3D PRINTING IN 2-STROKE ENGINE

When we talk about new technologies and new construction limits, we are referring in particular to additive technologies, more commonly called 3D printing in general, which everyone thinks they know about now but you will discover that, probably, you did not know it all. In fact, the most used 3D prints in this sector at a professional level are different, and have nothing to do with the printers that you can have at home. To have a complete knowledge, today we will talk to you about 5 types of 3D printing and how they have revolutionized this sector.

Here we see the ones we use and all their aspects going from wax to sand... to titanium. But first I want to talk about some equally important advantages in addition to the technical ones of each category that concern 3D printing in general: new construction limits and new development times.

1 new shapes and geometries that can be created:

English: But somehow everything has always been made and the old school artisan artists had average manual skills that would make the new generations envious and only dream about, commercial products have always had to be mass-produced, so as to be able to lower costs. Whether it was cylinders, crankcases, manifolds, carburetors or reed valve packs, all the complex metal parts were/are made up to TODAY (we are in the future as they all arrive) from MOLDS. The molds, made of various materials but usually for the majority of the pieces in question in metal, are in turn now made by CNC material removal, or built by hand, with wood, metal and resins up until a few decades ago, and for some still today. (even the molds in turn today are increasingly made via 3D printing in all sectors of industry)

The mold requires demoulding and therefore does not allow the creation of hermetic hollow objects, the creation of reticular structures, concave and convex surfaces on multiple axes... even the flow guide of our homepage would be practically impossible or very complex to create using traditional injection molding due to the difficulty in demoulding.

Molds for shell casting or injection can easily cost hundreds of thousands of euros, making it impossible to create prototypes for testing except by hand, and therefore with very long lead times.

THE second FUNDAMENTAL advantage is in fact the time in which it is possible to create and test a component, just update the design and print the object a second time and then assemble and test it, being able to redo it as many times as you want in a relatively short time, very little compared to traditional technologies.

Let's now see 5 different uses of 3D printing in the 2-stroke engine

-Chinese 3d metal printing:

This technology is now replacing the work of 5-axis CNC machinery, suitable for all small and medium details, it allows the creation of components with an unprecedented strength-to-weight ratio. Used to make entire engines, it allows to create complex geometries with a wide range of materials, including Alsi 10, an aluminum alloy suitable for most engine components generally made of aluminum, including cylinders. The material obtained does not require other treatments, and generally has mechanical characteristics comparable to a piece obtained from solid or cast.   

machine cost

cost of parts

uses

-3d print silica souls in sand

More commonly known as rapid prototyping casting, it has certainly been a revolution in the construction of cylinders for 2-stroke engines in particular and of all cast mechanical components, especially high-performance ones.

There is no company that does development on cylinders today, that does not use this technology, to make prototypes or small series, the advantages are too great. In fact it allows to create monolithic sand cores without shape limits from a simple design. Before this technology, the cores were created from many pieces obtained from complex counter-molds subsequently glued together... the gluing is always imprecise and the shapes obtainable from the counter-mold are very limited, prototype costs and times substantially reduced, precision, repeatability and very high possibilities. These technologies have so many advantages and are so young, that it is obvious that they represent the future in this and many other sectors. We must not be scared by the costs, but become masters of these technologies because in a few years they will have competitive prices even on large productions. Already today, speaking of internal cores, if there are less than 100 cylinders, it is not convenient for a company to make the counter-molds, especially for those looking for high precision performance. A cylinder cast in rapid proto costs less than a 3D printed cylinder in metal, but it requires more work and more time.

It can be used for both interior and exterior, but the latter can also be created through the classic system with a 3D printed model with FDM or SLA technology, presented below.

FDM and SLA

With names that sound like diseases, they are the most well-known and used 3D prints, by now we all have a friend who has one at home, for this reason I won't talk to you about it but I'll just explain where, how and why we use it.

resin is definitely the one we use less often, due to its "poor" mechanical characteristics and the high cost of sophisticated technical materials, as advantages it definitely has the best detail and the best finish among 3d prints. It can be used for molds, demonstration models or inserts not subjected to mechanical stress such as flow guides, taking care to use materials with catalyzations suitable for contact with oils, hydrocarbons and operating temperatures.

FDM, on the other hand, has many plastic or mechanically similar materials, it is undoubtedly the cheapest 3D printing, and generally has better mechanical characteristics than SLA, but with a much lower surface finish and also detail.

No classic material for these printers is suitable for prolonged use in contact with petrol or high temperatures, the suitable technical materials are very expensive and difficult to print, for this reason we only use it to make samples to test the measurements quickly or to create cheap foundry models even of large dimensions.

The exception is the TPU rubber inside our manifolds, that is currently the only FDM component that we think can work, also given the simplicity of changing it if it degrades over the years and the low cost. From experience, we recommend staying away from manifolds made of TPU FDM.

In addition to the difficulties of printing performance materials, this printing is very limited by the need for supports that often generate low quality areas depending on the shape we are printing.

table:

pro-con

SLS and MJF

The defects of resin and fdm printing are entirely solved by sls and mjf printers.

mjf is a brand of hp, who are leaders in the production of printers of this type.

These printers work by solidifying layers of thermoplastic polymer powders, such as those used for sand, thanks to which they do not require supports, and have high geometric and dimensional precision, excellent detail and an excellent surface finish that is superior to a fusion. It is possible to print different materials, and since they are dedicated to industry, they all have notable and different technical characteristics based on their use, such as polypropylene, nylon and polyurethane. Unfortunately, the cost is high, especially the machine, which costs well over half a million euros, but it is undoubtedly the best non-metallic 3D printing technology for mechanical applications. This is precisely the technology with which we make our manifolds and lamellar packs! For this reason, we use nylon pa12 exclusively printed at high resolution on hp mjf. After us, it was then increasingly used also in Italy by various manufacturers of aftermarket components for intake kits, but it is also used for cover casings, cooling hoods, impellers, cases, pulleys, bushings and much more.

3D printing and lost wax casting:

Last but not least, 3D printing is now able to produce wax models or materials with similar characteristics. The techniques are sla (only with industrial machinery) or fdm. These models can be used, as in the production of jewelry, to create castings of cylinders, casings or other. The model is embedded in a refractory plaster shell, which solidifies. The wax is melted and the plaster is used to cast the aluminum. This technique allows for very smooth castings, but it is not easy to master and few foundries are equipped to do it, for this reason, we have specialized in the use of rapid prototyping, which is simpler but above all reliable, does not risk having impurities inside the material and allows you to do more things. Other materials can also be used for this technology, and it is a technique sometimes used by enthusiasts who want to make a cylinder themselves thanks to the low cost of the material.