Double filament extruder design for 3D fused deposition modelling printer

The developing technology actualizes the products which the people had once dreamed of making and using. Since the early ages, people have created tools, properties and art objects in order to make their lives easier and to embody the idea created in the abstract world. The effort to embody the requirements, the ideas and the emotions has started in the early ages by knapping the existing stones and collecting them in a certain order. The developing technology and the increasing knowledge of people have provided the improvement of current materials and production techniques. Today, we can obtain the item that we imagine and need in a short time by making its 3D design thanks to 3D printers. The reason why we need 3D printers in the first instance is to be able to see to what extent actual models and the structures designed with developing analysis and design techniques overlap with each other, to understand the perception created on people by seeing the actual model of the product and to overcome the problems that have not been noticed in the design phase by viewing the product in three dimensional way. Producing the items with traditional production techniques requires the raw material suitable for the size of item, the labour and the arrangement of the tools which the production will be made with. On the other hand, in complex geometry, the production time and cost of the item including overhead operations is increasing exponentially. Developed 3D printer technology produces designed items with high quality, quickly and closely to the final product. There is no need for different materials in compliance with the diameter or thickness of the item as so in traditional methods because the materials which the production of the item is made of are in the state of powder, filament etc. When examining the history of 3D printers, the first 3D printer started when Charles Hull noticed that he could create a solid body by curing photopolymer material with laser light layer by layer. The first 3D item production was carried out in 1984 by using CAM. Later, Scott Crump noticed that he could produce 3D items by fusing polymer material on each other. This method found by Scott Crump was called Fused Deposition Modelling. In Modelling Apparatus for Three-Dimensional Objects, his first patent, Scott Crump defined the system which he found as that "The material in solid state is discharged from the tip of the extruder to the production section in a controlled manner by being fused at a certain heat. During the practice of apparatus, preferably CAD and CAM can be utilised. It can be practised on all materials which can correlate with the previous layer during solidification like self-hardening waxes, thermoplastic resins, molten metals, two-part epoxies, foaming plastics, and glass." Extruder provides the transition of the filament in 3D printer between solid-liquid and liquid-solid phases. The extruders which can apply more than one filament are called multiple filament extruders. In the production which is made with filament extruder, the primary structure and the backbone structure need to be manufactured from the same filament material since the extruder can apply one filament. The primary and the backbone structure's made of the same material complicates the finding out of the back-up part which is separated during the phase of cleaning of the item. Another disadvantage of this case is that the primary structure is damaged during the cleaning of the backbone structure due to the sameness of toughness of two structures. The backbone structure is generally made with water soluble filament in multiple filament extruders. The item is thrown to the water after production and the backbone structure perishes by dissolving in water. However, the price of the 3D printers that can apply multiple filaments is twofold of the normal 3D printers because the former uses two stepper motors instead of the motherboard. Besides, one extruder of the multiple filament extruder breaks down due to the newness of their motherboard and the problems encountered in the system and it works like filament extruders. It is thought that one extruder which can apply two filaments with only one stepper motor provides both the features of multiple filament extruders like ability to apply the backup filament and to print colourful and composite items and the advantages of the filament extruder like the price and stabile working. Extruder needs a mechanical system that arranges which filament will be applied in order to apply two filaments with only one stepper motor. Two alternative concepts have been designed around the ideas made in this in this direction. In Alternative 1, it is decided that separation of direction should be made by using clutch. Clutches are the mechanisms that provide the transmission of the energy from an item in the rotary state to another item in the same axis on request. In our mechanism, using clutch is profoundly proper because the energy must be transferred to the preferred place on request. We must use a clutch which can activate and deactivate itself automatically in the extruder that we will design since we cannot use any tool that will disturb the system from the outside excluding the stepper motor. We must analyze the clutch systems that transfer the energy according to the direction of rotation because the distinctive factor in the clutch that we will use is direction. Selection of one way clutch bearing for the segregation of power reduces asset-liability period of transition in certain requests to zero. Type A and type C filament drive gears come to the forefront when they are compared in terms of applying the filament without sliding. C type filament drive gear makes smaller marks on the filament in comparison with A type. Thus, it provides a more homogeneous fusion in the hot end. But the effect of this problem can be reduced with the arrangements made in the hot end. A type filament drive gear is more advantageous when the gears are compared in terms of the price. In view of certain requests, the design which will be made with A type filament drive gear seems more feasible. Alternative 2 is designed on the basis of the idea, that is, "a standard-size extruder which has a short transition time between two filaments and does not slide the filaments" as in the first design. During designing, which filament will be applied is determined in compliance with the direction of the rotation of the stepper motor as in the first alternative. Together with the direction of rotation, the mechanism positioned on the system provides propulsion of force by compressing the filament which will be applied. The same process in the Alternative 1 is valid for the filament drive gear in Alternative 1. For this reason, A type filament drive gear is used also in Alternative 2 as in Alternative 1. Alternative 2's way of work cannot be given due to the scope of confidentiality of Arçelik A.Ş and the content of the functions of movement. After evaluation criteria of the alternative are determined, coefficients are designated in accordance with the importance of these criteria for the system. During the utility-value analysis, these dispensed coefficients provide the calculation of the lower value's coefficient criteria by being multiplied with the coefficient of the upper criteria. The sum of all the lower criteria's coefficient of value in the system must be equal to 1. In the process of evaluating the system, a value score between 1 and 10 is given to the system. The given value scores provide the calculation of the weighted evaluation of the lower value criteria by being multiplied with the lower value's coefficient of the system. According to the utility-value analysis, Alternative 1 has taken 6.78 points while Alternative 2 has taken 4.64 points. The utility-value analysis shows that Alternative 1 is a better design than Alternative 2. In quantitative design process, selections of material and component are made based on the benchmark products, the current systems and the values of literature. In the tries made with the produced prototype, it is seen that the system functions properly. However, the behaviours which the system will show during the long-term working and the sufficiency of the received components' values will show up as a result of the long standing tests and the tries which force the limiting conditions. As a result of the tries and tests, it is expected that the designed extruder becomes ready for the production with the required modifications. When the product is attached to standard 3D printers applying one filament, it transforms them into 3D printers applying two filaments. The integration of the product to the all 3D printers will ensure the recognition of the brand in the sector along with the profit that will be obtained from the product.