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Design for Additive Manufacturing


Design for Additive Manufacturing

Approach your 3D printing designs with a Design for Additive Manufacturing mindset and unlock the full potential of your industrial 3D printer.

The importance of 3D printing designs

Design is the starting point for any industrial 3D printer process and will determine the success or failure of the final 3D printed output. When designing a part for additive manufacturing, it’s important to consider everything we’ve discussed in this guide, including the materials and processes that you intend to use. Each manufacturing process has specific design rules, guidelines, and constraints that a prototype or final part design must conform to.

What are the best design methods for the additive manufacturing process?

The overall method of creating 3D models for printing is known by the useful shorthand of Design for Additive Manufacturing (DfAM). This is a general set of principles and guidelines that will help any designer optimize designs for the constraints and attributes of the final object, taking into account the material used and the specific type of 3D printing process.

To help you understand the possibilities that DfAM can offer, and begin to plan for the design process, it's helpful to break it down into the following elements:
 

  • Part consolidation
  • Design freedom
  • Biomimicry

 

We will talk about these sections in detail below.

Part consolidation made possible with 3D printers

Reducing the number of parts in an assembly can speed up production and lower costs of the end product, especially if the differing parts are being produced by different companies or made using different manufacturing technologies. Consolidating assemblies can also improve the performance of the product, part, or object - increasing durability by having fewer seams, tighter tolerances, and reduced part interfaces, allowing less vibration and fewer paths for leaks. There can also be a weight reduction effect created by eliminating fasteners like nuts and bolts to hold different parts together.

Part consolidation case study

At HP, we are pioneering the use of HP Multi Jet Fusion (MJF) 3D printing technology to streamline processes throughout HP’s own supply chain. Our supply chain and engineering teams have identified myriad opportunities where 3D printing with HP MJF can replace traditional manufacturing methods.

An example is a tool in HP’s printhead manufacturing line – the drill extraction shoe. The nozzles of HP printheads are manufactured with a laser-cutting process, a process that uses water to prevent overheating of the laser and the silicon plates. The drill extraction shoe is used during cutting to remove the silicon sludge and water that continuously appears, enabling a more efficient laser-drilling process. Sufficient extraction pressure (~3 to 4.5kPa) and a clean extraction shoe are needed for proper laser drilling. The tool must withstand a certain amount of heat caused by stray laser pulses during the drilling process. As can be seen in the picture, the original CNC machined tool on the left is made of seven sub-parts, most of them mechanized from an aluminum block and two of them extruded from aluminum. 

The HP MJF redesigned part is on the right and has been consolidated into a single part. HP MJF helped enable:
 

  • The watertightness required for manufacturing aids that contain pressurized fluids, without needing to post-process or coat the parts 
  • The design to be optimized to reduce turbulence in the part using finite element analysis. The shape of the end of the pipe has been modified to optimize the flow during the section transition
  • Cost reduction of 95% versus the original part1
  • Weight reduction of 90% versus the original part thanks to topology optimization and material reduction2
  • Lead-time reduction from 3-5 days with CNC machining to just 24 hours with HP MJF
  • Assembly reduction by consolidating seven sub-parts into one single part

New design freedom thanks to 3D printers

Traditional manufacturing methods can often force designers and engineers into geometries that are easy to fabricate, such as the hard angles and circular holes produced by CNC machines. This can mean however that the final object is designed around the manufacturing method, and not around the need of the object being created. 3D printing turns this on its head. It gives designers the freedom to make a part based on the requirements after final object is made. It creates new possibilities for designers and allows them to work with a new level of complexity, often without additional cost.

With 3D printing, engineers are free to focus on the design of components and spend less time considering the limitations of manufacturing. 3D printed components have fewer stress points, smaller footprints, and overall better mechanical properties. Additionally, they can employ generative design and topology optimization tools, which let engineers set parameters including mount points and environmental stresses. It is also possible to reduce design time with geometries that are generated by Artificial Intelligence (AI) and run through a series of simulations to decide the optimal design.

3D printing can produce complex, lightweight geometries that were not possible with traditional manufacturing. This enables lighter parts with better performance, thanks to lattice structures and topology optimization. Moreover, 3D printing materials are often lighter than those available in traditional manufacturing.

