Precision Tungsten Alloy Component Manufacturing Process
Release time:
2025-11-18
1. Introduction
Tungsten alloys, primarily composed of tungsten (typically 85%–99% by weight) with additions of nickel, iron, copper, cobalt, molybdenum, and chromium, play an indispensable role in high-tech sectors such as nuclear, military, and medical industries due to their exceptional properties. These include extremely high density (16.5–19.0 g/cm³), high melting point, and outstanding mechanical strength, tungsten alloys play an indispensable role in multiple high-tech fields such as nuclear industry, military applications, and medical technology [1]. In the medical field, tungsten alloys are used to manufacture critical components for radiotherapy equipment. Their high density enables precise blocking and shaping of radiation beams, making them the primary material for collimators and radiation shielding [2]. These exceptional properties also present significant challenges in the processing and manufacturing of tungsten alloys. This paper aims to systematically and thoroughly explore the blank preparation processes and common machining methods for tungsten alloy parts, providing valuable references for their precision manufacturing.
2 Preparation Processes for Tungsten Alloy Part Blanks
2.1 Powder Metallurgy Technology
Due to their high density, melting point, and hardness, tungsten alloys cannot be manufactured using conventional alloy smelting processes. Powder metallurgy, a traditional and widely applied method for preparing tungsten alloy blanks, involves key processes as shown in Figure 1: tungsten powder preparation, mixing, forming, and sintering [3]. During tungsten powder preparation, techniques such as hydrogen reduction and ammonium paratungstate reduction are commonly employed to ensure powder purity. Simultaneously, the oxygen content, particle size, and shape of tungsten powder significantly impact the final properties and quality of the alloy, necessitating strict control. Excessive oxygen content degrades alloy performance, while particle size and shape affect the effectiveness of subsequent mixing and forming processes. For instance, uniformly sized tungsten powder facilitates more even mixing with other metal powders during blending, ensuring consistent alloy composition. During mixing, precise blending is achieved through mechanical stirring or ball milling to ensure uniform particle size and accurate proportions of all metal powders. Forming methods include cold isostatic pressing, die pressing, powder extrusion, and powder injection molding, enabling the production of complex-shaped components.
Sintering is critical for achieving the required density, strength, and other properties in tungsten alloys. The two-step sintering method [4] is widely adopted: During the pre-sintering stage, temperatures are typically controlled between 1000–1200°C. Within this range, low-melting-point metals like copper and iron reach liquid states, enabling solid-phase diffusion with surrounding tungsten powder particles. This process fixes the positions of tungsten alloy powder particles and ensures uniform filling, achieving blank shaping. This is immediately followed by the high-temperature sintering stage, where solid-phase and liquid-phase reactions occur between powder particles, ultimately forming a dense tungsten alloy structure. Controlling the sintering temperature and duration critically determines product performance. Excessive sintering time increases tungsten crystal size, compromising alloy density and overall properties. Conversely, excessively high temperatures cause volatilization of low-melting-point metals like copper and iron, reducing alloy density and mechanical strength. Sintering temperatures are typically maintained around 1400°C, with both pre-sintering and high-temperature sintering usually conducted under vacuum or inert gas conditions to minimize oxidation and volatilization of low-melting-point alloys.
A common process sequence involves: first, pre-sintering the formed tungsten powder compact in a hydrogen atmosphere at 1200°C for 1 hour to impart initial strength and electrical conductivity. This is followed by electrical self-resistance sintering, utilizing heat generated by the compact's own electrical resistance to further promote sintering.
