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Lecture

Issues with STL; DFAM

In course

ME-413: Introduction to additive manufacturing

The state of the art in the domain of additive production processes (the part is built by material addition without use of a shape tool) will be presented. The main application/benefits/shortcomings of the common additive processes as well as technologi ...

Description

This lecture covers the known problems related to the .STL format, such as the redundancy issue caused by rounding errors, alternative solutions to store .STL-like infos, control of .STL format regarding deviation height and minimal angle, issues with parts having high aspect ratio or being multimaterial. It also discusses Design for Additive Manufacturing (DFAM), typical mistakes to avoid, expected gains, and paradigm modification in manufacturing.

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Instructors (3)

Jürgen Brugger

I am a Professor of Microengineering and co-affiliated to Materials Science. Before joining EPFL I was at the MESA Research Institute of Nanotechnology at the University of Twente in the Netherlands, at the IBM Zurich Research Laboratory, and at the Hitachi Central Research Laboratory, in Tokyo, Japan. I received a Master in Physical-Electronics and a PhD degree from Neuchâtel University, Switzerland. Research in my laboratory focuses on various aspects of MEMS and Nanotechnology. My group contributes to the field at the fundamental level as well as in technological development, as demonstrated by the start-ups that spun off from the lab. In our research, key competences are in micro/nanofabrication, additive micro-manufacturing, new materials for MEMS, increasingly for wearable and biomedical applications. Together with my students and colleagues we published over 200 peer-refereed papers and I had the pleasure to supervise over 25 PhD students. Former students and postdocs have been successful in receiving awards and starting their own scientific careers. I am honoured for the appointment in 2016 as Fellow of the IEEE “For contributions to micro and nano manufacturing technology”. In 2017 my lab was awarded an ERC AdvG in the field of advanced micro-manufacturing.

Christophe Moser

Dr. Christophe Moser is Associate Professor of Microengineering and Industrial Relations at the Swiss Federal Institute of Technology in Lausanne. He was the co-founder and CEO of Ondax,Inc for ten years prior to joining EPFL. During this decade, he raised $15 million from corporate and venture capital sources to fund volume production of thick holographic components in glass and develop devices enabled by these components such as tunable add-drop multiplexers for telecommunications, ultra-narrowband notch filters for low frequency Raman systems, high power semi-conductor frequency-narrowed pumps for fiber lasers, single frequency fixed and tunable lasers for sensing and femtosecond pulse compressors for micro-machining applications. Dr. Moser has a Ph.D. in Electrical Engineering from the California Institute of Technology, a minor in finance and a bachelor degree in Physics from EPFL. He is the co-inventor of 24 patents, 14 peer reviewed scientific publications, 9 IEEE proceedings and a book chapter. Private interests include tennis, running, ski, basketball and family excursions. 2010: Associate Professor, EPFL, faculty Science Technique Ingenieur. 2000-2010: co-founder, CEO Ondax, Inc. 1995-2000: Graduate Research Assistant, California Institute of Technology. 1993-1995: Engineering Project manager , TESA. 1988-1993: Bachelor candidate in Physics, EPFL. MAIN PUBLICATIONS:

Moser C., Havermeyer F,.Ultra-narrowband tunable laserline notch filter, Appl. Phys. B, 95 (3), pp 597-601, 2009.

Moser C. ,Ho L., Havermeyer F,. Self-aligned Non-dispersive External Cavity Tunable Laser, 16 (21), 16691-16696 Optics Express, 2008.

Steckman, GJ , Moser C. et al. Volume holographic grating wavelength stabilized laser diodes, IEEE J. Of Selected Topics in Quantum Electronics, (13), 672-678, 2007.

Buse K, Havermeyer F, Liu W., Moser C, Psaltis D. Holographic Filters , Book Chapter Photorefractive Materials and their Applications, 2005.

Havermeyer, F; Liu, WH; Moser, C, et al. Volume holographic grating-based continuously tunable optical filter , Opt. Eng. 43 (9), 2017-2021, 2004.

Moser C., Maravic I., Schupp B., Adibi A, Psaltis D, Diffraction efficiency of localized holograms in doubly doped LiNbO3 crystals, Opt. Lett. 25: (17),1243-1245, 2000.

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Related concepts (13)

Round-off error

In computing, a roundoff error, also called rounding error, is the difference between the result produced by a given algorithm using exact arithmetic and the result produced by the same algorithm using finite-precision, rounded arithmetic. Rounding errors are due to inexactness in the representation of real numbers and the arithmetic operations done with them. This is a form of quantization error.

Rounding

Rounding means replacing a number with an approximate value that has a shorter, simpler, or more explicit representation. For example, replacing

with

, the fraction 312/937 with 1/3, or the expression with . Rounding is often done to obtain a value that is easier to report and communicate than the original. Rounding can also be important to avoid misleadingly precise reporting of a computed number, measurement, or estimate; for example, a quantity that was computed as but is known to be accurate only to within a few hundred units is usually better stated as "about ".

3D printing

3D printing or additive manufacturing is the construction of a three-dimensional object from a CAD model or a digital 3D model. It can be done in a variety of processes in which material is deposited, joined or solidified under computer control, with material being added together (such as plastics, liquids or powder grains being fused), typically layer by layer. In the 1980s, 3D printing techniques were considered suitable only for the production of functional or aesthetic prototypes, and a more appropriate term for it at the time was rapid prototyping.

Approximation error

The approximation error in a data value is the discrepancy between an exact value and some approximation to it. This error can be expressed as an absolute error (the numerical amount of the discrepancy) or as a relative error (the absolute error divided by the data value). An approximation error can occur for a variety of reasons, among them a computing machine precision or measurement error (e.g. the length of a piece of paper is 4.53 cm but the ruler only allows you to estimate it to the nearest 0.

Catastrophic cancellation

In numerical analysis, catastrophic cancellation is the phenomenon that subtracting good approximations to two nearby numbers may yield a very bad approximation to the difference of the original numbers. For example, if there are two studs, one long and the other long, and they are measured with a ruler that is good only to the centimeter, then the approximations could come out to be and . These may be good approximations, in relative error, to the true lengths: the approximations are in error by less than 2% of the true lengths, .

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