Will supporting design affect post-processing costs?

1. Basic ideas that back up the relationship between design and cost
The design of metal 3D printing support needs to find a compromise between "stable molding" and "cost efficiency." The main ideas behind it are directly tied to the expenses of post-processing:
The idea behind limiting contact area
There are three types of contact between support and parts: surface contact, line contact, and point contact. Surface contact can make things more stable, but it makes post-processing a lot harder. For example, titanium alloy aviation brackets with a surface contact design have a residual support area of 12cm², which needs 5 hours of manual polishing to meet the surface roughness requirement of Ra1.6 μm. With a point contact design, the residual area is only 2.3cm², and the mechanical polishing time is only 40 minutes. Suzhou Tianhong Laser's work demonstrates that for every 1 cm² decrease in contact area, the time needed for post-processing can be cut by 15% to 20%.
Exact control of the critical angle
various processes have various critical suspension angles: The SLM process normally needs support for structures that are hanging at less than 30 °, whereas the EBM process can loosen the critical angle to 35 ° because it melts at high temperatures. Leiming Laser's adaptive scanning method made it possible to print suspended structures without support at tiny angles of 5 ° to 35 ° by changing the laser power density on the fly. This cut down on the number of support materials needed by 78% and the cost of post-processing by 65%.
The idea of saving materials
The price of metal powder can go up to thousands of yuan per kilogram, and wasting supporting materials immediately raises prices. Using Inconel 718 nickel-based alloy as an example, standard support design leads to a waste rate of up to 18%, whereas the tree-like support structure created by topology optimization can keep the waste rate below 5%. An example of an aircraft engine part illustrates that the improved support design cuts the cost of a single piece of material from 2300 yuan to 850 yuan, a 63% drop.
2. Key elements that support design-driven post-processing costs
Supporting the risk of lasting physical injury
Tissue defects can happen when the support and the component interface have different amounts of thermal stress. When printing with 316L stainless steel, coarse columnar crystals can form where the grid support meets the solid. This makes the area 15% to 20% softer and cuts the fatigue life by 40%. To get rid of these concealed hazards, the heat treatment procedure needs to be longer, which means that the cost of post-processing for one piece will go up by 120 to 180 yuan.
The problem of making complicated structural support accessible
The turbine disk in the aviation engine has an inner channel diameter of only 2 mm. The standard support design causes the channel section to distort by more than 8%, which needs to be fixed through electrochemical dissolution. This technique needs a 41wt% nitric acid solution to be treated at 80 °C for 6 hours. The cost of one agent is 350 yuan, and there is a chance of corrosion uniformity.
The hidden expense of having to do things by hand
Data from the BMW IDAM automated production line shows that manual intervention is still needed to help with the removal process, which takes up 35% of the total post-processing hours. The labor cost is as high as 2.8 million yuan a year for a production line that makes 10,000 pieces a year. Rivelin Robotics' NetShape robot system uses force feedback control to reach a contact force accuracy of 0.1N level. This cuts the need for manual intervention to less than 5% and saves more than 2 million yuan a year.
3. Strategies on the frontier that help with design optimization
Structure that can stand on its own thanks to generative design
With the help of machine learning techniques, Autodesk Netfabb software can automatically construct biomimetic lattice support structures. This method cut the weight of a satellite bracket by 85% and got rid of the need for traditional support. It also changed the post-processing procedure from mechanical processing to simple heat treatment and cut the cost of a single piece by 1200 yuan.
Working together to come up with new ideas for multi-material systems
Belgian Materialise's bimetallic support technology uses the fact that Inconel 718 and pure iron oxidize at different rates at 800 °C to automatically peel off support. This method cuts the amount of support left over to less than 0.01mm, cuts the time needed for post-processing from 48 hours to 8 hours, and saves 650 yuan per piece.
Closed loop control of process tracking
High-speed cameras and infrared sensors in the Siemens Process Sight system keep an eye on the shape of the molten pool in real time. When there is a possibility of not enough support, the laser settings are changed automatically or extra support is created. When printing a complicated flow channel part, the technology cut the defect rate due to support from 18% to 0.3%, which saved more than 500,000 yuan a year in rework expenses.