Saturday, March 16, 2013

3D Printing: Hype or New Manufacturing Revolution?

Lately 3D printing has been in news a lot. People are talking about using 3D printing to fabricate a wide variety of artifacts including shoes, robots, drones, cupcakes, and kidneys. Is this just hype or a new manufacturing revolution? To answer this question let us review the desired characteristics in a manufacturing process. My personal wish list includes the following:
  1. No lead time
  2. No part-specific tooling
  3. No specialized expertise needed to run the processing equipment
  4. No setup time
  5. Low processing time (laws of physics prohibit wishing for zero processing time!)
  6. Low material cost
  7. Low equipment cost
  8. Low operation cost
  9. Ability to realize arbitrarily complex shapes
  10. Ability to process any material
  11. High accuracy
  12. No negative environmental impact
Now let us examine how 3D printing fares with respect to my wish list. 3D printing does not require any part specific tooling, complex process planning, or elaborate setup step. Instructions for driving 3D printers can be automatically generated from 3D CAD models in matters of seconds. Using most 3D printers does not require any specialized skills. Fabrication can begin within few minutes after getting the 3D model. So 3D printing looks very attractive in terms of items #1 through #4 in the list above.

3D printing is a slow process. So printing a large part takes a long time. Forming and consolidation processes such as stamping, molding, and casting are much faster in terms of processing time for making large parts. But for making small parts, 3D printing appears to be quite competitive because overall processing times are small. 3D printing is also quite attractive in terms of processing time for making large intricate parts in comparison to subtractive processes such as milling. For such parts, subtractive processes tend to be slow because they need to remove a large volume of material to create the final part shape.

Currently, many 3D printers use proprietary materials. So the material cost tends to be high. However, this is not an inherent limitation of 3D printing. As more companies compete in this space, the economy of scale should bring the material cost down.

Open source designs of 3D printers have led to a drastic reduction in prices for certain types of 3D printers. Currently there are 3D printers in the market that cost less than $1000. This development has made this technology accessible to a wide variety of users. High-end 3D printers are still very expensive. There are significant opportunities for developing low cost 3D printers that work with metals and high strength polymer materials.

The processing cost is a function of human labor cost, equipment cost, hourly operation cost and processing time. As discussed earlier, 3D printing does not require much human labor. Open source movement is bringing down the equipment cost. So the energy cost is the main component of the hourly operation cost. 3D printer power consumption is comparable to other manufacturing processes. So the main driver for the processing cost is processing time. As discussed earlier, 3D printing is a slow process. Therefore, processing costs tend to be high for making large parts. Most 3D printers require post-processing operations to clean parts. This step leads to additional costs.

3D printers are able to fabricate very complex shapes. Moreover, the increased geometric complexity of the part does not lead to increased cost in the world of 3D printing. This encourages use of parts with intricate internal cavities to enhance performance and reduce weight. The reduction in the amount of material used in the part also helps in realizing more sustainable products by minimizing the material use. However, designing geometrically complex parts manually using the current CAD systems is a very tedious and error prone task. So we will need to develop automated shape synthesis tools that can automatically create new shapes from the functional requirements to fully exploit the capabilities of the 3D printing technology.

Currently 3D printers offer limited material choices. In fact, most 3D printers only work with low grade plastics. There are few printers in the market that work with a selected number of metals. Increasingly, composites are being used in a wide range of products including aircrafts and automobiles because of their high strength, light weight, and corrosion resistance. The next generation 3D printers will need to be able to process polymer composites and a richer variety of metals.

3D printing is a process in which a part is build layer-by-layer. So layer thickness determines the part accuracy. It is possible to achieve reasonably high accuracy using 3D printing by using very small layer thickness. But this leads to high processing time and high processing costs.

Many different types of 3D printing processes exist with different levels of environmental impact. There exist 3D printing processes that have virtually no negative environment impact except the energy consumption. So clearly, eco-friendly 3D printers are possible. However, reducing the energy consumption will require significant further development in this area.

3D printing is expected to be useful both for in-home manufacturing and factory production. In fact 3D printing can be used to make tooling (e.g., mold and patterns) for traditional processes. It has already enabled e-commerce in the manufacturing sector. Designers are able to buy 3D printed parts over the Internet.

Facilitating the increased in-home use of this technology will require making this technology much more user-friendly. CAD systems are often used to create 3D models to be printed on 3D printers. People with limited technical expertise find CAD systems hard to use. CAD system user interface has to improve significantly in terms of user friendliness for a lay person to effectively utilize 3D printers for in-home use. The improved interfaces will enable the use of 3D printing in K-12 schools. It will also enable people with limited technical background to participate in the invention process.

So in summary, 3D printing has many desirable characteristics. It meets many unfilled needs in the market. So it is here to stay!

But let us remember that 3D printing is not a perfect process. In my opinion, 3D printing is a precursor to a new manufacturing revolution. Let us take inspiration from it and continue to look for a process that has all the desirable characteristics in the wish list presented above!