Home » DIN 913 / ISO 4026 Socket Set Screw Flat Point — Alloy Steel 45H Black

DIN 913 / ISO 4026 Socket Set Screw Flat Point — Alloy Steel 45H Black

DIN 913 / ISO 4026 — Socket Set Screw with Flat Point | Alloy Steel 45H | Grade 12.9 | Black Oxide

FULLERKREG DIN 913 / ISO 4026 socket set screws (grub screws) with flat point are manufactured to full DIN and ISO dimensional standards in alloy steel ML40Cr, heat-treated to 45H property class (equivalent to Grade 12.9), with a black oxide surface finish. These high-strength set screws deliver maximum clamping force and torsional resistance for demanding industrial, automotive, and tooling applications where performance and reliability are critical.

Product Specifications

Parameter Detail
Standard DIN 913 / ISO 4026
Type Socket Set Screw (Grub Screw) — Flat Point
Drive Hexagon Socket (Hex Allen Key)
Material Alloy Steel ML40Cr (Chromium-Molybdenum Alloy Steel)
Property Class 45H (Grade 12.9 equivalent per DIN 267-11 / ISO 898-1)
Surface Treatment Black Oxide (Blackening)
Thread Metric Coarse Thread (ISO 68-1)
Thread Tolerance 6H (internal) / 6g (external) per ISO 965
Tensile Strength Min. 1220 MPa
Hardness 39–51 HRC
Size Range M1.6 — M24
Length Range 2 mm — 60 mm (size-dependent)
Point Type Flat Point
Head Type Fully Threaded, Headless (Grub)
RoHS Compliant Yes

Key Dimensions (DIN 913 / ISO 4026)

Thread (d) Hex Key Size (s) Min. Thread Engagement Flat Point Dia. (dp) approx. Common Lengths
M1.6 0.7 mm 0.8 mm 0.80 mm 2, 3, 4, 5 mm
M2 0.9 mm 1.0 mm 1.00 mm 2, 3, 4, 5, 6 mm
M2.5 1.3 mm 1.25 mm 1.50 mm 3, 4, 5, 6, 8 mm
M3 1.5 mm 1.5 mm 2.00 mm 3, 4, 5, 6, 8, 10 mm
M4 2.0 mm 2.0 mm 2.50 mm 4, 5, 6, 8, 10, 12 mm
M5 2.5 mm 2.5 mm 3.50 mm 5, 6, 8, 10, 12, 16 mm
M6 3.0 mm 3.0 mm 4.00 mm 6, 8, 10, 12, 16, 20 mm
M8 4.0 mm 4.0 mm 5.50 mm 8, 10, 12, 16, 20, 25 mm
M10 5.0 mm 5.0 mm 7.00 mm 10, 12, 16, 20, 25, 30 mm
M12 6.0 mm 6.0 mm 8.50 mm 12, 16, 20, 25, 30, 40 mm
M16 8.0 mm 8.0 mm 12.00 mm 16, 20, 25, 30, 40, 50 mm
M20 10.0 mm 10.0 mm 15.00 mm 20, 25, 30, 40, 50, 60 mm
M24 12.0 mm 12.0 mm 18.00 mm 25, 30, 40, 50, 60 mm

All dimensions per DIN 913 / ISO 4026. Consult FULLERKREG datasheet or contact us for full tolerance tables.

Material — Alloy Steel ML40Cr

ML40Cr is a chromium-alloyed medium-carbon steel specifically selected for high-strength fastener production. Its composition and heat treatment characteristics make it the standard material for 45H / Grade 12.9 set screws.

Chemical Composition (ML40Cr)

Element Content (%)
Carbon (C) 0.37 – 0.44
Silicon (Si) 0.17 – 0.37
Manganese (Mn) 0.50 – 0.80
Chromium (Cr) 0.80 – 1.10
Phosphorus (P) ≤ 0.025
Sulfur (S) ≤ 0.025

Mechanical Properties — 45H Property Class (Grade 12.9 Equivalent)

Property Value Standard
Tensile Strength (Rm) Min. 1220 MPa DIN 267-11 / ISO 898-1
Proof Load Stress (Sp) Min. 1100 MPa DIN 267-11
Hardness 39 – 51 HRC (385 – 530 HV) DIN 267-11
Minimum Breaking Torque Per DIN 267-11 size table DIN 267-11
Heat Treatment Quenched & Tempered —

45H vs. Standard Property Classes

Property Class Material Tensile Strength Hardness Typical Use
14H Carbon steel Min. 700 MPa 22–32 HRC General purpose
22H Carbon / alloy steel Min. 900 MPa 32–39 HRC Medium duty
45H Alloy steel ML40Cr Min. 1220 MPa 39–51 HRC High-strength, heavy duty

45H is the highest standard property class for set screws per DIN 267-11, equivalent to Grade 12.9 in the ISO 898-1 bolt property class system.

