Posted on Sept. 24th, 2019, | By WayKen Rapid Manufacturing
Short-run production refers to manufacturing a small batch of parts in a very limited amount of time. Another definition for the machine shops that work in short runs is high-mix/low volume manufacturing facility. This type of production is the most challenging as the parts change rapidly and you have to reset your production line a number of times per month and keep it flexible at all times. Low volume manufacturing has been considered a costly expense. However, some modern technologies make it cheaper.
The Choice of Material
Reviewing manufacturing technologies is relevant when we have some knowledge of the material, otherwise, you could simply end up mentioning all the recently modified techniques over all the industries. The point is that metal and plastic processing techniques differ so much it isn't worth mentioning. Even metal parts can be manufactured by tens of hundreds of ways. So, in order to focus the scope of all the technologies, let's look at aluminum parts short-run production. Aluminum alloys are very durable, strong and the most important fact is they are easy to work with. That's why the majority of low volume production uses aluminum for their prototype short runs.
3D-printing also called rapid prototyping sinters aluminum powder into any form without any need for tooling or fixtures. By avoiding those things, the manufacturing process can be made considerably shorter. The process itself is quite slow right now so the more parts there are in a batch, the less the efficiency of the process. Ideally, 3d-printing is to be used for the first prototype of a very complex aluminum part. That way, the lead time is much shorter than that of any other process because you require virtually nothing to start producing right away. As the number of parts in a batch increases, however, the slow performance of the printers will show.
Low Volume CNC Machining
Short-run CNC machining of aluminum is a tricky business that must be set up correctly in order to be profitable. The main problem is that you have to act without having all the information even in the short run. You must always be ready for an unexpected urgent order and so keep all the possible stock samples in your supply cache so that you can start working right away while the rest of the blank material arrives.
CNC machine tools are unique pieces of equipment that allow the manufacturing of metal parts without the need to make part drawings or file manufacturing processes. You can take a CAD model of the part and with a little tinkering with a CAM system, you can quickly make an NC program that will coordinate the cutting tool movements of the CNC machine with a precision that is impossible for human machinists. This method significantly lowers production cost and time.
However, you'll still need to choose the correct aluminum cutting tools and fixtures and reset the machine tool so this process isn't the fastest but it yields the best quality and is often used as a follow up for the other rapid production processes. Another advantage of CNC aluminum milling and turning is the ability to scale up. Basically, if you have one NC program, you can make an unlimited number of parts with it.
Rapid Aluminum Casting
Rapid Aluminum casting refers to using 3d-printing of wax to create master models for further casting into sand forms. Sand casting has been known for a long time. Its weakness has always been the need to create a master-model: a mock-up of the manufactured part made of some soft material. This was usually done manually by the machinist. I suppose you can imagine how much time it took to get a master model like that. And what if it turned out to be faulty? Producing a wax master model takes about a day, and the whole process of casting will take a few weeks instead of months like it was before.
Rapid Aluminum casting refers to using 3d-printing of wax to create master models for further casting into sand forms. Sand casting has been known for a long time. Its weakness has always been the need to create a master-model: a mock-up of the manufactured part made of some soft material. This was usually done manually by the machinist. I suppose you can imagine how much time it took to get a master model like that. And what if it turned out to be faulty? Producing a wax master model takes about a day, and the whole process of casting will take a few weeks instead of months like it weeks instead of months like it was before.
Rapid Aluminum Forming
Rapid aluminum forming has always been a conventional process. The factory would design the dies: made of expensive steels, heat-treated, finished to the mirror-like surface and capable of producing an infinite amount of parts. It took an eternity to make does but once they were ready, the performance was outstanding. But does the modern short-run production need such sturdy dies?
The answer is no. There is no need for such dies, you can cut weeks off the tooling manufacturing by choosing a softer and simpler to process material. Aluminum forming doesn't require a lot of hardness and durability from the tool if the production is low volume. A soft die can withstand ten or even fifty processing cycles without much wear. And after that, you may not even need it anymore.
Rapid Cutting Aluminum with EDM
Rapid cutting aluminum with electrical discharge machining is extremely popular for rapid injection molding. With EDM you can make great cavities for the press-forms. Apart from that, EDM cutting can help you avoid the need to manufacture special cutting tools to manufacture complex holes with sharp edges in different parts. Otherwise, you'd have to make a broach, and it is a very expensive cutting tool.
There is one thing that should be noted. Advanced technologies do not make efficient manufacturing alone. Profitable machine shops exist because of their efficient resource management and smooth transition between part batches. That's why even if you don't have enough money for an expensive piece of equipment ( Metal 3D printers can cost a few million dollars), you can still significantly increase your profits by setting up efficient supply chains with your partners and by organizing your workflow.
And vice versa, you may have the best machine tools and sit idle waiting for those aluminum blanks to arrive from your untimely supplier. The modern development of production tends to increase information support between different stages of manufacturing and manufacturing process preparation. Those trends are expected to enhance efficient manufacturing much more than the newest techniques.