Description:AUTOMOTIVE PARTS AND METHOD OF MANUFACTURING THEREOF

Field of the Invention
The present invention relates to automotive parts and method of manufacturing thereof. More particularly, the present invention relates to manufacturing planetary gears in automobile transmission based on brazed sintering.

Background of the Invention
Sinter-brazing technology emerged as a solution to several challenges faced by industries in the production of automotive parts using traditional manufacturing methods. Traditional manufacturing methods often struggle to efficiently produce complex shapes and structures due to limitations in mold or die complexity, and machining processes. Sinter-brazing allows for the creation of complex geometries and intricate designs that are difficult or impossible to achieve with conventional methods. It involves the use of powdered metal alloys that can be molded into complex shapes before being bonded together through a brazing process.

Producing high-performance materials traditionally involves expensive processes such as casting or machining from solid materials. Sinter-brazing offers a cost-effective alternative by utilizing powdered metals that can be tailored for specific mechanical properties. This allows for the creation of parts with high strength, wear resistance, and other desirable characteristics without the need for extensive machining or costly raw materials.

Traditional manufacturing methods often involve material waste and high energy consumption. Sinter-brazing is relatively more environmentally friendly because it generates less waste (since it uses powdered metals efficiently) and can operate at lower temperatures compared to traditional melting and casting processes. Additionally, it can utilize recycled materials, contributing to sustainability goals.

Traditional manufacturing methods sometimes struggle to achieve consistent properties throughout a part, especially with complex geometries or large components. Sinter-brazing enables precise control over material composition and microstructure, resulting in parts with uniform mechanical properties across their entire volume. This is crucial for ensuring reliability and performance in automotive applications.
The sinter brazed automotive products are being manufactured typically by combining forging, machining, and welding. However, these manufacturing technique faces problems related to shape accuracy, manufacturing man-hours and efficiency, and the strength of welded joints.

In essence, the problems that existed in traditional manufacturing methods—difficulty in producing complex shapes, high costs of high-performance materials, environmental concerns, and inconsistent material properties—provided the impetus for the development and adoption of sinter-brazing technology in the automotive industry.

In the brazed joint, the strength may be compromised if the brazing surfaces are not properly joined by the brazing material and improper joining may occur if the distance between the surfaces to be brazed is irregular or if there is not enough brazing material to fill the gap between the components which in return weakens the brazed joint and makes it more susceptible to mechanical failure resulting in misalignment and which can alter the uniformity and the consistency of the spacing of the components, adversely affecting the joining of the surfaces during brazing and creating the potential for loss of some of the brazing material via overflow.

It is, therefore, desirable to bring improvement in the brazing process for manufacturing of automotive parts and overcomes challenges and obviates complexity existing in the prior arts.

Summary of the Invention
This summary is provided to introduce a selection of concepts in a simplified form that are further described below in the Detailed Description. This summary may or may not be intended to identify key features or essential features of the claimed subject matter. Nor is this summary intended to be used to limit the claimed subject matter’s scope.

Both the foregoing summary and the following detailed description provide examples and are explanatory only. Accordingly, the foregoing summary and the following detailed description should not be considered to be restrictive. Further, features or variations may be provided in addition to those set forth herein. For example, embodiments may be directed to various feature combinations and sub-combinations described in the detailed description.

The various objectives and embodiments of the present invention as presented herein are understood to be illustrative and not restrictive and are non-limiting with respect to the scope of the invention.

It is one of the objectives of the present invention to provide an automotive part with enhanced mechanical strength and durability through a sinter brazing method.

It is one of the objectives of the present invention to provide an automotive part with high dimensional accuracy and precision through a sinter brazing method.

It is one of the objectives of the present invention to provide an automotive part that incurs reduced manufacturing costs and provides increased efficiency through a sinter brazing method.

It is one of the objectives of the present invention to provide a sinter brazing based method for manufacturing an automotive part which is capable of producing complex geometries and designs.

