Week 3: LR-20 DOE and Gage R&R

This week was again another step away from hydration because there are other problems to overcome before we can continue the hydration process.

Similar to the LR-14 DOE, we ran another DOE except for the LR-20s. We wanted to again find if there is was any problems with the variance between shot to shot and cavity to cavity. After measuring the weights of 5 shots of LR-20 we found that the variance was a lot smaller cavity to cavity than what we found in the LR-14s despite some outliers. We concluded that there may have been a venting problem with the molding press.

We also ran a Gage R&R, standing for Gage repeatability and reproducibility, on a new program that was made to more accurately measure the plastic parts being made. The customer wants the parts to only have a certain amount of variance. A sample of the parts must be measured and analyzed to determine if the parts fit the criteria. However there are multiple ways of measuring these parts. We have a newer program that is a lot faster and more accurate. However we must run a Gage R&R to show that this new method is just as accurate if not more. A Gage R&R is a statistical tool helps investigate the amount of variability the measurement system is causing, or in more simple terms it determines how reliant the measurement method is. Unfortunately we were unable to analyze the data from the Gage R&R due to time constraints. I’m looking forward to next week where we will be able to determine if our new program is adequate. 

Week 2: LR-14 DOE

Hello again!

This week I will take a small step away from hydration because a customer wanted an "emergency" DOE analysis of the LR-14 press. Because the pressure exerted by the press can cause bending in the mold, we wanted to run an experiment to find evidence of this in the LR-14 mold.

Here's a little bit of background on the mold before I talk about the experiment: a mold is the object that allows the injected plastic to take the correct shape, in this case the shape of an LR-14 battery seal. This mold is placed in a molding press that injects plastic into the mold at the desired pressure, velocity, and temperature.

The LR-14 mold has 32 cavities meaning every injection of plastic, or shot, creates 32 LR-14 sized battery seals. Because the mold and the press can never be perfect there will always be variance between each cavity. However, we are trying to find the best combination of factors for the molding press to create the least variability from cavity to cavity and shot to shot.

Therefore an DOE on the LR-14 must be run to find any discrepancy in the molding press. We did two DOE's on the LR-14 mold. The first one consisted of 10 shots in which we weighted all 32 cavities in each shot and looked for the correlation in weight from shot to shot and cavity to cavity. After running a grouped box plot graph, we found little variance from shot to shot however the cavity to cavity variance was unclear. We decided to run a second DOE analysis of 5 new shots to compare the variance from cavity to cavity. We found that the LR-14 mold has negligible variance from cavity to cavity and therefore the parameters on the molding press are adequate for the particular mold. However we look to improve the parameters on the mold to make it more efficient for not only variance but also functional and cosmetic problems.

Week One: Basics and Project Goals

Week One: Basics and Project Goals

Hi everyone and welcome to my blog. Here, I will be documenting my experiences each week at Microtech Southwest.

Please keep in mind, I expect my project to change as I learn more about the production of batteries.

I plan on analyzing the effects of hydration on batteries. First, a battery is made up of an anode, cathode and an electrolyte. This is what allows the battery to do its job. But this is all kept contained by two plastic seals on the ends of the battery which is then wrapped by a metal cover. Topped off by a nail that runs through the middle to keep the battery together, the battery can only hold so much material. Companies are trying to find the best way to maximize the longevity of the batteries. These battery seals must be hydrated to a certain moisture level to be usable. However, battery companies are trying to make the seal as small as possible to increase the lifetime of their products. I want to see how much of a role hydration plays in this process.

               This week I started a Design of Experiments (DOE) on a burst test LR-14 (for C batteries) size battery seals. This will allow us to determine if these seals are still able to take the pressure of the gas inside the battery without exploding. Because of conflicts with work load, I was unable to analyze the data. I plan to use this project to expand my knowledge of statistics and see how it is implemented in industry. I look forward to what next week has in store!