Description
EP6C-20 Clamp Type Oldham Coupling — 20 mm Split-Collar Three-Piece Joint for Service-Friendly Drive Lines
The EP6C-20 clamp-type Oldham coupling is the field-service workhorse of the EP6C family. With a 20 mm outside diameter, 33 mm overall length, three catalogue bores (6, 6.35, 8 mm), and a torque rating of 1.6 N·m continuous / 3.2 N·m peak at 7 400 rpm, the EP6C-20 occupies the same duty class as the set-screw EP6-20 — but with a fundamentally different mounting philosophy designed around the realities of field maintenance, line changeovers, and high-mix production environments where motors and loads are swapped frequently.
The mechanical difference between this clamp variant and its set-screw cousin is the way each hub grips its shaft. The EP6C-20 hub features a precision-machined axial slot that allows the hub to deflect radially when a single M3 socket-head cap screw is tightened. The resulting circumferential clamping pressure secures the shaft without any point penetration, surface marking, or material removal. Loosen the screw, and the hub releases cleanly. Re-tighten, and the original clamping force is restored — with no positional history embedded in the shaft surface. That clean release-and-restore behaviour is the architectural advantage that defines the clamp type.
Specifications
| Parameter | Value |
|---|---|
| Model | EP6C-20 |
| Outside Diameter (ΦD) | 20 mm |
| Overall Length (L) | 33 mm |
| Hub Length (L1) | 10.5 mm |
| Clamp-Gap Width (F) | 4.0 mm |
| Bore-Centre Distance (E) | 12.5 mm |
| Bore Range (d1 / d2) | 6, 6.35, 8 mm |
| Rated Torque | 1.6 N·m |
| Maximum Torque | 3.2 N·m |
| Maximum Rotational Speed | 7 400 rpm |
| Moment of Inertia | 1.4 × 10⁻⁶ kg·m² |
| Static Torsional Stiffness | 58 N·m/rad |
| Parallel Misalignment | 1.4 mm |
| Angular Misalignment | 3.0° |
| Clamp-Screw Thread | M3 |
| Wrench Tightening Torque | 1.7 N·m |
| Mass (max bore) | 20 g |
| Backlash | Zero |
Materials
Anodised Aluminum Hubs
Hubs are CNC-turned from A2017-T4 aluminum and clear-anodised. The split-collar slot is wire-EDM cut for consistent gap geometry — critical to delivering uniform clamping pressure around the shaft. The hub’s outer face is precision-faced to maintain perpendicularity with the bore axis, supporting the slider’s angular tolerance budget.
Engineering POM Slider
Centre disc is moulded from POM-C copolymer — self-lubricating, oil-resistant, electrically isolating, and dimensionally stable from −40 °C to +100 °C. Two slider hardness grades are offered: standard for general drive duty, and a softer-durometer variant for applications where shock absorption is preferable to maximum torsional stiffness.
M3 Socket-Head Clamp Screws
Single M3 socket-head cap screw per hub, in SUS304 stainless A2-70. The 1.7 N·m wrench torque specification develops a clamping force of approximately 1 200 N at the split, sufficient to lock against the 3.2 N·m peak torque envelope. Industry-standard 2.5 mm hex key is sufficient for service.
Why Service Engineers Specify the Clamp Type
The set-screw versus clamp choice often comes down to the way the host machine will be serviced over its lifecycle. A set-screw, once seated, marks the shaft surface with a dimple. On subsequent reassembly, that dimple becomes a registration feature: the coupling will preferentially seat with the set-screw point in the original dimple. This is fine if the original install was correct. But if the original install was misaligned, or if the maintenance technician needs to clock the coupling to a different angular position, the dimple is now an obstacle that has to be either dressed out (with a fine file) or ignored (with the risk that the coupling slowly creeps back to the original position under vibration).
The EP6C-20 leaves no dimple. Whatever angular position you select on reassembly, that becomes the operating position. No dimple, no creep, no shaft dressing. For applications such as dispensing-pump heads, where the pump may be removed every few weeks for cleaning and re-aligned to a specific angular reference on the host machine, the clamp behaviour is the architectural feature that makes the maintenance workflow viable. The EP6C-20 has, over the years, become the default coupling on most high-cycle dispensing-pump designs for this reason alone.
Industry Applications
Pharmaceutical Dispensing Heads
Peristaltic, gear-meter, and syringe-driver heads on filling lines. Clamp release enables rapid pump-head changeover between drug formulations without coupling replacement.
Analytical-Lab Pump Banks
Multi-channel sampling pumps in chromatography front-ends. Each pump can be serviced independently without disturbing adjacent drive trains.
Quick-Changeover Production
Drive trains on production lines that change product format multiple times per shift. The clamp-release enables coupling reset within the changeover-time budget.