It is one of the objectives of the present invention to provide a sinter brazing based method for manufacturing an automotive part which energy-efficient process compared to traditional manufacturing methods, contributing to a lower environmental footprint.

Another objective of the present invention is to use a high-quality sinter-braze material with optimized combination to strengthen the planetary carrier with precision.

Another objective of the present invention is to provide a method which utilizes optimized processing conditions to achieve complex shapes and structural efficiency in planetary carrier.

Another objective of the present invention is to provide a method which involves simultaneous progression of sintering and brazing for consistency of material properties and low to zero wastage.

In accordance with one embodiment of the present invention, there is provided an automotive vehicle part comprising a pair of powder metallurgy based die formed compacts joined by a brazing filler material at a plurality of positions at the joining interface of the pair of die formed compacts by way of sintering in the presence of nitrogen and hydrogen, wherein said brazing filler material further comprises of a Cu-Ni-Mn Base fully infiltrated into the die formed compacts and having density ranging between 6.7 to 7.0 gram per cubic centimeter.

In accordance with one embodiment of the present invention, there is provided an automotive vehicle part comprising a pair of powder metallurgy based die formed compacts joined by a brazing filler material at a plurality of positions at the joining interface of the pair of die formed compacts by way of sintering in the presence of nitrogen and hydrogen, wherein said brazing filler material further comprises of a Cu-Ni-Mn Base fully infiltrated into the die formed compacts and having density ranging between 6.7 to 7.0 gram per cubic centimeter, wherein said automotive vehicle part is but not limited to planetary gears.

In accordance with one embodiment of the present invention, there is provided a method for manufacturing an automative vehicle part, comprising obtaining a pair of powder metallurgy-based die formed compacts, and introducing brazing filler materials having density ranging between 6.7 to 7.0 gram per cubic centimeter, at an interface of the pair of the die compacts and sintering the same at 1120 – 1140 °C in the presence of nitrogen and hydrogen for 25 – 40 minutes, for fully infiltrating the brazing filler material into the pair of powder metallurgy-based die formed compacts.

In accordance with one embodiment of the present invention, there is provided a method for manufacturing an automative vehicle part, comprising obtaining a pair of powder metallurgy-based die formed compacts, and introducing brazing filler materials having density ranging between 6.7 to 7.0 gram per cubic centimeter, at an interface of the pair of the die compacts and sintering the same at 1120 – 1140 °C in the presence of nitrogen and hydrogen for 25 – 40 minutes, for fully infiltrating the brazing filler material into the pair of powder metallurgy-based die formed compacts, wherein said method further comprises of preparing a base of Cu-Ni-Mn constituting brazing filler material having density of 6.9 gram per cubic centimeter, for introducing at the interface of the pair of the die compacts and sintering the same at 1120 °C in the presence of nitrogen and hydrogen for 28 minutes, for fully infiltrating the brazing filler material into the pair of powder metallurgy-based die formed compacts.

Brief Description of the Drawings
Figure 1 shows (A) Compacted planetary carrier assembly with brazing pallet, (B) Sinter-Brazed planetary carrier assembly.
Detailed Description of the Invention

Sinter brazing is a process that allows joining parts easily and efficiently with a high-quality sinter braze material. The proper processing conditions gets a brazed joint which is generally as strong, or stronger, than the base materials being joined.

Planetary carrier and other critical automotive parts shapes are complex due to hollow portions, intricate end face shapes, and the necessity of retaining planetary gears. Considering the sinter brazing technology, which is capable of near net shaping by die forming, it is appropriate to manufacture planetary carriers compared to other processes like machining and casting. By producing complex parts through simultaneous sintering and bonding, sinter brazing allows for time savings and cost reduction.

Sinter-brazing has notable applications in the automotive industry. It is a manufacturing process for creating complex, high-strength components like planetary carriers. Sintering involves pressing the metal powder into a desired shape followed by heating below its melting point until the particles bond together, forming a solid piece / sintered component. Further, a filler metal/alloy is melted to join the two or more sintered components together which strongly joins the two components upon cooling.

