Investment casting essays

Investment casting essays Investment casting or lost wax casting has been used by many different cultures for thousands of years. The Egyptians used investment casting to make bronze statues and the Chinese made vessels and a variety of other items by using investment casting. Therefore, it is by no means a new process. The most modern approach, which has been used since the middle of the twentieth century is called ceramic shell casting. Because this is the most modern form of investment casting, I will bee focusing on this particular process for the entirety of the paper. The two different types of patterns used in investment casting are called expendable and permanent. Expendable patters are made of wax, are joint less, and yield a casting with a higher degree of accuracy than the permanent pattern method. The permanent pattern method uses a pattern that is made of wood, steel, or some other type of solid material. Using the permanent pattern method is usually cheaper than the expendable pattern method. One disadvantage of the permanent pattern method is that the molds must be assembled in separate parts, which makes it less accurate than the expendable pattern method. The first step in investment casting when using the expendable pattern method is to manufacture a die. The die is made from strong alloys such as steel and Duralumin or softer fusible alloys where accuracy is less important. Steel dies are the best for long production runs and are machined from a solid piece of steel. Many dies are produced in two or more sections enabling the pattern to be removed once it is cast. After the die is done being machined it is coated with a parting agent or lubricant which helps the pattern to be extracted. The die is used repeatedly to make wax patterns for the investment process. Wax is the most common material used in investment casting. The wax has a low ash content, is compounded from natural and synthetic waxes and resins, and usua...

Occupational Therapy Essays - Computer Keyboards, Keyboard Layout

Occupational Therapy Essays - Computer Keyboards, Keyboard Layout Occupational Therapy We are a group of occupational therapists and a new client has come to our office with the following case history: Don is a 63 year-old amateur poet. He has several of his poems published in the local newspaper but has not yet been accepted by any literary journals. Three months ago, Don had a cerebellar cerebrovascular accident that has given him significant fine motor control limitations. He is not able to hold a pencil or a pen, and when one is taped in his hand, he can not produce recognizable printing. He is able to reach a range of nearly 5 feet from side to side but cannot pick up a 1-inch cube from the table. When asked to use a keyboard, he is as likely to strike two keys away from the target as the key he is aiming for. He is able to put his finger reliably into a square that is 2 inches on a side wherever it is located within his reach. He is not able to accurately place his finger into a square that is 1.5 inches on a side, however, unless it is located directly in front of him (Anson, 1997, p. 104). Don is frustrated by his condition and needs some assistance to continue his writing. We used the decision tree to evaluate which computer adaptation would be best for Don. We determined that Don has physical limitations to the computer but has full range of the keyboard. Due to his trouble targeting specific keys, it would be increasingly difficult to simultaneously press more than one key at once. The client has frequent accidental keystrokes because of the size of the small keys. His inability to strike a single key on demand led us to expanded range of motion. Having assessed that Don could strike larger keys accurately; we reached the alternative of expanded keyboards. Upon researching expanded keyboards, we found a great variety in what each keyboard offered. The 32 key layout with 2.5- inch keys did not provide an adequate selection for Dons writing needs. Most of the standard expanded keyboards with 128 keys only have 1.5-inch keys. Some examples are Key Largo and Unicorn Expanded keyboards. Key Largo is an expanded keyboard, which works through Discover KENX. It is useful for one with coordination problems. Unicorn Expanded keyboard established the standard 128 key expanded keyboard design. We had the opportunity (in A.T. lab) to try and compare the different expanded keyboards. We appreciated that a client with difficulty reaching small keys would find these keyboards more beneficial. All keyboards require an encoder, which interprets the key. When pressed it converts it to a keyboard code, that the computer could understand. Some computers come with a built in encoder and some without. These keyboards with encoders can be connected directly to the keyboard port of the computer. Therefore no internal adaptation is needed for the computer and it doesnt interfere with any software in the computer. This is beneficial because it can be used with any operating system and software the client may need. A disadvantage to this is that the keyboard codes are not readily adaptable. This means that the keyboard layout is fixed and cant be changed by the clinician. Another consideration is that this keyboard can not be connected simultaneously with the standard keyboard. Since plugging and unplugging the keyboard is not recommended, this option is better suited for a client who would be the sole user of the computer. Expanded keyboards that do not have the built in encoder, require an external device that would interpret the codes to the computer. Although this keyboard has the disadvantage of an external device, it offers flexibility in the keyboard layout and allows for various overlays that change the layout. An example of the latter is the Key Largo keyboard mentioned above. The problem with 1.5-inch keys is the clients inability to accurately reach a key of that size unless the keyboard is positioned right in front of him. An option would be to position the client in front of the computer with the keyboard mounted close enough for him to access. Although this alternative was a possibility we preferred to find

WEEK 3 DISCUSSION Essay Example | Topics and Well Written Essays - 500 words

WEEK 3 DISCUSSION - Essay Example Porter is clear in explaining that because a company is profitable and effective at a given moment; that is not necessarily the benchmark of how a company will perform in the future. Like science’s description of life on Earth, the corporation must continually evolve and become more efficient as it maintains a keen eye on its competitors. Most economists like to use the Japanese as a business model when it comes to efficiency and profitability. True the country’s top businesses seized upon a time period where Western companies seemed to be asleep at the switch. Yet their competition has seized upon strategy and in a sense is beating the country’s businesses at their own game and it appears several decades later that the opposition is winning (Porter). In using the Japanese model, Harvard Business Review points out that in 1970 Komatsu was a tiny bulldozer company hardly known outside Japan and had a minute sales fraction of Caterpillar, the American giant in the industry. Fifteen years later, Komatsu had expanded to a $2.8 billion company with as many product lines as their mammoth opposition. As well, they had expanded into the emerging industrial robotics area (Hamel). Did Caterpillar concern themselves with Komatsu in 1970? It is doubtful but had they done a Strategic Intent analysis at the time, they may not have had such a tremendous slice of profit removed in 1985. In a sense, Albani Perfumes is the current Goliath in its market of Latin America. With current sales of $10 million, it is still a relatively small company but has managed to do well against its current competitors. Yet as discussed in Week 2, China is making headway into the market with knockoff perfumes. It could probably be argued that Albani would not win a trade war with the world’s fastest growing economy and this would be rated at zero, Strong Negative