One to One Million: The Art of Scaling Metal 3D Printing with Precision

Prototyping is the genesis of and remains the strongest application for 3D printing. Going beyond, though, into final part production – particularly at scale – offers a full end-to-end workflow that more currently describes the goals for additive manufacturing.

Tuning that to the metal side of industry, the need to prototype, finalize, and scale into production for orders from one to one million parts is a major and growing focus. Sinter-based metal 3D printing is uniquely positioned to address these needs – and, in Holo’s case, is capable of doing so with incredible precision.

Sinter-Based Metal 3D Printing

When we talk about “sinter-based” technologies, we’re essentially discussing metal injection molding (MIM) processes that remove the mold.

These additive manufacturing (AM) processes include PureForm™ (Holo), binder jetting (like from Desktop Metal), Metal Jet (HP), and other bound metal printing (BMP) technologies. While each of these processes has its differentiating qualities and “secret sauce” to additively manufacture final metal parts, they have in common some essential qualities.

A unique approach to 3D printing in the front end of the process binds metal together. In the back end of each process, debinding and sintering stages are virtually identical to those used in MIM.

Precise Metal 3D Printing

As anyone familiar with AM well understands by now, 3D printing enables a certain freedom of complexity. Geometries previously impossible or requiring assembly can now be made in one part, in one print. Taking that capability to metal and scaling it both down (in terms of part and feature size) and up (in terms of volume production) is the major appeal for metal 3D printing as an industry solution.

When it comes to the mass production of complex, precise metal parts, turning to MIM without the mold opens up a new realm of possibilities.

Quality

In this context, “quality” is referring to fine-feature quality, encompassing precision, complexity, and dimensional accuracy of a final metal 3D printed part.

In order to attain the quality required for highly complex parts, the team at Holo stepped back to reexamine existing solutions and market needs. Approaching parts like spring arms for eyeglasses, grippers for a laparoscopic surgical tool, or, as seen above, finely threaded custom medical screws took some rethinking.

The PureForm approach utilizes a proprietary slurry of MIM powder and photoresistive polymer binder with high-resolution, high-throughput optical imagers. Understanding how to suit HD lithography printers to metal materials requires a lower metal loading due to issues of optical penetration. What could have been a bug in that lower metal loading, due to higher amounts of shrinkage, our engineers developed into a feature; resolution is improved because PureForm’s shrinkage is isotropic and predictable.

Predictability in final part dimension is vital, especially for the exacting industries we’re enabling, that require these finely detailed parts.

PureForm printing enables accuracy at typically 25µm (or 0.1% on a dimension), with a surface roughness of 1-3µm Ra, typically not requiring any finishing. That quality hits industry standard specs including MIF35 material properties.

Scalability

Another often-touted benefit of 3D printing on the whole is the capability of ramping up from prototype to production. Doing so at mass production scale has been a sticking point for wider adoption, but sinter-based metal 3D printing is uniquely poised to address volumes.

PureForm, for example, can hit cost points – at volume – that are lower than traditional manufacturing approaches like MIM or machining.

For certain geometries, this is also true compared to MIM at any volume. The removal of tool costs and requisite lead times also drastically slashes time and cost to production.

Especially working in a photopolymer process that can scale up, we like to say PureForm enables production of parts From One to One Million.

Ease of Deployment

MIM is familiar; that’s a given. Bringing PureForm™ into a MIM-familiar facility or production workflow is a smooth process, removing barriers to adoption along the way.

The end stages, including sintering, of sinter-based metal 3D printing already utilize MIM equipment like furnaces. Materials are also familiar – and, in the case of PureForm’s approach, are safe to handle, not requiring additional capital investment into powder handling equipment. The slurry approach removes barriers of safe handling or inert environments seen in many other metal AM approaches, again easing the deployment of a new production process.

The robustness of green parts also minimizes part breakage along the way, ensuring that volumes stay where they should be. With little-to-no secondary processing after sintering, PureForm also minimizes capital investment and operational costs related to fine finishing work.

Real-World Proven

Sinter-based metal 3D printed parts are already out in the world – at high volume.

We can’t speak to other technologies’ successes, but well over 10,000 PureForm parts have been shipped to customers in the medical, aerospace and defense, consumer, and semiconductor industries.

We’ve offered PureForm as a service as a vertically integrated supplier for some time now, and in 2023 introduced our H200 printer for direct sale as well for customers who want to produce their own parts in-house.

AMS 2024

I am looking forward to discussing these and many other aspects of Sinter-Based Metal AM at AMS 2024 alongside Ric Fulop, Co-Founder & CEO, Desktop Metal; and Ramon Pastor, Vice President and General Manager, Large Format Printing Business, HP.

Join us at AMS on day one, February 6, at 11:20am in Session 1: The Evolution of Series Production: Metals and Polymers, for Panel 3: Sinter Based AM, with moderator: Amy Elliott, Senior Scientist, Group Leader, Robotics and Intelligent Systems, Oak Ridge National Laboratory.