Machining productivity and technical economy are analysed (on)
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source:GERHOLD CNC Machining
When establishing machining procedure, must be in make sure premise of spare parts quality falls, rise labor productivity and reduce cost. That is to say, must accomplish high grade, high yield, low consumption. One, labor productivity of machining productivity analysis is the eligible product measure that points to a worker to be made inside unit time, perhaps point to production sheet the work time that product place spends. Labor productivity can be behaved for standard time and rated output two kinds of basic forms. Standard time calls man-hour norm again, it is to producing a technology to organize a condition, stipulate a product or working procedure of line of the some that finish need the time that spend; Rated output is to be below certain manufacturing organization condition, the regulation produces the standard of eligible product measure inside unit time. Current, most enterprise uses standard time to reflect labor productivity. (one) standard time standard time is the index that measures labor productivity not only, also be arrangement production plan, computation produces the important basis of cost, still be built or extend factory (workshop) the basis that chronometer calculates equipment and worker amount. Making reasonable standard time is the important step that moves worker enthusiasm, it is the method that technical personnel adopts computation or analogy commonly, the determine and analyses method that perhaps handles time actually through be opposite undertakes deciding. In use, standard time still should edit regularly, in order to make its maintain average and advanced level. In machining, finish the time T 0 that the place of a working procedure of a workpiece needs, call sheet floor-to-floor time. It divides composition by undermentioned ministry. 1. The time that the process such as condition of the dimension that basic time of of basic time T B is object of immediate change production, appearance, relative position, surface or material property spends. To machining character, the time that excises operation allowance place to use up directly namely (include cutting tool be cut or cut a time) . Basic time can be begged by formula piece. For example the basic time T B of turning is: The T B in type -- basic time (Min) ; L J -- the computational length of working travel mode, include to machine exterior length, cutting tool is cut cut length with (Mm) ; Z -- operation allowance (Mm) ; N -- the rotate speed coming back of workpiece is spent (R/min) ; F -- the feed of cutting tool (Mm/r) ; A P -- back penetration of a cutting tool is measured (Mm) . 2. Assisting of time T A to assist time is the time that all sorts of carries out to assure to complete basic work auxiliary movements need. It includes: Assemble and unassemble the time of workpiece, actuate and cutting tool of the commutation in stopping the time of the machine tool, treatment (wait like tool carrier dislocation) treatment of time, change is normative (if change cutting dosage) time, try to cut and be measured wait for the time that spend. The affirmatory method of auxiliary time follows manufacturing kind and different. Large quantities of mass-produced when, set reasonably to make assist time, need to disclose auxiliary action, disclose behavioral time each certainly respectively again, give finally integrated. Manufacturing criterion is approved in but basis before statistical data will decide. Odd the percent of commonly used and basic time comes a pre production estimation. 3. Serve time of technology of of T C of technical serve time is to point to during the job undertakes inside, spend the time that attending working ground, include commonly: Change cutting tool, lubricant machine tool, clear cut bits, build the time that rubs the place such as cutting tool, emery wheel and nap tool to use up. 4. Organizing of serve time T G to organize serve time is to point to inside whole job class, spend the time that attending working ground, include commonly: Get after the class before the class change reach clear away cutting tool, examination and test run equipment, lubricant equipment, change the yard ground, cleaning equipment time that spend is cleaned before cutting fluid and lubricant and class. 