- Tim on Hybrid Machining: Combining Additive and Subtractive in One Machine
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- Michael on Standard Work and Takt Time: Lean Manufacturing Principles Part 5
- Bob Warfield on The CNCCookbook Software Giveaway is Ending Soon!
- Brad on The CNCCookbook Software Giveaway is Ending Soon!
Since the CNCCookbook Blog is frequented by CNC machinists, I thought it would be useful to provide an overview on 3D printing from the perspective of someone familiar with CNC machining. I have four parts planned, and in this first part I’ll present a little history, describe why I (and many others) believe 3D printing is here to stay, discuss some terminology, and generally set the stage for future posts in the 3D Printing 101 series:
So, let’s get started!
A Little History
Ask three different people to describe what 3D printing is and you’ll likely get three different answers! One will probably answer from a technology perspective, describing the machines, materials and process. Another will describe how 3D printing enables making real-world objects from computer designs. And the third will talk about the manufacturing revolution that 3D printing is enabling. None of these descriptions are wrong and there are probably many more.
At its root, 3D printing is a form of additive manufacturing. Contrast this with machining methods – milling, drilling, cutting, turning – all subtractive manufacturing technologies. The basic idea of making a 3 dimensional object by building up small particles or strands of material is really as old as human history. Ancient pottery and baskets were created by building up layers of clay in the first case and reeds and other fibers in the second.
Coiled Yucca Basket
Photo from American Southwest Virtual Museum
Although the process was manual, the intent then was the same as it is today – to create an object from geometrically simple (powders, particulates, filaments, strands) starting materials. Of interest to machinists is this 1925 patent I uncovered in doing research for this post – Method of Making Decorative Articles. The inventor used arc welding to build up decorative metal objects in layers. Quite the water pitcher, this is the kind of innovation that fuels advancement!
Although the basic concept for 3D printing has been around for centuries, Charles Hull (co-founder of 3D Systems) is considered to be the inventor of modern 3D printing. His process, stereolithography, enables creating a 3 dimensional form from digital data. It is this key concept – digital data describing an object that is then printed additively – that defines 3D printing as we know it today. Hull’s process laid down thin layers of an ultraviolet curable material, one on top of another, until the complex 3D structure was built up. In the decades since Hull’s invention, a variety of additive manufacturing technologies have been developed and I anticipate many future developments in this area.
In 2005 Dr. Adrian Bowyer a the University of Bath founded RepRap.org. His vision was to create an Open Source 3D printer that could print most of its own components – a self-replicating machine. With this concept, Dr. Boyer put in motion a world-wide movement for personal 3D printing. The technology was based on plastic filament extrusion printing, a technique called Fused Deposition Modeling (FDM) – the laying down and fusing of a filament of plastic or metal. In the RepRap case, the filament is plastic, typically PLA (polylactic acid) or ABS (acrylonitrile butadiene styrene). RepRap 1.0 was the “Darwin” printer shown here, a simple machine whose frame is made from hardware store variety threaded rod and printed plastic connectors. Most of the RepRap derivative machines use a similar “Tinker Toy” construction.
Why 3D Printing?
Today when you hear “3D printing” on the news or in a casual conversation the source rarely describes the underlying technology. The focus is usually on the items being produced. Everything from functional organs (kidneys) to bicycles to prosthetics to toys to robotic aircraft to cars and 1000s of other items have been “printed”. Initially, 3D printing supported rapid prototyping use cases to quickly, and usually inexpensively, fabricate models or a small number of parts. Traditional machining techniques require work-holding and fixturing, expensive raw materials (relatively speaking), and skill. Not that 3D printing doesn’t require skill, but it is skill that can be developed without a machining background and does not require expensive tooling (how many end-mills have been sacrificed to CNC beginners?) and heavy machinery.
As 3D printing technology advances it is enabling the manufacture of objects that can not be fabricated with traditional technologies. The printed organs mentioned earlier are an example of a unique application for this technology. Other, equally amazing, applications are being developed and announced at an increasing rate. One particular favorite of mine is the Gear Bearing designed and shared by Emmett Lalish on the Thingiverse site last month. This is a fully functioning replacement for a ball bearing that can act as both a needle bearing and a thrust bearing. Its most interesting feature is that it is printed in one piece, it can not be disassembled without breaking it and it can not be manufactured by traditional subtractive technologies. While primitive in its initial “plastic” implementation, the concept is sophisticated and opens the mind to an interesting future of objects that can be only manufactured with additive technologies.
I hope this post has given you a little taste for what all the fervor is about! At the end of the day, many of the components of 3D printers are conceptually (if not practically) the same as 3 axis milling machines and routers. In my next post in this series, 3D Printing 101: Part 2: Mechanics, I’ll dig into the mechanical details on RepRap style (or more accurately Fused Deposition Modeling) printers.