Surface Finish — Black Oxide

  • Process: Hot alkaline blackening — a chemical conversion coating that forms a thin magnetite (Fe₃O₄) layer on the steel surface
  • Appearance: Uniform matte black finish with a professional, low-reflectance appearance
  • Coating Thickness: Typically 1–2 microns — no significant dimensional change, preserving thread tolerances
  • Corrosion Resistance: Moderate — provides basic protection against light oxidation; supplemental oil or wax treatment recommended for enhanced protection in humid environments
  • No Hydrogen Embrittlement Risk: Unlike electroplating, black oxide does not introduce hydrogen into the steel — critical for high-strength Grade 12.9 fasteners where hydrogen embrittlement is a serious concern
  • Adhesion: Excellent base for supplemental lubricants and thread-locking compounds
  • Temperature Resistance: Stable up to approximately 300°C

Flat Point — Design & Function

The flat point is the most versatile set screw tip geometry. Combined with the high clamping force of Grade 12.9 / 45H, it delivers exceptional holding performance:

  • Non-marring clamping — distributes force over a broad flat area; does not indent or damage polished or hardened shafts
  • Frequent adjustment — can be loosened and repositioned without leaving permanent marks
  • High clamping force — the 45H grade allows significantly higher tightening torques than standard grades, maximizing friction-based holding power
  • Hardened shafts — flat point is the correct choice when the mating shaft is hardened steel
  • Thin-walled components — lower risk of deformation compared to cup or cone points

Flat Point vs. Other Set Screw Point Types

Point Type Standard Best For Shaft Marking
Flat Point DIN 913 / ISO 4026 Non-marring, frequent adjustment, hardened shafts None / Minimal
Cup Point DIN 916 / ISO 4029 Permanent locking, soft shafts, high torque Circular indent
Cone Point DIN 914 / ISO 4027 Permanent location, V-groove shafts Deep indent
Dog Point DIN 915 / ISO 4028 Precise location, keyway-free shafts None (pin engagement)
Oval Point ISO 4026 variant Curved surfaces, pivot points Minimal

Typical Applications

The combination of 45H / Grade 12.9 alloy steel and flat point geometry makes these set screws the preferred choice for high-load, precision-critical applications:

  • Machine Tool & Tooling: Securing cutting tool holders, collets, boring bars, and milling arbors where maximum clamping force is essential
  • Automotive & Motorsport: Drivetrain components, gear assemblies, camshaft collars, and high-performance engine parts subject to vibration and high torque
  • Industrial Machinery: Securing pulleys, sprockets, gears, cams, and shaft collars in heavy-duty power transmission systems
  • Robotics & Automation: Precision positioning of servo motor shafts, encoder wheels, and actuator components requiring repeatable, high-force clamping
  • Hydraulic & Pneumatic Equipment: Locking adjustment screws and valve components under high operating pressures
  • Aerospace & Defense (non-flight critical): Ground support equipment and test fixtures requiring high-strength fasteners
  • Press & Die Tooling: Securing die components, guide pins, and adjustable stops in stamping and forming tools
  • General Heavy Industry: Any application where standard-grade set screws have proven insufficient under load or vibration

Installation Guidelines

  • Thread engagement: Minimum engagement length = 1× nominal diameter (e.g., M8 requires min. 8 mm engagement); for maximum holding power, 1.5× diameter is recommended
  • Tightening torque: Use a calibrated torque wrench; 45H / Grade 12.9 allows significantly higher torques than standard grades — refer to the torque table below
  • Lubrication: Apply molybdenum disulfide (MoS₂) paste or equivalent anti-galling compound to threads; reduces friction coefficient and ensures accurate torque-to-clamp-force conversion
  • Hex key: Use a high-quality, calibrated hex key (Allen key) of the correct size — see dimension table above; worn or undersized keys risk rounding the socket at high torques
  • Shaft flat: For maximum holding power, machine a flat on the shaft at the set screw contact point; this converts friction-based holding to positive mechanical engagement
  • Locking: For high-vibration applications, use medium-strength thread-locking adhesive in addition to correct torque; do not rely on torque alone in severe vibration environments
  • Hydrogen embrittlement: Black oxide finish does not introduce hydrogen — safe for Grade 12.9 / 45H. Never use electroplated fasteners at this strength level without baking treatment
  • Do not substitute lower grades: If a 45H / Grade 12.9 set screw is specified, do not substitute with lower property classes — the application load calculations are based on the specified grade

Recommended Tightening Torques (45H / Grade 12.9, MoS₂ Lubricated)

Thread Torque (N·m) — Reference
M2 0.12 N·m
M2.5 0.25 N·m
M3 0.45 N·m
M4 1.05 N·m
M5 2.10 N·m
M6 3.60 N·m
M8 8.80 N·m
M10 17.5 N·m
M12 30.0 N·m
M16 75.0 N·m
M20 145.0 N·m

Reference values for MoS₂-lubricated 45H / Grade 12.9 alloy steel set screws. For dry installation, increase values by approximately 25–30%. Always verify with your engineering team for safety-critical applications.

