Molybdenum and Tungsten Alloys for Plastic Injection Molding Applications

assembly parts tzm and tungsten_h.c.starck.pngWith the innovation of new alloys, H.C. Starck has surpassed market demands for higher performance products, especially in the plastic injection molding industry. H.C. Starck’s TZM alloy, composed of titanium (0.50 wt. %), zirconium (0.08 wt. %) and the balance in molybdenum, has mechanical and thermal properties that exceed pure molybdenum. The small alloying additions of titanium and zirconium form carbides that significantly increase the toughness, hardness and wear resistance of pure molybdenum while maintaining good thermal properties of high thermal conductivity and low thermal expansion. TZM alloy has high strength and elastic modulus at elevated temperatures along with good abrasion and corrosion resistance that make it useful for hot runner nozzle applications.

In some plastic injection molding applications, tungsten high density alloys are the preferred material. H.C. Starck’s tungsten high density alloys consist of molybdenum (4 wt. %), nickel (4 wt. %), iron (2 wt. %) and the balance in tungsten. Tungsten alloys exhibits high strength and elastic modulus at high temperatures along with high thermal conductivity and low thermal expansion along with the benefit of being easy to machine.

H.C. Starck’s Advancements in Alloy Development

With nearly 100 years of powder metallurgy expertise, H.C. Starck is constantly at the forefront of technological advancement, and innovative research and development of new products together with our industry partners.

H.C. Starck’s extensive in-house state-of-the-art laboratory facilities with the latest in analytical tools, testing equipment, modeling and simulation software, assist engineers in developing new products and materials along with the evaluation of product performance. Our advanced material modeling and simulation capabilities support the rapid development of new products and processes at H.C. Starck.

Fabricated Hot Runner Nozzle Parts from H.C. Starck Alloys

Injection molding nozzle parts fabricated from H.C. Starck’s alloys are utilized in hot runner nozzles. Recent advancements in hot runner systems make it easier to seamlessly inject molten plastic into a shaped mold. H.C. Starck alloy thermal properties insure that the molten plastic is heated uniformly during the hot runner nozzle transfer process. The gate between the hot runner nozzle and injection of the molten plastic into the mold is critical for reduction in color changes and a higher quality of molten plastic. Hot runner systems have seen a significant savings in reduced cycle time and decreased waste material.

H.C. Starck’s fabrication capabilities include machining of refractory alloys to match customer’s design and technical specifications.

Plastic injection molding applications employ hot runner nozzles in hot runner systems for a variety of applications such as automotive, electronics, industrial, medical, packaging, sports and recreation, where plastic components are required.

H.C. Starck’s TZM alloy is consolidated by two primary methods:

  •   Vacuum Arc Casting (VAC)
  •   Powder Metallurgy (PM)

Vacuum arc cast (VAC) materials have finer microstructural features that result in higher abrasion resistance, corrosion resistance, and increased strength. A major attribute of the vacuum arc cast (VAC) process is the superior results obtained when alloying metal powders. Complete melting and blending of molybdenum with alloyed powders takes place in a vacuum arc furnace to assure a homogeneous material is produced.

The availability of products from both powder metallurgy (PM) and vacuum arc cast (VAC) gives users many options in selecting a material to satisfy their specific application requirements. Mill products available from either process include forging billets, bar, rod, sheet, plate and foil.

Powder Metallurgy

Molybdenum TZM produced by powder metallurgy (PM) is manufactured by compacting > 99.95 % pure powder and alloying materials into billets that are sintered and subsequently worked into finished wrought forms. Only the highest commercially pure powders are used.

Vacuum Arc Cast

Products made by the vacuum arc cast (VAC) process are available exclusively from H.C. Starck. Arc cast mill products exhibit excellent workability, weldability and good machining characteristics with lower oxygen, greater ductility and fracture toughness relative to powder metallurgy.

In the vacuum arc melting process, 99.95 % minimum pure molybdenum powder with or without required additions is compacted, sintered, arc melted, and cast to produce an ingot weighing up to one ton. All these processes take place under vacuum.

H.C. Starck’s Capabilities with Tungsten High Density Alloy

From custom blending tungsten powders to near-net shaped blanks and precision machined finished components, H.C. Starck controls the whole process internally providing high quality products for critical mission applications.

H.C. Starck custom blends its tungsten powders to meet our customer’s requirements. We also have the ability to tailor material properties beyond what is required by ASTM. Having the flexibility to meet a customized specification is one of H.C. Starck’s many strengths.

Tungsten Alloy K1705 Material and Mechanical Properties

K1705 tungsten alloy materials provide a solution in a wide range of applications requiring concentrated weight or density in a limited space. These lead-free parts meet legal requirements and recommendations to protect the environment.

Mechanical Properties


K1705

Tungsten content

Density

%

g/cm³

90.0

17.3 ± 0.2

Hardness
HV30
≤ 360
Tensile strength
(typical value)
MPa
900
Yield strength
(typical value)
MPa
825
Elongation
(typical value)
%
8
Young`s modulus
(average value)
GPa
330
Median coefficient of linear
thermal expansion
20 - 100 °C


10-6/K


4.5
20 - 300 °C
10-6/K
5.1
20 - 450 °C
10-6/K
5.3
Thermal conductivity
W/mK
≥70
Electrical conductivity
(average value)
%IACS
MS/m
13
7.5
Specific electrical resistance
(average value)
µΩm
0.13
Permeability µ

> 1.05

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  • PDS number/_version
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