Design for Manufacturing (DFM) of Refractory Metal Parts

Design for Manufacturing (DFM) of Refractory Metal Parts

Design for Manufacturing (DFM), also known as Design for manufacturability, is a crucial aspect of product development that focuses on optimizing the design of a product for efficient and cost-effective manufacturing. The three main goals of Design for Manufacturing are reducing waste, reducing cost, and improving quality.

More than any other factor, a product’s design has the greatest impact on the total cost of production and directly impacts the types of processes and number of operations that a manufacturer utilizes to produce it on the factory floor. DFM involves designing a product with manufacturability in mind. This means considering the capabilities and limitations of the manufacturing processes that will be used to produce the product. Your DFM design should adhere to good manufacturing principles and focus on individual parts and components with the goal of reducing or eliminating expensive, complex or unnecessary features which would make them difficult to manufacture. 

DFM also involves optimizing the design for efficient assembly. By limiting the number of features and required tolerances, you will decrease the complexity of the manufacturing processes required to produce the individual parts. This helps to control production costs by increasing the quality and minimizing the fabrication time required to produce all the assembly’s components. In addition, creating a good DFM gives you the ability to accurately calculate R&D and high-volume production costs upfront and will benefit your customers through lower total cost of ownership.

optimizing the design for efficient assembly
Optimized design of tantalum parts for efficient assembly

Another key consideration in DFM is the selection of materials. Designers need to choose materials that are readily available, cost-effective, and suitable for the intended manufacturing processes. They also need to consider factors such as material compatibility, durability, and environmental impact. By selecting the right materials, manufacturers can avoid issues such as material shortages, high costs, and production delays.

With refractory metals, the more complex the design, the higher the risk is that the part will not be easily reproducible. Therefore, a simple design is usually the best way to go in terms of cost, ease of manufacturing, use, and maintenance.

When creating your DFM for refractory metals, your first consideration should be the metal-type you require, as some refractory metals are much more difficult to precision-machine than others;

Pure Tungsten – Commercially pure tungsten (99.95% min.) has the highest melting point (3410 degrees C) of the four common refractory metals. It offers exceptionally high strength at very high temperatures. Its high-temperature strength, combined with its good electrical resistivity have made it a popular choice for many applications. However, pure tungsten metal is ultra-hard and brittle. It’s high ductile-to-brittle transition temperature makes it extremely difficult to machine at room temperature. It is prone to cracking & breaking during machining and is particularly difficult to cut without leaving large chips and scratches. While brittle at room temperature, heating it, when possible, will improve its ductility and machinability.

Tungsten Heavy Metal Alloy (WHA) – Tungsten Heavy Metal alloys are typically 90 – 97% tungsten with the balance of their composition being a combination of nickel and/or iron & copper metals which increase the ease of machining and the ductility of the alloy. In fact, Tungsten Heavy Alloy (WHA) is the easiest to machine of all refractory metal alloys. The various alloy compositions of WHA are identified in the ASTM B777-15 specification. Choose tungsten heavy metal alloy (WHA) when your application requires a maximum concentrated weight in the smallest possible space. Because of the physical properties of tungsten heavy metal alloy, it is often used as both a weight and structural member, radiation shielding, projectiles, boring bars and grinding quills. Important Note: Tungsten heavy metal alloys are unsuitable for use in high temperature applications approaching or above 1450° C (2642° F) at which point pure tungsten should be considered.

Molybdenum – Molybdenum is number 42 on the periodic table with a melting point of 2610 degrees C and a density of 10.22 gm/cc. Moly has many properties that make it an excellent candidate for fabricated parts and it is the most commonly used refractory metal. Of all the refractory metals, molybdenum (& TZM alloy) are two of the most machinable refractory metals and can be machined by most conventional methods & processes at room temperature. Molybdenum is weldable and can also be bent & formed, but should be heated prior to forming to avoid cracking.

Tantalum – Tantalum, number 73 on the periodic table, is one of the most corrosion resistant metals available. It is used in chemical reactors, medical implants and highly acidic environments. Tantalum and its alloys are midway between tungsten and molybdenum in density and melting points. Its thermal conductivity is one-fourth that of molybdenum and its coefficient of expansion is one-third greater. Tantalum’s elevated temperature strength is low compared with tungsten & molybdenum. Due to its relative softness tantalum can be worked easily at room temperature. Because it is soft, it isn’t prone to chipping, and with proper tools and coolants the required surface finishes can be achieved with good results.

Niobium – Niobium, also known as Columbium, is number 41 on the periodic table and has a density of 8.57 gm/cc. With a melting point of 2468 degrees C, it qualifies as a refractory metal. Niobium can be found in electrolytic capacitors, superconductor alloys, gas tubing, vacuum tubes and nuclear reactors. It has many properties that make it an excellent candidate for fabricated parts that must be made of a refractory metal. It can be machined by normal machining techniques and offers good ductility and weld-ability under a clean, dry inert gas or a vacuum.

In conclusion, design for manufacturing is a critical aspect of product development that focuses on optimizing the design for efficient and cost-effective manufacturing. By considering factors such as simplification, material selection, assembly optimization, and overall production process, designers can create products that are easier to manufacture, resulting in reduced costs, improved quality, and faster time to market.

Rembar has been machining, forming & fabricating refractory metals since our founding in 1950. Our knowledgeable & experienced sales engineers can assist you with creating a Design-For-Manufacturing part that will meet the machining, forming & surface finish limitations of the specific metal-type you choose. We can also assist you with choosing the right refractory metal for your application.

Use our on-line Fast Quote form to submit your DFM request or, for fastest service, call us at 914-693-2620 and speak with one of our sales engineers.

Rembar for Refractory Metals. Quality & Service since 1950.