In the present invention, green powder metallurgy (PM) compacts are formed by pressing metal powder into the desired shape under high pressure, before sintering, wherein during sintering, these compacts are combined with a brazing alloy and in the fabrication process, various parameters such as brazing material density, weight, and sintering conditions like temperature, time, and atmosphere are optimized to achieve the best separation force and improved assembly strength and accuracy, wherein the precise assembly of compacts is achieved by external spline shape correction, oil groove formation, and FEM stress analysis optimizing strength and weight of the alloy.
In the present invention, sinter-brazing techniques are employed that improve the bonding between components, resulting in a stronger and durable final product, wherein rigorous testing and quality control are conducted to ensure that the carrier can withstand high stress and strain, wherein advanced manufacturing technologies, such as CNC compacted press and high accuracy tooling’s are implemented to achieve precise dimensions and tolerances and regular calibration of equipment and adherence to strict process controls to maintain high accuracy.
In the present invention, optimized material properties such as hardness is and wear resistance through advanced powder metallurgy and customized material compositions are obtained to meet specific application requirements.
The process of advanced powder metallurgy is employed to manufacture a planetary carrier with superior material properties. Powder metallurgy involves compressing and heating powdered metals to form a solid piece. This method allows for precise control over the material’s structure and properties. To achieve the required hardness and wear resistance, the material composition is carefully customized. The powder mixture includes a 0.20-0.50% percentage of Molybdenum, known for its extreme hardness, combined with a 1.0-3.0% copper that enhances toughness. By adjusting the ratios of these components, the material's properties meet the specific demands of the application.
In accordance with one preferred embodiment of the present invention, the powder mixture includes a 0.40% percentage of Molybdenum, combined with a 2.0% copper to enhance hardness and toughness.
In the present invention, streamlined production processes and minimized waste through lean manufacturing principles are adopted, resulting in automated key stages of production to reduce labor costs and increased throughput.
To improve efficiency, the factory automated several key stages of production by installing robotic arms to handle repetitive tasks, such as loading and unloading parts from compaction machines and packaging, including the loading of brazing material pallets. These robots work faster and more accurately than human workers, reducing labor costs and minimizing errors. Additionally, an automated quality control system using sensors and cameras is implemented to inspect the planetary carriers for defects during the production process. This system can detect and reject faulty parts in real-time, reducing the amount of rework required and ensuring that only high-quality products reach the final packaging.
In accordance with one embodiment of the present invention, advanced Computer Numerical Control (CNC) control compacted press and advanced tooling techniques to create intricate and complex designs are adopted and 3D modeling, and simulation software is utilized to design and test complex geometries before production.
To achieve the required precision, a hydraulic CNC compacted press is used, which is equipped with advanced control systems that allow for highly accurate control of pressure and positioning during the compaction of powdered metals. The CNC system ensures that each planetary carrier is formed with exact dimensions and consistency, even when producing intricate and complex shapes. The designed planetary carrier requires thin walls and complex internal features with varying thicknesses from 2 to 6 mm. The advanced CNC-controlled press precisely compacts the powder into these shapes with minimal variation between parts. This precision is critical for ensuring that the planetary carriers fit correctly into the transmission assembly and function as intended under high stress.
The hydraulic press applies additional pressure of up to 800 MPa uniformly across the part. This high-pressure compaction reduces porosity and increases the overall density of the part. The result of this controlled hydraulic pressing is a significant improvement in the density and material strength of the planetary carrier. For instance, the final density achieved is 7.10 g/cm³, leading to enhanced mechanical properties such as tensile strength, yield strength, and fatigue resistance.

