Published 9/12/2022

Understanding HP's Metal Jet: Beyond Part Geometry, Now It's About Modularity, Automation and Scale

Since introducing its metal binder jetting platform at IMTS in 2018, HP has made significant strides to commercialize the technology as a serial production solution. We got an early preview of the just-announced Metal Jet S100.

Stephanie Hendrixson

Executive Editor, Additive Manufacturing

Modular, Scalable Production Solution

First, it should be noted that the product on offer is not just a 3D printer, but a suite of modular equipment for production-scale metal binder jetting. Metal Jet S100 (“Solution 100”) actually includes four distinct stations, between which portable build units can travel (very much like the build units for the Multi Jet Fusion [MJF] platform that move between the printer and postprocessing station). With multiple printers and build units, customers can run continuous production and easily scale up. The components of the system are:

The Metal Jet S100 is not a single printer, but a full suite of equipment for metal part production. It includes (left to right): mobile build units, the Powder Management system, the Metal Jet 3D printer, the Curing Station and the Powder Removal system. Photo Credit: HP

Powder Management system, which automates blending, sieving, and loading fresh or reclaimed powder into build units without human contact. A single system can serve up to six Metal Jet 3D printers. The S100 is compatible with standard metal injection molding (MIM) powders; thus far HP has qualified 17-4PH and 316L stainless steels, with additional steels, nickel and cobalt alloys, and other materials in the works.
The Metal Jet 3D printer itself, which uses printheads similar to those applied in the MJF system to deposit binder into a bed of metal powder to build up “green” parts. The binder itself is an aqueous latex suspension or long-chain polymer. A distinctive feature of the printer’s operation is that it can jet the binder for each layer in two passes, which allows for greater infiltration into the powder; this approach combined with the binder chemistry provides greater strength to the green parts.
A Curing Station, which uniformly heats the build unit to cure the binder. Post-cure, HP says its binder jetted parts contain only about 1.5% binder by weight, depending on geometry.
The Powder Removal system, which uses ultrasonic vibration to remove and collect unbound powder from parts in a fully enclosed environment, so that it can be returned to the Powder Management system for reuse. Like the Powder Management unit, this system automates what can be a tedious and time-consuming step, allowing operators to focus on other tasks. And like the Powder Management unit, each Powder Recovery system can serve half a dozen printers; users can pick and choose the pieces of the solution they need, and scale accordingly.

Notably not included in the line-up is a sintering furnace, the necessary last step to fully solidify binder jetted metal parts. This is because the process is compatible with any commercial sintering furnace, from lab-sized units to large-scale production vacuum furnaces. Customers have the option to use equipment they may already have, or to outsource the sintering (the stronger nature of the green parts simplifies the prospect of shipping them for this step).

The modularity of the S100 is one of its key advantages. Users can scale up by adding the equipment as it is needed, and build out a factory such as this one suited to mass production. Photo Credit: HP

Users and Applications

The distinct binder chemistry and jetting process used in Metal Jet makes it possible to produce larger-than-typical components with this modality — exceeding 1 kg. This capability is no guarantee that prints will be economical at this size, Pastor says, but the range makes it possible to consider types of parts that would not previously have been a fit for binder jetting, or comparable processes like MIM. Like other forms of 3D printing, design freedoms are an advantage of the Metal Jet platform — but the company sees automation and efficiency as more significant.

Process step consolidation, rather than design freedom, is now the chief concern for metal parts producers.

“Customers are engaging not because of geometry, but because of process step reduction,” Pastor says. While binder jetting may require several stages, they are all part of the same additive manufacturing process and with a platform like Metal Jet can be automated and consolidated under the same roof; that means a faster, streamlined route to near-net metal parts.

Until now, fewer than two dozen companies have used the Metal Jet solution in testing. But the handful of these 22 companies that have been named publicly offer a glimpse of the kinds of users and applications HP anticipates. On the one hand, they are OEMs — Schneider Electric, Domin Digital Motion, Volkswagen and Legor. On the other hand, they are contract manufacturers — GKN and Parmatech. This is intentional, Pastor says.

While today most additive manufacturing equipment is owned by service bureaus and contract manufacturers, these companies tend to operate at a “tier one” level (GKN and Parmatech are examples of this), directly fulfilling orders placed by OEMs. Pastor (and fellow HP leaders) anticipate that the balance will shift as more OEMs become convinced by and committed to additive manufacturing, and at the same time, contract manufacturers will still remain important part producers. “We want to build factories,” Pastor says, and both these types of businesses — OEMs and advanced contractors — are well-positioned to adopt additive into full-scale production.

Identifying Part Candidates for Metal Jet

As to types of components suitable for Metal Jet, applications engineer Alejandra de la Hija has established five indicators for candidate parts over the last few years of working with early access partners:

Functionality/performance. Components like heat exchangers can achieve greater functionality through designs made possible by 3D printing, especially if they can be created from scratch for the Metal Jet process.
Size and weight. Lightweighting parts and reducing their mass has implications on material usage and product performance metrics like fuel economy, range and payload. The recommended size for a Metal Jet part is about the volume of a tennis ball, and weighing 500 to 600 grams.
Assembly. Consolidating several parts into one not only reduces labor, but also can simplify a product’s bill of materials and reduce the number of parts held in inventory.
Design variance. “Mass production can still be high-mix, low volume,” de la Hija says. With conventional manufacturing this would mean tooling up for each variation, but with additive it can mean developing part families with shared process parameters but slightly different geometries. Similar but different parts can still be produced together or with the same processes.
Cost efficiency. The ability to batch and stack parts with binder jetting offers some benefits over other metal 3D printing processes such as laser powder bed fusion where this is not possible, one of which may be lower cost. But it is also important to find applications where Metal Jet is more economical over conventional options, “otherwise, user leadership will eventually kill that project,” Pastor says. A good rule of thumb, according to de la Hija, is to think about complexity versus other processes; if a part would take more than four tool changes or setups to machine, it may be a good candidate for Metal Jet.

In most cases just one of these potential benefits is not enough reason to choose Metal Jet, but HP has collected a number of production part successes from its early access partners already that illustrate how they can work in tandem:

Metal Jet Early Access Partner Applications

This A-frame pillar for the Volkswagen T-Roc convertible is large for a binder jetted part, but nonetheless almost 50% lighter than the part it replaces. VW uses Metal Jet to produce this part for this weight savings but also for ease in manufacturing: it replaces 8 discrete parts, and the automaker can easily produce A-pillars in several different sizes without multiple sets of tooling or setups.

Schneider Electric is using 3D printed air filters like these made by GKN inside its NSX breaker. Metal Jet offers complexity that enables new power filter shapes that reduce gas, pressure and heat impact, while also providing productivity gains and environmental benefits.

Source: Schneider Electric

This putter head produced by Parmatech for Cobra Golf illustrates improved functionality and performance by virtue of controllable weight distribution and localized stiffening to provide better performance in terms of haptics and sound. Such a complex design would not be practical or cost efficient to scale with another manufacturing method.

Lumenium, a developer of general-purpose and hybrid electric engines in various sizes, produces high mixes of parts like these in low volumes. Metal Jet provides efficiency in producing these variations as many different part numbers can be packed into a single build. Parts can be manufactured as needed rather than in specified batches, reducing inventory and enabling responsiveness to customer demand.

Jewelry company Legor is an early adopter that has been working in precious metals along with stainless steels on the Metal Jet platform. Metal 3D printing is an alternative to a multi-step investment casting process for items like rings and watch cases, and could provide cost savings and sustainability benefits as well.