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Molybdenum Set Screws

Molybdenum set screws possesses a very high melting point of 2620°C, a low coefficient of thermal expansion and a high level of thermal conductivity. Because molybdenum set screws have the ability to withstand extremely high temperatures without changing shape, expanding or softening significantly, they are ideal for high strength / high temperature applications that are shielded from oxygen. Exposing molybdenum set screws to oxygen above 600°C will cause them to readily oxidize.

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Molybdenum set screws find their way into high temperature vacuum furnaces, glass production, military and space applications where oxygen is not present.

Extreme high temperature stability & strength
Maintains strength at elevated temperatures
Low distortion at high temperature
Molybdenum must be used in vacuum or inert gas at high temperatures

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RAYCHIN LIMITED

Name: Molybdenum Set Screws
SKU: 0

Molybdenum Set Screws · Grub Screws · Cup / Cone / Flat / Dog Point · Inch & Metric · Pure Mo / TZM / MoLa

Molybdenum Set Screws: Ultra-High Purity Refractory Metal Grub Screws for Extreme Temperature Environments

Pure Mo (≥99.95%) | TZM (Mo-Ti-Zr-C) | MoLa (Mo-La₂O₃) | ASTM B386 / B387 | ISO 4026-4029 / DIN 913-916

RAYCHIN LIMITED is a leading manufacturer of Molybdenum Set Screws – precision headless fasteners produced from refractory molybdenum and its alloys, delivering exceptional high-temperature strength, thermal stability, and corrosion resistance in extreme environments. With a melting point of 2623°C (4743°F) and the ability to withstand temperatures up to 1700°C in vacuum or reducing atmospheres, molybdenum set screws retain structural integrity where conventional materials fail. Set screws (grub screws) are fully threaded with a hex socket drive and various point styles to secure rotating components such as electrodes, heating elements, and collars onto shafts in high-temperature furnaces and vacuum systems. Our comprehensive product line includes molybdenum cup point set screws, cone point set screws, flat point set screws, and dog point set screws – all manufactured to the highest precision standards. Available grades include Pure Molybdenum (≥99.95%), TZM alloy (Mo-0.5Ti-0.08Zr-0.02C), and Molybdenum Lanthanum (MoLa) with enhanced recrystallization temperature. Our portfolio includes all standard and custom configurations manufactured to NAS, AN, MS, ANSI, ASTM, ASME, SAE, API, NACE, ISO, DIN and KS standards, including ASTM B386/B387, ISO 4026-4029, and DIN 913-916. Whether you require molybdenum set screws for high-temperature vacuum furnaces, semiconductor sputtering equipment, sapphire crystal growth systems, or aerospace propulsion components, RAYCHIN delivers precision, quality, and full traceability. All mechanical properties are presented in MPa and ksi (kilopound per square inch).

molybdenum set screwsmolybdenum grub screwsmolybdenum cup point set screwsmolybdenum cone point set screwsmolybdenum flat point set screwsmolybdenum dog point set screwspure molybdenum set screwsTZM set screwsMoLa set screwsASTM B387 set screwsrefractory metal set screwshigh temperature set screwsvacuum furnace set screwssemiconductor set screwsmolybdenum alloy set screwsISO 4026 molybdenumDIN 916 molybdenum

Molybdenum Set Screws – Point Styles & Configurations

Cup Point Set Screws

Molybdenum cup point set screws feature a cup-shaped indentation on one end. This is the most commonly used point style, designed for quick, semi-permanent or permanent applications where the sharp edge of the cup point can bite into the mating surface to provide maximum resistance to loosening under extreme thermal cycling. Ideal for securing heating elements and electrodes in high-temperature vacuum furnaces. Available in M2 to M36 and #0 to 1" sizes.

Cone Point Set Screws

Molybdenum cone point set screws have a sharp, conical point that delivers the strongest clamping force due to deep penetration into the mating shaft. They are typically used for permanent assembly applications where maximum holding power is required and shaft deformation is acceptable. Excellent for heavy-duty furnace assemblies and downhole tool retention in high-temperature environments. Conforms to ISO 4027 and DIN 914 standards.