In addition to CNC control, advanced tooling techniques to create the dies and molds used in the compaction process are employed. These tools are engineered to withstand the high pressures involved while maintaining the fine details of the design. Multi-part dies are used to form complex geometries that would be difficult or impossible to achieve with traditional tooling. Advanced materials, such as CPM9V tool steel, and titanium nitride coatings are applied to these tools to extend their lifespan and maintain their precision over long production runs.

Before initiation of physical production, 3D modeling and simulation software to design and test the planetary carrier's complex geometries are used. Detailed digital models of the carrier, including all its intricate features, are created. This allows us to visualize how the part will look, and function once produced, and also to simulate how the powder will flow into the mold during compaction and how the part will behave under different pressures.

In the present invention, environmentally friendly practices are adopted, such as recycling excess material and reducing energy consumption, to ensure compliance with environmental regulations and to minimize the carbon footprint of the manufacturing process.

Sinter-Brazing method is applied in fabrication of planetary carrier through traditional Sintering using Brazing paste which provides satisfactory bonding and strength. Furthermore, Sinter-Brazing is also applied using nitrogen and hydrogen atmosphere along with the material. It achieves superior bonding and mechanical properties by minimizing oxidation and impurities, leading to the best results.
In the present invention, there is provided an automotive part made from standard Iron-Based Powders and alloyed Powders (e.g., Fe-Ni-Cu) to enhanced strength and wear resistance, achieving the best results, wherein an optimized brazing alloy (e.g., Ni-Cu based) is employed for improved bonding and mechanical properties, achieving superior results.
In the present invention, the melt temperature of the braze alloy (i.e. Ni-Cu based) is lower than the parent parts (i.e. Fe-Ni-Cu), wherein the parent parts are wetted by the brazing alloy without themselves being melted, capillary force draws the molten braze in the gap between the parts being brazed and in sinter-brazing, green PM compacts are configured with a brazing alloy and sintered simultaneously, producing sintered PM parts that have been brazed together, wherein a copper-nickel-manganese based brazing alloy is used and which partially infiltrates, and then alloys with iron (Fe), raising the melting point, limiting infiltration.
Table 1 below illustrates different trials being carried out for manufacturing of the planetary gears:

Sl. No. Density Brazing Material Brazing Material weight Sintering Temp. Sintering time Sintering Atmosphere Separation Force (Spec. 30 kn Min.)
1 6.80 g/cm3 Cu-Ni-Mn Base 3.50 gm 1140°C 35 minutes Nitrogen + Hydrogen 8 kn
2 6.80 g/cm3 Cu-Ni-Mn Base 3.00 gm 1140°C 30 minutes Nitrogen + Hydrogen 15 kn
3 6.80 g/cm3 Cu-Ni-Mn Base 2.50 gm 1130°C 30 minutes Nitrogen + Hydrogen 20 kn
4 6.90 g/cm3 Cu-Ni-Mn Base 2.00 gm 1130°C 28 minutes Nitrogen + Hydrogen 40 kn
5 6.90 g/cm3 Cu-Ni-Mn Base 2.00 gm 1120°C 28 minutes Nitrogen + Hydrogen 45 kn

Based on the above table, the following observations are made in the above 5 trials:

