Set Screw Holes: surface_finish Ra 3.2 μm or better

Component Specifications

Definition

Set screw holes are precisely engineered cylindrical or threaded cavities machined into hub components, typically positioned radially or axially to accept set screws. These holes serve as anchoring points where set screws exert clamping force against shafts, gears, or other mating components to prevent relative motion, transmit torque, and maintain precise alignment in mechanical assemblies. The holes are characterized by specific thread specifications, depth, diameter, and positional accuracy relative to the hub's centerline.

Working Principle

Set screw holes function by providing a threaded interface where set screws can be tightened to create radial pressure against a shaft or component. The screw's tip (flat, cup, cone, or knurled) engages with the mating surface, generating friction and mechanical interference that prevents rotational slippage and axial movement. The hole's thread geometry converts rotational torque from the screwdriver into linear clamping force, while the hole's depth and diameter ensure proper screw engagement without compromising hub structural integrity.

Materials

Typically machined into the same material as the hub: carbon steel (AISI 1018, 1045), alloy steel (4140, 4340), stainless steel (304, 316), aluminum (6061-T6, 7075), or ductile iron. Threads may be cut, rolled, or tapped with material hardness considerations to prevent stripping.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Tolerance	H7 for hole diameter, ±0.1mm positional
Hole Depth	1.5D to 2.5D (where D is screw diameter)
Countersink	82° or 90° for flat head screws when specified
Thread Size	M3 to M12 metric, #4-40 to 1/2-13 UNC/UNF imperial
Thread Type	ISO metric coarse/fine, UNC, UNF, BSW
Thread Class	6H for internal threads
Surface Finish	Ra 3.2 μm or better

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 4762, ISO 4026, DIN 913, DIN 914, ASME B18.3

Parent Products

This component is used in the following industrial products

Hub

The central mounting component of a mixing impeller that connects the blades to the drive shaft.

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Mounting Hub

A mechanical component that serves as the central mounting point for a drive shaft assembly, providing secure attachment and alignment.

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Engineering Analysis

Risks & Mitigation

Thread stripping under excessive torque
Stress concentration around hole edges
Corrosion in threaded areas
Improper alignment causing uneven clamping
Fatigue failure from cyclic loading

FMEA Triads

Trigger: Insufficient thread engagement depth
Failure: Screw loosening under vibration or load
Mitigation: Design holes with minimum 1.5D engagement; use thread locking compounds; specify proper tightening torque

Trigger: Poor hole alignment with mating component
Failure: Eccentric loading and premature wear
Mitigation: Implement precise machining tolerances (±0.05mm); use jigs/fixtures; verify alignment during assembly

Trigger: Material incompatibility between screw and hub
Failure: Galvanic corrosion or thread galling
Mitigation: Select compatible materials; use anti-seize compounds; specify protective coatings

Industrial Ecosystem

Compatible With

Shafts, gears, pulleys, couplings, sprockets, rotors

Typical Suppliers & Equivalents

SKF, Timken, NTN, Dodge, Browning, Lovejoy

Compliance & Inspection

Tolerance

Positional tolerance ±0.1mm, thread pitch diameter tolerance per ISO 965-1 6H class

Test Method

Go/no-go thread gauging, coordinate measuring machine (CMM) verification, torque-to-failure testing, vibration testing per ISO 16047

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

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CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Set Screw Holes

Manufacturer profiles associated with Set Screw Holes.

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Frequently Asked Questions

What is the primary function of set screw holes in hubs?

To provide secure threaded anchoring points for set screws that prevent relative rotation and axial movement between the hub and mating components like shafts or gears.

How deep should a set screw hole be machined?

Typically 1.5 to 2.5 times the screw diameter to ensure sufficient thread engagement without weakening the hub wall, with exact depth depending on material and load requirements.

Can set screw holes be added to existing hubs?

Yes, through drilling and tapping operations, but careful consideration must be given to wall thickness, existing stress concentrations, and alignment with mating components.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Set Screw Holes