Incorporating the right combination of metal alloys is crucial to producing quality MIM parts. So too is ensuring that the proper ratio of binding agent to metal powder is used.
PTI has been able to overcome this challenge by working with Latitude Manufacturing Technologies’ agar binder system. It eliminates the need to remove the binder before sintering, which had been a major hurdle for producing larger MIM parts.
High-strength and light weight
Aircraft engines and their components require components that can withstand extreme temperatures, pressures, and corrosive environments. Metal Injection Molding (MIM) is an ideal production method for producing these components, because it can accommodate the use of high-performance alloys like Inconel and Hastelloy that offer strength, corrosion resistance, and high tensile and compressive properties.
MIM parts can also be produced with complex shapes and geometries, allowing designers to create intricate designs that would not be possible with other fabrication methods. For example, MIM parts can include threads and holes that can be integrated directly into the park design, reducing the need for post-processing.
MIM parts are also characterized by superior mechanical properties, including ductility and fatigue resistance. These characteristics can be further enhanced by using Hot Isostatic Pressing (HIP), which eliminates pores and other defects to enhance the material performance of the part. In addition, dimensional inspection is performed on MIM parts to verify that they meet the specified tolerances.
Complex shapes and geometries
MIM technology is capable of producing parts with complex geometries and tight tolerances that are difficult or impossible to produce using other methods. This makes it ideal for a range of aerospace applications that require precise shapes and dimensions.
MIM can produce parts in a variety of metals, including titanium alloys, nickel-based superalloys, and low-alloy steels. These materials offer excellent mechanical properties, corrosion resistance, and thermal stability at high temperatures. This enables them to be used in jet and gas turbine engines to support their performance and efficiency.
MIM is a cost-effective manufacturing process for parts that are larger than what can be produced by injection molding, but smaller than what can be fabricated by other production processes like casting and machining. It also enables designers to combine multiple components into a single part, eliminating screws and adhesive bonding, and reducing both weight and assembly costs. Dimensional inspection, using coordinate measuring machines (CMM) and optical comparators, is essential for ensuring that MIM parts meet specified tolerances.
MIM allows manufacturers to use a variety of metals. Iron-based alloys such as stainless steels, tool steels, and iron-nickel magnetic alloys like Kovar and Invar work well with MIM, as do hard metal blends like cemented carbides and cermets, and refractory metals like tungsten. Using the right material and implementing effective inspection techniques, MIM parts can achieve tight tolerances.
PTI is working to offer a wider choice of metal powders and alloys for MIM, as well as improved debinding methods for larger, thick-sectioned components. Currently, removing the binder from large green parts can be time-consuming and expensive, but PTI’s new agar binder is based on water and a gelatin-like seaweed-derived material that is easily evaporated.
Aircraft designers are increasingly specifying MIM for a wide range of key components such as bushings, fasteners, wing flap screw seals, and seat belt adjustment levers. By eliminating machining and replacing forgings, MIM can significantly reduce costs while delivering superior strength and durability.
MIM Parts for Aerospace: Enhanced Performance in Challenging Environments
Titanium and titanium alloys are used in aerospace components to provide high strength-to-weight ratios, corrosion resistance, biocompatibility, and other properties. These materials can withstand the extreme temperatures, pressures, and corrosive environments found in jet and gas turbine engines.
The initial mold used in the MIM process is critical to producing accurate parts. Any deviations in the cavity’s geometry will directly impact dimensions, surface finish, and material properties of the final component.
Feedstock rheology is also crucial in MIM technology. The viscosity of the powder/binder mixture must be consistent during injection to ensure that it flows smoothly into the die cavities and avoids segregation. In addition, the particle size distribution of the metal powders must be tightly controlled so that they pack more densely, resulting in higher density parts. Finally, shrinkage is also important to consider as it will affect the dimensions of the ‘green’ compacts after the molding and sintering process.