1. Braze Material Completely Infiltrates the PM Part
2. Braze Material Completely Infiltrates the PM Part
3. Braze infiltrates and freezes before it spreads through the entire joint
4. Capillary force draws the molten braze in the gap between the parts being properly brazed.
5. Capillary force draws the molten braze in the gap between the parts being properly brazed and separation force observed
In the present invention, the planetary carrier has been designed as a structure consisting of two sinter-brazed components in order to form three steps that carry planetary gears and to manufacture this product, two die-formed compacts are assembled accurately and unified into one body by bonding together with brazing filler metals located in 3 positions, wherein after sintering, the external spline is further subjected to specific shape correction with a sizing die.
The planetary carrier is engineered as a sophisticated component composed of two separate pieces that are sinter-brazed together. Each component is designed to contribute to the structure that supports the planetary gears. The manufacturing process involves creating two die-formed compacts—pre-shaped parts made using high-pressure die compaction of metal powders. After sintering, the external spline of the planetary carrier, which interfaces with other components in the transmission, may not be perfectly shaped. To correct this, a sizing die is used to precisely adjust the spline’s dimensions.
Further, an oil groove is machined in each sliding surface that carry planetary gears, wherein pockets are then bonded to the other compacts to form an oil groove in a hollow portion that cannot be obtained by machining, and when the planetary carrier is designed, its strength is analyzed using the FEM stress analysis method and this analysis made it possible to thin the portions that did not affect the strength and thereby minimized the weight of the carrier without degrading the required characteristics.
For internal hollow sections or intricate passages that cannot be machined directly, additional components with pre-formed oil pockets are bonded to these areas. These pockets create oil channels within the hollow sections, ensuring that lubrication reaches all necessary areas without requiring complex machining operations. The strength of the planetary carrier is analyzed using FEM (Finite Element Method) stress analysis to optimize its design. FEM analysis reveals that certain areas of the carrier experience lower stress and can be thinned without affecting performance. This allows us for the reduction of excess material from non-critical areas, thereby enhancing the component’s efficiency and reducing its overall weight while maintaining its strength and durability.
While the invention is amenable to various modifications and alternative forms, some embodiments have been illustrated by way of experimental results in the tables and are described in detail above. The intention, however, is not to limit the invention by those experimental results and the invention is intended to cover all modifications, equivalents, and alternatives to the embodiments described in this specification. The first die-formed compact shape the internal structure of the carrier, including the steps where the gears will fit. The second compact form the outer shell and additional features. These two pieces are assembled and bonded together using brazing filler metals at three critical points.

The embodiments in the specification are described in a progressive manner and focus of description in each embodiment is the difference from other embodiments. For same or similar parts of each embodiment, reference may be made to each other.
It will be appreciated by those skilled in the art that the above description was in respect of preferred embodiments and that various alterations and modifications are possible within the broad scope of the appended claims without departing from the spirit of the invention with the necessary modifications.

Based on the description of disclosed embodiments, persons skilled in the art can implement or apply the present disclosure. Various modifications of the embodiments are apparent to persons skilled in the art, and general principles defined in the specification can be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not limited to the embodiments in the specification but intends to cover the most extensive scope consistent with the principle and the novel features disclosed in the specification. , Claims:We Claim:

1. An automotive vehicle part comprising a pair of powder metallurgy based die formed compacts joined by a brazing filler material at a plurality of positions at the joining interface of the pair of die formed compacts by way of sintering in the presence of nitrogen and hydrogen, wherein said brazing filler material further comprises of a Cu-Ni-Mn Base fully infiltrated into the die formed compacts and having density ranging between 6.7 to 7.0 gram per cubic centimeter.

2. The automotive vehicle part as claimed in claim 1, wherein said automotive vehicle part is but not limited to planetary gears.

3. A method for manufacturing an automotive vehicle part, comprising:
obtaining a pair of powder metallurgy-based die-formed compacts; and
introducing brazing filler materials having density ranging between 6.7 to 7.0 gram per cubic centimeter, at an interface of the pair of the die compacts and sintering the same at 1120 – 1140 °C in the presence of nitrogen and hydrogen for 25 – 40 minutes to fully infiltrate the brazing filler material into the pair of powder metallurgy-based die formed compacts.

4. The method as claimed in claim 3, further comprises of preparing a base of Cu-Ni-Mn constituting brazing filler material having density of 6.9 gram per cubic centimeter, for introducing at the interface of the pair of the die compacts and sintering the same at 1120 °C in the presence of nitrogen and hydrogen for 28 minutes, for fully infiltrating the brazing filler material into the pair of powder metallurgy-based die formed compacts.

5. The method as claimed in claim 3, wherein said brazing filler materials consist of an atomized pre-alloyed mixture of nickel, copper, and manganese metals and are compacted into pallet form.