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RapidMade|How does the HP Jet Fusion (MJF) 3D Printer Work?

Table of Contents

HP Multi Jet Fusion Technical Overview

A disruptive 3D printing technology for a new era of manufacturing

Three-dimensional printing of useful objects and machine parts is becoming a reality. 3D printing offers the ability to produce—both rapidly and at low cost—short runs or one-of-a-kind parts. HP’s development of HP Multi Jet Fusion technology includes new HP Jet Fusion 3D Printers and an Open Platform that will revolutionize the design, materials, manufacturing, and distribution of 3D parts to drive the digital transformation of manufacturing.

Introduction

For more than 30 years, HP inkjet technologies have disrupted and led a broad range of printing markets. HP Multi Jet Fusion technology leverages HP’s deep assets in imaging and printing to take the digital transformation of printing off the page and into a three-dimensional world of highly-functional, high-value manufactured items.

HP Multi Jet Fusion technology offers high build quality at up to 10 times the speed and at the lowest cost relative to competitive 3D printing solutions in the marketplace today. These breakthroughs in quality and speed will accelerate the widespread adoption of 3D printing to create a digital transformation of manufacturing as widespread and profound as the way HP Thermal Inkjet has changed the landscape of conventional printing markets and applications. As with other HP products, HP Jet Fusion 3D Printers will offer users HP’s key values of reliability, ease of use, versatility, and an end-to-end digital workflow.

This article provides details on HP Multi Jet Fusion and HP’s strategies and vision to introduce a new era of digital manufacturing.

3D Printing

Whereas manufacturing by milling, grinding, and cutting removes material from a workpiece, additive manufacturing— “3D printing”—is a digital technology that creates objects by selective material addition. This allows each 3D-printed part to be unique in the same way that each page printed by an inkjet or laser printer can have unique content. 100% customized content page-to-page and part-to-part is a capability digital technologies bring to 2D and 3D printing.

Prime applications for 3D printing include the functional and aesthetic components of machines, consumer and industrial products that are manufactured in short runs of typically less than 1000 units, highly-customized and high-value products that can be one-of-a-kind, and parts with complex internal and external 3D geometries.

Before 3D printing, parts with complex surfaces, moving elements, and internal fluid passages were assembled from subcomponents that were aligned and assembled with fasteners and/or adhesives. In conventional parts—especially those designed to handle air and liquids—joints and sealing surfaces may be points where mechanical failure and leakage occurs. Because 3D printing builds objects from a stack of thin cross-sections, complex parts can be produced either as a monolithic structure or from many fewer subcomponents. 3D printing has the potential to simplify design and manufacturing processes and to reduce processing time and costs. Parts can be made by 3D printing that cannot be made by other methods, and this creates many new possibilities for innovations in design, form, and function.

To meet the needs of a broad range of applications, a 3D printing solution should offer the desirable attributes of high productivity, low cost of hardware, low cost per part, high build quality, and choices in materials and material properties for strength, elasticity, and other properties. While commercial 3D printers have been available for more than thirty years, adoption of 3D printing has been limited to niche markets and applications because all of these attributes have not been available from a single technology or 3D printing solution. Until now.

HP Multi Jet Fusion was conceived to overcome the tradeoffs and constraints limiting current 3D technologies. And,
HP Multi Jet Fusion has the unique ability to produce parts with controllable physical and functional properties at each point in a part. Offering speed, quality, strength, and novel functionalities, HP Multi Jet Fusion will accelerate the adoption of 3D manufacturing across a wide range of industries and applications.

HP’s vision is to revolutionize part design and manufacturing with streamlined workflows and new capabilities for 3D printing. The supply chain for finished, high-value items will be fundamentally changed by the ability to manufacture parts where they are needed and on-demand. HP’s Multi Jet Fusion Open Platform will bring down barriers to adoption of 3D printing through collaborative innovations in materials, printing hardware, and design and production software.

RapidMade|How does the HP Jet Fusion (MJF) 3D Printer Work?

HP Multi Jet Fusion Technology

HP Multi Jet Fusion is built on decades of HP’s investment in inkjet printing, jettable materials, precision low-cost mechanics, material science, and imaging. With custom materials and innovations in how a large working area can be printed and cured rapidly, HP Multi Jet Fusion delivers advantages in build speed and control over part and material properties that are beyond the capabilities of other 3D printing processes. By jetting HP functional agents using HP printheads, material in the working area can be fused, detailed, and transformed point-by-point.

