What are the processes and advantages of metal 3D printing?

What is the process of metal 3D printing

Powder Removal: AM parts build “down” in a powder-bed fusion system as new layers are added to the top, which means that parts are buried in powder when they are done. After the build has finished and the parts/build plate have cooled, the machine operator has to remove all of the powder from the build volume and sieve/filter/recycle it for later use.

Stress Relief: The heating and cooling of the metal as the part builds layer-by-layer leads to internal stresses that must be relieved before the part is removed from the build plate. Otherwise, the part may warp or even crack. Stress-relieving the part requires an oven or furnace (preferably with environmental controls) that is big enough to fit the entire build plate.

Part Removal: Most companies use wire EDM to remove parts from the build plate, however many machine shops are starting to use a bandsaw because it is faster and the bottoms of the parts must be finished anyway.

Heat Treatment: Heat treatment (aging, solution annealing and so on) improves the microstructure and mechanical properties of the parts and is necessary for nearly all AM parts. In many cases, this step also requires an environmentally controlled furnace with the ability to regulate the temperature and cool-down schedule. Heat treatment may affect the dimensions of the parts, so most people prefer to heat-treat parts before they machine/finish them.

Hot Isostatic Pressing: Instead of heat treatment, many aerospace companies are starting to use hot isostatic pressing (HIP), which is frequently used in the casting industry to improve the fatigue life of cast parts. A HIP system costs substantially more than a furnace/oven and comes with its own safety measures due to the high pressures (100 megapascals or more) at which it operates. Like heat treatment, HIP costs $500 to $2,000, but you often do not need to heat treat the part if you HIP it.

Machining: Machining of mating interfaces, surfaces, threads, support structures and more likely will be required to ensure dimensional accuracy of the finished part. Few AM parts meet specifications “as built,” and if nothing else, the surface of the part that was connected to the build plate will need to be finished.

Surface Treatments: Surface finishing also might be required to improve surface finish/quality, reduce surface roughness, clean internal channels or remove partially melted particles on a part. When outsourced.

Inspection and Testing: Metrology, inspection and nondestructive testing using white/blue-light scanning, dye-penetrant testing, ultrasonic testing, computed tomography (CT) scanning and more will be needed after post processing and possibly at multiple points during post processing. Destructive testing of sample parts and analysis of witness coupons (for example, tensile bars), powder chemistry, material microstructure and more also may be needed to gather data to help with process qualification and ultimately part certification.

Post-Process CNC Machining to Improve Tolerances and Surface Finish
Like many 3D printing processes, support structure removal is required on DMLS parts. Typically parts are first removed from the build plate using wire EDM or a band saw and then support structure material is removed with hand tools. That works well in many cases, but sometimes additional machining options can be necessary for critical features that require tighter tolerances or improved surface finishes.

In general, the DMLS process can produce parts with tolerances of ±0.1 to 0.2mm plus for each additional mm. But with post-process CNC machining, tolerances as tight as ±0.05mm can be achieved. In order to machine these features, a drawing must be provided in addition to the CAD file that calls out the features and required tolerances. During the quoting and design review stages, one of our applications engineers will review the file to determine if the stated tolerances are achievable.

Post-process machining can also be used to improve surface finish quality. As-built surface finish roughness on DMLS parts can range from 3µm to 12µm Ra depending on orientation, material, and layer thickness. Through post-process CNC machining, a surface finish of Ra 0,8µm is possible.

The added precision of CNC machining lends itself well to producing holes and threading as well. For most metals, we recommend designing tapped holes no smaller than M1.6 or diameter 1.00 mm.

What are the benefits of 3D printing metal?
Cost per part is consistent at low and high volumes
Complex parts are not more difficult to 3D print than simple parts.
Metal 3D printing can create parts that are impossible to make with any other fabrication method.
Metal 3D printing cost per part is the same at low and high volumes

conventional fabrication has high cost per part at low volumes
In virtually every manufacturing method, cost per part drops significantly as part volume increases.

Metal 3D Printing subverts this by utilizing a largely automated process that incurs almost no overhead costs. There’s minimal extra upfront labor in printing the first part over the 100th, and the system uses the same amount of consumables on every part.
3D printing has a stable cost per part and is not dependent on print volume. As a result, it can be the most economical way to product low volume parts.

In metal 3D printing, complexity is free
Years of design for manufacturing training have left most engineers hard coded to design parts that are as simple to fabricate as possible. The justification behind this is as simple as it is economical: for the vast majority of fabrication processes, added complexity equals added cost. Complex parts require more work to program machines, more advanced machines to do the fabrication, and take more time to complete. Across most fabrication methods, this stays remarkably consistent; everything from mills to cast parts are affected. Metal 3D printing is not.

3D Printers can make parts no other machine can
Every fabrication method has limits — 3D printing is no exception. However, due to its unique process, metal 3D printing is capable of fabricating parts that cannot be made with any other platform. The result is parts that can be truly optimized for their use case rather than limited by traditional manufacturing constraints.

WKproto is a professional rapid prototyping and low-volume production manufacture specializing in 3D printing, CNC machining, and Vacuum Casting. Our factory and parter factories enable rapid prototyping of designs from our customers and low volume production for market verification.

We have three factories. 3D printing factory meets the demands of most 3D printing services with 100 SLA machines, 10 SLS machines, 10 MJF machines, 10 SLM machines, and 20 FDM machines. CNC machining factories for processing metals, plastic and more materials with more than 200 machines for CNC milling/CNC lathes/EDM / Wire EDM and the Vacuum Casting factory is for low volume production for ABS、PC、PP、PE、PA、POM、PMMA、PVC.