Modular Robot Tooling
End-effector drive coupling on collaborative-robot tool-change interfaces. Repeatable clamp engagement supports the dimensional repeatability required for trajectory accuracy.
Photogrammetry & 3D-Scanning
Rotary-stage drives on photogrammetry and 3D-scanning equipment where field setup and teardown is routine. Clamp tolerates daily install/remove cycles.
Small-Format Elevator Door Drives
Auxiliary door-operator drives in passenger lifts. Clamp engagement preserves shaft hardness profile in the safety-critical door system.
Why Choose Ever-power
Certifications
EP6C-20 production runs under ISO 9001:2015 certified controls. RoHS, REACH, and CE conformity documentation is supplied as standard. For pharma customers, USP Class VI material declarations for the slider are available with the PEEK upgrade.
Customisation
Standard bore set (6, 6.35, 8 mm) covers most NEMA 14/17 stepper and Φ8 mm servo shafts. Mixed-bore variants (e.g., 6.35 × 8 mm for imperial-to-metric transitions), oversized bore variants up to 10 mm, and PEEK slider upgrades for chemical-process applications are documented custom-build options. Quick-turn 5-piece prototype builds are supported for new-product development.
Engineering Support
English-speaking application engineers respond within 24 hours. STEP, IGES, Parasolid, SolidWorks, Inventor, Creo, and CATIA native files are available. For complex selection problems we offer free engineering review: send your motor and load specs, and we will recommend the appropriate EP6C size with a documented rationale.
Customer Reviews & Case Studies
★★★★★
Finland — Pharmaceutical Filling OEM
Used in: Peristaltic-pump head drives across a 12-channel parallel filling line. Pump heads removed and CIP-cleaned every shift.
Feedback: “Quick coupling release-and-restore was the design requirement that took us to the clamp type. The EP6C-20 has not delayed a single CIP cycle in 19 months of operation across this line. Pump operators report it is materially faster to service than the spider couplings on our previous machine generation.”
★★★★★
Romania — Cosmetics Contract Manufacturer
Used in: Drive coupling on a multi-product cream-filling head; 3–4 product changeovers per day with full clean-down between batches.
Feedback: “The clamp engagement means our line operators can break and remake the drive in seconds during product changeover. This was a meaningful improvement over the previous set-screw spec, which our QA team had flagged as a foreign-particle risk because of the chip generated on first set-screw seating.”
★★★★☆
New Zealand — 3D-Scanning Equipment Builder
Used in: Rotary-stage drive on portable 3D scanners deployed for archaeological and engineering survey work.
Feedback: “Equipment is set up and torn down on average twice per week in remote field locations. The clamp engagement has survived hundreds of install cycles per scanner without any positional drift. Knock one star only because we wish a black-anodised version were available — our equipment livery is matte black, and the clear-anodised hub is visually inconsistent in marketing photos.”
Frequently Asked Questions
How many install/remove cycles can the EP6C-20 sustain?
The M3 clamp screw is engineered for at least 500 install/remove cycles within its elastic range. The hub itself supports unlimited cycles — its life is bounded only by the clamp screw, which is consumable. Replacement clamp screws are stocked separately and inexpensive.
Does the EP6C-20 generate particulate during installation?
No. Unlike a set-screw — which can shed a small metal chip when the cup-point first seats on a fresh shaft surface — the clamp engages without surface penetration. This is one of the reasons the EP6C-20 is the default specification for pharma and clean-process drive trains.
What is the angular install repeatability?
The clamp itself imposes no preferred angular index on the shaft — any angle within the hub-engaged length is permissible. For applications requiring repeatable angular index, the EP6C-20 can be combined with a shaft-mounted timing flag at the customer’s preferred angle.
Can I retrofit an EP6C-20 onto an existing EP6-20 install?
Yes. The two couplings share the same outside diameter, the same overall length, the same bore options, and the same slider geometry. Retrofit is a drop-in swap — the only line-item change is the wrench used for installation (2.5 mm hex for the clamp screw versus 2.0 mm for the set-screw).
Are USP Class VI materials available?
Yes — a USP Class VI compliant PEEK slider variant is offered specifically for pharma-grade and bio-process applications. Aluminum hubs do not contact the process stream so do not require USP-class certification, but supplementary RoHS, REACH, and biocompatibility documentation can be issued on request.
Quote EP6C-20 for Quick-Service Drive Lines
For pharma, cosmetic, and service-intensive equipment OEMs, the EP6C-20 is one of the most-specified clamp Oldham couplings on the market. Browse Ever-power’s complete coupling catalogue, learn more about our manufacturing capability, or proceed to quote enquiry below.
