Case Study: Fluid Matter Exchanger

Process: Metal Additive Manufacturing (AM) Binder-Jet Sinter Based Process

Material: 316L stainless steel

Density: > 96% of theoretical density

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End Use and Function

While relatively simple in appearance on the outside, this fluid matter exchanger is extremely complex on the inside. The exchanger has large and small channels throughout, and filters scattered within the part, allowing for matter to flow in specific ways. A total of over 50 independent cavities can be counted within the part. The hollowness, internal channels, internal filters, and other complex features of the fluid matter exchanger make it a part only viable through AM. Some examples of these features include the 0.5mm filter holes, 0.75mm wall thicknesses, and twenty-one #2-56 threaded holes printed directly on the part.

Fabrication

Due to the intricate geometry, depowdering was a primary concern. Utilizing CAD, the development of innovative air nozzles was essential for clearing out the loose powder from the various channels and cavities inside the fluid matter exchanger before sintering. Zero powder can be left inside the channels and filters preventing the proper flow of matter and function of the apparatus in the field. Simple handling of these parts in the green state is critical, as the extremely thin walls crack when too much pressure is exercised on them. Internal and external braces were placed in areas that would not affect the function but would aid and reinforce the part for handling during depowdering in the green state and prevent distortion or cracking during sintering.  

After sintering, the fluid matter exchanger is inspected and measured with respect to the tolerances on external dimensions. Some post processing is done by the end-user, like welding of the end cap and connectors to the fluid matter exchanger. Advanced tests are performed on each part by the customer, including testing of flowability within the many internal channels and sections as well as pressurized leak testing. These tests are critical in validating the performance of the fluid matter exchanger and ensuring it can be used in the final product.

Results

Currently there is no other practical way to manufacture this part. The compact design is a direct result of combining multiple components into one part, which is only achievable through AM. All of the channels, filters, and other key features packed into this fluid matter exchanger make it a very complex part. Based on previous designs, over a dozen machined and welded/brazed components would have been used to create a design that was less efficient.

The fluid matter exchanger is larger than the typical part for metal Binder-Jet processing and includes many of the smaller more detailed features achievable by Binder-Jet. The duality of this part, being large but at the same time one of the most complex, demonstrates the superior capabilities of AM.