Synchronous, scalable architecture for high productivity

A key innovation in HP Multi Jet Fusion is a high-speed, synchronous architecture that builds parts layer-by-layer. As shown schematically in Figure 1, dual carriages scan across the Working area in perpendicular directions: one carriage recoats the working area with fresh material, and the other prints HP functional agents and fuses the printed areas. This separates the processes of recoating and printing/fusing so that each process can be separately optimized for performance, reliability, and productivity.

RapidMade|How does the HP Jet Fusion (MJF) 3D Printer Work?

In an HP Jet Fusion 3D Printer, a part, or a set of parts, is built layer-by-layer over a working area inside an HP Jet Fusion 3D Build Unit. After job completion, the build unit is rolled into an HP Jet Fusion Processing Station for cooling, unpacking the parts, and recovery and refreshing the build material. While those processes are completing, a build unit that has been refreshed by the HP Jet Fusion Processing Station can be rolled back into the printer for continuous production.

The depth of the build unit and working area determine the dimensions of the largest part that can be produced. For example, HP Jet Fusion 3D 4200 and 3200 printers have a working area of 15W x 11.2D x 15H inches (380W x 284D x 380H mm) for a build volume of 2440 cubic inches (40 liters). 

HP Multi Jet Fusion uses scalable HP Thermal Inkjet technology to make print bars of different widths by stacking printheads across the width of the scan. Just as this capability allows HP to scale its 2D printing solutions from the desktop to more than 100 inches wide, HP can create a range of HP Jet Fusion 3D printing solutions with working areas of different sizes. HP printheads can also be stacked along the scan direction to add more nozzles for speed, functionality, and nozzle redundancy for dependable printing quality.

Building parts by HP Multi Jet Fusion

The build begins by laying down a thin layer of powdered material across the working area. For example, in Figure 1, the material recoater carriage scans from top-to-bottom. Next, the printing and fusing carriage with an HP Thermal Inkjet (printhead) array and energy sources scans from right-to-left across the working area. The leading energy source preheats the working area immediately before printing to provide consistent and accurate temperature control of each layer as it is printed. The printheads now print functional agents in precise locations onto the material to define the part’s geometry and its properties. The printing and fusing carriage now returns left-to-right to fuse the areas that were just printed.

At the ends of the scans, supply bins refill the recoater with fresh material and service stations can test, clean, and service the printheads on the printing and fusing carriage as needed to ensure reliable operation.

After finishing each layer, the surface of the work area retracts about the thickness of a sheet of office paper, and the material recoater carriage scans in the reverse direction for optimum productivity.

The process continues layer-by-layer until a complete part, or set of parts, is formed in the build unit.

Fusing and Detailing Agents

With HP Multi Jet Fusion, each layer of a part is defined by an area that is fused (or transformed) surrounded by unfused powder. HP 3D High Reusability PA 12 powder was designed to minimize powder waste and can be reused in a later build.

For high strength and surface quality, it is important that the new layer bonds to any previously-fused material below it and the edges are smooth and well-defined. This is accomplished with multiple agents applied by the array of HP printheads. Figure 2 takes a close-up look at the process described in Figure 1.

RapidMade|How does the HP Jet Fusion (MJF) 3D Printer Work?

The process begins by recoating the material in a thin layer across the work area, as shown schematically in Figure 2a.
Figures 2b-d represent what happens on the first scan of the printing and fusing carriage. Temperature at multiple points across the work area have been measured, and in Figure 2b energy is applied to the fresh layer to control the material temperature immediately before printing agents.

In Figure 2c, Fusing Agent (“F”) is selectively printed where particles will be fused together.

In Figure 2d, Detailing Agent (“D”) is selectively printed where the fusing action will be either reduced or amplified. In this example, the Detailing Agent reduces fusing at the boundary to produce a part with sharp and smooth edges. Agents are printed at 1200 dpi (X and Y) in HP Jet Fusion 3D 4200 and 3200 Printers.

In Figure 2e, the material is exposed to fusing energy, and selected areas now fuse. The fused material bonds to the layer below if that layer was fused on a previous cycle. Because HP Multi Jet Fusion can produce parts with Z-axis tensile strength comparable to the tensile strength in the X and Y planes, it overcomes the limitation of reduced Z-axis strength found in some other 3D printing technologies.

