Shells for Radio Controlled Cars - Essay Example

Content List of Figures ................................................................................... 3 Introduction ..................................................................................... 4 Planning ............................................................................................ 4 Brainstorming .................................................................................. 6 Manufacturing ................................................................................. 7 Materials ......................................................................................... 10 Shape and Style ............................................................................... 11 Critical Dimension ........................................................................... 12 Marketing ....................................................................................... 13 Reference ....................................................................................... 15 List of Figures Figure 1 ............................................................................... 8 Figure 2 ............................................................................... 9 Figure 3 ............................................................................... 10 Introduction Motor vehicles have been in use for a long time, just like RC cars. It is important to note that the shell may not be determining factor or aspect of the RC car in terms of whether it can move or not. However, the shell is an essential component because without it, the RC car would look like Frankenstein rather than a car meaning that it would only be a combination of batteries, wire and spring. The shell is the outlook of the RC car because it brings out its beautiful look and makes it interesting and worthwhile. The shells or RC cars exist in many forms, sizes, shapes and colors to make it more appealing to different people. Planning: Ganttchart to show how the project will progress Brain storming Manufacturing Shells for RC cars can be manufactured using a variety of ways, which have similarities but differ in different ways. The common aspect with all the manufacturing processes is that they require a mould or pattern that takes the shape of the car shell so that the design of the shell can be similar. The moulds are also different because some of them are positive whereas others are negative (Groover 2013). Before manufacturing begins, the company must choose the best process in terms of a variety of needs. For instance, the manufacturing process to be chosen should be fast, time conscious and should also have the ability for a high product output but at the same time produce high quality products. It should also use readily available and cheap raw materials rather than expensive ones. As stated above, many processes exist that can be applied when manufacturing RC Buggy shell. These include Compression moulding, Reaction Injection Moulding, thermoforming and transfer moulding. All these manufacturing processes are viable for manufacturing an RC Buggy shell. This paper will discuss all these manufacturing processes in terms of their viability, advantages and disadvantages and make a recommendation on the one that is the most viable option among them for manufacturing an RC Buggy shell. Reaction Injection Moulding: This is one of the methods that are used to manufacture shell for RC cars. In this method, the manufacturer has to build a special mould using a pattern that is similar to the shape of RC buggy Shell. After the first process, the manufacturer can then start working with the material that should be used. This is important because the method requires a mixture of two materials that must be put into a mould cavity, where a chemical reaction is introduced so that these two materials can react to form a solid in a solidification process that creates a cross-link between the materials that are used. After this process, the mold or pattern must be heated, as the polymer arrives at cavity. This requires the use of low temperature to enable an exothermic reaction to occur. Cooling of the material should be done quickly in succession to the above procedure which should take less than a minute to ensure that the cooling is done effectively on top of the fact that the size of an RC body shell is very small, which requires less time. This process is important because it produces rigid foams, elastomeric parts, polyurethane and flexible foam (Rimmfg 2014, Swanson 2013, Groover 2013). The advantages of this process include the fact that it uses low injection pressure and that low shrinkage occurs because of the technique used. It also produces high dimensional accuracy in the product. Compression Molding: this process involves two molds where one acts as female and other one acts as the male mold. The molds must be the same in shape so that when compression is done the shell that is produced is desirable. The female mold is placed at the bottom while the male mold comes on top. In this process, one has to use charge materials that are put in between the two moulds. The charge must be compressed and be cured to complete the process. It is simpler compared to the first method. Heating is done using electric resistance, steam or oil circulation. However, there are several aspects that must be controlled and they include molding temperature, compression pressure, and time of compression. Heating the charge helps to reduce the time taken in the process. The process uses a variety of materials that include TS and Elastomers that have melamine, phenolics, urea-formaldehyde, urethanes, epoxies and Elastomers (Swanson 2013, Groover 2013). The figure below shows compression molding. Figure 1 Compression Molding Transfer Molding: This is another method that uses molds but the charge used is loaded into the chamber. The chamber is used to heat the material before pressurized it into the mould cavity using plunger. After heating, the charge cures in the mould cavity where the shell is produced. The cavity is formed in a manner that reflects the design of the shell of RC car so that when the charge cures, the shell that is produced is desirable. This process has two varieties as can be seen in figure 2. At the top is the plunger method, while the pot method is at the bottom. When compared, transfer molding is precise when making the shell and it can produce complex parts compared to compression molding (Swanson 2013). The figure below shows transfer molding. Figure 2 Transfer Molding Thermoforming: This is the most common method because many manufacturers of RC Buggy shell use it meaning that this is the best suit process. It is the most economical in terms of the time taken to make a shell and also the cost involved because the raw materials used are available and cheap. The process is also simple and easy to use. The process involves heating a plastic sheet and deforming it to create a design of the shell using a mold. The molds used here include a positive mould or a negative mould. Both molds work similarly. The only difference is that the negative mould is concaved and in the positive mould, the sheet is draped over the mould. The process involves heating the materials using radiant electric heaters at either one or both side of sheet thereby softening it. The heat is put over positive or negative mould then creating a vacuum in the cavity because of the atmospheric pressure that is