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Basic Knowledge 3D Printing in Tool and Mold Making

| Author / Editor: Rosemarie Stahl / Isabell Page

Will 3D printing replace mass production in the near future? - No! But this can improve mold making processes and increase production efficiency.

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(Source: Pixabay / CC0 )

For several years now, there has been a lot of talk about disruptive innovations and technologies. A number of trends are said to be able to change the manufacturing industry forever. Smart manufacturing, digitisation, Industry 4.0 and lately also 5G are set to disrupt how we work. In all these cases, what is meant is that if the technology succeeds, it will change and transform existing markets and value networks. The problem is that no one can truly say whether a technology succeeds or not.

In 1996, Nokia presented the first smartphone to a world that was just not ready for it yet – or maybe Nokia's marketing team was not able to convince the world that it needed the smartphone. The company that was able to successfully launch the smartphone was, of course, Apple, nine years later. Many innovations have failed the test of time. Another example is Google Glass. Once praised as the next leap in consumer technology, it was discontinued in 2015 (There is however still a so-called Enterprise Edition for working environments).

There are countless stories like this in technology – products that failed almost immediately. The interesting thing about the story of Google Glass is that it was hyped so much and finally had to surrender to real concerns: People did not like to be secretly recorded. That is the thing with disruptive technology. It might be groundbreaking and it might be innovative. But it is only disruptive if it eventually manages to change or displace existing markets.
One such innovative technology is Additive Manufacturing (AM), so-called 3D printing. But what is that anyway?

Definition of 3D Printing

3D printing refers to a process in which a component is built up layer by layer on the basis of digital 3D design data by depositing material. It's a production process which differs clearly from conventional, ablative production methods. For example, instead of milling a workpiece out of a solid block, additive manufacturing builds up components layer by layer from materials that are available as fine powder. Various metals, plastics and composites are available as materials.
This manufacturing method is used in rapid prototyping - the construction of visual and functional prototypes. Product development and market launch can thus be significantly shortened. In the meantime, maybe because of the many advantages of 3D printing in foundries, the technology is increasingly finding its way into series production.

The 3D Printing Hype

Additive manufacturing has also been praised many times as a game changer for the supply chain. It was said that 3D printing would lead to household production of goods, that there would be more local production instead of centralised plants. One very common news title was “3D printing will change the world”, followed by texts stating that “life on earth will soon change radically” and “instead of customers, we are now creators”. Those headlines are now more than five years old and it seems that the world is still pretty much the same. The hype was exaggerated, expecially concerning the influence 3D printing would have in our private lives. However, there are areas in which 3D printing is widely accepted as an important technology, especially in the automotive and aerospace industry. It just has not reached the point where it replaces existing markets. Rather it enhances them. One reason for this is that 3D printing is not quite as simple as you might imagine. There are several reasons why additive manufacturing is so complex.

1. 3D printing needs a broader knowledge base:
In many cases, knowledge of the various technologies and the associated advantages and disadvantages and applications is simply not available. Since many of these technologies have not been on the market for decades, it will take quite some time before the knowledge has spread. For example, only a few universities are really specialised in AM technology.

2. 3D printing demands a rethinking of design:
It is very important to be familiar with this process. Before actual production, there is construction – and this differs clearly from the traditional subtractive methods, so much so that the design process looks completely different. This starts with the fact that support structures have to be included in the planning phase and continues with the fact that the company takes nature as its model and imitates bionic structures completely removed from the usual forms.

3. Post-processing:
It doesn't stop with printing: Another building block is the knowledge of the process itself. How time-consuming are the construction phase, the production phase and the post-production phase really? How quickly can you hold a finished part in your hands? How long will it take to achieve the surface finish that is needed?

3D Printing in Tool Making

In toolmaking, additive manufacturing can be applied in different stages of the process.

1. Rapid Prototyping:
Rapid Prototyping is used to create physical models to review and validate a design. It is a typical application for additive manufacturing technologies as other methods are more cost-intensive. The advantage of using 3D printing here is that the model's design and functionality can be reviewed very quickly, thus reducing lead times.

2. Rapid Tooling:
Rapid Tooling is the method of producing a tool using additive manufacturing. This is especially useful when the tool is used to produce small series. A traditionally manufactured tool is often much too cost-intensive. If a tool is manufactured additively, it also has the same advantages as in rapid prototyping, namely, design changes can be applied more quickly.

3. Rapid Manufacturing:
Rapid Manufacturing does not apply 3D printing per definition. However, this manufacturing method stands for quick and flexible methods to produce parts without using tools. Nevertheless, it often involves additive manufacturing. Rapid Manufacturing especially makes sense when a part not only needs to be produced quickly but also has a geometry that is hard to realize with traditional methods.

4. Other applications in toolmaking:
Particularly in toolmaking, there are many other possible applications of 3D printing. While the aforementioned applications describe the direct production of either finished part or finished (prototype) tool, additive manufacturing can also be applied to manufacture components or parts. This may include producing mold inserts or even equipment needed to optimize the manufacturing process.

3D Printing in Mold Making

Another common application is the optimization of the mold itself. Here, speed is not the decisive factor but rather the added possibilities that additive manufacturing offers. With 3D printing, cooling channels can be added to injection molds that cannot be produced with traditional methods like millling and drilling. Using additively manufactured cooling channels within the tool, even areas that are difficult to access – for example, those surrounding the ejector and slider – can be cooled conformally. The injection molding cycle can run much more quickly than before. As a consequence, cycle times in injection molding can be reduced by up to 40 % if the temperature profile is homogenised simultaneously.

By using 3D printers, foundries can produce sand casting molds without tools. This is a economical way to produce components with complex geometries in small series. In addition, 3D printed molds do not require CNC milling or other special tools, thus ensuring maximum freedom of design. Another advantage is that foundries save a lot of time when producing 3D-printed molds.

Advantages of 3D Printing

Additive manufacturing shows its strengths where conventional manufacturing reaches its limits. The technology starts where construction, design and manufacturing have to be rethought in order to find solutions. It enables a design-driven manufacturing process in which the design determines the production - and not vice versa. In addition, 3D printing allows for highly complex structures that can be extremely light and stable at the same time. It guarantees a high degree of design freedom, functional optimization and integration, the production of small batch sizes at reasonable unit costs and a strong individualization of products even in series production.

Read more about the possibilities of additive manufacturing and the limitations of this process:

Application Examples for an Efficient Use of AM

These applications all represent extremely individual processes and solutions. The decision as to whether such an implementation is worthwhile for a company must always be made on a case-by-case basis.

In order to convey a good idea of what is possible, the case studies are evidence of how different companies use 3D printing in prototype, mold and toolmaking.

This article was first published by ETMM.

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