GBC-SCS20 Aluminum Clamp Type Shaft Collar – 20mm Bore
The GBC-SCS20 aluminum clamp-type shaft collar is the workhorse of the SCS series, fitting 20 mm bore shafts on IEC 90-frame motors, SFU2005 ball screws, and 20 mm linear gantry rails. OD 40 mm, face width 12 mm, M5 screw, optional 6 mm keyway. Stainless steel variant available on request.
MOQ: 50 pcs. Minimum order value USD 1,500; mixed orders and trial quantities welcome.
20mm Bore Aluminum Clamp Shaft Collar – Motor Output & Linear Guide End-Stop Gold Standard
| Parameter | Value | Note |
|---|---|---|
| SKU / Model | GBC-SCS20 | GBC SCS Series |
| Bore Diameter (d) | 20 mm | Shaft tolerance h6 recommended |
| Outer Diameter (D) | 40 mm | |
| Face Width (B) | 12 mm | |
| Clamping Screw | M5 socket-head cap screw | 5 mm hex key required |
| Slot Width (W) | 1.5 mm | Enables radial flex for clamping |
| Keyway Width (K) | 6 mm | Standard: plain bore; keyway optional on request |
| Shaft Tolerance | 20.000 / 19.987 mm | ISO 286 h6 |
| Material | Aluminium alloy | Anodized finish available on request |
| MOQ | 100 pcs | Custom engineering drawings accepted |
Product Overview
If one bore size could be called the workhorse of the entire SCS series, it is 20 mm. The GBC-SCS20 covers the output shaft diameter of the overwhelming majority of IEC 90-frame and NEMA 34-frame motors, the journal size of widely available SFU2005 ball screws, and the guide-shaft diameter of the most common 20 mm precision linear rails used in gantry, portal, and Cartesian robot structures. The 40 mm OD and 12 mm face width deliver the radial stiffness and clamping area needed for the diverse load profiles across these applications, while the M5 clamping screw — now approaching its upper practical load range — provides installation simplicity without requiring a torque multiplier or powered tooling in production assembly. The 6 mm keyway option is consistent with DIN 6885 keys for 20 mm shafts and covers sprocket, pulley, and cam-disc mounting requirements across virtually all major standards.
Key Features
Shaft Surface Protection
The split-clamp principle spreads clamping force uniformly across the full bore circumference, preventing the point indentation and fretting corrosion that set-screw collars create at the contact point. The shaft remains undamaged and fully repositionable throughout the product's service life.
M5 High-Torque Clamping
The M5 socket-head cap screw provides a proof-load capacity approximately 60% higher than the M4 screws used in smaller SCS collars. This increase in clamping force is matched to the larger bore and OD at this size range, ensuring reliable retention under sustained bidirectional axial loading.
Dual Axial-Location Function
A single collar acts as a positive end-stop against a bearing or housing shoulder. A pair of collars sandwiches any shaft-mounted component at a freely adjustable position — a versatile alternative to machined shaft steps that eliminates re-machining costs when axial positions need to change.
Lightweight Aluminium Alloy Body
Aluminium alloy construction keeps collar mass below 30 g for all bore sizes in the 20 mm OD range, minimising the rotational inertia penalty in dynamic drive assemblies and the static load penalty on vertically mounted shafts.
6 mm Keyway Option for Torque Locking
A standard 6 mm DIN 6885 keyway can be broached on request, enabling the collar to transmit rotational torque simultaneously with axial positioning. Specify at order — default supply is plain bore.
Typical Application Scenarios
Electric Motor Output Shaft End-Stops
IEC 90-frame and NEMA 34-frame motors with 20 mm output shafts are the backbone of conveyor drives, pump drives, and fan drives across countless industrial sectors. The SCS20 provides a positive mechanical stop against the motor end-shield that retains the driven sprocket or coupling half under axial loads generated by chain tension, belt pull, or thrust-coupling misalignment forces.
SFU2005 Ball Screw Fixed-End Supports
The 20 mm journal of SFU2005 ball screws is supported at the fixed end by angular-contact bearing pairs in BK20 bearing blocks. The SCS20 applies the required axial pre-load to the outer ring by collar position, complementing the lock nut on the threaded screw end and providing a redundant anti-rotation function via the keyway option.
