Consolidated cycle schedule of orders execution and volumetric-calendar calculations of production progress
Based on the cyclic schedules for individual orders, a consolidated cyclic start-up schedule is issued for the production of all products (figure 6.2), provided by the production program for the next planning period (on the annual plan, half-year or quarter scale). When constructing a composite schedule, the line scale is drawn on the calendar scale, corresponding to the duration of the individual stages of the manufacturing cycle for each product (order). For clarity, each stage of the production cycle is usually depicted in a different shading. The starting points for the construction of the composite schedule are the production timelines planned according to the plan.
The compilation of a consolidated schedule is accompanied by verification calculations of the loading of assembly areas and various groups of equipment at the blanking and machining stages of the production process, which are performed when selecting each version of the start-up of products manufactured in parallel in the same calendar interval (period). The purpose of verification calculations is to clarify how much the capacity of the enterprise's workshops ensures compliance with the terms of product manufacturing established by the cyclic schedules.
In cases where the capacity is not sufficient for the parallel processing of various products (orders), technical and organizational measures for the bottlenecking of bottlenecks are designed and implemented. It can also be done by adjusting the cyclic graphs (individual -
Fig. 6.2. Aggregate Product Launch/Release Schedule
dual and composite) by shifting the initial stages of work to an earlier time, i.e. due to the increase in the regulatory lead.
Volume-calendar calculations should begin with assembly shops, where the use of production areas is crucial. The calculation is made in the form of a schedule for loading assembly areas, which is built on the basis of a consolidated cycle schedule (see Figure 6.2). The plot is constructed in two coordinates: the vertical dimensions are the dimensions of the assembly areas in square meters, and horizontally the nominal time fund in days (see the lower part of Figure 6.2).
Guided by the terms of the beginning and the end of the work on the consolidated schedule, as well as the size of the area necessary for the assembly of each product, rectangles depicting the loading of the assembly shop (in m2/h) are plotted on the graph. The dimensions of the rectangles correspond to the product of the required area for the assembly of the corresponding product and its assembly cycle according to the composite schedule.
When plotting a rectangle, depicting the assembly of products for different orders, sometimes superimposed on each other. To eliminate overlapping, the assembly work shifts to the left; to begin their implementation earlier than stipulated by the consolidated schedule. The corresponding adjustments are made to the summary schedule.
All volume-calendar calculations related to the distribution of work over time are applied proceeding from the assumption that the laboriousness of the product is distributed evenly within each stage of production and that within each stage the structure of the laboriousness of the article does not change with time.
These assumptions underlie the so-called principle of the average density of distribution of works relative to their cycle. The average overall density of work for the manufacture of the product during, for example, the stage of machining this product is determined as the quotient of the division of the planned labor intensity of the machining of all parts of the article under consideration for the duration (days) of the machining stage of production of this product. This indicator is used for large-scale calculations.
The average overall density of work for the manufacture of parts of this product in the workshop in question is determined as a quotient from the division of the planned laboriousness of these parts manufactured in this shop, the duration of the machining stage of the product in question. The average density of work of a particular type of machining of parts of this product in the workshop is determined as a quotient of the division of the planned labor intensity of a particular type of machining of the parts of this product manufactured in this shop for the duration of the machining stage of the product in question. Based on the average densities of specific works in the shops, from the sequence of work and the time frame for their implementation, the computational calculation of the loading of all types of equipment of the machine shops is carried out according to the combined cycle schedule.
The final result of the formation of a composite graph, for example, such as in Fig. 6.2, is obtained after repeated searches of different variants. To meet the deadlines, special economic and mathematical methods are usually used (for example, the method of the integral indicator, the method of packing small rectangles into one large, the method of balancing the load with the capacity through the static or statistical rhythms of the distribution of work relative to their production cycle).
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