Tim Elsner Nate Vetsch Caleb Glantz Andy Johnson Silicon Rubber Tim Elsner Nate Vetsch Caleb Glantz Andy Johnson

Silicon Rubber Properties Mechanical High tear and tensile strength Great flexibility Thermal Wider range than most other rubbers Electrical Exceed similar materials in insulating ability Non-conductive Maintains dielectric strength through wide temp range 9/19/2018

Silicon Rubber Properties Chemical Water resistant Chemical resistant including: Some acids Oxidizing agents Ammonia Isopropyl alcohol Bio-Compatibility Comply with FDA guideline for medical products Tasteless and odorless Doesn’t support bacteria growth Doesn’t corrode other materials Most importantly have superior compatibility with human tissue 9/19/2018

Tour of MN Rubber Lead by Jeff Amundson, Operations Manager Thank You Jeff Litchfield Plant Horizontal injection molding Liquid silicone molding (LSR) Extensive automation Clean room finishing facilities Thermo-set silicone injection molding Standard products: ground rubber balls, o-rings & Quad-Ring Seals LSR are very automated One man for 4 machines Visual inspection machine for 100% defect free Testing room use six sigma principle to ensure quality 9/19/2018

Cool things on tour Automated visual inspection machine for deliver Cryogenic de-flashing process DOE to optimize with in the next year Quality inspection room Not just a myth, SQC is used! O-ring defect separator Overall cleanliness Baffling ball grinder Recycling of flash for profit! 9/19/2018

Automated Visual Inspection www.dyn.com/cdinsp.html 9/19/2018

Cryogenic De-flashing Machine www.devicelink.com/company98/c/c00374.html 9/19/2018

Pampered Chef Spatulas Minnesota Rubber Complete in-house production Handles injection molded plastic “scoop” injection LSR Nearly full automation One man producing 500/hr Four machines are run by one person -all they have to do is load the spatula handles www.mnrubber.com 9/19/2018

Liquid Silicon Injection Two part silicon Mixed in injection machine www.vestaweb.com/manufacturing/molding.htm 9/19/2018

Liquid Silicon Injection Actual machine Hopper is replaced by hoses to drums with silicon parts separated www.emachineshop.com/machines-molding/injection-molding.htm 9/19/2018

MN Rubber Spatula Process 9/19/2018

MN Rubber Spatula Process 9/19/2018

MN Rubber Spatula Process 9/19/2018

Our Experiment Received pre-mixed HTV gum rubber 9/19/2018 Simplified process -no need to mix or set pressures or flow rates -plus don’t have equipment to conduct exact process 9/19/2018

Our Experiment Modeled two part injection with compression molding Heat die Insert precise amount of material Compress in machine Leave for time to set Remove Post bake for more complete cure 9/19/2018

Our Experiment 24 Full Factorial Die temp 275 & 300°F Dwell time 4 & 5 minutes Post bake temp 350 & 600°F Post bake time ½ & 2 hours 9/19/2018

Our Experiment 9/19/2018

Our Experiment Results Response variable is hardness Durometer Shore A scale Measured with tensile tester Force vs. Displacement Correlated to Shore A scale 9/19/2018

Testing methods Ideal Modified Method Load cell measured force Distance is measured by the top beam moving down http://www.checkline-europe.com/hardness_tester/ 9/19/2018

Results Die time and temp Die time prob>f=.419 insignificant Die temp prob>f=.272 insignificant Potentially made insignificant by requiring sufficient cure for ease of release The die temperature and time were found to be insignificant to the model and our response variable being, hardness/durometer. There was only a 59% confidence that our die temp is significant and only 73% confident that our die temp is significant. During our experiment we made the assumption that we had to get a cured and filled part. Not realizing that we potentially had eliminated these factors. 9/19/2018

Results Post bake time and temp Bake time prob>f = .0036 significant Bake temp prob>f = .0321 significant Interaction prob>f = .0118 significant The post bake time and temp were both found to be significant to our model and the durability of the key chains. As well as both being significant alone, their interaction was also significant. 9/19/2018

Interactions The red line represents the high level of the post bake temp. The black line shows the low setting of the post bake temp. They aren’t parallel which shows that there is a significant interaction. 9/19/2018

Conclusions Die time and temp both set to low Save energy and time Post bake at high temp and least amount of time possible Low cycle times 9/19/2018

Thank you Jeff Amundson for a good tour Darryl for making test indentor Bill for answering never ending questions Seth for helping with lab equipment 9/19/2018

QUESTIONS ? 9/19/2018