Four M’s of Additive Manufacturing

Four M’s of Additive Manufacturing

Introduction

3D Printing or Additive Manufacturing is transforming the manufacturing sector currently and soon it is believed that it will bring out lot of changes across different verticals.To unleash the potential of Additive manufacturing it is so important to understand the way it functions and its constituents. In this article, I shall try to explain the important components of 3D printing and also try to deep dive into four important factors that drive this Industry.

Important Components of Additive Manufacturing

  1. A CAD model of the final part or object which contains the design in a standard format( .stl mostly)
  2. Raw Material – Mostly it can be in powder form,filament, welding consumables and Liquid droplets.
  3. A mechanism or tool for laying materials
  4. A digital control system which transforms the raw material to end product which consists of several layers.

Factors Driving Additive Manufacturing

There are four important factors which drive the Additive Manufacturing Industry. They are

  • Making
  • Materials
  • Metrology
  • Market

The Making

AM is capable of producing fully functional parts in a wide range of materials including Metals,Ceramics,Polymers and Composites.Among these, polymers have been the “Adam & Eve” of 3D printing as the process itself evolved only with plastics for Rapid prototyping purpose. With dedicated research & technological developments,we were successfully able to 3d print metals,ceramics,composites, nano-materials and even materials of biological origin as well as pharmaceuticals.

But as per standards there are only seven process namely

  1. Binder Jetting( BJ)
  2. Direct energy deposition( DED)
  3. Material Extrusion( ME)
  4. Material Jetting( MJ)
  5. Powder bed fusion (PBF)
  6. Sheet Lamination ( SL)
  7. Vat polymerization(VP)

Below is a flow-chart representing the seven different AM technologies.

Image Courtesy : 3D Hubs

In AM,it is important to figure out the energy source for a particular type of process and its associated challenges. For example, If we use plasma arc for 3D printing Titanium alloys it is important to shield the component from oxidation.

Materials

Materials play a significant role in AM especially because the way AM handles materials is very different from the conventional manufacturing methods. The feedstock material for AM may be in the form of,

  1. Solid powder
  2. A Filament of standard diameters or lengths
  3. Wire consumables of standard diameters
  4. Sheets of standard dimensions
  5. Liquid or gaseous precursors

Feed-stock preparation would require customization to suit the particular end application and the intended technology. Obviously, we need feed-stock in filament form while carrying out FDM process and in powder form while doing SLS process. Even a slight variation in properties of the feedstock can significantly impact the properties of the final component.

Heating and cooling are the essential steps in Additive Manufacturing as heating fuses the material and deposits in a specific geometry whereas cooling controls the solidification pattern which in turns controls the microstructure and mechanical properties. In a certain process, it is wise to choose an AM process with less heat input such as Binder Jetting. But here it is important to select the binders in a particular viscosity and surface tension range as it plays a major role in determining the final part properties.

As concerned with AM, it might also be possible that the current material selection strategy is inadequate and may be many tailor-made or new materials have to be sought to suit AM of a certain product. So we have to make sure the material must be rightly designed for AM. For existing materials we have to rightly map the technologies for better results.

Ceramics being a material which can withstand high-temperatures without undergoing oxidation can be manufactured through powder bed fusion techniques(Single step process). In case we go for Binder Jetting (multi-step process), where the final part is manufactured after several stages there will be several challenges with respect to selecting the appropriate binder.

Polymers have been very popular as materials for AM as it is used in a wide range of applications. This has been the ‘go-to’ material for 3D printing due to its relatively low-melting point and excellent ability to flow when molten and its chemical stability.

Metal Additive Manufacturing has been evolved into a reliable and effective form of 3D printing over the past 20 years. The only challenge when it comes to Metal Additive Manufacturing is that metal particles are more susceptible to environmental degradation.Also post-processing must be given based on the thermal history of the component.

Composite and Hybrid materials have slowly started evolving recently. Composite manufacturing has been tried using Laminated Object Manufacturing (LOM) and FDM with dual nozzle extruders.

Measurement

Metrology in AM can be carried out inside the building chamber( in-situ) or outside the chamber ( ex-situ)

A schematic representation of metrological approaches in AM

In-situ approach integrates metrological tools along with the heat source or the nozzle to investigate the melt pool, deposition, freezing and consolidation. In-line NDT technique can also be developed to check the parts for any defects.

In ex-situ or Offline metrological approach, a part of the sample can be extracted out of the chamber for measurements and analysis.

The Market

Today AM is used in all sectors of Industries covering the basic food to shelter to clothing and represents a multi-billion dollar Industry. This technology high value low volume products with high design flexibility and low cost. This makes for way for the realistic expectation that,

“Additive Manufacturing cannot replace Conventional Manufacturing but it can complement it in all the possible ways”

This is the reason why some of the world’s biggest manufacturers like Airbus,Boeing,GE and Ford have looked upon AM as an important tool in realizing Industry 4.0.Globally,an estimated $ 642.6 million in revenue was recorded for AM goods.The potential of 3D printing to cut the dependency on labour-intensive process will enable it to play a significant role in Economies of developing countries.

Conclusion

Having discussed the four M’s in Additive Manufacturing it is important to address the challenges faced in ‘Materials’ and ‘Metrology’ which will automatically drive the‘Making’. There is also a significant Interest from Industry in taking up AM as one of the main production Engineering routes for the next generation.

References

  • Syed A.M.Tofail, ( Febraurary 2018).”Additive manufacturing: scientific and technological challenges, market uptake and opportunities“. Reference paper link
  • Ben Redwood.”Additive Manufacturing Technologies: An Overview“,3D Hubs,reference link

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