Tuesday, March 14, 2023

Production Industrial Engineering - Six Sigma Case Studies in Machining Processes


Six sigma method attempts to reduce defects and improve the process output parameters while achieving the lowest variance. In the direction of defect reduction, six sigma study helps in moving towards zero defects. Six sigma method has to be used by industrial engineers in all process improvement studies using process charts.

Six Sigma Simple Explanation


DMAIC Method

Six sigma method determines the best factor level combination that gives the optimal output with the least variation.

Hence the starting point is the output variable whose measurement or measure is to be optimized and its variability made minimum. The next step is the identification of factors that have an effect on the output variable of interest. The third step is determining the possible levels of each factor that can be employed.

With this as the input information, Taguchi method of experimental design is used to determine number of experiments to be done. The experiments are done and results are statistically analyzed to get the factor level combination that gives the best output variable with the least variance.

Further improvement of the system can be done by engineering modifications that  permit more levels of the factors or introduction some completely new factor that can five better performance of the output variable. Industrial engineers have to look for engineering improvements on a continuous basis. Industrial engineering is primarily engineering improvement.


Six Sigma Case Studies  in Machining Processes



2018

Materials Today: Proceedings
Volume 5, Issue 1, Part 1, 2018, Pages 104-112
Optimization of Process Parameters based on Surface Roughness and Cutting Force in MQL Turning of AISI 4340 using Nano Fluid


The aim of this research work is focused on optimization of process parameters under Minimum Quantity Lubrication (MQL) using nano fluid in turning of AISI 4340. A study of effect of process parameters in turning of AISI 4340  on the cutting force generated and machined surface roughness is carried out. In the experiment conducted, five values of feed rate, three values of depth of cut, two values of cutting speed and tool nose radius respectively, are used. The test pieces were turned on a CNC lathe machine.  

From result analysis, it was found that, feed rate played a major role in producing lower surface roughness followed by depth of cut whereas cutting speed has least significance in producing lower surface roughness.  It was observed that MQL with nano fluid (MWCNT) showed lowest surface roughness as compared to conventional flood system. Thus, with proper selection of process parameters under MQL mode with nano coolant, it is possible to achieve good surface roughness, reduce tool wear while maintaining the cutting forces and temperatures at reasonable levels.



Development of Six Sigma methodology for CNC milling - PDF
Mar 30, 2018 - Six sigma implementation during milling process.  Numerical Control (CNC) machine operation. 
by MN Ismail

Development of Six Sigma methodology for CNC milling process improvements
October 2017, IOP Conference Series,  Materials Science and Engineering 257(1):012009
https://www.researchgate.net/publication/320791815_Development_of_Six_Sigma_methodology_for_CNC_milling_process_improvements

Justifying Six Sigma Projects in   Manufacturing Management

Tapan P. Bagchi, Narsee Monjee Institute of Management Studies, Shirpur
NMIMS Review, 2012
The paper gives justification for investing reducing sigma of ball bearing outer race and inner race grinding operation.
http://www.nmims.edu/NMIMSmanagementreview/pdf/april-may-2012/05-justifying-six-sigma-projects.pdf




Six-sigma Project on Coolant/Chip System Improvement – Batch 1
2011
IMTMA organized a formal program focused at “performance of the coolant & swarf management on machine tools” through Six-sigma approach during May/ June 2011.
http://www.imtma.in/index.php?page=6&subid=178

Improvement of a Production Process with The Use of Six Sigma - PDF
Key words: production process, Six sigma, improvement, Critical-to-quality tree, machine tools (saw, milling machine, CNC turning machine, grinding)
by I Veža - ‎2004 


2006
Ready for Six Sigma

To upgrade machining process capability, Prof. Jerard is conducting research on the process capability of machine tools.

 Currently, CNC manufacturers are providing  two indicators of precision: positioning accuracy and repeatability. But what is the standard deviation of a machine tool?  For example, a machine tool with a standard deviation of 0.002 in. can achieve a six sigma quality level  only when the tolerance band of a part is 0.022 in. If the standard deviation doubles to 0.004 in.,  jump from six sigma quality level to 66,800 defects per million (three sigma).

If machine tools have be made with smaller standard deviations,  error sources such as machine axis squareness, encoder inaccuracy, tool and workpiece deflection, thermal expansion, tool runout and tool wear etc. have to be understood and their impact on standard deviation has to be found. Many of these factors change with time, environmental conditions and usage.


http://americanmachinist.com/beyond-cutting-zone/ready-six-sigma


Updated on 14 March 2023,  19 September 2020,  21 September 2019, 6 March 2015

1 comment:

  1. Leaders within a company need to adopt a continuous improvement culture in order to promote it throughout the company.
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