Figure 2f shows the fused and unfused areas at the edge of a part. The working area now retracts in preparation for the next recoating, printing, and fusing cycle.

Figure 2 is a general overview of the process steps in HP Multi Jet Fusion technology. In specific HP Jet Fusion 3D Printers, the order of steps may be rearranged and additional agents—Transforming Agents—may be applied during printing.

Pixels and voxels

Images in conventional prints and electronic displays are formed from pixels—picture elements. Pixels are the dots that are printed (or emit light) at a specific number per inch (“dpi”), at a specific size, and with a specific color.

The 3D analog of the pixel is the voxel, for “volume element.” In 2D printing, pixels are arranged on a surface in a regular grid. In 3D printing, voxels are also printed in a regular 2D grid and a voxel has depth. The voxels form a thin layer that is the image of a part’s cross-section, and many such layers are stacked to form a 3D object. Specifying the properties of each voxel defines a 3D-printed part point-by-point over its surfaces and within its volume.

An analogy between printing pixels in a monochrome image and printing voxels by conventional 3D technologies highlights the advanced capabilities of HP Multi Jet Fusion. In a monochrome 2D printer, a pixel is either printed or not, and in conventional 3D printers a voxel is either fused or not. HP Multi Jet Fusion advances 3D printing in the same way that adding color to 2D inkjet printing expanded the capabilities, applications, and markets it could serve. In 2D printing, multiple inks— cyan, magenta, yellow, and black—can be combined in pixels to print an image with a wide range of colors. Using multiple agents, HP Multi Jet Fusion prints voxels with a range of physical and functional properties—including color.

Figure 3 shows a 2D pixel and two (2) 3D voxels printed in layers 100 microns thick. HP Multi Jet Fusion can print up to 1200 voxels per linear inch in each layer. Figure 3 illustrates the analogy between monochrome 2D pixel printing and conventional 3D binary voxel printing. HP Multi Jet Fusion voxels are shown in color to signify the potential of HP Multi Jet Fusion to take 3D printing to new levels. The breakthrough of printing voxels whose properties can be individually controlled is made possible using HP’s Transforming Agents in the HP Multi Jet Fusion process.

RapidMade|How does the HP Jet Fusion (MJF) 3D Printer Work?
Transforming Agents

HP’s vision for HP Multi Jet Fusion technology is to create parts with controllably variable—even quite different— mechanical and physical properties within and across a single part or among separate parts printed simultaneously in the build unit. This is accomplished by the use of additional agents—called Transforming Agents—to control the interaction of the Fusing and Detailing Agents with each other and with the material to be fused. Depositing Transforming Agents voxel- by- voxel across each layer allows HP Jet Fusion 3D Printers to produce parts that cannot be made by other methods.


In HP Jet Fusion 3D Printers, properties that HP Transforming Agents could control within and across a part include

⦁ Dimensional accuracy and detail
⦁ Surface roughness, texture, and friction coefficient
⦁ Tensile Strength, elasticity, hardness, and other material properties
⦁ Electrical and thermal conductivity
⦁ Opacity or translucency in plastics
⦁ Color: embedded and at the surface

Figure 4 shows parts made by a future HP Jet Fusion 3D Printer that can print with color. Transforming Agents print combinations of CMYK primary colors in each voxel. Color can be 3-dimensional—within the part or on its surface—to produce visible indications when material is removed by wear or damaged. This allows visual inspection to determine if a part must be replaced, and embedded color can provide anti-tampering features. In addition to visible colors, materials that emit specific colors only when illuminated by ultraviolet light (e.g., quantum dots and fluorescent dyes) can provide unobtrusive or hidden text and codes for security, identification, and other purposes.


Using HP Transforming Agents to modify material properties, a part can have durable, hard surfaces with a low friction coefficient where contact and wear will occur, and different properties elsewhere to meet other functional requirements.


The ability of HP Transforming Agents to deposit conductive traces both embedded inside the part and on its surface offers the possibility of building intelligent parts that can measure and report their state during operation. For example, advanced HP Jet Fusion 3D Printers under development have built parts with embedded strain gage arrays—Wheatstone Bridges— that can accurately measure loads on the part during operation. This eliminates additional assembly operations, where strain gages must be precisely positioned and glued in place. Conductive traces can connect embedded and surface sensors with electronic circuits that process and report part status in real-time using visible indicators—such as light-emitting diodes—or by low-power wireless technologies.

