Metal Binder Jetting (BJ3D) is an additive manufacturing process that builds parts in a composite metal that is 60% stainless steel and 40% bronze. Using a CAD file, a machine will 3D print a part cross-section by cross-section at 0.004” (0.1mm) layers by precisely depositing binder in a stainless steel powder bed. BJ3D uses 316L/Bronze, which is highly-corrosion resistant and easy to tap and post-machine.
After this stage, the part is “green” and very easy to damage while handling. The part is then placed in a furnace and infiltrated with bronze to replace the binder and fuse the powder particles together to create a fully dense and extremely tough part.
Design freedom may be limited due to the fact that parts are constructed from a bed of metal powder that must be able to clear, and parts will shrink when cooling. However, BJ3D typically has more design flexibility than Metal Laser Sintering (DMLS/SLM) because no support structure is required.
We’ve created some tips below with more information on how to make sure that your part is a great fit for binder jetting:
Wall thicknesses for BJ3D depends on if the wall is a supportive or non-supportive structure (e.g. text), and on the overall size of the part. For non-supportive structures, be sure to hold a thickness of at least 0.04” (1mm). Supportive wall thicknesses increases from 0.04” (1mm) to 0.125” (3.175mm) as part size increases up to 12”, so a general rule of thumb is to make sure to use as large of a wall as possible. Walls and features below the 0.04” (1mm) tolerance are at risk of blowing away or breaking off.
For non-supportive structures, be sure to hold a thickness of at least 0.04”
Like every other additive manufacturing technology, adding fillets is a great way to increase structural support for overhanging surfaces and part connections. Be sure to add the largest fillet possible to incorporate the largest amount of surface area between features.
Adding fillets is a great way to increase structural support for overhanging surfaces and part connections.
Cantilever surfaces, and supporting structures are extremely fragile when un-infiltrated and may break during depowdering and handling. Adding ribs will greatly increase the support strength and reduce the risk of breakage.
Adding ribs will greatly increase the support strength and reduce the risk of breakage.
Overhanging structures, walls without interior supports, or fragile features have the risk of breaking during depowdering or handling in the un-infiltrated state. To reduce the risk of breakage, utilize fillets, ribs, arches, and other self-supporting structures to increase structural integrity. Thickening fragile features if possible is another great way to prevent them from being blown away during depowdering.
A self-supporting structure