Saturday, November 5, 2016

More Cncerning Three D Printing

Three-D printing has been making inroads into part manufacturing since the beginning of this century. The impetus for this progress is because we need to make parts faster and cheaper. If only one part of a kind, such as a forging die is needed, now it appears to be that Three-D printing is the way to go. Also, if a complex, thin walled part that is made of expensive material and much waste as chip or scrap is generated  form the part, then again Three-D printing may be the answer. I attended a show in New Jersey last week and  examples of parts were on exhibit that demonstrated both situations discussed above.
However, Three-D printing requires not only a precise computer engineered model to produce a complex part, but  also  either an electron beam or a laser to melt the particles deposited as fine incremental layers that are built to generate the volume of the part desired. These components are expensive and mandatory start-up expenses that cost $600,000 to $1,000,000.
Powders are also expensive in respect to wrought, cast or forged alloys .These powders are mostly gas atomized, requiring protection to minimize surface oxidation. As a result, depending on the powder size distribution required to distribute the thin layers for melting, these powders may cost as much as $100 per pound. Although, there are increasing numbers of gas atomized powder producers, alloy compositions are more limited as opposed to wrought compositions, which are readily available commercially.
Once a decision has been made that the cost and time saved is justified, then production of the part may also yield additional problems. First, thickness of the powder layer and the direction of the laser or electron beam required to melt the powder layer requires careful consideration or else porosity, contamination between layers  or inconsistency in chemistry may result. The part, if used in a critical application where safety and lives are at risk, must satisfy the physical and the mechanical properties of the wrought alloys already satisfying the properties required of the part for performance. In this case, almost a secondary operation, known as hot isostatic pressing is required to assure a pore-free structure. Additional heat treatment may also be necessary to provide a uniform microstructure rather than a non-uniform cast structure. Required properties of existing specifications must be assured.
In addition to the internal core properties, the surface of the part may also require careful consideration and modification. Most parts in service fail either from corrosion, fatigue, impact or wear. Therefore careful consideration of the surface is  required. Three-D parts normally have rough surfaces that require some modification to provide a desired surface finish. In addition, some surface modification may be required to protect the working surface from the environmental factors causing the part to corrode, fatigue, wear or fracture from impact.
As we have described, there is still much work to be accomplished before advanced manufacturing becomes competitive with current processing. However, at least two prime manufactures within the past week have become more committed to continuing development of the current processes. General Electric has a consortium in process whereby they are studying how these processes can be used in their applications, such as turbine engines, windmill construction and other areas as well. An off the road equipment manufacturer has also challenged innovators to come up with ideas that will increase the use of advanced manufacturing processes to reduce cost and time for production for three of the components that are used on their equipment. Yes, there is much interest in advanced manufacturing and MagnaTech believes that we can assist in overcoming currently troubling problems.. 

No comments:

Post a Comment