Engineering – Page 4 – CA Work Experience Program

Day 7 at Pentair: Field Trip!!

Today was a special day, because Mrs. Rai took me down to the Sanford office. This location is where everything is manufactured and where all the engineers work. So, the dynamic of the area is very different. In Sanford, everything and everyone is constantly moving and talking and working. It was a very cool experience to see what a real engineer does on a daily basis. This is where Mrs. Rai used to work before she got promoted, and she knew everyone! Everyone was glad to see her, and they seemed to miss her too. We tagged along with one of Mrs. Rai’s friends named David. David showed us around the entire facility and explained what he was working on. It was a lot of fun because I was learning a lot and drawing a lot connections from my chemistry class too. David was currently working on heating pumps, so he broke down how every piece was made and the entire assembly process for me. I could explain it, but it would take super long and I probably would get some things wrong, so enjoy these pictures I took.

After following David around for a couple hours, I headed into the engineer’s office with Mrs. Rai and we met with all her old engineering buddies. They were glad to hear that I was interested in their field and said it was a lot of fun. They also loved to make fun of Mrs. Rai for leaving. After that, Mrs. Rai and I headed to another part of the factory where we saw some plastic injection machines. This is something I had learned about yesterday, (remember the complex diagrams I talked about?) and it was really neat to see the process in person. Then, just like that, it was time for lunch and time to leave Sanford ;( We ate sandwich place in Sanford and then headed back to the Cary office.

We arrived in Cary at about 1:45, only to see Mrs. Rai’s computer was off limits because it was updating a new software. The update was supposed to take up to an hour, so we had some free time on our hands. The free time went by quickly, and it was time for two back to back meetings to end out the day, for me. For the first meeting, Mrs. Rai was just monitoring and listening in, so there wasn’t much contribution from our side of the call. The second meeting didn’t happen because one of the other members was unable to make it! And, just like that, it was 4 and my day was done!

Day 5: Analyzing the Blueprints

Today at good ol’ SEPI, I worked with a contractor and an engineer from a group called “IDIAS.” I learned later on that this name came about by taking the maiden name, Saidi, of the company owner, Sepi, and spelling it backwards. Pretty cool. It also sounds like “ideas,” which is also pretty cool. Basically, one of their main jobs is to secure construction project permits that the government bids out to different civil engineering or construction firms, so that they can work on more projects and in turn make more money for the company. Because SEPI is a relatively small and new firm, competition is everywhere, so IDIAS is very important. I was given some blueprints to look at for a government warehouse used for military training exercises, and boy were they detailed! My head hurt from trying to read all of the tiny print and small symbols that filled every page. There were hundreds of pages detailing the tiniest aspects of the building, from top to bottom. My head still hurts from thinking about the tiny print, so I’ll end this one here.

Day 4: Protect the Environment!

Today, I met with the environmental team at SEPI. Their main responsibility is to predict and monitor the environmental impacts that different construction projects can have. This includes the impact on wetlands, endangered species, ecosystems, wildlife, etc. Their job also includes securing permits for construction projects that may impact the surrounding environment from the state. I was with a team today whose job is to go and scout out different potential project sites and the environment around them. They take notes of any wetlands or bodies of water nearby, types of plants, soil, and other environmental aspects, and then place flag markers on or near any notable areas. Their job site today was a mile-long stretch of road in Durham, but the area was pretty urban and didn’t have much vegetation or soil to observe, so we ended up just leaving and eating lunch at Smash Burger instead. A successful day in my book!

A picture from Tuesday where I was watching a guy dig up a water shut-off switch, because I don’t have any pictures from today.

Day 6 – Finishing Our Print Jobs

Today at Chesterfield, Brian and I continued to refine our Cary Academy charger horse print before sending it to the carbon printer. The print itself only took about 15 minutes since the job was so short; however, something went awry! Turns out that the models we printed were too thin and did not have enough integrity to stay intact. That, on top of the fact that the ring hole was too big, caused the structure to fracture. So, we went back to the computer and refined the design so it would be thicker and the hole would be smaller. After a lengthy cleanup process, getting the resin off of the products, the new pieces were finally ready to be put into the oven. Brian proceeded to print out more of his reservoir designs since some of the ones from yesterday warped in the oven and did not function properly today. After about an hour, the new reservoir print was complete. Yet another small mishap occurred: one of the tubes in the half moon reservoirs was broken and rendered the entire model to be experimentally useless. Unfortunately, we had to toss those and were only left with three working reservoirs. We cleaned and cleaned until all the resin was sucked out using isopropyl alcohol and a syringe. All the products were put in the oven at the end and we will return back tomorrow to pick them up.

