Published on November 7, 2007
Iowa Paint Manufacturing Co.Viscosity Analysis: Iowa Paint Manufacturing Co. Viscosity Analysis Presented By: Ruchi Patnaik Co-Author: Piyanka Roy Iowa Paint Manufacturing Co.: Iowa Paint Manufacturing Co. Since 1933, Iowa Paint has been making quality paint and coatings More than 1400 colors available The choice of professional painting contractors for quality paints Paints and coatings meet and/or exceed U.S.Government paint specifications Satin Acrylic House Paint: Satin Acrylic House Paint Very durable for interior walls and ceilings Good color retention Easy water clean-up Low odor Dries to tough finish Rooms can be used almost immediately Objective: Objective Improve viscosity for batches of paint Determine precision of viscosity measurements (and identify removable sources of imprecision) Find the appropriate quantity of Hydroxyethyl Cellulose (HEC also known as A44) to be added for various desired adjustments of viscosity Viscosity: Viscosity Viscosity of paint is increased or decreased by addition or removal of the following three elements A44 (Hydroxyethyl cellulose) T49 (Water) Resin Current Situation: Current Situation Low initial incoming viscosity Final viscosity requirement: 95-100 Krebs Use of A44 to increase viscosity Paint produced in 2000 or 4000 gallon tanks Use of trial and error to get to desired viscosity Why A44?: Why A44? High thickness efficiency Low water solubility Excellent color development and color acceptance Compatibility with a broad range of paint ingredients Batch-to-batch uniformity Good brush and roller application Non-sagging properties Analysis: Analysis Gage R&R study for lab measurement precision Homogeneity test for within vat sampling variance Regression Analysis Gage R&R: Gage R&R Repeatability is variation typical of that seen in repeat measurements for a particular operator on a particular specimen Reproducibility is variation that can be attributed to differences between operators Gage R&R: Gage R&R Two different batches of paint Two measurements by each of 4 group members for each batch Use of viscometer and stop watch to measure viscosity Viscosity measured at 77Fahrenheit Gage R&R Data: Gage R&R Data R&R Calculations: R&R Calculations Equations for repeatability and reproducibility: ^ ^ Source DF SS MS Parts 1 52.5625 52.5625 MSA Operators 3 0.6875 0.2292 MSB Interactions 3 0.6875 0.2292 MSAB Error 8 0.5000 0.0625 MSE Total 15 54.4375 I (parts) = 2 J (Operators) = 4 m = 2 Within-Vat Sampling: Within-Vat Sampling Five samples from one batch of paint Two measurements by each of 4 group members for every sample Use of viscometer and stop watch to measure viscosity Viscosity measured at 77° Fahrenheit Within-Vat Data: Within-Vat Data Operator Within-vat Calculations: Within-vat Calculations Equations for locations: ^ Source DF SS MS Locations 4 30.850 7.713 MSA Operator 3 0.275 0.092 MSB Interaction 12 2.350 0.196 MSAB Error 20 7.500 0.375 MSE Total 39 40.975 Results of Measurement Precision Studies: Results of Measurement Precision Studies Gage R&R Calculations repeatability = 0.250 Krebs reproducibility = 0.327 Krebs To combat reproducibility variation, keep operator fixed ^ ^ Results of Measurement Precision Studies: Results of Measurement Precision Studies Within-Vat Calculations repeatability = 0.612 Krebs locations = 0.922 Krebs To account for location variation, sample from several locations and either physically mix, or average measurements ^ ^ Historical Data: Historical Data Historical Data: Historical Data Plot of all nine samples in order to examine the slope Regression Analysis: Regression Analysis Use of Minitab software to find relationship between amount of A44 added and mean viscosity increase Equation found is in terms of: Add ‘x’ pounds of A44 in every 1000 gallons of paint to increase viscosity by ‘y’ Krebs Minitab output for regression analysis gave 1.19 lbs. of A44 additive to be added to 1000 gallon tank for 1 Kreb increase Regression Output: Regression Output The regression equation is: visc = 87.3 + 1.19 added + 5.51 z1 + 5.01 z2 + 6.25 z3 + 3.51 z4 - 2.21 z5 + 1.38 z6 - 0.21 z7 + 0.77 z8 Derived Equations: Derived Equations For 1000-gallon tank: y = 1.19 * x For 2000-gallon tank: y = 1.19 * 2x For 3000-gallon tank: y = 1.19 * 3x For 4000-gallon tank: y = 1.19 * 4x Equations were derived for each size of tank used by Iowa Paint, where y = pounds of A44 & x = desired viscosity increase (Krebs) Viscosity Table: Viscosity Table Table for the amount of additive appropriate for various tank sizes Viscosity Plot: Viscosity Plot Plot of viscosity increase versus A44 addition for the 1000-gallon tank Viscosity Increase (Krebs) Conclusions: Conclusions Several factors play a role in viscosity measurements One source of variation relates to measurements done by different people Another relates to tank location of the sample obtained Historical data provides quantitative guidance for viscosity adjustment Recommendations: Recommendations Make sure that only one person handles the viscosity measurement Samples for measurement of viscosity may be taken from different areas of paint tank and mixed or measurements averaged Use the equations, table and chart derived from historical data to eliminate trial and error (and get correct viscosity) Aftermath: Aftermath Company is willing to try it out! Able to give the company an acceptable solution to implement Derived accurate amounts of Hydroxyethyl Cellulose to add to achieve desired viscosity level Graphical and tabular representation of solution for easy reference Acknowledgements: Acknowledgements Dr. Stephen Vardeman Professor Iowa State University Mr. Mark Angerer Technical Director Iowa Paint Manufacturing Co. Questions?: Questions?