 11 stepper, dual-coupling tower configuration.
Feed-back: “Cost per axis is unchanged versus the rigid coupling we previously specified, but warranty returns for binding lead-screws dropped by half in the first quarter after the switch. Would recommend, with a note that operators should keep set-screw torque conservative — these are small fasteners.”
Vanliga frågor
Can the EP6-16 be reversed in direction without performance penalty?
Yes. The three-piece architecture is rotationally symmetric — clockwise and counter-clockwise transmission characteristics are identical. There is no preferred direction, which is why the EP6-16 is commonly specified for bidirectional indexing applications.
What is the typical service life at rated torque and speed?
For a continuously operating EP6-16 at 0.5 N·m and 6 000 rpm with parallel offset under 0.3 mm, expected disc life exceeds 50 million revolutions before slider wear becomes detectable. Replacement of the centre disc only — without removing the hubs from their shafts — restores as-new performance.
How do I tighten the M3 set screws correctly?
Use a 1.5 mm hex key and apply 0.7 N·m. Both set screws on a hub are separated by 90°; tighten each in two passes. Light Loctite 222 is recommended where shock or vibration is expected; do not apply Loctite to the slider face.
Is the EP6-16 suitable for vacuum environments?
POM has a modest outgassing rate that disqualifies it from UHV (<10⁻⁶ Pa) service. For high vacuum below 10⁻³ Pa we recommend specifying an alternative slider material — PEEK or PTFE-filled grades are typically suitable. Please contact engineering for vacuum-rated variants.
What lead time can I expect for 100 pieces?
Standard bore combinations (4-4, 5-5, 6-6, 5-6, 4-6) ship in 5–7 business days from order confirmation. Custom bore-to-bore combinations add roughly 7 working days. Air freight to most regions arrives within 3–5 days thereafter.
Need a Bulk Quote or a Custom Bore?
Whether you are specifying the EP6-16 for a 50-piece prototype build or a 50 000-piece annual MRP plan, our engineering desk is ready to help you finalise bore, keyway, and material selection. Visit our about-us page to learn how we serve global OEMs, browse the full product catalogue, or jump straight to a quote.
