Grand Valley State UniversityPadnos School of EngineeringEGR 367: Manufacturing ProcessesLaboratory Exercise 5: Blow Molding of Polymeric MaterialsSantopreneCalipersThe group with which I worked was assigned santoprene to blow mold. Santoprene is a thermoplastic material with properties similar to rubber when molded.The blow molder was heated to a temperature of 145 degrees Celsius. There was not a separate temperature for the barrel and the nozzle, as there are on some blow molders. Both the nozzle and the barrel were set to the same temperature. After the blow molder had warmed up, the barrel was purged of excess material from previous use by loading santoprene into the barrel and pushing material out until only santoprene was emitted from the nozzle.Mold release was applied to the nozzle and mold cavity. With the hopper filled with santoprene, the plunger was pulled down and molten santoprene was emitted from the nozzle. The tube of molten material was guided onto the air supply nozzle. The molten material was clamped into the mold, and the air supply was turned on. After about ten seconds to cool with the air pressure on, the mold cavity was unclamped and the part was removed.Two samples were made at 145 degrees. Measurements were taken on the best sample. These measurements are recorded in table 1. There were no useable parts produced by the santoprene at 145 degrees.The injection process was repeated to produce parts at 165 degrees Celsius and 185 degrees Celsius. The results are shown in Table 2.Other groups performed the same experiment using Low Density Polyethelene (LDPE) and High Density Polyethylene (HDPE). The results of those experiments are given in tables 3 and 4:Grand Valley State UniversityPadnos School of EngineeringEGR 367: Manufacturing ProcessesLaboratory Exercise 5: Blow Molding of PolymericMaterials10-8-02 Dale Slotman Partners:Hung NygungDan ShirkeyAdam VerBeek Abstract: The effects of process variables and chemical composition of polymeric materials on the wall thickness and flash percentage of blow molded parts were investigated. Three types of polymers were used: low density polyethylene, high density polyethylene, and santoprene. The three materials were blow molded into small bottles and measurements were taken. The low density polyethylene performed the most consistently. Flash ratios were at about 30 percent for all materials at all temperatures. Higher temperatures resulted in lower wall thickness for santoprene and low density polyethylene. Higher temperatures for high density polyethylene produced higher wall thickness. Flash percentages had little correlation to temperature.Introduction: Blow molding is a simple process used to create hollow parts. Blow molding is taking a tube of molten material (usually plastic), putting a mold around it, and pumping air into it. This forces the molten plastic into the shape of the mold (assuming that the plastic does not break or is not too strong for the air pressure). Blow molding is used for producing items such as plastic bottles and other thin walled plastic containers. High density polyethylene is one of the most common materials used in blow molding. Other materials include polypropylene and polyvinyl chloride.The objectives of this laboratory exercise include: to reinforce the student's knowledge of polymeric materials and the process used to form them, give the students hands-on experience in blow molding, and to investigate the effects of chemical composition on the processing of blow molded parts. Experimental Procedure:Apparatus / Materials Needed: - Blow Molder - High Density Polyethylene - Low Density Polyethylene - Santoprene - Mold Release Agent - Scale - Calipers Procedure: The group with which I worked was assigned santoprene to blow mold. Santoprene is a thermoplastic material with properties similar to rubber when molded.The blow molder was heated to a temperature of 145 degrees Celsius. There was not a separate temperature for the barrel and the nozzle, as there are on some blow molders. Both the nozzle and the barrel were set to the same temperature. After the blow molder had warmed up, the barrel was purged of excess material from previous use by loading santoprene into the barrel and pushing material out until only santoprene was emitted from the nozzle. Mold release was applied to the nozzle and mold cavity. With the hopper filled with santoprene, the plunger was pulled down and molten santoprene was emitted from the nozzle. The tube of molten material was guided onto the air supply nozzle. The molten material was clamped into the mold, and the air supply was turned on. After about ten seconds to cool with theair pressure on, the mold cavity was unclamped and the part was removed. Two samples were made at 145 degrees. Measurements were taken on the best sample. Thesemeasurements are recorded in table 1. There were no useable parts produced by the santoprene at145 degrees.The injection process was repeated to produce parts at 165 degrees Celsius and 185 degrees Celsius. The results are shown in Table 2. Other groups performed the same experiment using Low Density Polyethelene (LDPE) and High Density Polyethylene (HDPE). The results of those experiments are given in tables 3 and 4:Results:Table 1: Sample at 145 deg C.Temperature: Thickness 1 Thickness 2 Thickness 3AverageThicknessWeight145 deg C 2.66 mm 1.58 mm 1.31 mm 1.85 mm 15 gTable 2: Santoprene at 165 and 185 deg C.Temperature: Thickness 1 Thickness 2 Thickness 3Average ThicknessWeightWeight of Flash165 deg C 2.2 mm 1.85 mm 0.18 mm 1.41 mm 11.5 g 3.81 g185 deg C 1.9 mm 1.14 mm 0.14 mm 1.06 mm 11.35 g 3.9 gTable 3: LDPE Experimental ResultsTemperature: Thickness 1 Thickness 2 Thickness 3Average ThicknessWeightWeight of Flash145 deg C 2.146 mm 2.077 mm 4.305 mm 2.843 mm 16.5 g 5.8 g160 deg C 1.473 mm 1.471 mm 3.503 mm 2.149 mm 16 g 1.4 g185 deg C 1.321 mm 1.791 mm 3.223 mm 2.102 mm 16.5 g 7.8 gTable 4: HDPE Experimental ResultsTemperature: Thickness 1 Thickness 2 Thickness 3Average ThicknessWeightWeight of Flash140 deg C 2.00 mm 1.45 mm 1.05 mm 1.5 mm 12.7 g 3.2 g140 deg C 1.91 mm 0.85 mm 0.75 mm 1.17 mm 12.7 g 3.9 g140 deg C 2.26 mm 0.90 mm 1.07 mm 1.39 mm 13.3 g 4.8 g140 deg C 2.28 mm 0.88 mm 0.56 mm 1.24 mm 10.2 g 2.9 g160 deg C 3.63 mm 1.45 mm 1.49 mm 2.19 mm 15.7 g 6.6 g160 deg C 3.86 mm 1.08 mm 2.49 mm 2.48 mm 13.2 g 4.1 g160 deg C 2.61 mm 0.70 mm 0.95 mm 1.42 mm 14.3 g 6.1 gTable 5: Average ThicknessesMaterial