Heavy Metal Manufacturing: Creating a Splash in 3d Printing Industry
This year, metal 3d printing and rapid prototyping have already seen a couple of great advancements. Starting from the nanoscale to the building of a whopping twenty four million dollar manufacturing facility, all these are clear signs of the fact that metal additive manufacturing is advancing rapidly. In the last five years, the growth of the industry has been explosive. In 2013, the sale of metal 3d printers had increased by seventy five percent in that single year. Fast forward three years and recently there has been a twenty million pound investment in the sectors of UK metal powder companies. This huge sum was invested in order to commercially produce their powders for medical, aerospace and automotive industries.
Experts opine that they have never seen a research sector that has flourished this rapidly. Even though additive manufacturing has been in the industry for more than twenty years, it was unclear whether it could be used in the automation of 3d parts until recently. Four years ago, the technology was truly taken to the next level by using it in combination with 3d printing. At that time, a few aerospace related companies began to experiment with the creation of new metal additive manufactured parts. Today, these parts, created through additive manufacturing, are taking their place proudly in real plane engines.
The following five advancements have been predicted in the 3d printing scene, and are destined to create a splash in the industry.
• Porosity Manipulation
It should be possible to design for or totally eliminate the internal porosity of parts. This is going to have a very significant influence on the resistance of fatigue and the rate of building. At present, there are occurrences of unavoidable metal porosity levels when using the default settings of the 3d printer. If the parts are subject to cyclic fatigue loading then the porosity can turn into a crack, making it a consistent problem for metal additive manufacturing. There are three main sources of porosity- porosity of powders, key holing i.e., local vaporization of metals, and being surrounded by molten metal causing a pore and lack of powder fusing.
First of all, powder porosity can be removed by extensive research with powder manufacturing companies. The other parts, however, have to be addressed by bringing a change in the additive manufacturing process. It will be a prevalent technology in the next five years. It is also believed that engineers of the design department will be able to both eliminate and manipulate porosity very soon. If there is a uniform microstructure of parts with uniformity in properties, then it becomes easier to understand and design the entire process. Materials with smaller grain sizes can be the constituents of parts that are of high strength, and in places where there are concentrations of stress. This is very similar to steel case hardening. There are now designers who are designing parts and also the process by which the part can be made faster, finished smoother or with a point based design of microstructure.
• Design of Process
The process design is going to change drastically, due to the fact that the additive manufacturing process can be designed concurrently with the geometrical design of a part. Currently, direct metal additive manufacturing processes tend to operate in a rather narrow range of variables such as travel speed and beam power. This happens because the techniques for this process were developed on an experimental basis. As soon as there was the discovery of a working combination of travel speed and beam power, there was little research done to find any other possible combinations. Besides, there are five other major variables in the metal additive manufacturing process like travel speed, power, thickness, local geometry and fusing point temperature. In the future, we can expect to have more process variables to manipulate the process.
• Newer Powders
There is already a lot of research going on for the creation of a wider range of metal powders for additive manufacturing. This means that there will be various diameters of the currently existing metal powders. Looking farther into the future, though, it is expected that there will be advancement in new alloys which can exploit high rates of cooling of the metal additive manufacturing process. If the conditions are known, then the alloys can be put to advantageous use to create better properties of the materials. There is yet to be any other process with such a high rate of cooling. The exploration of new alloys is still in the initial stages.
• Control and Monitoring
The day that the metal additive manufacturing process can be monitored and controlled is not too far. Presently, there is usually a thermocouple mechanism that regulates the overall temperature of the build chamber, and the process may or may not have that information in the control loop form. In this regard, a lot of research is currently underway. Thus, we can expect to have some improvements in monitoring in the next few years. The next step would be to improve the changing of the process, in addition to feedback control and the provision to fix things as the process goes on.
• Microstructure Manipulation
The microstructures and their properties of parts can vary at different locations through manipulation of the process variables, while building the parts. As opposed to the present ‘feed-forward’ approach of metal additive manufacturing, it should be possible in the future to manipulate the process variables in order to get a specific variation in the microstructures of parts. This is possible with the electron beam and powder bed based ARCAN method, used in TI-64 Titanium alloys. It has been possible to manipulate some part of the microstructure of the system. Some microstructure features can also be controlled by choosing which process variables to feed in advance.
Even though the role of metal additive manufacturing is debatable in the industry, it may have already gone to a point where it is creating a stir. There are people within the industry who express their doubts about the impact of the technology in the future. The sudden leap from research stages to commercial manufacturing is a concern for many. However, with the rapid development of metal additive manufacturing in rapid prototyping and 3d printing, that leap of faith can definitely be taken.
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