Sand Casting Techniques

MME 3210 Materials Processing Techniques Laboratory Assignment – Sand Casting of an Aluminium 13wt% Silicon Alloy 1) Process Attributes Waste shown yellow* Waste shown yellow* After taking part in the sand casting laboratory session it was made clear that the process possessed many advantages and disadvantage, both from the process itself and from the final part produced. Observing the process step by step it was noted that the tasks carried out by the operator were not very difficult (i. e compacting sand, pouring liquid metal) and so giving the advantage of only requiring a low skill level.However, although the process did not involve a large amount of skill it was observed to be very labour intensive and took a long time to complete one cycle of the process (around 30mins). Having a long cycle time is clearly a disadvantage as time is money in the manufacturing industry but this could be slightly reduced if multiple moulds were prepared simultaneously. Another advantage obs erved during the sand casting procedure was that the equipment used was not very expensive and unlike other casting processes the mould was reusable.With only a low capital investment needed this would make short production runs viable. Probably the most noticeable disadvantage to the sand casting method was the low material utilization. In the labs example (seen left), almost a third of the material used is lost to the riser, runners and feeder. Particularly in today’s waste conscious culture this can cause many problems, however it can be tackled by better design. 2) Process Problems Shrinkage: Shrinkage defects in the final product are usually the result of a feeding defect.As shrinkage naturally occurs during the solidification process, if liquid metal is not sufficiently fed through the feeding system to compensate then it will result in an indented surface. The surface defect was clearly shown in the lab example (shown left). A shrinkage defect normally occurs on the la st part to solidify, so logically in the labs case the shrinkage occurred on the surface of the thickest part Furthermore the big defect problem of a surface sink was observed in the sand casting lab session (shown left).A sink such as this would give major dimensional inaccuracies and would probably have to be redone as it would be unsuitable and uneconomical for further processing. Solution: One way in which an engineer could reduce the effects of shrinkage is to design the mould to compensate for the shrinkage during solidification (i. e making the mould larger). Also due to shrinkage being mainly associated in being a feeding problem, the redesign of the feeding system would reduce the set back. Making the feeding sprue thicker would ensure that the system continues to feed liquid metal to the cavity, thus preventing shrinkage.Furthermore utilizing a uniform part thickness would also tackle the problem reducing residue stresses and leading to uniform cooling. Rough Surface Textu re: The defect causes an undesirable distorted surface finish and is formed due to the texture created from the compacted sand used to create the mould cavity. The effect was observed in the part created from the lab session and can be seen right. Solution: The rough surface effects created from the mould sand can be significantly reduced by using sand with very small grain size.Particularly for the face sand which lines the surface of the mould cavity, if the grains used are very fine then surface finish will be improved dramatically. Porosity: The defect of porosity occurs because of the liquid metal used to create the part can hold large amounts of dissolved gasses. As the liquid metal solidifies, the materials new solid form can no longer hold these gasses and so they form bubbles. These bubbles can be generated both on the surface of the material and internally, thus they effect the strength of the materials solid form and resulting in a decrease in mechanical properties.Effect s of porosity shown above* Effects of porosity shown above* In the lab example holes were added in the sand to allow gas and moisture to escape, however effects of porosity were still clearly visible. Solution: The solution to eliminating the undesirable effects of porosity is based around minimizing the amount of gas that is in the liquid metal. One way in which gas inclusion to the liquid metal can be reduced is to minimize the effects of turbulence experienced during the filling process.Similarly to solving the problem of shrinkage, this can be solved by redesigning the filling system. The design used in the lab example used the bad design set up. With the sprue placed at the top of the mould cavity, the liquid metal flows fast splashing in to the mould cavity below and resulting in turbulence and gas inclusions. If the good design set up is implemented then the liquid metal will flow slower and because runner is fed into bottom of the mould cavity with several gates, splashing w ill be significantly reduced, turbulence minimised and inclusion of gasses eliminated.Good design Good design Bad design Bad design 3) Advantages for using Aluminium – Silicon alloy having 13wt% Si: * Aluminium alloys supply reasonably high tensile strength in relation to density, compared with other alloys such as cast steel. * Corrosion resistant in normal environment. * High fluidity of composite melt provides easy transfer and pouring of material to mould (demonstrated in lab shown below). * Utilizes a Eutectic system, reducing defects such as porosity. * Silicon within eutectic results in: Increased corrosion and wear resistance. * Reduced thermal expansion coefficient. * Improved casting and machining characteristics. *Increasing silicon content within alloy will magnify these properties accordingly * Different Al and Si within Eutectic act as a hindrance to dislocation movement. * On part completion, alloy material can be easily polished and painted for an aestheticall y pleasing surface finish. 4) Nucleation Solidification does not happen instantaneously but occurs by a process of nucleation and growth.All pure crystalline solids have a given melting temperature (Tm), although when above this temperature the material will be in a stable liquid state, if cooled to a temperature equal to Tm then the material will start to crystalize. This usually involves some degree of undercooling for crystal nuclei to form. Free Energy Of system Free Energy Of system From the graph above it can be seen that by increasing the undercooling ? T, the free energy also increases ? G. Gets steeper as T is decreased Gets steeper as T is decreased There are different types of nucleation, homogeneous and heterogeneous.Although homogeneous almost never occurs in real life it can be used to build a model of the more realistic heterogeneous nucleation. Heterogeneous occurs on an existing nucleant but unlike homogeneous the nucleated cap is a solid rather than a sphere, thus less atoms are required. Process usually requires liquid to wet the nucleant surface. Growth For growth to be sustained, the temperature of the melt must be less than the melting point. The speed in which growth occurs can be controlled by the amount of undercooling applied, with a large amount of undercooling resulting in rapid growth.In addition the growth also depends on how fast latent heat is removed during crystallization. Both these aspects contribute to the temperature gradient of the melt which affect crystal formation. Constitutional Undercooling Usually caused by non-equilibrium concentration gradient, constitutional undercooling is more likely to be found in alloy casting rather than in pure materials. Seen in the diagram right, the amount of constitutional has a large impact on the type of crystal growth. Looking at the solidification of Al 13% Si, it would be expected to solidify under eutectic solidification.Due the fact that it is a composition of two materials, alum inium and silicon, and that during the lab the material solidified at a single temperature (room temperature). Furthermore it also provides the lowest melting temperature for the materials used. This is an energy savings in a production area. 5) From the many defects created during the creation of the lab example part it was clear that something in the process needed to be changed in order to produce a part of a more acceptable quality.As highlighted earlier, a main area for improvement was with the method of delivering the liquid material to the mould, particularly focusing on the design of the feeder. The current feeder design used is very basic and can be seen right. The set up uses a thick single vertical cylindrical shaft with a very small taper, delivering liquid metal directly to the cavity via a single runner. Concentrating on feeder design, one way in which defects can be reduced is by supplying the cavity with a smooth constant volume of flow.As the current feeder is very thick, the material is delivered very fast to one area of the cavity causing turbulence and inclusion of unwanted gas. This undesired effect could be minimized by changing the set up of having one large feeder to possibly 3 smaller ones. The use of multiple feeders would allow a more evenly distributed and constant metal flow. In addition the angle of taper could be increased to assist constant volume flow. Cavity Cavity Multiple feeders Multiple feeders Each of the feeders used should be reduced in thickness as much as possible, still maintaining the desired flow rate.This is important as although deliverance of material is critical, the amount of waste material must be reduced as much as possible. Although only visual inspection was applied to the produced lab part, if it was discovered that the defects main cause was that of impurities within the solidified material than the Cosworth ‘’upward fill’’ system could be employed. Due to its upward fill the p rocess eliminates the problem of impurities within the liquid melt and impurities that sink or float are discarded. References http://www. acetake. com http://www. rheocast. com www. electrochemsci. org/papers/vol4