RapidMade|How does the HP Jet Fusion (MJF) 3D Printer Work?
3D Materials

HP’s first Jet Fusion 3D Printers use HP 3D High Reusability PA 12, a strong, multi-purpose thermoplastic that optimizes build cost and part quality. With the HP Multi Jet Fusion process, this material can produce functional parts with excellent
mechanical properties,9 high dimensional accuracy,1 and fine detail. HP 3D High Reusability PA 12 is ideal for making parts with complex surfaces and internal shapes for housings, panels, enclosures, and connectors. And, it can make functional parts with moving subcomponents such as gears, rotational joints, and sliders.

HP’s material portfolio includes a family of thermoplastics for future generations of HP Jet Fusion 3D Printers that will include PA 11, PA 12 reinforced with glass beads, flame-retardant materials, and elastomers.

Ceramics and other materials compatible with the HP Multi Jet Fusion process are also being investigated and developed. Excellent feature resolution, high dimensional accuracy, hardness, wear-resistance, high strength, and high solid density after sintering are objectives of HP’s advanced 3D materials development activities.

 

Large pipe details printed 3d printer

HP Multi Jet Fusion Open Platform: collaborating to advance 3D printing

The goal of the HP Multi Jet Fusion Open Platform is to develop and foster industrial collaborations to drive the widespread adoption of 3D printing across industries.

Materials

The HP Multi Jet Fusion Open Platform enables partners including Arkema, BASF, Lehmann&Voss&Co., Evonik, and others to participate in the development of new HP Multi Jet Fusion materials. With their experience and understanding of a broad
range of customer needs and applications, these partners will accelerate the development and adoption of HP Multi Jet Fusion solutions, and offer manufacturing economies of scale that can reduce the cost of 3D printing supplies.

Software and workflow

The STL 3D file format, first developed in 1989 for the 3D printing solutions of that era, has shortcomings with long processing times and limited dimensional precision that pose barriers to the production of complex, high-precision parts by new technologies such as HP Multi Jet Fusion. STL cannot make use of the advanced capabilities of HP Multi Jet Fusion because it only allows geometric representations—and not a voxel-based description—to be sent from the CAD software to a 3D printer or other applications. To realize the full potential of 3D printing, new features and capabilities are needed in 3D CAD software, and this is an area where HP is actively contributing.


HP is a founding member of the 3MF Consortium,10 whose purpose is to define a new 3D printing format that allows 3D design software to communicate full-fidelity 3D models to other applications, services, and 3D printers.11 Industry leaders in 3D CAD, 3D printing, software companies, and selected customers are working together through the 3MF Consortium to develop a versatile and highly-capable 3MF file format.

HP 3D printing solutions include the HP SmartStream 3D Build Manager and HP SmartStream Command Center to prepare, send to print, and monitor 3D printing jobs. For part creation, HP offers 3D design software customized for HP Multi Jet Fusion from industry leaders Autodesk® (Autodesk® Netfabb® Engineer for HP) and Materialise Magics (Materialise Build Processor for HP Multi Jet Fusion).

Future Potential

Just as HP’s traditional printing solutions evolved from inkjet-based desktop printers in the 1980s to HP’s high-speed commercial and industrial printing solutions of today, HP research and development will drive the evolution of HP Multi Jet Fusion technology beyond the materials and capabilities of HP’s first-generation 3D printing products. HP is investing in long- term efforts and collaborations through the HP Multi Jet Fusion Open Platform to deliver 3D printing solutions with advanced capabilities, materials and material handling, and optimized 3D manufacturing workflows.

HP Thermal Inkjet technology underlies the productivity and capabilities of HP Multi Jet Fusion. To get a sense of the potential and scalability of HP Thermal Inkjet in 3D printing, HP’s 2D printing solutions stack HP printhead modules to build printers with four, six, or more colors of ink and offer a wide range of printing formats from 1 inch to more than 100 inches wide. Using HP Thermal Inkjet, future HP Jet Fusion 3D Printers will be able to deliver more kinds of functional agents and build parts in working areas even larger than today.

