Resistor Manufacture and Optimization - Book Report/Review Example

Report Introduction Resistor s back the early 1920s during the period they were the main technology separating the 1920s radio with the later designs. Carbon resistors were the first categories of resistors and used regularly due to the thermal performance of the resistor. Compared to the Wire Wound resistor, carbon resistors could be used in the AC circuit due to their performance. Over time, changes in technology have given rise to new and efficient types of resistors. There are two categories of resistors, variable resistor and fixed resistor. These resistors are used in circuits as passive components. Passive components are components with the inability to amplify or increase voltages, signals or currents but with the potential to reduce the voltage, currents and wave. Although a passive component, resistors are essential in any electric circuit. Resistor Manufacture and optimization Resistors are the readily used electric components present in the market. Though common, their role vary depending on the circuitry with the main reason for use is to provide resistance to current, at times used to regulate resistance such as the use of variable resistance. They are necessary for the creation of several appliances. The oldest types of resistor are the carbon resistor. Resistor types Carbon Composition resistor Carbon resistors are the common, and the oldest type of resistors by composition type resistor. They are readily available, cheap and used in general purpose circuits. The resistor is composed of a mixture of finely ground carbon dust or graphite and a non conducting ceramic powder to bind it together. It is the oldest design. The resistance value is determined by the amount of carbon inserted in the filler. The resistors in this order do not have close tolerance compared to carbon or metal film types. Typical tolerances of the resistors are +/- 10% or20%. The advantage of the resistor type is the ability to work in high voltage pulses compared to all the other types of resistors (Wilson and Williams, 2011). Carbon film resistor The manufacturing procedure of the resistor is similar to metal film resistor. The change being, the tolerance of carbon film resistor is higher at +/-5%. Small resistors from this category are reasonable and often sold in batches. Metal film resistors The resistor in this category is a combination of small rods of ceramics coated with metal or metal oxides such as nickel alloy or Tin oxide. The resistance value is obtained from the thickness of the coating layer. The greater the coating covering the lower the resistance value and vice versa. The metal film resistors come in a variety and with a wide range of resistance values but with extremely low tolerance of +/- 1% or less (Wilson and Williams, 2011) Wire Wound resistor Wire wound resistors vary in construction and physical appearance. The main component of the resistor is the resistive wire made of alloy such as Nickel/Chromium or a combination of copper, Nickel and manganese wrapped a ceramic rod and coated with flame proof cement (Wilson and Williams ). The value of resistance of such resistors is remarkably low, but can dissipate large amount of power leading to heat generation. The heating makes it necessary for high power wire wound resistor to be finned, by bolting the case to a metal chassis to diffuse the heat produced. This type of resistor can cause fire, therefore, several actions are taken including covering with cement or flame proof material. The tolerance of the resistor can be standardized at 1, 2 and 5%. The resistors are usually housed in the aluminium for heat dissipation (Olhager and Persson). SMT Resistor These are resistor types are common in modern appliances. SMT stands for surface Mount technology. The manufacture of the resistor involves the depositing a film of resistive a material on a tiny ceramic chip. The edges are then ground accurately or cut using a laser to give a precise resistance. The resistance value is dependent on the width of the resistor film. The tolerance of the resistor is low at +/-0.02%. The advantages of the resistor are ease of assembly because of the automatic assembly methods, and it has exceptionally low heat dissipation (Wilson and Williams ). Other resistor type Other resistor types include resistors made from a combination of the types of resistors listed above. They include; high power metal film resistors, fusible Wire wound resistor, PCB Mounting Wire wound and 5 Watt Wire wound resistor. Resistor parameters Resistors are measured using ohms, but there are other factors affecting the performance of the resistors which include; temperature coefficient and frequency response. Temperature affects the performance of resistor in a minimal degree. The materials used in the manufacture are not affected by changes in temperature. The small change in temperature does not affect the functioning of the resistor. The resistance change due to 1 degree change in the temperature will not be more than 50Ω for every 1MΩ of the resistor value. This value state is for metal film resistor. Carbon