The past two days have been short, giving me some extra time to reflect upon my experience thus far. With only two days left, I am beginning to access the general conclusions I have made regarding the WEP. I never thought this program would have such an effect on my potential career interest. Coming out of junior year, I already knew that I was more of a STEM person and leaned toward engineering. Having taken Advanced Chemistry, chemical engineering and materials science were definitely up for consideration, but my WEP at Duke has truly helped develop my knowledge and further my interests. Dr. Gall’s lab is rather unique since it is a crossroads between mechanical engineering and materials sciences. I have limited knowledge in regards to mechanics and therefore remain apprehensive, yet mixing it in with something I am familiar with (chemistry) gives me an easy opportunity to further explore my potential interests in the two. Additionally, I am in awe of Dr. Gall’s lab particularly because of the drive each student has to achieve success. Dr. Gall is rather entrepreneurial based, meaning all his research goes to creating legitimate products that help people and not just publishing papers. All of these things intrigue me. Dr. Gall’s research compels me to consider the broader spectrum, because there are in fact multiple realms of engineering that share a common goal: to develop applications that further the state of humankind. Ultimately, working in this lab has given me just a glimpse at how far my passion truly extends to.

Charger Horse Keychains (Two Different Batches)

Day 6

Today, I shadowed some software engineers today. I can’t tell you what they showed me, but I learned a lot about embed programming and low-level programming. I got a chance to try programming in virtual studio. Virtual studio is very different from any IDE I had ever programmed in. It was much easier to program in as it is easier to move the aspects around than to reset the value across a grid. I made a project with two radio buttons and a single button that updated everything. Depending upon which radio button was clicked when the update button was clicked different text would show. I also had time to work on the software for my project. I began by writing out an algorithm design and implementing code. I used example libraries to help me as I am not as familiar with C as java. Additionally, Zack had an idea to create a user interface. This meant connecting Arduino and another IDE called Processing. This is done through serial communication, something I had never done before. This creates a series of calls and responses. While this makes the program more interesting, it creates some challenges as multiple messages can not be sent. Therefore, the messages must be combined into something that can be passed into a single message and then decoded on the other side. I created a way to put together and decode a message. Check it out below. Tomorrow I shall try to finish up the code and put everything together, as I shall make a presentation on Thursday about my project. Luckily, I have documented very well so it shall be easy to prepare. I hope that as I begin to try to fit everything together that I haven’t made any errors.

Day 6 at Pentair: Mixing Drinks

After an enjoyable 3-day weekend, it was time to head back to the office today. The day consisted mostly of meetings and learning another step in the engineering process. At 10:00, Mrs. Rai and I headed to the Arctic Ocean for the first meeting of the day. Ironically, this conference room was warmer than the rest of the building. This meeting was a weekly check in with one of Mrs. Rai’s design engineers who works from Texas. She reported to Mrs. Rai what she had been up to for the past week and they discussed future plans. After the meeting, we headed back to the cubicle where Mrs. Rai printed out three long sheets of paper, with drawings and lines and numbers and other confusing things. She told me to try to dissect as much as I could, and after about 5 minutes, I was lost. She then explained that this is the document that engineers send suppliers, the people who will actually make the product. She further explained that most suppliers will require two types of outlines or drawings: machining and casting. The casting is the overall shape of the product, and the measurements don’t have to be too accurate. The supplier uses the casting outline to create a ‘rough draft’ of the product. When they want to fine tune this, they look to the ‘machining’ outline. This is much more specific, with measurements going to the thousands of an inch! After all of the explaining, I think I finally understood everything that was on the originally confusing pages. It was pretty neat to see the drawings and plus I felt really legit holding the large pieces of paper that contained such complex images. After this fun learning experience, it was lunch and then the second meeting of the day.