5. Natural need and need of nature of of breathing space T N and breathing space are a worker the time that needs to use up on the refection inside working class and contented physiology. When actual amount of labor is calculated, to simplify odd a computation of time, normally T C, T G, T N the percentage that 3 part-time unified melt into hold T B and T A, namely the β in type -- the percentage that T C, T G, T N holds T B, T A. Because this is odd a floor-to-floor time T 0 is usable computation leaving type: Odd floor-to-floor time should not include the following content: With the auxiliary time of basic time coincide; Change or the machine tool settling time that place of exchange labor foreword needs; Because produce condition of organization, technology undesirable the time loss that causes accidentally with the worker; Be repair or make the 6 of time that replace the workpiece of reject and influences cost. of settling time T J settling time is to point to in be being produced group by group, to change workpiece or the time that change process and undertake to equipment and tooling readjust place needs, call preparation again -- terminative time. Settling time is labour produce a batch of products artificially or 0, component, the time that prepares to be used up with end activity place. If be in odd or in be being produced group by group, when beginning to machine a batch of spare partses every time, the worker needs to be familiar with cutting tool of the craft file, semifinished product that get, material, tooling, installation and clamping apparatus, attune to work the machine tool and other tooling time that spend. After machining a batch of workpiece to end, need to tear open next mixing to remand the finished product of tooling, deliver time that spend. Both neither of settling time T J is to be used up directly go up in every spare parts, also not be to spend the time inside a class, spend the time on a batch of workpiece however. Consequently apportion is T J/N to the time on every workpiece, n is batch. 7. Timeliness of valuation of of valuation time T P weighs sheet again business accounting norm, it is the standard time that shows a process that completes a product sets, it is the enterprise undertakes planning, business accounting productivity and the basis when undertaking economic accounting. Accordingly, valuation time should by sheet floor-to-floor time T 0 and apportion arrive the settling time on every workpiece (T J/N) two parts composition. Mass-produced in, n value is greater, 0 of ≈ of T J/N, can ignor. So (2) the craft way labor productivity that improves labor productivity is a when measure manufacturing efficiency omnibus index, it is not a simple engineering technology question, be organized with the design of the product, production however and supervise the work closely related, improve product structure design, improvement to production is organized and supervise the work so, it is the strong step that improves productivity. From machining craft the respect makes one simple analysis below. 1. of cut standard time is cut standard time, answer above all cut the proportion in taking standard time is majorrer. In sheet in pre production, auxiliary time and prepare terminative time place to hold proportion bigger, should reduce auxiliary time right now; Be in large quantities of mass-produced in, basic time place holds proportion bigger, answer right now cut and basic time. (1) ① of of of cut and basic time increases cutting dosage V C, F, A P, OK and cut basic time. This is machining in use extensively effect method, but should use big cutting dosage, the key is the carrying capacity that increases a machine tool, especially the durability of cutting tool. ② decreases or length of coincide cutting journey. If what graph 3 -89a shows,be amalgamative labor situation; B place is shown machine to use much knife; C place is shown to use transverse cut. If graph 3-90 place is shown,③ uses many treatment. (2) shorten auxiliary time takes sheet when auxiliary time when the 50%~70% above of time, if use,raise cutting dosage to raise productivity to won't obtain big effect, should consider cut and auxiliary time right now. ① uses advanced and efficient clamping apparatus. This can assure to machine quality not only, still can decrease to assemble and unassemble and search greatly the time of workpiece. ② uses multitask treatment. If graph 3-91 place is shown,be duplex operation clamping apparatus, make assemble and unassemble the auxiliary time of workpiece and basic time coincide. ③ uses successive treatment. If graph 3-92 place is shown,be vertical milling machine of successive circumgyrate workbench. ④ is used examine actively or the number demonstrates automatic measurement unit, can decrease stop machine metrical time. ⑤ is used all sorts of change quickly change device of knife device, cutting tool fine tuning knife, automatically to reach but dislocation cutting tool, in order to decrease in cutting tool assemble and unassemble, blade is ground, the time that spends to the field place such as the knife. (3) cut preparation is terminative ① of time makes clamping apparatus and cutting tool efficient generalization. ② uses advanced treatment facilities to plan terminative time in order to decrease. If use machine tool of numerical control machine tool, hydraulic pressure profile modeling, sequence control machine tool,wait. 2. Use of advanced technique (1) use advanced semifinished product to produce a method, raise semifinished product precision, reduce the amount of labor that cutting machines. (2) use little, machine craft without cutting. If boil,press the method such as treatment. (3) use non-traditional machining. If use line electrode electric spark,treatment machine tool machines die to be able to reduce workload of a lot of benchwork. CNC Milling