Flat Point Set Screws

Molybdenum flat point set screws have a flat, smooth bearing surface. This economical style is used when components need to be frequently adjusted or repositioned, as they minimize shaft deformation and allow for repeated removal and reinstallation without damaging the mating surface. Ideal for instrument adjustments in semiconductor processing equipment and precision furnace instrumentation. Conforms to ISO 4026 and DIN 913 standards.

Dog Point Set Screws

Molybdenum dog point set screws feature a cylindrical projection (dog) that extends beyond the thread. The dog fits into a mating hole in the shaft, providing positive axial location and preventing movement under high shear loads and thermal expansion. Available in extended and half-dog point configurations. Used extensively in crystal growth furnaces, glass melting electrode assemblies, and turbine components where positive location is critical. Conforms to ISO 4028 and DIN 915 standards.

Drive Types & Socket Configurations

Molybdenum set screws are available with hex socket drive (Allen) as standard, providing positive torque transmission for high-strength applications. Precision-formed sockets ensure consistent engagement and minimize cam-out during installation in corrosive environments. Slotted drive options available for traditional applications. Custom drives (Torx, tamper-resistant) available upon request. All sockets precision machined to prevent galling.

Custom & Non-Standard Set Screws

Need special point geometries, non-standard lengths, proprietary drives, or unique thread forms? RAYCHIN engineers design and produce custom molybdenum set screws to your exact specifications – any grade (pure Mo, TZM, MoLa), any condition (stress relieved, recrystallized), with full material traceability. Minimum sizes down to M1.6 available. Prototype to production volumes supported. In-house metallurgical laboratory ensures optimal performance for your application.

Critical Applications of Molybdenum Set Screws

High-Temperature Vacuum Furnaces

Molybdenum set screws are essential in vacuum furnace construction, securing heating elements, thermocouple fittings, heat shields, and hearth assemblies. They maintain structural integrity at temperatures exceeding 1700°C (3090°F) in vacuum or inert gas environments where superalloys fail. Cup point set screws provide maximum grip on heating element rods, while dog point screws ensure positive location of refractory metal components under thermal cycling.

Semiconductor & Sputtering Equipment

Molybdenum set screws in semiconductor manufacturing equipment, including sputtering targets, PVD chambers, ion implanters, and wafer processing systems. Molybdenum's low coefficient of thermal expansion (5.1 x 10⁻⁶ /K), high thermal conductivity (142 W/m·K), and non-contaminating properties (no outgassing) make it ideal for ultra-high-vacuum (UHV) environments. Essential for securing electrodes, shields, and process kits. Cleanroom packaging available for contamination control.

Sapphire Crystal Growth & Glass Melting

Molybdenum set screws used in sapphire crystal growth furnaces (Kyropoulos, Czochralski) and glass melting electrodes. Molybdenum withstands molten glass corrosion and extreme temperatures required for LED sapphire substrate production. Set screws secure crucible assemblies, heat shields, and electrode holders in aggressive molten environments. Cone point screws provide deep penetration into refractory components for maximum holding power.

Aerospace & Defense

Molybdenum set screws in rocket engine components, nozzle assemblies, re-entry vehicle heat shields, and supersonic aircraft skin elements. Molybdenum alloys maintain strength at extreme temperatures where other metals would soften or melt. Used in thrust vector control systems and high-temperature structural joints. Locking set screws prevent loosening under extreme vibration during launch and re-entry.

Nuclear Engineering

Molybdenum set screws in nuclear reactors, particle accelerators, and experimental fusion devices. Molybdenum exhibits excellent resistance to radiation damage and retains mechanical properties under neutron irradiation. Used for fuel cladding supports, control rod mechanisms, and plasma-facing component fasteners. Flat point screws allow for adjustment without damaging critical components in high-radiation zones.

Medical & X-ray Equipment

Molybdenum set screws in X-ray tube assemblies, radiation shielding components, and medical isotope production equipment. Molybdenum's high atomic number and thermal properties make it suitable for X-ray targets and collimators. Set screws secure targets and cathodes under high-voltage, high-temperature operation. Cleanroom packaging available for medical device applications requiring strict contamination control.