Personal Ethics Essay Example | Topics and Well Written Essays - 1500 words

Personal Ethics - Essay Example It should also be noted that what a society may consider morally upright might not apply to other societies. This means that personal morality may vary from one society to another. In addition, an individual may go against the society ethical norms and embrace different values depending on his or her conscience and judgment (Howard & Korver, 2008). My personal code of ethics is developed from ethical relativism, which points out that what a society believes in will influence the other person either positively or negatively. In this case, individuals in most cases are influenced by society to make choices for themselves, which in the end may assist in shaping their personal ethical values. The developmental theory coming into play is the learning theory. According to this model, learning ethics values and behaviors takes place through the process of reinforcement and association. Human ethics are shaped by ones society and they define how one is going to apply them in real life situat ions. During my childhood, my society used to frown on me when I engaged in dishonest activities and so through positive reinforcement, honesty became one of my ethical values. My society shaped me positively by enabling me to learn virtue ethics (Howard & Kover,2008). The Ethical system that shapes my codes of ethics is the ethics of virtue. Basing on ethical relativism where the society shapes ones behaviors and ethical standards either positively or negatively, my society instilled virtues ethics in me as I value doing what is right basing on values that are upheld by virtue ethics. The main values that ethics of virtue has promoted include integrity, humility, honesty, respect, being responsible, trust, being principled and trust. Most of these virtues are engrained in almost every society and they form the basis of morality in the world. Upholding positive values that are promoted by ethics of virtue enhance positive human interaction, promote fairness and justice, and enabled one to appreciate and respect the society and other people. In addition, virtue is essential in minimizing perceived immoralities such as crime, child prostitution, war and other social evils. As a woman, upholding my virtuous codes of ethics has been instrumental in my positive behaviors especially when dealing with my family members, children and the society in general. As a woman, my caring, gentle and good behaviors can be attributed to the virtues that I uphold and the social norms that I was subjected to by my society (Kowalski,2012). When applying the ethical codes, I have faced a number of dilemmas, some of which threatened the basic tenets of my beliefs and moral behaviors. One of dilemma is how to handle a situation that requires sound judgment such as a criminal case involving murder. This situation requires fairness and justice without pity or mercy but according to my codes of ethics, humility and mercy are some of the major values that dictate my codes of ethics. I alw ays manage this dilemma by applying the value of principle where I make my decision basing on what I feel is right for a given situation without being dictated by other ethical values that the society may have instilled in me. Further, in solving ethical dilemmas, I consider the environment of a given situation before making any judgment. For example, if a problem occurs between family members, I use the value of

