3D printing

What’s 3D printing?

Quote 3D printing is essentially a layer-by-layer, additive-manufacturing idea. There are many craft methods that borrow this kind of thinking, ranging from construction production to nano-stacking. However, the mainstream 3D printing is mainly concentrated in the manufacturing industry, and the single-unit manufacturing scale is on the millimeter to 10-meter scale.

Below we are talking about 3D printing methods at this scale as well. In order not to lose the integrity, we first introduce the characteristics, then the industry application, and finally the process method. For commercial applications, my personal thoughts will be mentioned.

2. Features of 3D printing

2.1 Unique advantages of 3D printing

In terms of characteristics, the layer-by-layer stacking method of 3D printing has a high degree of flexibility, a high degree of customization, and a very low sensitivity to the manufacturing difficulty and manufacturing cost of the part shape. For some complex parts with a large number of curved surfaces that are very difficult to machine, the advantages of 3D printing are obvious.

For example, the following types of geometry, for traditional machining, often require expensive machining centers with more than 5 axes to complete. For 3D printing, however, such parts are not significantly different from printing a wrench. At the same time, for this advantage, topology optimization is an important direction of 3D printing design. Such parts can have reasonable strength and extremely low weight.

2.2 3D printing has strong part integration

In the past, for products with complex internal structures, such as hydraulic cylinders, hydraulic valves, and stamping dies with internal channels, they often needed to be split into multiple parts, which were precisely assembled through complex connectors and mating surfaces.

However, due to the emergence of 3D printing, it is completely possible to integrate several pieces in the past into one piece. The hydraulic product giant MOOG has developed a fully integrated hydraulic component of hydraulic cylinder and hydraulic valve a few years ago. Boston Dynamics also uses a large number of 3D printed integrated parts in its structure. This integration trend and design method must also be one of the development directions.

2.3 3D printing is suitable for small and medium batch production

3D printing tends to produce only a single or a few pieces at a time. Economically, the marginal cost of 3D printing decreases slowly or even stays the same as volume increases. As a result, 3D printing is not very suitable for mass production, and from the perspective of existing applications, it is generally concentrated in small batch customized production, and production of medium and larger batches is rare. Such as aircraft parts, rocket parts production, etc.

2.4 3D printing is suitable for Industry 4.0

The machine autonomy of 3D printing is very high, and it often only needs to pass in the CAD model of the part to print it autonomously. No need for traditional manufacturing, repeated card loading, positioning, etc. From this point of view, it not only saves time and cost, but also is very suitable for the intelligent and unmanned production of the so-called Industry 4.0.

2.5 The main problems

From the perspective of existing production problems, most 3D printing methods are very slow, the surface roughness of the final product is poor, and subsequent finishing operations such as grinding and milling are still required. Due to this obvious problem, the research trend is mainly divided into two groups.

One group takes “hybrid manufacturing” as the leading development direction, which integrates 3D into traditional machining centers. There are already DMG machine tools in this direction, such as: DMG 3D Milling machines, such as; another group advocates continuing to improve 3D process performance. On the whole, the two factions are not contradictory, but the focus of development is different.

3. Application areas

From application areas, mainly include, medical industry (human replacement implants), aerospace industry, mold manufacturing, parts repair, automotive and rapid design. Let me show you, by field, how far it has developed.

3.1 Application example

Medical industry First of all, from the medical industry, human body substitutes such as artificial teeth, artificial knees, etc. often have the following characteristics:

1) extremely high geometric complexity.
2) need to be customized separately.
3) Titanium alloys with high processing cost and low human body repulsion are often used. This kind of demand is a great challenge to the traditional processing industry, both in terms of processing difficulty and processing cost. And the above happens to be the area where 3D perfectly solves.

At the same time, studies have shown that due to incomplete fusion in the production process of laser metal sintering (SLS), there are fine cavities inside, which are similar to the structure of bones, which improves the adaptability of the human body.

On the other hand, it also has a similar strength to the bone in terms of strength, which avoids further damage caused by the uneven strength of the bone and the substitute when the replacement area is stressed. As can be seen from the picture on this page, the existing 3D alternatives already have good alternatives. There must be commercial development prospects in this field!

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