created on mould cavity. The moulds used are cold to help harden the sheets when the vacuum pump is turned off to allow the removal of the sheet (Swanson 2013, Groover 2013). The figure below shows the thermoforming process Figure 3 Thermoforming The most viable method to use for shell manufacturing would be thermoforming because it is very simple, has fewer requirements compared to the others and produces minimal scrap material. When the manufacturer is careful, the process could produce a shell without any scrap metal. It also involves using a positive mold and drape over the sheet, which is economical because a permanent mould is produced and can be used to manufacture thousands of RC buggy shells (Groover 2013). The process also uses a vacuum former, which is easy use in the production of the shell. Materials An RC buggy shell can be manufactured using a variety of materials because it does not have many constraints or requirement. However, the material used should be light, cheap and easily available. Such materials include aluminum, fiber glass, polycarbonate, ABS plastic among others (Lisa 2014). The most preferable material is polycarbonate because it has remarkable toughness and can be used both in high and low temperatures and it has high strength compared to other materials (Bpfn.d.). Manufacturing the shell involves combinations of these properties because RC buggy shells go through many hardships from the races. When in races, the RC cars are driven in high speeds where they crash on their shells in certain cases or jump over hurdles landing on their shells. Therefore, the shell must be able to withstand such stresses and should also be strong and be beautiful to the customers who want to buy them. They should meet customer expectations. Shape and style The shape and style of RC buggy shell are dependent on the type of RC Buggy, which could be off road or street racer among others. The kind of race that the car will be involved in determines the shape and style. Different aspects of aerodynamics also determine the style and shape because most designers wants to get the best streamline shape that can be made. The following paragraphs will summarize the important aspects to be considered (Gartner 1999). First, drag is a force that should be overcome for the car to move forward. Drag consists of two forces that include frontal pressure (frontal area) and rear vacuum. Frontal pressure is caused when the air flows around the front of the car. The air molecules come towards the front of the car is compressed causing the air pressure to increase in front of the car compared to the molecules moving alongside the car at a lower pressure (Gartner 1999). To improve the car shell or make it more effective and be able to withstand the pressure and reduce drag force, the frontal pressure must be decreased. The rear vacuum comes because of a hole created in the air as the car passes through it as the car goes through the air, the air behind through the sides and on top of the car. However, the area directly at the rear of the car is empty, in other words a vacuum is formed. This vacuum forms as hole that is made faster than the molecules filling the empty space forming something called flow detachment. The shape and size of the shell of the car can solve this. The shape should be narrow and long from both back and front to allow time for the molecules to fill the vacuum with the same speed that it is formed. Any object that moves through air producers either down-force or lift force. The shape of the car can create down force by using reversed wings that push the car down towards the track, thus strengthening the traction. Lift force comes about where there is low pressure produced by the body shape of the car above it. To attain the required pressure can be created through manufacturing a shape that reduces the speed of air molecules. The shell of the RC should be constructed in a ways that provides a minimum front area that increases the speed and acceleration of the car. This affects the rear bodywork and the aerodynamic devices that include parts, such as the spoiler that produces a down force that brings about high pressure above the trunk area. In addition, inverted wings can be used because there are more efficient and produce more down force compared to drag. The aerodynamic theory explains that bodywork in the front cab be lower compared to the back of the car, thereby decreasing the airflow that passes under the car and also reduce the air pressure by producing a vacuum effect (Gartner 1999). Critical Dimension Critical Dimensions of the shell refer to the dimensions that could affect the function of the RC car and its safety if it is too small or too big (Maelabn.d.). RC buggy Shell does not have any critical Dimension. It only needs to be large enough to cover the RC buggy car’s parts, accessories and also provide the safety of the components of the car. If it is not the right size, the above aspects would be damaged and the safety would not be provided as much as it is important. Marketing The marketing of an RC car is an important aspect and it brings up an essential question, who will be buying an RC buggy car? There are customers that would consider buying RC cars. There are people who love the RC car as a passion and would spend any extra cash to buy it for passion. These are people who will not think twice about buying an RC car. There are also people who are professional racers and compete in races. These are the people who use their time and money on RC cars because it is a source of income and also pleasure for them. It does not matter if they have other professions such as teaching or banking. Their ages and professions vary as well as experience. However, the most important thing is that they form a strong customer base for RC cars and would be among the first people to buy them. USPs: unlike other shells that break or get damaged every time a race takes place and poses a risk to the life of the occupants and the parts of the car, there is a variety of shells of RC cars that people can choose from. Therefore, one must consider several aspects before they decide to buy RC shells, for instance the materials used and the place of purchase. These Shells are made with beautiful outlooks that could make it difficult for a person to know which one is the best. When going to race, people will look at the shell and like it but the quality will be noticed by a few and will only be important to the racer. Therefore, one should be careful and only buy the best shells that are well built, with the right shape and size. The buyer should also consider the use of the RC car before buying the shell. It is therefore important to think carefully and clearly before making the final decision to buy an RC car shell. References Rimmfg (n.d.) Reaction Injection Moulding [online] available from [21 June 2014] Swanson, P. (2013) Polymer processes [online lecture] module 102 EMM, 21 October 2013.Coventry: Coventry University. Available from [21 June 2014] Lisa (2014) Vacuum Forming. [Online] available from Bpf (n.d.) Polycarbonate [online] available from [21 June 2014] Groover, P.M. (2013) Principles of Modern Manufacturing. Singapore: John Wiley & Sons Gartner, M. (1999) Aerodynamics[online] available from [21 June 2014] Mae lab (n.d.) Dimensions [online] available from < www.maelabs.ucsd.edu/mae156/A/resources/Design-Process/Dimensioning/Why-Engineering-Drawings.ppt+&cd=16&hl=en&ct=clnk&gl=uk> [21 June 2014] Read More