Fitness program for Snooki from jersey shore Essay

Fitness program for Snooki from jersey shore - Essay Example cise, exercise gives individual the benefits that cannot be achieved from dieting as it allows the individual to boost their metabolism while making sure the body burns the fats that are not needed. Exercise can be used to build muscles, enhance the shape of the body and result in a firm and toned body while dieting alone cannot promise a body that is firm and toned. When combined with dieting, exercise increases the rate of losing weight (Caballero, Allen and Prentice, 411). Nicole â€Å"Snooki† Polizzi is a reality TV personality and dancer who is famous for being a member of the cast of the MTV reality show Jersey Shore among other shores including talk shows. She has struggled with anorexia while growing up as a consequence of cheerleading but her parents helped her deal with the disease. As an adult, she gained weight especially when she was starring in Jersey Shore. This fitness program is aimed at assisting her reduce her weight to healthy levels through working out and a healthy diet. This fitness program takes between four to twelve weeks depending on the weight that is to be lost. It should be followed together with healthy eating and a control of portions, which means eating the appropriate food in the required quantities at the correct times so that it can be easier to burn pounds of fat each week. The program will include a resistance program that will assist in gaining muscles meaning that progress will have to be monitored through body measurements as well as body fat percentages. In order to maximize the reduction of body fat, the type of food and its portions should be changed to fit the new way of life. Losing weight can be achieved with the kind of diet a person takes but in order to increase the muscle strength and cardiovascular fitness, gym workouts will be required. Therefore, a weight loss fitness program should stimulate as much fat as possible through three full body workouts every week with two day of cardiovascular exercises and two

Responding to Groupthink and Faulty Reasoning at NASA Case Study - 6

Responding to Groupthink and Faulty Reasoning at NASA - Case Study Example From this paper it is clear that if group members have doubts but lack appropriate evidence to support their position, their doubts and concerns should still be communicated to authorized personnel who have the competencies and qualifications to evaluate the matter and substantiate whether there are valid support for the doubts. The important thing is that the concern has been effectively communicated and relayed to higher authorities.  The reporter stresses   "if I were head of NASA, I would have launched a rescue shuttle in as far as I am confident that the second shuttle would not meet the same fatal accident regarding the first foam strike that happened with Columbia. I would also solicit as much information as evidently possible to determine alternative courses of action where the Columbia crew could make it back to Earth as innovatively possible.   As indicated, NASA has followed these steps to change its culture and to resist groupthink: safety worries are encouraged to be communicated and are not out rightly dismissed; teams of engineers conduct simulations on diverse scenarios to assist in addressing problems and concerns; cross-checking of interventions, suggestions and recommendations from one team of engineers are validated by another group of engineers from a different research center to avoid group think and to encourage taking diverse perspectives; worst case scenarios are proactively established including establishment of contingency plans in these situations. If these changes and activities are continued to encourage innovative thinking, the agency could indeed continue with its progress. Progress could be slow at first but it is always better to be slow than sorry. "

