Explanation : Product-Oriented Facility Layout/Line-Processing or Flow-Line Layout: In product-oriented facility layout, machines and equipment are placed in the order in which they are used in making the product. This layout is also called the line layout as the materials and machinery required are arranged in one line, depending upon the sequence of operations required for the product. The materials move from one workstation to another sequentially without any backtracking or deviation. Under this, machines are grouped in one sequence. Therefore, materials are fed into the first machine and semi-finished goods from one machine travel automatically to another, i.e., the output of one machine becomes the input of the next. For example, in a paper mill, bamboos are fed into the machine at one end and paper comes out at the other end. The raw material moves very fast from one workstation to another with a minimum work in progress storage and material handling. Production-oriented facility layout is useful when the production process is organized in a continuous or repetitive way.
Explanation : Definitions:
1. A multiple activity chart is a chart in which the activities of more than one worker or machine are recorded. Activities are recorded on a common time scale to show the inter-relationship.
2. “A Multiple activity chart is a form of process chart recording the related sequence of work of a number of operators
and/or machines on common time scale.”
Types of Multiple Activity Charts : The multiple activity charts is broadly classified as worker-machine process chart and gang process chart. A worker-machine chart is used for recording and analysing the working relationship between operator and machine on which he works. It is drawn to time scale. Analysis of the chart can help in better utilisation of both worker and machine time. The possibility of one worker attending more than one machine is also sought from the use of this chart.
A gang process chart is similar to worker machine chart, and is used when several workers operate one machine. The chart helps in exploring the possibility of reducing both the operator time and idle machine time.
Symbols Used in Multiple Activity Chart : The multiple activity charts use three symbols as shown in Table.
Blank rectangle or space is used to show that one of the two i.e., man or machine is idle.
Dark coloured rectangular space shows position/period of independent activity for man/ machine is busy.
Stripped space shows when both man and machine are working together i.e., combined activity.
Explanation : The American Society for Quality Control defines quality as “the totality of features and characteristics of a product and services that bears on its ability to satisfy given needs.” Quality control exercises can be carried out in two ways: after-process control and inprocess control. In after-process control, the specific features of the products are measured and compared with the pre-established specifications of the product. In-process control techniques measure the product attributes at various intervals during the manufacturing process in order to identify deviations from the established norms. Statistical quality control can be used for both process control and product control. Several techniques of in-process control such as flow chart, Pareto analysis, cause and effect (fishbone diagram), and control charts are available.
Control charts can be broadly classified into two categories. These are: (1) control charts for variables and (2) control charts for
attributes. x chart and R chart can be placed in the first category and c chart, p chart and np chart can be placed in the second category.
x chart is the chart of averages constructed using sample means for a series of small random samples, over a period of time whereas
R chart is a plot of sample ranges. p charts graph the percentage (proportion) of defectives per sample whereas c chart graphs the number of defectives per item or unit, np chart is used to control the actual number of defective items in a sample when the sample size is constant.
In some cases, statistical process control is neither viable nor desirable. In these cases, acceptance sampling is used for quality
control check. In acceptance sampling, a sample is selected from a lot or batch. On the basis of the information obtained from thesample, a lot or batch is accepted or rejected. In general, acceptance sampling plans can be broadly classified into three categories: single-sample plan, double-sample plan, and multiple-sample plan.
Explanation : The criterion of Realism (Hurwicz Criterion) : This criterion suggests that a rational decision-maker should be neither completely optimistic nor pessimistic and therefore, must display a mixture of both. Hurwicz, who suggested this criterion, introduced the idea of a coefficient of optimism (denoted by a) to measure the decision-maker's degree of optimism. This coefficient lies between 0 and 1, where 0 represents a complete pessimistic attitude about the future and 1 a complete optimistic attitude about the future. Thus, if a is the coefficient of optimism, then (1 – α) will represent the coefficient of pessimism. The Hurwicz approach suggests that the decision-maker must select an alternative that maximizes. H (Criterion of realism) = a (Maximum in column) + (1 – α) (Minimum in column). The working method is summarized as follows. (a) Decide the coefficient of optimism a (alpha) and then the coefficient of pessimism (1 – α). (b) For each alternative select the largest and smallest payoff values and multiply these with a and (1 – a) values, respectively. Then calculate the weighted average. H by using the above formula. (c) Select an alternative with the best anticipated weighted average payoff value.