Additive Manufacturing (AM) has transformed traditional manufacturing by introducing design flexibility, material efficiency, and opportunities for performance optimization. However, achieving consistent quality, especially at scale, remains a challenge. To meet this challenge, the standard response from industries working with mission-critical applications such as aerospace, nuclear, medical, etc., is to post-process components in Hot Isostatic Pressing (HIP). Doing this eliminates any internal pores, voids, microcracks, and Lack of Fusion (LoF) defects, thereby improving mechanical properties, and enabling the highest possible component reliability for the respective applications.
Achieving a substantially higher manufacturing rate, especially for the PBF-LB technology, can reduce cost significantly whilst combining the best features available in AM: To design components having small-sized features and produce these at volumes, with minimal lead time and low cost.
A large part of AM research and development in the past years, particularly the PBF technology, has been focusing on improving deposition rates, using strategies such as multiplication of melting points (e.g., parallel lasers), optimization of the heat source (e.g., beam shaping), improvements to raw materials (e.g., flowability and packing) and specific deposition strategies (e.g., printing during powder spreading), etc. The combined effect of these improvements has resulted in a substantial increase in deposition rate on a Moore’s law path. However, it is still considered too slow and expensive for many high-volume applications, preventing these from evolving through using basic AM possibilities.
Solving the Productivity - Quality Dilemma when Increasing Processing Speed
Current and available improvements in AM deposition rates could be multiplied using a combined AM + HIP manufacturing strategy (Figure 1), presenting great opportunities for cost-effective, high-volume manufacturing. The technical feasibility of this strategy has been proven in multiple research activities from renowned institutes and universities around the world (see reference list), showing the different opportunities available to address basic AM productivity issues, while achieving a quality level usually exclusive to mission-critical applications. This opens opportunities for additive manufacturing of high volume, cost-sensitive applications, in using lightweight component design, improving manufacturing cost, lead times, material utilization, and energy savings.
Ramping up PBF productivity to fully absorb a HIP CAPEX
When working in R&D, it is realized that there, too often, is a discrepancy between what is technically feasible and what is economically viable, a fact that will be a discouraging obstacle for further innovations. The “speed printing” strategies have shown possibilities to ramp up PBF deposition rates a factor up to ten (10) times the standard printing rate, intuitively making it the way to go when setting up an AM manufacturing flow. However, this is not the case for single prototypes and low series production of components having a low ratio between printing time (actual time the printer is building the component) and the total time the printer is occupied (load/unload, gas purge, etc.).
For large-scale manufacturing however, that is when the actual build time constitutes the significant part of the total printer busy time, printing multiple components on one build plate, using multiple parallel printers and when printing large, single components that takes days or even weeks to print, it is obvious that even small improvements in deposition rate will have major impacts on the volumes possible to produce.
Calculating different high-volume printing scenarios makes it possible to visualize (Figure 2) when the added benefits from using the AM + HIP scenario reach the HIP CAPEX break-even point (“HIP for Free”). That is, the payoff scenario necessary to motivate adopting the strategy in the first place.
Already when increasing the print rate by a factor of 1.25 (e.g., using the PBF-LB parameter window as shown in work by Herzog et al) it can be shown that the strategy makes financial sense in high-volume scenarios. That is, producing AM technology-enabled parts, and getting HIP-quality components, at no additional cost.
Further improvements ready for implementation
In addition to the potential cost reductions presented by the AM + HIP strategy, modern HIP equipment can offer features that make further process integrations possible:
In-situ heat treatments: Performing heat treatments in the HIP unit during the densification process, leaving the components on the build plate (when feasible), performing necessary heat treatments (stress relief) and specific heat treatments (enhancing mechanical properties) adapted to the specific alloy being processed.
Clean HIP: Reducing surface oxidation during HIP/heat treatment using Quintus Purus® to eliminate the need for additional costly, time-consuming, process steps. A notable benefit especially for titanium alloys prone to form a brittle alpha case surface layer during standard HIP processing.
Exploring novel strategies: Using LoF defects for initiation of recrystallization or partially melting powder particles to minimize influence from prior particle boundaries (PPBs) in near net shape (NNS) -like printing scenarios.
Low-hanging fruit and Remaining challenges
Having an operation already up and running using PBF and HIP as mission-critical industries e.g., medical implants for the large joints, will have obvious and immediate benefits from implementing a speed-printing strategy. This can achieve a substantial production volume increase without the need for increasing CAPEX. However, to harvest the opportunities as presented, there are also some deposition technology-specific factors to consider and sort out to choose the best strategy for the intended application and material:
1. Printing process gas or vacuum
- High levels of entrapped argon gas may reduce fatigue and impact energy properties (although limits have not yet been defined).
- Nitrogen process gas can be used for additional in-situ alloying for some materials and allows for higher porosity after printing
- Printing in a vacuum will allow for a full PM-NNS strategy (PBF-EB)
2. Shell printing (printing a gas-tight shell and leaving loose powder inside)
- Design for sufficiently smooth shell–core transition to handle macro textures in melted powder–sintered powder interface
- Reproducibility in powder compaction and accurate shrinkage calculations
As these factors are known with consequences and solutions investigated in the referenced research, awareness will make it possible to navigate to the correct strategy for speed/quality optimization
Conclusion
The integration of Additive Manufacturing (AM) and Hot Isostatic Pressing (HIP) can represent a significant advancement in manufacturing, presenting a new level of application-specific optimization of design, productivity, and quality. Bridging the gap between technical feasibility and economic viability can transform challenges into opportunities, enabling high-volume, cost-sensitive industries to harness the full potential of modern production technologies.
With the AM+HIP approach, manufacturers can achieve component reliability and scalability, combining the best of two worlds, and redefining the possibilities for diverse sectors, from aerospace to automotive.
The future lies in embracing this integrated strategy, not just as a solution to existing limitations but as a foundation for sustainable, efficient, and transformative manufacturing practices. As adoption grows and technological advancements continue, AM+HIP will undeniably be an important part of industrial production of the future.
Read the full whitepaper at Whitepaper ǀ HIP for free: Speed printing unleashed
Author Anders Magnusson Business Development Manager and Technical Advisor – Quintus Technologies