resistors have a temperature coefficient of around 200 to500 ppm 0c. Frequency response Resistors should act as pure resistors, but in high frequencies, some resistors will depict capacitance or inductance because of the property called reactance which depends on the frequency of AC. Carbon composition resistors with a resistance of about 10kΩ act as pure resistors at frequencies of MHz range. Power dissipation "is the amount of heat a resistor can generate without causing it to overheat"(Wilson and Williams). Wire Wound resistors dissipate much power compared to other types of resistors. Resistor noise Resistor noise is comprised of three main types namely; "thermal contact and shot noise"(Wilson and William). Thermal noise is dependent on temperature, resistance and band width. Shot noise is as a result of changes in bandwidth and average DC current. Contact noise depends on band width, average DC and material geometry and type. In terms of noise, carbon composition resistors are the loudest while Wire Wound are the quietest followed by metal film, metal oxide and Carbon film. Thermal noise is calculated using the following equation (Wilson and Williams). Vt = SQRT(4kTBR) Where:          “Vt = the rms noise voltage          k = Boltzmanns constant  (1.38∙10-23)          T = temperature (Kelvin -  room temperature = 300K)          B = noise bandwidth (Resistor types—does it matter? Aiken. Amplification). bandwidth = 20kHz, typical guitar amp bandwidth = 5-10kHz)          R = resistance(Resistor types—does it matter? Aiken. Amplification) From the equation, it is visible “noise varies in direct proportion to the square root of the resistance” (Wilson and William, 2011) Contact noise The noise is dependent on the resistor material, size and average DC current. Carbon composition, carbon film, metal oxide and metal film resistors produce contact noise predominantly. Wire wound resistors are not affected by contact noise. Shot noise This noise type is dependent on the average DC current. The higher the average DC current, the more noise is produced. The lower the average DC, the lower the noise, as such, the average DC current must be at the lowest level, to reduce shot noise. Conclusion Resistors are indispensable in electric system even though they are passive components. Several technological changes have contributed to the development of new resistor types such as the SMT which is a simplified and yet effective resistor. Factors affecting resistors are minimal, due to the type of composition, and method of manufacture, which are both candid and basic. Analysis of resistor manufacturing output Machine 1 Machine data Category Resistors no bin % Cumulative% unit value total value premium 2855 -0.01 28.55% 28.55% 0.016 45.68 high 1735 -0.02 17.35% 45.90% 0.012 20.82 standard 3681 -0.05 36.81% 82.71% 0.005 18.405 low 1656 -0.1 16.56% 99.27% 0.001 1.656 reject 73 -0.11 0.73 (%) 100.00% 0 0 total 10000 1 3.5643 0.034 86.561 mean 17145 Descriptive analysis Rejection rate = is calculated using the formula below (Number rejected/production number) x 100% = (73/10000)*100% = 0.73% Machine II Data Category Resistor no frequency cumulative frequency % cumulative % unit sales value total value premium 3334 3334 3334 33.34% 33.34% 0.016 53.344 high 1938 1938 5272 19.38% 52.72% 0.012 23.256 standard 3586 3586 8858 35.86% 88.58% 0.005 17.93 low 1118 1118 9976 11.18% 99.76% 0.001 1.118 reject 24 24 10000 0.24% 100.00% 0 0 total 10000 10000 95.648 mean 2000 Descriptive analysis Machine II Mean 2000 Standard Error 670.1229738 Median 1938 Mode #N/A Standard Deviation 1498.440523 Sample Variance 2245324 Kurtosis -1.715900009 Skewness -0.252448745 Range 3562 Rejection rate= (Number of resistors rejected/production number)*100% = (24/10000)*100% = 0.24% The need for recalibration The data analysis done led to the conclusion that, machine I requires to be recalibrated. This is because of the following reasons. First, the machine has higher rejection rate of 0.73% which is an indicator of increased production cost due to a higher number of product failure. The cost of production is a vital aspect in business, as such, the minimal the manufacturing cost the better (Brandimarte). Materials used in the production of resistors are relatively cheap but if wasted it may cause a decline on the profit margins. Secondly, the standard deviation from the mean value of the produced items is higher. The increased variation from the mean shows that the products produced will fall slightly below the precision required for the resistor. Additionally, from the descriptive analysis undertaken for machine I, show that the distribution of the data is abnormal as shown by the histogram for the data. Information obtained from the data set Machine II production output follows the normal distribution which gives rise to the bell shaped curve if plotted on the graph. The distribution of data between the Ranges given is clear and is evident in the distribution of values from the mean. From both sides of the mean, the value, distribution of the values is almost even and decreasing as it moves away from the mean value with the furthest vales being