International Standards & Global Designations – Molybdenum Set Screws

RAYCHIN LIMITED manufactures molybdenum set screws from vacuum arc melted (VAR) or powder metallurgy (PM) material conforming to the most widely used national and international specifications. All material is traceable to the mill.

Designation	Standard / Specification	Description
Pure Molybdenum	Mo ≥99.9% – ≥99.95%	Unalloyed molybdenum, highest purity available; excellent thermal conductivity, low vapor pressure; melting point 2623°C
ASTM B386 / B386M	Molybdenum and Molybdenum Alloy Plate, Sheet, Strip, Foil, and Ribbon	Covers grades 360 (vacuum arc melted pure Mo), 361 (powder metallurgy pure Mo), 363 (TZM-VAM), 364 (TZM-PM)
ASTM B387 / B387M	Molybdenum and Molybdenum Alloy Bar, Rod, and Wire	Primary material specification for molybdenum set screw stock; covers same grades as ASTM B386
TZM Alloy	Mo-0.5Ti-0.08Zr-0.02C	Molybdenum alloy with titanium, zirconium, carbon for enhanced strength and recrystallization temperature (~1400°C)
MoLa (Mo-La₂O₃)	Mo with 0.3-0.6% Lanthanum Oxide	Dispersion-strengthened molybdenum with improved ductility and high-temperature stability
ISO 4026:2003	Hexagon socket set screws with flat point	Dimensional standard for flat point set screws, M1.6 to M24
ISO 4027	Hexagon socket set screws with cone point	Dimensional standard for cone point set screws
ISO 4028	Hexagon socket set screws with dog point	Dimensional standard for dog point set screws
ISO 4029	Hexagon socket set screws with cup point	Dimensional standard for cup point set screws
DIN 913	Hexagon socket set screws with flat point	German standard, equivalent to ISO 4026
DIN 914	Hexagon socket set screws with cone point	German standard, equivalent to ISO 4027
DIN 915	Hexagon socket set screws with dog point	German standard, equivalent to ISO 4028
DIN 916	Hexagon socket set screws with cup point	German standard, equivalent to ISO 4029
ASME B18.3	Socket set screws (inch series)	Dimensional standards for inch-series set screws

ASTM B386 ASTM B387 Pure Mo 99.95% TZM MoLa ISO 4026 ISO 4029 DIN 913 DIN 916 ASME B18.3

Chemical Composition (Weight %) – Molybdenum Alloys for Set Screws

Our molybdenum set screws are produced from vacuum arc melted (VAR) or powder metallurgy (PM) material conforming to ASTM B386/B387 and industry standards.

Pure Molybdenum (Grade 360 / 361) – Mo ≥99.95%

Element	Min %	Max %	Typical
Molybdenum (Mo)	99.9	Balance	99.95
Iron (Fe)	—	0.010	0.004
Nickel (Ni)	—	0.005	0.002
Silicon (Si)	—	0.010	0.0013
Carbon (C)	—	0.030	0.0028
Oxygen (O)	—	0.0070	0.005
Nitrogen (N)	—	0.002	0.002
Aluminum (Al)	—	0.002	0.0005
Calcium (Ca)	—	0.002	<0.001
Magnesium (Mg)	—	0.002	<0.0005

TZM Alloy (Grade 363 / 364) – Mo-0.5Ti-0.08Zr-0.02C

Element	Min %	Max %	Typical
Molybdenum (Mo)	Balance	Balance	~99.0
Titanium (Ti)	0.40	0.55	0.50
Zirconium (Zr)	0.06	0.12	0.08
Carbon (C)	0.01	0.04	0.02
Iron (Fe)	—	0.010	0.005
Nickel (Ni)	—	0.005	0.002
Silicon (Si)	—	0.010	0.005
Oxygen (O)	—	0.0030	0.002
Nitrogen (N)	—	0.002	0.001

MoLa Alloy (Mo with Lanthanum Oxide)

