Production cycle

Basic Concepts

Description

essence of modern production planning and control method proposed requirements are: the ability to accurately represent the actual production process model, production control 4 basic objective parameters (high efficiency, low inventories, short production cycle, on-time delivery) dependencies can be stated correctly. To do this, we must first carry out a detailed examination of the production cycle.

in the use of the term production cycle, must distinguish between the actual and planned. Planned production cycle to allow time limit, the actual production cycle by cycle.

Details

In considering the case of a plant task flow, it is common practice to each step of each task is decomposed in the timeline. To receive material from the finished products to the part or assembly sent intervals generally called "duty cycle." This is a rather imprecise term; More precisely, it should be called "duty cycle phase", "interval." A step used is the smallest unit of time, it is referred to as a step cycle. Further definition of the production cycle and division of the different components in the literature and practical applications. Heinemeyer will examine the task is divided into three levels. There are various processes in the task layer, from OPI to OPK. Each step in the operation level is decomposed into the following five sections: with the previous models, this division after the machining step before a waiting time and transport time in the home after a step. The first procedure, it starts at the date of a task delivered; starts at the date of completion of the other processing steps of the machine before the procedure. Typically, a manufacturing task composed of multiple parts - called manufacturing batch. Part 1 to n traffic conditions at the level of a single unit, i.e. the level to inspect a workpiece. As can be seen, there is an additional part of each latency time within a number of parts of the process, which is called latency batch.

in the production and processing plant of discrete, usually concentrated batch of parts for transport, processing and control center in the working order. Therefore, in the case of the whole investigation process level just sufficient quantities. Only when high-volume manufacturing flow only necessary to discuss the case of a single part or sub-batch, because the processing time is greater than the time interval, the need for coordination of overlapping successive step.

Step Time (TOP) with respect to the cycle time (TL) is very small, usually 2% to 10%. Thus the machining can be omitted record start time (tPB) and ready to start date (t SB) carried out (the mission time is calculated from these two values ​​is sufficient) during analysis and control.

In order to process time (TOP) calculated just before processing track work center end date (TPER), this work center processing end date (tPE), and the step time obtained by the task time (TOP ).

period calculation

is a simplified calculation of the flow elements may be discussed as follows:

actual production cycle (TL) by the difference between the two and tPEU Report Date of tPE calculated. To calculate a step interval (TIO) must know the time step (TOP). Step time is equal to the efficiency factor (ER) multiplied by the task time (TO) divided by the working capacity (CDAY) corresponding to daily work center. For example, the task time (standard hours) was 12 hours, where the efficiency coefficient of 120%, work center occupied by the task for 12 hours /1.2=10 hours. If the work center to work in the production capacity of 8 hours a day, the process time is 10/8 = 1.25 days. For a batch, the time is equal to the task preparation time (TS) and the processing time for each task (TPO) sum. Product processing time and task processing time equal to one-piece (TPU) with a bulk value (Q),.

Step a transport time interval (TT), latency (TWA and TWB) composition. Only in the case of poor transport organization of transport time was more important. During the waiting time also typically include other times required for quality control checks on the time and work in the center and not the process file, such as: scribing the workpiece, burrs cleaning or inverted. Fault also causes latency, but only the effect on the power cycle in the range of seconds or minutes, the highly automated manufacturing and assembly equipment, the only significant fault. The main part of the process time interval waiting time in the queue before the work center. Only in special cases, such as the particular study, the various components of step fishes time interval were collected and analyzed.

Thus, the process time (TOP) and the step interval (TIO) flow element configuration can be used as the basis

cycle calculated length of the production cycle primarily to depend on the equipment and technology and other technical material conditions, but plans to improve the organization and management, can effectively shorten the production cycle.

products production cycle comprises a single production cycle and batch production cycle.

single product cycle

simple one-piece construction product, a production cycle for the sum of products in various stages of the production process cycle. If a single product is composed of multiple parts, the development of the production cycle is relatively complex, not only to consider the production cycle and the assembly of the parts of the product, but also consider the parts produced in each of the parallel cross-case process stages , parallel cross-section that time should be deducted from the overall production cycle.

product batches cycle

batches of product from a single product cycle is basically the same, except that the parts and products to be considered in the manufacturing process moves. Different moves, the length of the production cycle is different. The key part of the development of batch production cycle is to determine the number of parts of the production process cycle.