Standards & Compliance

  • DIN 913 — Socket set screws with hexagon socket and flat point
  • ISO 4026 — Hexagon socket set screws with flat point
  • DIN 267-11 — Technical delivery conditions for fasteners — set screws; defines 45H property class (tensile strength, hardness, breaking torque)
  • ISO 898-1 — Mechanical properties of fasteners made of carbon steel and alloy steel; Grade 12.9 reference
  • ISO 965-1 — Metric screw thread tolerances
  • RoHS 2011/65/EU — Restriction of hazardous substances compliant

Packaging & Ordering

  • Available in standard retail packs, engineering bulk packs, and full-box quantities
  • Custom quantity packaging available for OEM, toolroom, and wholesale customers
  • Each pack labeled with: Part number, Thread size × Length, Material (ML40Cr), Property Class (45H), Standard (DIN 913 / ISO 4026), Surface (Black Oxide), Quantity
  • Bulk orders: contact FULLERKREG for volume pricing and lead times

Quality Assurance

  • 100% dimensional inspection on critical sizes per DIN 913 / ISO 4026
  • Hardness testing per DIN 267-11 (39–51 HRC) on every production batch
  • Breaking torque testing per DIN 267-11 size requirements
  • Material certification available on request — confirms ML40Cr alloy steel composition
  • Thread gauge inspection (Go/No-Go) per ISO 965
  • Heat treatment records (quench & temper parameters) maintained for full traceability
  • Black oxide coating uniformity inspection on each batch

Frequently Asked Questions

Q: What does 45H mean for set screws?
A: 45H is the property class designation for set screws defined in DIN 267-11. It specifies a minimum tensile strength of 1220 MPa and a hardness range of 39–51 HRC. It is the highest standard property class for set screws and is equivalent to Grade 12.9 in the ISO 898-1 bolt classification system.

Q: What is the difference between DIN 913 and ISO 4026?
A: DIN 913 and ISO 4026 are technically equivalent standards for socket set screws with flat point. DIN 913 is the German standard; ISO 4026 is the international equivalent. Dimensions and tolerances are identical — parts are fully interchangeable.

Q: Why is black oxide used instead of zinc plating for Grade 12.9 set screws?
A: Electroplating processes (including zinc plating) introduce hydrogen into high-strength steel, creating a risk of hydrogen embrittlement — a form of delayed brittle fracture that can cause catastrophic failure without warning. Black oxide is a chemical conversion coating that does not introduce hydrogen, making it the safe and standard surface treatment for Grade 12.9 / 45H fasteners. This is specified in ISO 4042 and DIN 267-11.

Q: Can I use these set screws in corrosive environments?
A: Black oxide provides only basic corrosion protection. For mildly corrosive environments, apply a supplemental oil or wax coating after installation. For environments with significant moisture, chemicals, or salt exposure, consider using stainless steel set screws instead. Contact FULLERKREG for guidance.

Q: What hex key (Allen key) size do I need?
A: Refer to the dimension table above. Examples: M3 requires a 1.5 mm hex key; M6 requires a 3.0 mm hex key; M10 requires a 5.0 mm hex key. For Grade 12.9 torques, always use a high-quality hex key to avoid rounding the socket.

Q: How do I maximize holding power with a flat point set screw?
A: Machine a flat on the shaft at the set screw contact point. This converts the holding mechanism from pure friction to a combination of friction and positive mechanical engagement, significantly increasing resistance to both axial and rotational movement. Apply the correct tightening torque using a calibrated torque wrench.

Q: Are these RoHS compliant?
A: Yes. FULLERKREG 45H alloy steel set screws with black oxide finish are manufactured without restricted hazardous substances and are RoHS 2011/65/EU compliant.

Q: Can I get a material test certificate (MTC)?
A: Yes. FULLERKREG provides Mill Test Certificates on request, confirming the ML40Cr alloy steel chemical composition and heat treatment property class (45H).

FULLERKREG — Precision Fasteners to DIN / ISO Standards. For technical support, custom sizes, or bulk quotations, please contact our engineering team.

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