TITLE: DESIGNING A SPORTS CAR WITH HELP OF CAD/CAM

INTRODUCTION

Computer aided design is a software that allows one to draw technical drawings both in 2 D and 3 Dimensions. Computer aided manufacturing is a software that enables the designer to issue a command to the machining equipment on what operations need to be done on a workpiece for it to have the required features and dimensions at the end of the process. Some of the tasks include the milling and boring operations. CAM has been considered to be a numerical programming tool that has made work easier for the designers as opposed to the old traditional design process. It’s a more reliable, secure and accurate tool in design and machining process. The paper is about the designing and machining of a sports car with the help of CAD and CAM software’s (Fard et al. 2016).

REPORT AND ANALYSIS

1. Discussion

Question one

a. Feeding rate is determined by the following formula

I.P.R. = Number of Flutes x Chip load

Where I.P.R = the machining feed rate

Number of flutes = 4

I.P.R= 4 * 10 = 40 mm per unit time.

b. cutting surface speed is determined by the following formulae

SFM = 0.262 x D x RPM

Where SFM is the cutting sped of the tool

D = diameter of the tool

RPM = to the revolutions per minute of the

For this case the cutting diameter D= 12 mm

With the RPM = 1160

SFM= 1160*0.012*0.262

=3.64704 m/minute

The primary objective of using this tool path is to improve the efficiency when working on smooth curves of the sporting car design. The tool height should be maintained in the same position this will help eliminate unnecessary cutting. To develop and maintain a high feed rate on the planar machine the tool plane should as smooth as possible. The best way to achieve this is by using a framework which optimizes the tool path. What it uses is level curves generated by a scalar function as a product of the surface of the tool path. This information helps the framework to develop a function which minimizes on the energy that is required for a perfect finish but at the same time fulfilling the primary objectives of having a clean surface finish for the model or design of the car. This framework can plan and design the optimal tool path with relevance to the required smoothness as well as the degree of the scallop curves (Fard et al. 2016).

Work holding method refers to the approach that will be used to hold an object as it is being machined. For this case, the machining process is the planar machining. In this design, a 5 axis work holding mechanism will be used. This is attributed to the high degree of flexibility of the mechanism allowing accurate developments of complex curved surfaces. The mechanism has five options which include the following, enabling one to center the ice as well as the development of the serrated jaws. In sections where serrations are required, a standalone hydraulic component helps to put required depressions on either side of the workpiece more saw the position of the wheels in the car. The serrations coincide with the serrations made on the vice jaw that makes the workpiece accessible from all possible angles. This helps avoid unnecessary mechanical stops during the machining process as well as producing a perfect surface finish. Devoital mechanisms will be essential in developing the smooth accurately required curves on the body surface of the workpiece. The fixture is designed with corresponding cutter holding mechanism that allows the cutter to effectively cut tight angles from the workpiece without unnecessary movement interferences. A special cap screw device is used to apply the required force on the clamp to ensure the workpiece stays in its position during the machining process. The advantage of the five-axis fixture is that it allows the user to fix more than one part of the design at a given time (Fard et al. 2016).

High efficiency will be achieved through the use of a specially designed is the planar tool. The tool is capable of generating algorithms for multiple path axes. In our case having the planar tool is essential since the work holding mechanism is of 5 axes which are compatible with the algorithms of an efficient machining operation. This design helps the machining tool to handle freeform surfaces easily; it considers the kinematic capabilities of the cutting tool are ensuring perfect curves are easily obtained. Instead of focusing on how to minimize the width of the strip being cut from the workpieces, this algorithm also takes into consideration the material removal rate in general. Such an approach takes into consideration between the width of the cut strip as well as the kinematics involved in the cutting tool working principle. Automatic adjustment of the tool with relevance to the path helps improve the efficiency of the cutting process. The path tool algorithm procedure is the best approach in ensuring high-quality work is produced with good efficiency (Fard et al. 2016).

