This is a sub-topic of my 3D Printing course.
Introduction
3D-Printing has quickly become a ubiquitous means of prototyping and manufacturing. But it is wise to understand what other means of manufacturing are out there in order to understand where 3D-Printing fits in and what makes it so powerful.
Wood Manufacturing
Looking way back, some of the first man-made objects were constructed from wood and stone. Today working with wood is viewed as a bend between art and craftsmanship. We don’t find genuine wood in many products these days – I think this is mainly due to the perception that it’s “tacky” from being overused in the 1980’s. That said – I hold wood working among my most dear hobbies.
The key thing about wood working is that it often takes substantial skill and practice to make your end product look good. So for a completed product, your labor costs may be high. But for prototyping, wood working really shines. I can easily drill a hole where ever I need, glue a block here are there, shave off a corner to increase clearances, etc.
Hand Tools
Hand tools are a double edged sword when it comes to wood working. They are often cheaper which lowers the barrier to entry, however there is often an increase in required skill to utilize, and take an increased amount of time to execute a task with.
Power Tools
The flip side of hand tools are power tools – you can complete things quickly, but they come with a more substantial cost (and they tend to take up a lot of space in the shop). Not to mention, there is an added danger with using these machines.
An interesting (and very relevant) branch of power tools are CNC tools. CNC stands for Computer Numerical Control – which essentially means that a computer automates the movement of a tool according to instructions you give it. CNC tools allow for highly accurate and highly repeatable products, with little effort required from the person while manufacturing. THAT SAID – There is normally training involved in using the tool properly, and a lot of up front effort do develop the design to be produced using CNC tools. Not to mention CNC machining can be very slow and is not suitable for mass-manufacturing. A final note – CNC tools used in wood working always using subtractive manufacturing methods – meaning that it is removing material from some bulk piece to result in a smaller piece.
Metal Manufacturing
Crafting metal dates back as far as 4200 BC with copper bowls, and later tools and weapons. How metal is made is worthy of an entire degree, so we won’t get into that – but we can talk about manufacturing with it. It should come as now surprise that engineers and makers often want to utilize metal when creating strong parts – but this often increase the mass of the part (when compared to non-metal alternatives). Even more so than wood, metal takes substantial skill to work with, but there is also often less emphasis on aesthetics of metal parts.
Machining
You can use hand tools for metal working, but it will require extensive effort and sweat. When making a custom shape out of metal, a subtractive process is usually used to cut a billet (a solid block) of metal into the desired shape. These tools are normally extremely expensive (when compared to wood working) and require training in order to achieve the accuracies that are often desired.
I thought the mill deserved to be highlighted with it’s own video. You can clearly see that this tool can be manipulated along 3 dimensions – similar to how 3D Printers move. And of course CNC Mills exist as well, which allows for creating 3D metal objects.
Welding
Now I know what you’re thinking – that’s only “sort of” additive manufacturing. Just fusing one piece of metal to another piece doesn’t quite feel additive. ITS TIME FOR A QUICK DIGRESSION FOLKS.
Way back in the 70’s, my crazy Grandpa Moose acquired the rights to a steam shovel that was allegedly under Wixom Lake (in down-state Michigan). After almost 100 years of being under water, it was eventually revealed (due to a bunch of catastrophic dam failures and flooding), and my dad is now restoring it.
Sitting under water for that long has degraded many of the metal structures. So in order to keep things as original as possible, dad is filling in holes in the structure using welding. It is literally adding material into a very custom shape in order to make the part complete again (note some of the excess weld was ground down). (If you’re interested in more of this story – check out this video)
Casting
I’d be remiss if didn’t at least mention metal casting – the idea of making a mold, and pouring liquid metal into it, letting it solidify in the desired shape. This is another means of additively manufacturing metal
Polymer Manufacturing
When dealing with Polymers (plastics), you can use almost all of the same tools mentioned above in addition to some of the techniques I’m about to go over. Though these methods are achievable on small scale and for prototypes, they’re normally much more suited for high volume manufacturing.
Injection Molding
Injection molding involves creating a negative mold (IE an object that’s interior is the exact shape you want to create) and then injecting it with molten plastic. The construction of molds which can be used repeatedly and consistently release the cast part is something that takes substantial skill.
A key example of injection molding are Lego:
Thermoforming
A manufacturing method that’s near in dear to my heart is Thermoforming. There was a time where the town that I grew up in, Beaverton, was the “Thermoforming Capital of the world” because so many companies that made these machines were based there. One of those companies was Lyle Industries, which was founded by my great grandparents. Grandpa Bill put a lot of work into streamlining thermoforming machines and contributed plenty of innovations that are now used in factories all over the world. (sorry there should have been another digression warning)
So how does thermoforming (also called vacuum forming) work? The idea is fairly simple – create a mold of the part you want, get a sheet of plastic hot, then stretch it over the mold while drawing a vacuum to pull it down tight.
3D Printing
3D Printing is a means of producing plastic parts additively. We’ll get into how it works later in this module.
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