This meeting was one of the longer ones I have joined, lasting for around an hour. There were four people on the call, two from Florida and one from Canada. This meeting was to discuss of of Mrs. Rai’s side projects, a tracker pro. I don’t know too much about the product, but judging from the meeting, it was not ready for sale. The meeting seemed to be all over the place, but I think Mrs. Rai did a great job of keeping everyone focused on the subject at hand. After this lengthy meeting, both Mrs. Rai and I were quite tired, so she decided to take a break and show me something interesting in the break room. All of the filtering equipment on the floor was made by Pentair, obviously, which meant that they had some really tricked out faucets. One of the sinks would release carbonated water, and on the side of the sink were different flavors that could be added to this special water. So, I spent the next 20 minutes exploring and mixing and drinking the flavored water. They were all pretty good, but now my stomach kind of hurts, but it was worth it!

Day 5

Today, I did a lot of research about transistors. There are two different groups of transistors ones that work off current and ones that work off voltage. For both, they are made up of layers of silicon called n and p layers depending upon what the silicon is mix with. The p is for positive and the n is for negative. LED’s are made from layers of this silicon. The silicon will only allow voltage to flow in one direction from n to p just like on an LED. There a two different types of current transistors npn and pnp which describes the ways the layers of silicon are laid out. Transistors are great for acting as switches or amplifying current. One great depiction a ran across in my research was about a hearing aid which used a transistor to increase the current to make the sound louder. MOSFET transistors work by voltage. MOSFET uses a metal oxide to separate the path in which current will flow until a greater voltage is applied. An important part to a transistor is the three pins which vary in name depending on whether they are voltage or current based. They are the variable, in, and out (my names for simplification across both types of transistors). Current flows in only one direction in transistors which is why I renamed them in and out. The variable pin is what is used to determine if current will flow or not. For the current to flow, the VGS (voltage between the variable and the out pins) must be greater than the Vth (voltage threshold) of the particular transistor. I did all this research to understand how I must connect my pump and power supplies together in order for a transistor to act as a switch. I tinkercaded my circuit to show how I would connect everything to an Arduino board. The following are pictures of how everything got connected. I ended up using 1 analog port and 4 digital ports. I have three LED’s on my breadboard to indicate water tank status. Additionally, the yellow device pictured below is a resistance sensor that can be used to detect how much water is present. This sensor will output numbers from 1023 all the way too 300 which we and the computer must be able to interpret. Additionally, the black and silver tower on the red board is a transistor that I mentioned above. I was able to solder this transistor, resistor, and ports to the board to create something that is a bit easier to use. However, we did not find this to be the case. Once I had soldered the board, I was trying to test the board, but we were unsure of how to plug the board into the circuit and which inputs were connected to which part of the transistor. Therefore, we did as one person called it, the bleep test. A basic connectivity test showed us which parts were connected and were able to diagram the circuit out. If you are wondering why it is called the bleep test, it is because the volt meter bleeps with the there is a path between the two nodes. Today, I was also able to test the pump which works very well and should be able to move a lot of water in very little amount of time reducing the amount of time we will need to run the pump for. I also got a chance to test the resistive sensor for values for various amounts of water present. I believe that a sensor value between 650-750 maybe even higher would indicate need for watering. I am not sure if I have mentioned this yet in my blog, but I have been doing a lot of math that I haven’t posted. From sizing of the casing of the device to sizing of resistors, math is completely necessary and fun (as long as you get it right on the first try not the 8^th). To give you an example of how a resistor calculator might go, I propose the following. Begin with the fact that in a closed circuit that the voltage drops across every component must cancel out the initial voltage. Therefore, if I have a 5V power supply to supply a LED and resistor, I must know the voltage drop across the LED. Simple in fact, just plug it in and measure with a volt meter.

5V-V(drop across LED) – V(drop across resistor)=0

5V-V(drop across LED)=IR

The I or current can be found from the same guide that told you that 5V is output from a pin on an Arduino.

(5V-V(drop across LED))/I=R

Simple Math.