2.2 Additive Manufacturing Processes
Traditional powder metallurgy methods can only produce blanks with relatively regular shapes. For complex-structured tungsten alloy parts, especially those with intricate cavities, the blanks require complex machining after forming to ultimately meet part specifications. Currently, there are no effective machining methods for complex enclosed internal cavities, which also limits the design possibilities for tungsten alloy parts. Additive manufacturing technologies offer new solutions for designing and producing tungsten alloy parts. Commonly used metal additive manufacturing techniques include Selective Laser Melting (SLM), Laser Stereolithography (LSF), Wire Arc Additive Manufacturing (WAAM), Laser Powder Bed Fusion (L-PBF), and Laser Directed Energy Deposition (L-DED) [5,6]. Table 1 compares the advantages and disadvantages of different additive manufacturing processes for producing tungsten alloy parts. SLM can fabricate parts with complex geometries but suffers from issues such as surface roughness, high interlayer residual stresses, and dimensional limitations, making it suitable for small parts. LSF yields fine, uniform, and dense microstructures, enhancing mechanical properties and corrosion resistance. However, mismatched process parameters may cause fusion defects in deposited layers. WAAM is suitable for manufacturing large, monolithic aerospace structural components with high forming rates and high density, though it produces parts with relatively poor surface quality. Typical tungsten alloy parts manufactured using additive manufacturing technologies are shown in Figure 2. Compared to traditional powder metallurgy methods, additive manufacturing offers distinct advantages in producing complex-structured tungsten alloy parts. It not only enables the fabrication of components with intricate geometries and cavities to meet specialized design requirements but also achieves layer-by-layer material deposition, improving material utilization and reducing costs [7].
2.3 Process Comparison and Selection
Powder metallurgy and additive manufacturing are currently the two primary methods for producing tungsten alloy blanks, each with distinct advantages and disadvantages in blank preparation. A comparison of tungsten alloy blank preparation processes is shown in Table 2. Powder metallurgy is a relatively more mature process, yielding superior material density and offering advantages in stable batch production. Additive manufacturing, a newer process developed in recent years with various derivative techniques, excels in producing structural components with complex cavities.
To achieve higher comprehensive performance, tungsten alloy components in cutting-edge fields such as aerospace, defense, nuclear industry, medical equipment, and electronics are trending toward increasingly complex structural features—including thin walls, curved surfaces, and porous structures—which traditional powder metallurgy methods struggle to address. Directly using additive manufacturing to produce pure tungsten alloy parts with high relative density and no defects still faces technical challenges. The metal indirect 3D printing technology—Powder Extrusion Printing (PEP)—combines “3D printing + powder metallurgy.” It utilizes tungsten alloy powder adapted with a binder, shapes the material via 3D printing equipment, and then undergoes post-processing through powder metallurgy's debinding and sintering processes. This ultimately yields structural components with high density and superior performance. This technology offers a novel solution to challenges in machining tungsten alloys and producing complex structures. Its low-temperature forming and high-temperature sintering characteristics effectively address issues like deformation, cracking, and porosity commonly encountered in other 3D-printed tungsten alloy processes.
3. Machining of Tungsten Alloy Parts
The high density of tungsten alloys subjects cutting tools to immense cutting forces during machining. This demands tool materials with exceptional hardness and wear resistance, while tool design must also carefully consider the distribution and balance of cutting forces. The high hardness of tungsten alloys (typically >40 HRC) significantly accelerates tool wear during cutting, impacting machining accuracy and tool life. Tool longevity and machining efficiency thus become critical factors in cutting operations. Tungsten alloys exhibit relatively low thermal conductivity, making it difficult for heat generated during cutting to dissipate rapidly. The cutting edge operates under high temperatures, prone to thermal stress that causes tool deformation and accelerated wear [8]. Tungsten alloy chips form granular particles, complicating chip evacuation. These chips readily accumulate in the cutting zone, forming chip buildup that degrades surface finish quality and may damage tools and machine tools. A comparison of cutting tools and process parameters for machining tungsten alloy parts is shown in Table 3. In engineering practice, PCBN tools represent one of the optimal choices. Typical tungsten alloy parts processed by cutting are illustrated in Figure 3.
