Lathe: Evaluation of environmental footprint Summary The main environmental impact is quantified by a calculation of power usage whilst the lathe is idle and operating, as the use of coolants and lubricants were deemed insignificant and the lathe is operated manually. Furthermore, there is no energy usage due to a ‘warm-up’ time. As will be explained, it was decided the most appropriate calculation of power would from the equation: P=VI Specification Supplier Rice Machinery Inc. Producer SHARP Model number 1340F Serial number 236901 Supply voltage / V 440 (3 phase) Supply frequency / Hz 60 Full load ampage / A 4.3 Motor Lasert Motor 3 Measurements Warm-up Idle Operating Voltage / V 0 440 440 Current / A 1.57 2.00 (for 0.1” cut depth) 2.30 (for 0.2” cut depth) N.B. All operating measurements where taken for typical operating conditions, i.e. 1600 rpm with a feed rate of 0.01 in/rev.Assumptions It would also be possible to evaluate the energy usage of the lathe by multiplying the duration of use by an estimation of power from Power = Us x Material Removal Rate However, because the lathe is manual, the feed rate and depth of cut will vary whilst teams are using it and hence an estimation of MRR would not lead to a more accurate calculation of energy usage. In addition, the current drawn does not vary significantly for various cut depths and consequently an average value of current is used. Analysis of additional elements On the manual lathe no coolants are used. A lubricant is available if required and it may be brushed onto the work piece by each team. Consequently, the quantity was deemed to be insignificant, particularly as it is would be so small it would be difficult to measure. The lubricant used in the shop is ‘Tap Magic Cutting Fluid with EP-xtra’. The environmental effects are minimal because it does not contain any ozone depleting substances or regulated chemicals and it is non-corrosive and bio-gradable. However, it may release toxic fumes when burned; including but not limited to : hydrogen chloride, hydrogen sulfide, carbon monoxide, and short chain hydrocarbons. It is stable at ambient temperatures and pressure, however elevated temperatures and exposure to strong alkalis, oxidizers, and/or acids will promote decomposition. Such decomposition results in the release of hydrogen chloride, hydrogen sulfide, and sulfur from the product. At normal room temperatures, decomposition is virtually nil. Exposure to strong direct sunlight may cause decomposition and discoloration of some components present in this product. As this is not too harmful we felt our conclusions were justified. The lathe is manual so no power is required for the computer/controller. No abrasives are used. Practical procedure for applying the model to determine the environmental impact 1. Weigh the workpeice before commencing the machining operation 2. Record the total duration of ‘idle time’, measured in seconds 3. Record the total duration of ‘operating time’, measured in seconds 4. Calculate the energy use of the machine by multiplying the three columns above i.e. Energy use / J = duration x volts x ampsWarm-up Idle Operating Voltage / V 0 440 440 Current / A 1.57 2.15 Duration of use / s Energy use / J = duration x volts x amps 0 5. Weigh the workpiece after finishing the machining operation and record the reduction in weight mass before (measured in 1) – mass after (measured at 5) = mass lost _______________ - ______________ =
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