Post-machining is an integral part of the secondary post-processing for parts created using HP Multi Jet Fusion (MJF) technology. It involves various machining techniques to enhance dimensional accuracy, refine geometric tolerances, and improve surface finish. This article provides an overview of post-machining processes, each crucial for achieving precise specifications and high-quality finishes in MJF parts.
Surface Grinding for Flat Surfaces:
Surface grinding is an abrasive machining process used to create flat surfaces with fine finishes and accurate tolerances. It involves removing material from the part’s surface using a grinding wheel or disk.
- Design Considerations: Parts need additional material on machined surfaces to achieve desired results. The recommended additional thickness is at least 0.5 mm.
- Outcome: Achieves very flat surfaces with a high degree of finish and accuracy.
Milling for Enhanced Surface Quality:
Milling is a versatile machining process that uses rotary cutters to remove material from a part. It’s used for achieving tighter tolerances and glossy surface finishes.
- Machining Parameters: The recommended parameters include cutter types, feed rates, and speeds, which vary depending on the part’s geometry and the desired surface quality.
- Result: Produces parts with improved surface roughness (Ra values), reaching up to 0.30 µm.
Turning for Cylindrical Parts:
Turning is a machining process where the part is rotated while a cutting tool moves in a linear motion. This method is ideal for cylindrical or round parts.
- Accuracy and Surface Finish: Turning can achieve high geometric accuracy and surface finish, with roughness values reaching up to 0.60 µm.
- Application: Particularly effective for improving concentricity, perpendicularity, and parallelism of cylindrical parts.
Achieving Precision in Small Features:
Post-machining allows for the implementation of small features like threads, ensuring accurate and repeatable results. This is crucial in applications where very tight tolerances are required.
Enhancing Geometric Tolerances:
In addition to dimensional accuracy, post-machining processes like grinding, milling, and turning can improve geometric requirements like flatness, concentricity, perpendicularity, or parallelism.
Importance of Post-Machining in MJF:
While MJF technology offers impressive accuracy and detail, post-machining processes are essential for applications that demand ultra-precision and high-quality surface finishes.
Post-machining plays a pivotal role in the secondary post-processing of MJF 3D printed parts. By employing techniques such as surface grinding, milling, and turning, manufacturers can enhance the precision, surface quality, and geometric tolerances of their parts, ensuring they meet the most stringent requirements of various applications. This advanced level of finishing opens up new possibilities for MJF technology in high-precision industries.