4 Grinding Process for Tungsten Alloy Parts
Grinding, as a micro-cutting method, is suitable for machining high-hardness materials such as tungsten alloys. As shown in Figure 4, grinding wheels primarily consist of abrasive grains, pores, and a bonding agent in specific proportions. The abrasive grains feature obtuse angles, typically ranging from 90° to 120°. During tungsten alloy grinding, the resulting grinding debris exhibits a granular form. Due to its relatively low viscosity and toughness, chips are readily evacuated and less likely to clog the grinding wheel's pores [9]. Consequently, grinding wheels with larger pores can be employed for tungsten alloy processing to enhance grinding efficiency and machining quality. In the grinding zone, heat tends to accumulate, potentially causing grinding burn. To effectively address this issue, high-pressure, high-flow forced cooling measures are required to promptly dissipate heat generated during grinding, thereby reducing thermal deformation and stress in the grinding zone. Water-based emulsions are typically selected as cutting fluids to ensure optimal cooling performance. The grinding process parameters for tungsten alloy parts are listed in Table 4.
Pure tungsten or tungsten-nickel-copper alloy parts exhibit low magnetic properties. For thin-walled components, reliable clamping with conventional electromagnetic chucks is challenging. Vacuum suction fixtures [10] can be considered for mounting. A vacuum-positioning fixture for tungsten alloy parts is illustrated in Figure 5.
5 Wire-Cut EDM Processing of Tungsten Alloy Parts
Tungsten alloys possess high melting points and hardness. Machining can be performed using high-hardness tools such as coated tools, PVD tools, and ceramic tools. However, tool wear is significant, and features like pores, narrow slots, and irregular holes are difficult to machine with these conventional tools. Electrical discharge wire cutting (EDM) is a specialized machining process. Its fundamental principle involves generating pulsed spark discharges between a continuously moving fine metal electrode wire (typically copper or molybdenum) and the workpiece. The resulting temperatures, typically reaching 8000–12000°C, are sufficient to melt or even vaporize the surface layer of tungsten alloy, thereby achieving workpiece cutting. The relative motion between the electrode wire and the workpiece enables the entire cutting process to form the desired shape on the workpiece surface. Figure 6 illustrates the use of wire cutting to process irregular holes in a tungsten alloy blank. When machining tungsten alloy parts via wire cutting, high temperatures cause phase transformations in the cut surface, resulting in a metamorphic layer that loses the alloy's characteristic properties. To address this, a “cut-and-repair” method is employed, progressively reducing the cutting depth and pulse power parameters to restore the altered layer.
6 Conclusion
This paper investigates and summarizes the blank preparation, common machining methods, and processing challenges for precision tungsten alloy components. Regarding blank preparation, powder metallurgy offers relatively mature processes, yielding superior material density and advantages in stable batch production. Additive manufacturing, a newer process developed in recent years with diverse process routes, excels in producing structural components with complex cavities. For machining, PCBN tools offer advantages by achieving high tool life and reducing the impact of tool wear on machining accuracy. Grinding technology excels in processing regular surfaces, delivering superior surface quality. For hole and slot features, wire cutting achieves high machining efficiency. The aforementioned blank preparation processes, along with machining, grinding, and wire cutting methods, effectively enhance the manufacturing quality and production efficiency of precision tungsten alloy components, providing technological support for related industrial development.
References: Special Feature Planning: Precision Machining Technology and Equipment for Small Structural Components; Precision Tungsten Alloy Component Manufacturing Processes - Guo Zhao
Stardust Technology's spherical tungsten alloy powder is produced using advanced RF plasma spheroidization technology. Leveraging the R&D capabilities of the Guangdong New Materials Research Institute, it features high purity (≥99.95%), low oxygen content, and high sphericity (≥95%). The powder exhibits a smooth surface free of satellite particles, with uniform and controllable particle size distribution. The product integrates tungsten's high hardness with the superior properties of alloying elements, offering excellent flowability and high bulk/tapped density. It is compatible with processes such as 3D printing, powder metallurgy, and thermal spraying, finding extensive applications in high-end fields including aerospace, electronics, and precision manufacturing. It provides high-quality raw material support for high-temperature and high-load scenarios. For more product information, please contact our technical manager Cathie Zheng at +86 13318326187.
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