Day 5 – Carbon Printing Fun

After a traffic-packed morning on I-40, I made it back to Chesterfield for another day of fun and adventure! Today, I worked with Brian, a PHD student working to create orthopedic applications. The issue Brian is trying to tackle involves patients that have deteriorated knee joints that require fillers to help their mobility. Often times, the surgery required to install these fillers will lead to bacteria-caused infections, complicating the process and potentially requiring extra-procedures that might damage the patient’s health even more. Once more, there are not many effective methods to apply antibiotics to these infections once the surgeries are complete. Thus, Brian is developing a specially designed reservoir containing antibiotics that is to be put within the bone implants to combat potential infections. Antibiotics are either stored in a paste or a hydrogel inside of the reservoir. The goal of the project is to create a reservoir which will be easily implemented into the fillers, but also to have an extended amount of extrusion time. After a surgery, the reservoir is intended to constantly extrude antibiotics from the paste to the patient’s blood for a period of over 90 days. In order to achieve an extrusion process for such a long time, the reservoir must be carefully designed to let out small amounts of antibiotics over a large period of time. Brian is studying the numerous amounts of designs up for consideration.

Essentially, the design is a half moon shape since that will most easily fit into the knee filler’s open space. Current knee fillers are made of a bone cement material that is not particularly strong, so Brian is making his filler prototypes with a stronger material, RPU 60, a polyurethane. Some of the reservoir prototypes are also being made in the form of cubes for easier testing. As depicted in the images, each of these reservoirs has a holes, or channels, in the walls so that antibiotic paste can disperse into surrounding liquid overtime. The diameter, length, and orientation of these channels are the main factors being tested. As you can see in the image with the half moon samples, there are tiny channels on the walls where the antibiotics can escape. These holes may also connect to tubes that extend into the reservoir. The length of these tubes is a strong factor that affects the time it takes for all the antibiotic paste to disperse into surrounding liquid. The longer the time, the better. Brian has already made hundreds of different reservoir samples using a carbon printer in the lab, and has tested reservoir samples for antibiotic concentration, obtaining massive collections of useful data. One of his designs has exceeded the expected 90 day requirement and reached a 105-day span until all the antibiotics were extruded into surrounding liquid!

Brian creates all of the reservoir samples using a carbon printer: a sophisticated machine that prints using resin and a UV light. This machine even has a foot-motion activated door! First, the desired compound is ejected using a gun into a beaker. The RPU 60 material that Brian uses contains two components that need to be mixed thoroughly before printing. The gun’s tip helps to mix them well. As depicted in the image below, the gun’s nozzle has a long spiral design that receives two separate substances but quickly mixes them thoroughly. After the required amount of resin is extruded from the bottle (77 mL in this print), it is poured into a clear bed in the printer. The door closes, and a platform lowers into the bed to touch it. The technology behind the print lies in the UV light. As UV light shines underneath the bed, any resin exposed to the UV light will solidify. The plate above helps to create a mask above any resin that is not to be solidified. Layer by layer, the plate raises by only a few millimeters per hour to create the print. Each a layer receives a unique mask that will cover parts that don’t need to be solidified and expose parts that do. After about 2 hours, our print was successfully made to an extremely high precision quality. Today, we printed two more unique reservoir designs, a funnel used to aid in pouring the powder into vials to make the antibiotic paste, and a stirring rod. Brian designs all his prints using AutoCad, a highly sophisticated program that allows for extremely precise creations that can take hours upon hours to design.

The finished products were quite a sight! They were stuck to the top plate, as usual, but the carbon printer has some quirky characteristics, one being that a lot of the original resin is stuck to the products. The resin is highly viscous and is a slight pain to clean up. Nevertheless, there are certain cleanup procedures that make the process a little easier. First, the items are pried off of the top plate and placed in a tub of isopropyl alcohol (2-proponal) and shaken until the viscous resin gets off of the solid products. At the same time, the clear tub and top plate are both cleaned out with isopropyl alcohol and acetone is used to wipe down the clear tub’s glass. Though messy, the cleanup process is crucial to ensuring that the finished products set properly and that the printer’s parts can be reused for future prints. To clean the hollow cubes thoroughly, a syringe is used to pump isopropyl alcohol in and out of the small channels to ensure a resin-free product. After everything is sparkling clean, the products are placed in an oven set at 120 *C for 4 hours to allow the material to achieve its highest potential in terms of its structural properties.