Precision Linear Gantry Structures
Portal and gantry machines for laser cutting, plasma cutting, and waterjet applications mount 20 mm guide shafts in pillow blocks. The SCS20 defines shaft end positions within these pillow-block assemblies, prevents longitudinal shaft migration under the thermal expansion cycles that occur during long cutting sequences, and acts as a failsafe end-of-travel stop for driven carriages.
Dimensional Guide & Shaft Fit Specification
The three principal dimensions — bore d = 20 mm, outer diameter D = 40 mm, and face width B = 12 mm — define the spatial envelope of the collar in an assembly. The slot width W = 1.5 mm runs the full face width and is the feature that allows the collar to flex radially as the M5 screw closes the gap. Specify the mating shaft to ISO 286 h6 tolerance (20.000 / 19.987 mm) for the optimal combination of sliding fit before clamping and maximum retention force after clamping.
GBC accepts custom orders for alternative bore tolerances (H7, js6), reduced OD profiles to clear adjacent components, extended face widths for higher axial holding force, and surface treatments including natural anodize, hard anodize (25 µm), and electroless nickel plating. Submit your engineering drawing via the contact page for a fast quotation.
Model Selection Guide
For 18 mm shafts in textile and fan applications, the GBC-SCS18 at 40 mm OD is directly comparable. If your shaft is 22 mm, the GBC-SCS22 steps up to a 45 mm OD while maintaining the 12 mm face width, and is the preferred choice for heavier gearbox and machine-tool auxiliary shafts.
| Model | Bore | Relation |
|---|---|---|
| GBC-SCS18 | 18mm | ← Smaller |
| GBC-SCS20 | 20 mm | ◀ Current |
| GBC-SCS22 | 22mm | → Larger |
Installation Procedure
- Prepare the shaft: Clean and degrease the shaft in the clamping zone. Verify diameter within h6 tolerance (20.000 / 19.987 mm). Remove any burrs or nicks with a fine file.
- Slide and position: Slide the GBC-SCS20 onto the shaft to the required axial location. Use a calibrated depth gauge or a pre-machined spacer as a reference for repeatable positioning.
- Clamp progressively: Using a 5 mm hex key, tighten the M5 screw in two or three incremental steps, checking axial position after each step to correct any settling. Torque M5 screw to 4.5 N·m using a full-length 4 mm hex key. For motor-shaft applications, verify the shaft key and keyway engage without side play before tightening the collar — a rocking key indicates keyway oversize and will reduce transmitted torque capacity.
- Load test: Apply the expected axial service load (manually or via the driven machine) and confirm zero collar movement. For vibrating or cyclic-load applications, re-verify screw torque after the first full operating shift.
Frequently Asked Questions
Is there a stainless steel version of the SCS20 available?
How many SCS20 collars are needed to fully support a 20mm shaft in a pillow block assembly?
What is the correct hex key size for the SCS20 clamping screw?
Related Products
Explore adjacent sizes and related components in the GBC range:
- GBC-SCS18 – 18mm bore aluminum clamp shaft collar — smaller bore for finer shaft diameters
- GBC-SCS22 – 22mm bore aluminum clamp shaft collar — next size up for higher axial capacity
- Browse the full GBC SCS Shaft Collar series — available bore sizes from 6 mm to 60 mm
Get a Quote or Submit Your Drawing
Minimum order quantity is 100 pcs. Custom bore tolerances, keyway options, extended face widths, and surface treatments are available. Supply your detailed engineering drawing for an accurate quotation from the GBC team.
The GBC-SCS20 aluminum clamp-type shaft collar is the workhorse of the SCS series, fitting 20 mm bore shafts on IEC 90-frame motors, SFU2005 ball screws, and 20 mm linear gantry rails. OD 40 mm, face width 12 mm, M5 screw, optional 6 mm keyway. Stainless steel variant available on request.
MOQ: 50 pcs. Minimum order value USD 1,500; mixed orders and trial quantities welcome.
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