Element	Min %	Max %	Typical
Molybdenum (Mo)	Balance	Balance	~99.5
Lanthanum Oxide (La₂O₃)	0.3	0.6	0.4
Other impurities	—	0.10	<0.05

Metallurgical note: Molybdenum is a refractory metal with a body-centered cubic (BCC) crystal structure. Pure molybdenum set screws are typically supplied in stress-relieved condition (recrystallization temperature ~1100°C). TZM alloy offers significantly higher recrystallization temperature (~1400°C) and improved creep strength through carbide dispersion strengthening. MoLa (lanthanated molybdenum) maintains ductility after high-temperature exposure due to oxide dispersion pinning grain boundaries. All molybdenum set screws should be handled with care due to limited ductility at room temperature, becoming more ductile above ductile-to-brittle transition temperature (DBTT). Minimum available size is M1.6.

Complete Mechanical & Physical Properties – Molybdenum Set Screws (MPa / ksi)

Molybdenum set screws are supplied in various conditions (hard/stress relieved, soft/annealed) per ASTM B387. Data represent typical values based on industry standards and are compared with tungsten alloys for reference.

Mechanical Properties – Pure Molybdenum vs. Tungsten Alloy

Property	Pure Molybdenum	Tungsten Alloy (W-Ni-Fe)	Notes
Tensile Strength (MPa)	515-690	1100-1500	Tungsten alloys have higher strength
Yield Strength 0.2% (MPa)	380-620	—	Mo suitable for dynamic loads
Hardness (HRC)	25-35	25-35	Comparable hardness
Elongation (%)	10-20	5-10	Mo more ductile
Fatigue Resistance	Good	—	Mo reduces fracture risk under dynamic loads

Mechanical Properties – TZM Alloy Set Screws

Condition	Tensile Strength (MPa)	Tensile Strength (ksi)	Yield Strength 0.2% (MPa)	Yield Strength 0.2% (ksi)	Elongation (%)	Hardness
Stress Relieved	860-1035	125-150	690-860	100-125	8-15	300 HV
Recrystallized	620-760	90-110	550-620	80-90	15-25	230 HV

Physical Properties – Pure Molybdenum vs. Tungsten

Property	Pure Molybdenum	Tungsten	Notes
Density (g/cm³)	10.2	19.3	Molybdenum lighter, better processability
Melting Point (°C)	2623	3422	Tungsten higher, Mo sufficient for most applications
Thermal Conductivity (W/m·K)	138	174	Both excellent, Mo aids rapid heat dissipation
Elastic Modulus (GPa)	324-329	411	Very high stiffness
Thermal Expansion (x10⁻⁶ /K)	5.1	4.5	Very low CTE

High‑Temperature Performance of Molybdenum Set Screws

Molybdenum and its alloys are renowned for exceptional high-temperature strength and stability. Pure molybdenum maintains useful mechanical properties up to 1700°C (3090°F) in vacuum or reducing atmospheres, with TZM extending capability further through carbide strengthening. Molybdenum has a melting point of 2623°C (4743°F), making it ideal for the highest temperature environments. However, molybdenum oxidizes rapidly above 600°C in air, forming volatile MoO₃, limiting use to vacuum, inert gas, or reducing atmospheres unless protected by coatings. In semiconductor manufacturing equipment, molybdenum set screws are designed to withstand interior temperatures of 500-1000°C in ion generators, light sources, and processing chambers.

Elevated Temperature Capabilities

Property	Pure Molybdenum	TZM Alloy	MoLa Alloy
Melting Point (°C)	2623	~2600	2623
Max Service Temp (vacuum/inert)	1700°C (3090°F)	1400-1500°C (2550-2730°F)	1700°C (3090°F)
Recrystallization Temp	1100-1200°C (2010-2190°F)	1400°C (2550°F)	1300-1500°C
Thermal Conductivity (W/m·K)	138	126	138
Oxidation Onset in Air	600°C (1110°F) – sublimation begins in oxidizing atmosphere

Molybdenum set screws support use with vacuum equipment in high-temperature environments. In oxidizing atmospheres above 600°C, sublimation will occur; use is therefore recommended only in vacuum, inert gas, or reducing atmospheres. For air applications, protective coatings (MoSi₂, Al₂O₃, Y₂O₃) may be applied.