Design freedom case study

With HP MJF 3D printing, a part’s weight can be reduced while still maintaining its robustness. This is because HP MJF can produce parts that have nearly the same mechanical properties3 for the XY axes compared to the Z axis. Therefore, in the design process, there is no need to factor in mechanical behavior. The example below shows an internal part from an HP large-format printer, originally produced with CNC (the part on the left), that has been redesigned for HP MJF (the part on the right), enabling a 50% cost reduction, 93% weight reduction, and 95% carbon footprint reduction.4

Design optimization to enable lightweight parts helps improve machinery and production line performance. This can ultimately contribute to increased energy efficiency, higher throughput, longer equipment lifespan and reduced maintenance costs. Unique, non-standard parts with geometric complexity can be produced easily, so that machinery and production line manufacturers can provide customized solutions adapted to each machine and floorplan dimension. Unlike traditional production methods, with HP MJF customization or geometric complexity, even for low volumes, do not imply incremental time or cost increases.

Design for Additive Manufacturing (DfAM) case study

FICEP Steel Surface Systems (S3) is a high-tech engineering, research, and development company and a leading manufacturer of machines for structural steel fabricators. FICEP S3 also provides installation and maintenance services for steel fabricating equipment. In addition, it provides after sales service and spare parts, including 3D printed parts using HP MJF technology.

The daVINCI Automatic Paint Line primes and paints structural steel. During the development of the paint line, FICEP S3 faced several constraints and decided to see if they could be resolved using HP MJF technology. In some cases, the parts used in the Automatic Paint Line were too complex for machining. In others the weight of producing them in metal put too much stress on the rest of the system. The company also looked at injection molding, but also found it to be less than optimal. Part of the problem was complexity. In one example, a mold would have needed 11 different components just to be manufacturable. On top of that, each time a change was required, molds would have to be remade.

The other problem was strength. With a traditional process like injection molding, they couldn’t make parts that were strong enough to support the rigors of daily use–especially because of the weight concern associated with other parts. They needed to create several parts that together were of lighter weight, permitting faster movements and more precision. The parts also needed to be mechanically strong, and resistant to chemicals and temperature fluctuations. 

HP MJF helped enable FICEP S3 to:

 

  • Optimize the design of a robotic arm from the Automatic Paint Line to reduce its size allowing for shorter acceleration and deceleration, improving the line’s overall precision
  • Reduce the overall weight of the machine. FICEP S3 estimates it yields a 72% savings in energy when compared with competitive machines
  • Redesign the brackets that support the robotic arm and identify over 40% of the parts in the Automatic Paint Line that could be improved,  including pulleys, axles, and structural components
  • Manufacture spare parts quickly and at a low cost, without having to maintain a large inventory 
  • Customize parts for specific needs depending on the application

Data courtesy5

Biomimicry for 3D printing

In nature, biological systems have had millions of years to specialize certain functions and to solve certain mechanical problems. Just like these natural systems have been mimicked in architecture and art (Art Nouveau as a concrete example), oftentimes it is possible for modern manufacturers and designers to learn from and adopt these natural solutions into their product designs. This process is known as biomimicry.

However, one of the key challenges for biomimicry is that traditional manufacturing only allowed for the creation of low complexity objects. Imagine, for example, the incredible complexity of the honeycomb shape, inspired by the interior of a beehive. To make this shape by most manufacturing methods would be extremely difficult, as well as time and cost intensive. 

3D printing changes that dynamic and makes biomimicry possible. This opens up countless doors for designers and manufacturers alike and is helping to deliver innovative solutions to some of the world’s most complex problems.

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Footnotes and disclaimers

  1. Cost reduction data according to HP: Cost per part: CNC machined $450. HP MJF $18.
  2. Weight reduction data according to HP: CNC machined part weight 575 g. HP MJF part weight 52 g.
  3. Based on HP’s unique multi-agent printing process. Excellent dimensional accuracy and fine detail within allowable margin of error. Based on dimensional accuracy of ±0.2 mm/0.008 inches on XY for hollow parts below 100 mm/3.94 inches and ±0.2% for hollow parts over 100 mm/3.94 inches, using HP 3D High Reusability PA 12 material, measured after sandblasting. See https://www.hp.com/go/3Dmaterials for more information on materials specifications. Based on the following mechanical properties: Tensile strength at 48 MPa (XYZ), Modulus at 1700 -1800 MPa (XYZ). ASTM standard tests with HP 3D High Reusability PA 12 material. See https://www.hp.com/go/3Dmaterials for more information on materials specifications.
  4. Cost reduction calculated based on: Aluminium machined part = $22, MJF part = $11. Weight reduction calculated based on: Aluminium machined part = 355g, MJF part = 23g. Carbon footprint reduction calculated based on: Aluminium machined part carbon footprint: 19.7 kg CO2 eq. MJF part carbon footprint: 0.97 kg CO2 eq
  5. Data courtesy of FICEP S3