the lowest (Hesselbach and Christoph). The number of resistors rejected for not falling in the bracket of the four categories of classification for machine one, is 73 units per 10000 units produced while that of machine II is 24 units per 10000 units produced. The rejection rate for machine one is higher and shows that the machine has several problems that must be solved in order to restore confidence in the system. Unit price The unit price is given as a fraction of the pound which may seem abstract, but in a real situation is correct. Therefore, the development of unit price at the pricing phase aids in the easier calculation of revenues that can be generated. The unit price is determined by factoring all the aspects of production including the projected profit margin for each unit produced. The result of the application of the approach is the ease of determination on whether a production line is functioning normally or is problematic. The total cost of the units produced per machine varies with machine I at 86.561, with Machine II, total cost is 95.648. The values indicate that with the same amount of raw material machine II is able to produce higher revenue. Companies employ the use of unit price because it makes analysis of performance of the business using break even analysis (BEA). Break Even Analysis is vital for manufacturing firms because it enables the firm to determine the level of production that will not cause loss (Greeff and Ghoshal). The point at which the revenue covers the total cost of production of the products without making a profit or loss is thus determined by the break even analysis. Production yield per category of resistor Machine II has a higher yield compared to machine I. the rejection rates of the above machines is widely apart. Machine II has a lower rejection rate thus high yield. The efficiency of the machine is also high as depicted by the volume of premium, high and standard quality resistors produced by the machine. The percentage of premium, high and standard category of resistors is at 89% for Machine II, while for the same category resistor for machine I am at 82%. Thus, on the high end products, machine II is performing poorly. The low quality products are produce more by machine I which is a sign of poor yield of the plant. Despite the performance of the machines, they are still below the expected yield. Machines with high precision will have a percentage of above 95% thus; the products will be of high standards with little failures Recommendations Machine I must be calibrated to improve its efficiency. The process of manufacture must be analysed in order to identify issues that are causing changes in the precision of the machine. Machine precision is affected by other operational factors including the quality of raw materials, technology employed and the quality of workmanship (Ao). Conclusion Resistors are components that are passive in nature but vital for the development of electronic circuits. With the changes in technology, it is easier for the manufacture of precision resistors as witnessed in with the SMT resistors which are mounted on the circuit board and cut to precision using laser. The performance of the resistors depends on the material of manufacture, operating conditions, and the current type. Most resistors perform better in situations where, the composition material is not affect by any thing. Resistor noise is as a result of several factors which influence the performance of the resistors noise result from composition or current type. Wire wound resistors are affected by thermal noise while carbon resistors are affected by short noise. During the processing operation, optimization of the process is paramount. The more precise the plant, the better the results, and the higher the revenue generated. Machine II depicted a higher quality of products with greater performance values compared to machine I. Such precisions in production relate to reduction of production cost and increase in the revenue generation. Therefore, process improvement is needed for continuous production and quality improvement. Works Cited Ao, Sio-Iong. Electronic Engineering and Computing Technology. New York: Springer, 2010. Brandimarte, Paolo. Optimization Models and Concepts in Production Management. Chicago: Gordon and Breach, 2005. Greeff, Gerhard and Ranjan, Ghoshal. Practical E-manufacturing and supply chain management. Michigan: Newnes, ,2004. Hesselbach, Jürgen and Herrmann Christoph. Functional Thinking for Value Creation: Proceedings of the 3rd CIRP International Conference on Industrial Product Service Systems, Technische Universitat Braunschweig, Braunschweig, Germany. London: Springer,, 2011. Olhager, Jan and Fredrik Persson. Advances in Production Management Systems: International IFIP TC 5, WG 5.7 Conference on Advances in Production Management Systems (APMS 2007), September 17-19, Linköping, Sweden. London: Springer, 2007. Resistor types—does it matter? Aiken. Amplification. (n. d.). Available at: http://www.aikenamps.com/ResistorNoise.htm> Wilson, Peter and Tim Williams. The Circuit Designers Companion. New York: Elsevier, 2011, 2011. Read More