Several strategies are essential in reducing the total cycle time in the machining process of the model. The first one is to gather all the relevant information concerning the model design. This involves getting all the computations and measurements accurate as well as the customer preferences of the same design. With such information, once the machining process kicks off there is minimal wastage of time in consulting about the specifications of the model because the designer has all the necessary details. Applying the simulation software will allow the user to be able to accurately verify all the details of the model before it’s forwarded to the machining process. Such a process helps avoid errors and unnecessary stops once machining process has begun. The use of the 5 axis work holding allows accessing of more than one part during the machining process essential in reducing the total cycle time. One should also be able to select the best tooling device that works well with a 5 axis holding mechanism. The final item is that one should be able to match the machine chosen to the required job specifications. For instance, the operator should be able to have a base that can fully handle the high speeds that the machine tool will be operating on the selected workpiece model. Having the entire five-axis operating at the same speed helps to avoid delays time in the machining process. Enhancing the discussed five aspects will help in minimizing the time wastage lapses that were being encountered. This will helps in reduction of the cycle time a lot as its starts from the designing stage up to when it the model is out of the machining process (Iqbal et al. 2014, 812).

There are three main strategies which can be used to improve the efficiency of the machining process. Maintaining of the chip load at a constant value helps the machine to be able to operate under an initial high-speed value that has been given which is in line with the capability of the machine. It is an achievable task because for the different access positions required during machining one should be able to select the best work holding mechanism that can ensure accurate results are obtained. Secondly one can improve the efficiency by minimizing the feed rate loses. This involves the excessive cutting of the model due to poor control of the feed rates. It can be achieved through smart machining where there are minimum losses incurred during feeding. However achieving such a state is not easy for the operator because the machines are not ideal. Finally one can also use the maximum processing speed capability of the machine. However, for such a method there will be inaccuracies encountered when extremely sharp and accurate bends are required. A good example is the car model being designed. It just needs optimal speed not too much. This strategy proves to be the most difficult to implement fully. From the three discussed maintaining of the constant feed rate through a constant tool height and a sharp cutting tool is a realistic approach as it can be easily controlled by the operator unlike the other two strategies discussed (Iqbal et al. 2014, 812).

Question two

Punched tape is the first data transfer tool which can be used. It contains a tape with specifically designed holes that instructs the machine on how to do various operations related to machining of a given model. It’s one of the most reliable methods as it has a long lasting lifespan as well as being easy to repair compared to the other methods of data transfer (Iqbal et al. 2014, 813).

Floppy disk drive refers to a small magnetic storage medium that provides more efficient use of space about the amount of information stored when compared to the punched tape. It can store small programs as well as allow easy transfer of files and instructions from one point to the other. However one of the disadvantages of the type of data transfer is that it is easily affected by magnetic property making it less reliable in the industry (Iqbal et al. 2014, 813).

It is one of the modern methods of data transfer from the computer to the machining equipment. It entails the transfer of data informs of binary digits form source to intended destination which instructs the machining equipment of the required operation on a given model. It allows the user to input data into the system with the aid of a remote thereby improving the flexibility of data transfer process. It is one of the best methods preferred in data transfers machining process alongside the use of a network to send data from the computer to the machining equipment which is the best method used in at the moment in the industry (Iqbal et al. 2014, 813).

Networks

Set of computers are linked by a network that allows several designers to input data to the machining equipment at the same time and give it the command to begin the machining process. Its the most reliable and portable method of data transfers in the computer aided manufacturing process when it comes to machining (Iqbal et al. 2014, 813).

There are three main steps involved in the development of a tool path during machining of the model. The three are summarized by the following flow chart diagram.

The first step is tool path interpolation process where bulk material is removed from the curves as well as the blanks. This helps to come up with a rugged profile that will undergo further surface finishing. Surface finishing process will then be developed to ensure a perfect finish is obtained at the end of the process. The surface and residual finishing of the initial profile will greatly determine the quality of the final piece of work after undergoing the smooth machining process. The residual should be as little as possible to lower the chances of inefficiency as well as rapid tool wear (Huang et al. 2015, 1230).