In the afternoon, Brian and I designed a Cary Academy charger horse keychain on AutoCad, and we plan to print it out tomorrow using the carbon printer! After much troubleshooting, the design turned out fairly pleasing. Although today was a short day, I learned substantial knowledge about the different medical applications 3D printers can truly bring forth. With all the advanced technology Chesterfield Lab has, there are an endless amount of possibilities for the devices one can create. The sky is truly the limit on this one!

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Day 4

Today, I was with the digital group who is one of two groups of electrical engineers at Plexus. I finished up some CAD in the morning for the box for everything to sit into. I realized that I needed screws that would go into the sides of the box, but my sides were probably too thin for standard screws to go into and I forgot some important holes in the side of the box. These ended up sounding kind of basic written down but they didn’t present so easy on CAD. Kyle showed me how they use CAD for laying out circuits for boards. It was also interesting to learn about the various ways things can be soldered with both wave and with paste. After a really fun lunch, I visited the lab in which I was introduced the wide variety of lab equipment that they have at Plexus. I was shown how you can use an oscilloscope and all the different wave forms that you can see. We also talked about how box waves are formed using many different sin waves. There is another piece of equipment that graphs frequency over power which would show many spikes at many frequencies for a box wave. After spending some time doing calculations using a multimeter and information provided by the manufacturer, I was able to find the resistors needed. My biggest design challenge was that I needed to control a 12V pump off a 5V Arduino. I couldn’t power the pump through the Arduino for obvious reasons so therefore, I had to have a switch to control this, which created another problem. I didn’t want the user to have to flip a switch every time the plant needed to be watered. Therefore, I needed a Transistor. Transistors allow power to flow when the voltage proved to one of the pins is sufficiently high or low. This solved my problem. The one main electrical component that I still have out standing is the sensor for soil level. This should be fairly easy to install but will need to be tested for the values for high and low. I can’t believe that it is already day 4 and we are almost half way through. I have included some photos below of my notebook with some electrical diagrams and calculations about resistors below.

Day 4 at Pentair:

The first of half of the day at Pentair consisted of mostly meetings. The first meeting was between Mrs. Rai and one of her project members down in Florida. The meeting was held in the arctic ocean.. Brr. This was a weekly meeting where the two would discuss weekly progress and problems. Mrs. Rai explained the more they talked, the more problems they would find, therefore she liked to keep the meetings short 🙂 In between the first and second meeting Mrs. Rai had me read the PCO or product change order. This was a lengthy document, which Mrs. Rai said would definitely put me to sleep, but said it was a document that every Pentair employee had read once, almost like a rite of passage . Thankfully, I didn’t dose of, but I really didn’t understand too much of the form. The form was basically explaining the process that an employee had to take in order to change a key aspect of a product. The process was long and thorough, nothing slips through the cracks at Pentair! After this lengthy read, we headed into the next meeting of the day, which was in the Indian Ocean! This meeting was similar to the last, in that both were weekly checkups. However, meeting number 2 consisted of a lot more people, the whole team, from Florida, Samford, and here. Mrs. Rai warned me that these meetings can sometimes get choppy with arguments and bickering, but thankfully this one stayed pretty clean. The team followed a similar schedule as the first meeting: checkups and problems. There were definitely more problems with this project than the last, which was unfortunate, but expected. After these two lengthy meetings and the reading, I was pretty tired and ready for some lunch.

After lunch, Mrs. Rai and I crossed the hallway to another cubicle of a lady who worked in finance. She helped Mrs. Rai with her budget request, making sure everything was in check, before Mrs. Rai sent in the corporate office in Minnesota. After that quick meeting, Ms. Eason showed up! It was great to see a familiar face! After that short meeting, phew lot of meetings today, it was time to resume my side project with the Geneva Mechanism. Today was step 3: running the simulation. It was frustrating but after many attempts, it finally worked! The project was a success and I was quite proud of the accomplishment, even though I couldn’t have done it without some help.