20-06-2012, 12:46 PM
run chart implementation
RUNCHARAT.docx (Size: 675.65 KB / Downloads: 34)
PROBLEM STATEMENT
The current method of recording the critical dimensions in the machine shop is time consuming as the operator has to note dimensions for each component, also it is difficult to analyze the recorded data. Revise the method such that the recording and analysis will be easy.
EARLIER METHOD
• Previously all the critical dimensions were noted in the format below shown.
• The purpose of this recording was to facilitate the supervisor to ensure the quality of the components by insuring that all the functionally critical dimensions lie within the tolerance limits.
Disadvantages
1. Variation in the manufactured components was recorded in the tabular form by writing down all the readings for the critical dimensions of each component this writing process consumed time.
2. The data did not facilitate its purpose of supervisory inspection as supervisor has to first locate the dimension and the tolerance in the drawing and then analyze the recorded data for inconsistencies.
DESIGN OF NEW FORMAT
• The team came up with a possible solution of run charts
• Run charts also known as run-sequence plot is a graph that displays observed data in a time sequence. Often, the data displayed represent some aspect of the output or performance of a manufacturing or other business process.
• Thus using the principles of run charts a new format was designed using the MS-Excel in which the critical dimensions for a component will be entered by the supervisor. The upper and lower limit values of these dimensions will be divided into convenient ranges of dimensions. For 20 components empty boxes were designed in front of each dimension ranges. The control limits were shown in red color and the mean dimension was shown in green color for visual aid in inspection.
• For identifying the run charts of a particular component the part name and number can be used and are entered while preparing the run chart for respective component. For recording other variable details such as machine used, drawing revision number, operator name and date empty spaces were provided.
• Now the operator will have to just put a dot in respective box corresponding to proper dimension range and component number. Thus recording time will be reduced.
• The dots will be connected by a line to obtain a trend. And thus the records will aid in analysis of the data.
RESULTS AND FINDINGS
• Time required to record the dimensions of the job was reduced.
• The analysis of the data became easy and helped in monitoring the quality of the manufactured components as the data shown the critical dimensions of a component at a glance.
• The causes of variations can be predicted by the analysis of the run charts.
CONCLUSION
Run chart is a tool for quick recording variations in a manufacturing process and can be analyzed to identify the causes of variations.