Corrosion Resistance of Molybdenum Set Screws

Molybdenum exhibits excellent resistance to many corrosive media, particularly in reducing environments and in the absence of oxidizing agents. Compared to tungsten alloys, molybdenum has slightly stronger corrosion resistance in certain chemical environments, especially in reducing atmospheres. However, rapid oxidation occurs in air above 600°C.

Oxidation Resistance: Forms volatile MoO₃ above 600°C in air; requires protective atmosphere or coating for high-temperature air service.
Reducing Atmospheres: Excellent stability in hydrogen and other reducing environments, even at high temperatures.
Acid Resistance: Good resistance to hydrochloric acid (HCl) at moderate temperatures. High solubility in concentrated sulphuric acid and nitric acid.
Liquid Metals: Excellent resistance to liquid lithium, sodium, potassium, and bismuth, making it valuable in nuclear coolant systems.
Hydrogen: Excellent resistance to hydrogen attack even at high temperatures (unlike steel).
Glass Corrosion: Outstanding resistance to molten glass, widely used in glass melting electrodes and stirrers.
Comparison with Tungsten: Tungsten alloys require surface coatings for enhanced corrosion resistance in strong acids or salt fog; molybdenum alloys have slightly stronger corrosion resistance in certain chemical environments, particularly in reducing atmospheres.

Manufacturing Standards – Molybdenum Set Screws

All molybdenum set screws are manufactured and tested to meet the following standards:

ASTM B386ASTM B387ISO 4026ISO 4027ISO 4028ISO 4029DIN 913DIN 914DIN 915DIN 916ASME B18.3EN 10204 3.1/3.2

We offer surface finishes: black (as-machined), chemical cleaned, ground, polished, and passivated. Special coatings (MoSi₂, Al₂O₃, Y₂O₃) available for oxidation protection. Cleanroom wash and cleanroom packaging available for semiconductor, medical, and aerospace applications – batch cleanroom packing provided for orders containing multiple items of the same size. Full traceability and destructive/non‑destructive testing available (UT, PMI, MPI). ISO 9001, AS9100D, ISO 13485 certified.

Why RAYCHIN LIMITED – The Molybdenum Set Screw Authority

Refractory metal expertise: Decades of experience with molybdenum, TZM, and MoLa alloys. We ensure precise processing: stress relieving, recrystallization annealing, and surface finishing per ASTM B386/B387 standards. In‑house PMI verifies chemistry of every heat. Our molybdenum set screws achieve full traceability and certified properties. Familiarity with molybdenum's machining characteristics ensures proper thread formation without chipping or tearing.

Global certifications: ISO 9001, AS9100D, ISO 13485 (medical), PED, API Q1, NADCAP accredited processes. All set screws supplied with EN 10204 3.1/3.2 certifications, material test reports, and NACE compliance when required. Cleanroom packaging certified for semiconductor and medical applications.

Precision point forming & thread rolling: CNC machining and precision thread rolling ensure accurate point geometry and thread form per ASME, ISO, and DIN standards. Class 2A/3A/6g thread fit. 100% inspection available. Special tooling for molybdenum's unique machining characteristics (brittle behavior at room temperature). Minimum size down to M1.6 available.

Custom solutions: Special point geometries, proprietary drives (Torx, tamper-resistant), non‑standard lengths, and tailored packaging. In-house metallurgical laboratory and failure analysis capabilities. Prototype to production volumes supported. Cleanroom wash and packaging available for sensitive applications.

Contact the molybdenum set screw experts

Request a quotation for molybdenum set screws, grub screws – any point style (cup, cone, flat, dog) – any standard (ASME B18.3, ISO 4026-4029, DIN 913-916) – any grade (Pure Mo, TZM, MoLa) – any condition (stress relieved, recrystallized), any quantity. Global delivery. Mechanical data in MPa/ksi available for all products.

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