The second step is the generation of a trajectory for the tool path. Algorithms are designed in relevance to the proposed trajectory after which they undergo a series of trajectories. The validation process of the developed curves takes place where the curve is designed and visualized (Huang et al. 2015, 1230).

Simulation and verification form the last stage of the tool path development process. The simulation is done by the designed algorithms which are verified to be accurate before the actual machining process is done. The simulation helps to minimize on the practical testing of the designed tool path associated (Huang et al. 2015, 1230).

The process used in producing the model as milling in the machining process. This provided a flexible approach through which the different curves of the model could be developed. The method with the aid of a 5 axis work holding mechanism was provided with efficient access to more than one part at the same time. This a helped to reduce the circle time in the machining process, The use of the CAD and CAM software allowed proper verification of all the designed parameters before the actual milling process. With the milling as the main method of machining, it was easier to develop all the perfect curves as required (Pedagopu et al. 2014,175).

The critical boundary condition in the milling process is regulation of the temperature of the milling tool. Having a thermostat attached to one end of the tool helps in detecting its temperature prompting releases of more or less of the coolant during the milling process. This helps reduce the stress on the tool due to overheating. The other way is to ensure the work holding device is a reliable one able to have the workpiece in a fixed position. This will help avoid unnecessary adjustments of the tool height due to movements in the workpiece. Using a 5 axis work holder helps the tool maneuver through the workpiece without unnecessary adjustments in its height (Pedagopu et al. 2014,175).

The best way to avoid block transferred during the machining process as it affects the final surface finish quality is by having a work holding mechanism which enables the model to be accessed from more than one axis. Utilization of the 5 axis work holding mechanisms helps avoid unnecessary block transfer during the machining process. In most cases, block transfer occurs when the workpiece has to be transported from one holder to the other (Pedagopu et al. 2014,175).

Gantt chart

 Duration Reporting relationship identification of the design Coming up with model which is representative of the expected design Project team manager identifying required materials Selecting required materials fro different parts of the model Project team manager design specifications Determining the measurements of various components of the model Project team manager machining specifications Milling process, with a 5 axis work holding mechanism Project team manager matching the machine with design specifications Identifying the machine that can work effectively with the required specifications Project team manager tool path identification and validation Developing of the tool path as well as related algorithms Project team manager simulation Running the algorithm through a simulation software to check whether is gives the required output Project team manager machining Actual sending of data to the milling machine for processing the workpiece to produce the required workpiece Project team manager

CONCLUSION

The designing and development of the model for the sports car were achieved because of the application of CAD and CAM in the machining process. These software’s provide a high degree of accuracy, precision, reliability minimizing losses incurred in the normal machining process. With a computer controlled machining process, the machining is only done once the simulation of the same has been done and verified to be the desired one. This technology helps to correct any design issues before actual machining process that is accurate and time-saving.

Reference

Iqbal, H., Sheikh, A.K. and Samad, M.A., 2014, April. Introducing CAD/CAM and CNC machining by using a feature based methodology in a manufacturing lab course, a conceptual framework. In Global Engineering Education Conference (EDUCON), 2014 IEEE (pp. 811-818). IEEE.

Huang, R., Zhang, S., Bai, X., Xu, C. and Huang, B., 2015. An effective numerical control machining process the reuse approach. Merging feature similarity assessment and data mining for computer-aided manufacturing models. Proceedings of the Institution of Mechanical Engineers, Journal of Engineering Manufacture, 229(7), pp.1229-1242.

Pedagopu, V.M. and Kumar, M., 2014. Integration of CAD/CAPP/CAM to augment the efficiency of CIM. Int. Rev. Appl. Eng. Res., 4(2), pp.171-176.

Fard, M.J.B., Nowak, A. and Francis, B.R., ICAM Research Corporation, 2016. Device, system and methods for automatic development and optimization of positioning paths for multi-axis numerically controlled machining. U.S. Patent 9,465,380.