Summary

HP Multi Jet Fusion is built on HP’s core competencies in precision low-cost mechanics, precision metering and placement of agents, high-volume manufacturing, material science, and imaging. Compared to other commercially available 3D printing technologies, HP Multi Jet Fusion and its 3D printing materials will define new levels of part quality, part functionality, and offer up to 10 times the build speed2 at the lowest cost.3
A unique feature of HP Multi Jet Fusion is its ability to modify material properties voxel-by-voxel to produce controlledvariability in mechanical and physical characteristics within and across a part. This capability enables a host of new possibilities in the design and function of parts that cannot be produced by traditional manufacturing methods or other 3D printing solutions.
HP’s entry into 3D printing will offer users a 3D printing ecosystem with advanced user interfaces, software for 3D part creation and production, and 3D printers optimized to deliver end-to-end productivity and economy that will drive the digital transformation of manufacturing.

3D printer jet engine printed model plastic

1 Based on dimensional accuracy of ±0.2 mm/0.008 inches measured after sand blasting with HP 3D High Reusability PA 12 material, and with the following mechanical properties: Tensile strength at 45- 50 MPa (XYZ), Modulus 1600-1900 MPa (XYZ). ASTM standard tests with HP 3D High Reusability PA 12 material. See hp.com/go/3Dmaterials for more information.
2 Based on internal testing and simulation, HP Jet Fusion 3D average printing time is up to 10x faster than average printing time of comparable FDM & SLS printer solutions from
$100,000 USD to $300,000 USD on market as of April 2016. Testing variables: Part Quantity-1 full build chamber of parts from HP Jet Fusion 3D at 20% of packing density versus same number of parts on above-mentioned competitive devices; Part Size 30 g; Layer thickness: 0.1 mm/0.004 inches.
Fast Cooling enabled by HP Jet Fusion 3D Processing Station with Fast Cooling, available in July 2017. HP Post Processing Station with Fast Cooling accelerates parts cooling time versus recommended manufacturer time by SLS printer solutions from $100,000 USD to $300,000 USD, as tested in April 2016. FDM not applicable. Continuous printing requires an additional HP Jet Fusion 3D Build Unit (standard printer configuration includes one HP Jet Fusion 3D Build Unit).
3 Based on internal testing and public data, HP Jet Fusion 3D average printing cost-per-part is half the average cost of comparable FDM & SLS printer solutions $100,000 USD to
$300,000 USD on market as of April 2016. Cost analysis based on: standard solution configuration price, supplies price, and maintenance costs recommended by manufacturer. Cost criteria: printing 1 build chamber per day/ 5 days per week over 1 year of 30-gram parts at 10% packing density using HP 3D High Reusability PA 12 material, and the powder reusability ratio recommended by manufacturer.
4 For example: gears, sliders, rotating joints, and other kinematic elements.
5 Fast Cooling is enabled by HP Jet Fusion 3D Processing Station with Fast Cooling, available in July 2017. Material handling includes automated mixing of fresh and recycled powder, sieving, and loading. Consistent performance is achieved with reusing powder with a 20% powder refresh rate.
6 Continuous printing requires an additional HP Jet Fusion 3D Build Unit (standard printer configuration includes one (1) HP Jet Fusion 3D Build Unit).
7 The retraction of the working area, on the order of 100 microns, allows a new layer to be printed. The actual range of layer thicknesses that can be produced depends on the HP Jet Fusion 3D Printer. For example, the HP Jet Fusion 3D 4200 Printer can produce layer thicknesses between 0.07 – 0.1mm (0.0027 – 0.004 in.). For the latest technical specifications visit hp.com/ go/3Dprint .
8 With up to 80% powder reusability, HP Jet Fusion 3D print solutions with HP 3D High Reusability PA 12 deliver consistent performance with the highest postproduction surplus powder reusability compared to any other powder-based 3D printing technology using PA 12 material.
9 Tensile strength at 45-50 MPa (XYZ), Modulus 1600-1900 MPa (XYZ). ASTM standard tests with HP 3D High Reusability PA 12 material. See hp.com/go/3Dmaterials for more information on materials.
10 For more information, visit 3mf.io.
11 For more information, visit hp.com/go/3Dsoftware.

© Copyright 2016-2017 HP Development Company, L.P.
The only warranties for HP products and services are set forth in the express warranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shall not be liable for technical or editorial errors or omissions contained herein.

4AA5-5472ENW, Rev. 9, May 2017.