The Enlightenment Era Essay Example | Topics and Well Written Essays - 750 words

The Enlightenment Era - Essay Example This era condemned going with old, traditional ways of thinking only so that rational and carefully thought-of theories are formulated that are in time with the current events, of 18th century thereof. (E. Cassirer et al., 2007). Philosophy is a complete organism or system that is concerned with the human character and the world that exists. What this interaction basically is and how the human mind or the person itself interacts with the world he lives in. Philosophy is a question. It provokes mankind to answer questions and theories, and subjects a human to how life is lived and how is he living it, or how he is treating other people etc. This philosophy does not have some physical form, rather mostly through the expression in words. (Thomas, 2005) Metaphysics is a branch of philosophy. This is related to things like what reality is and what existence is defined as. And how do both of these function together. The enlightenment Era gave birth to this idea. Sometimes, this era is also known as the "age of criticism" and rightly said so because all formerly beliefs were questioned so that science and logic could follow through. Kant studied metaphysics closely and his knowledge of the functioning of society was based on metaphysics. He said that society has to retreat from what effect objects bring to the mind. He said that the new philosophy should be how the mind affects everything around it and those same objects. (Hunt, 2004). As far as the eighteenth century philosophers are concerned, they did some great work to bring this era to light. Some of these include Kant in Germany, the Encyclopedists in France, David Hume (1711-76) in Scotland and d'Holbach (1723-89). These philosophers became famous for their own different ideologies and concepts related to philosophy. There are many other popular and renowned names also that are worth mentioning like Plato, Ren Descartes, Aristotle etc. (Hunt, 2004). There have been many different philosophical ideas including rationalism, empiricism, the Encyclopedists, the analytic and synthetic, logic and also determinism. Philosophy is dependent on all of these. Other ideas that floated through this century are science, religion, morality, truth, reason, faith, belief, class, power, rationality etc. And all philosophers have written or shown their works through the expression of one of these or the other. The major philosophers of this age were Kant and Voltaire. Victor Hugo Voltaire is a huge name in the world of philosophy when we talk about the eighteenth century. Apart from Voltaire, Kant and John Locke have been great thinkers too. Locke defined empiricism and his works greatly relate to this field of philosophy. (Hunt, 2004). John Locke, Thomas Hobbes, and Jean-Jacques Rousseau are some other names in the Enlightenment Era who have been said to create great works as thinkers in this period. The most famous of these works being "noble savage" and endorsement of the idea of free trade principle. The patron of these works was Rousseau. Because of this afore-mentioned work, relations pertaining to political and economic criteria were greatly affected. Many views changed and the association promoted this free trade concept. However, Roman Catholic views and theories were then

The Stress of Working in a Call Center Essay Example | Topics and Well Written Essays - 750 words

The Stress of Working in a Call Center - Essay Example Each day that I reported for work, I was on the receiving end of the harshest berating, the meanest insults, and the most intellectually insulting comments that one would only wish on his worst enemy. To make matters worse, I had no right to stand up for myself and let them know that I was just a person tasked to receive their complaints. I wasn't the enemy. I was there to help. Or at least, let them vent to a certain degree. But these clients took complaining to a whole new level. Every time I was demeaned as a person, I felt like shouting at the person on the line, or simply disconnecting the headset and running off crying or to let off some steam. But I wasn't allowed to do that. I needed to stay on the line no matter how I felt. Rather than taking my anger out on the clients, I made sure that I spent at least an hour a day releasing my anger and stress. They say nothing beats boxing when it comes to releasing stress. That is exactly what I did. Each day, I would get home from my shift and pop a boxing game into my X-Box Kinect and jab away for a few minutes in order to remove the stress and anger that I had pent up inside of me. Then on the days that I had off, I made sure to get a full body massage in order to relax my body, mind, and soul even for only a few hours a day. These two regular stress-busting practices of mine were definitely the way to go. I would return to work refreshed and with a new perspective on my job situation and how to deal with it. I learned that work stress could actually be released even on the job if I simply had a way to let it out as I did my task. That was when the stress ball massager became a daily part of my work life. Every time I got a problem call, I take the stress ball and squeeze it as I felt my tension and anger building up inside of me. All of the negative emotions that I wanted to unleash on the client transferred to the stress ball.  

Managing Communication in Business Essay Example | Topics and Well Written Essays - 2500 words - 1

Managing Communication in Business - Essay Example Organizational communication is very important as for a business to precede and expand, the management should have strong communication ties with its employees. Non-verbal communication is a category of communication that plays a crucial role in terms of organizational communication. In this paper, all kinds of non-verbal communication are described that can affect organizational communication. Along with the description of forms of non-verbal communication, the factors such as gender, age and culture are also analyzed in the paper. After description of all the forms of non-verbal communication, a conclusion is given. The conclusion summarizes the whole essay in a short form. Kinesics can be explained as body movements (Pelachaud, et. al 1996). There are many kinds of bodily movements such as making use of emblematic signs through hands or fingers, making use of hands or legs to stress on or illustrate something, by regulating spoken or listened words and sentences, expression of feelings through bodily movements and gestures and by making use of some adapter to indicate towards a meaningful situation (Depaulo 1992). Body movements are employed in many ways to communicate non-verbally (Argyle 1988). Making use of emblems, adapters, illustrating, adjusting and revealing feelings and gestures, all come in kinesics. In an organizational setting, people make use of kinesics to communicate and by repetitive usage of some bodily movements; people identify them (Burgoon, et.al 1996). For different cultures, people make use of different emblems for the same message. For example, for admitting to some suggestion, many people make use of bowing the head a little, while others can make use of hands to indicate, â€Å"Yes† (Gudykunst and Ting-Toomey 1988). Through body movements, people can communicate their feelings and expressions (Harbridge 1998). In case, a person is tense, he/she can move back and forth that is a clear sign of