UNR composites is a team focused on building a composite curing oven for use by UNR students and staff. Composite curing ovens are very specific and highly controllable heating devices that when used properly will cure composite materials. The curing process is an integral step in creating materials such as carbon fiber. Temperature needs to be precisely controlled during the curing process in order to properly cure a composite. Different composite materials require different curing temperatures and times. The more functionality and controllability a composite curing oven has, the more versatility it will have to cure different types of composites.
Having a composite curing oven at UNR will allow for groups such as the Formula SAE and the Human Powered Vehicle team to incorporate lighter stronger composites into their design in hopes of becoming more competitive in the future. With the advancement of composites it is important to stay on the leading edge of manufacturing processes and design.
The composite oven will consist of an 6×4 x 4 foot oven box as shown in the solidworks diagram below.
Proof of Concept
The Proof of Concept consisted of a portion of the oven wall with an adjustable thickness. This design allows for multiple thicknesses of insulation to be tested in order to confirm the results from the engineering analysis. In order to test the PoC one side of the wall was exposed to a temperature of approximately 550˚F. The temperature of the other side of the wall was then monitored until the wall had reached a steady state. The results from the PoC showed that the results from the engineering analysis are correct. The initial results obtained from the full engineering analysis showed that an insulation thickness of 2.5 inches would be required to maintain an outside temperature of less than 110˚F. This is given a worst case scenario of an inner surface temperature of 750˚F and an ambient air temperature of 90˚F. In practice the oven will not exceed 500˚F and the ambient air temperature will be approximately 65˚F.
Final Design Review
Due to the generous donations from Jensen MetalTech, Ray Heating Mechanical Systems, and Ranshu Inc., UNR Composites was able to fabricate a 96 cubic foot oven with all the capabilities of an industrial oven at a fraction of the cost of a commercial oven. No major changes have occurred since initial design plans and testing of the proof of concept. Equipped with easily accessible components including a temperature controller, a vacuum pump, air circulation fan and two household electric oven heating elements, the oven will allow for the curing of carbon layups up to 6 feet in length and 3 feet in height and width. The temperature controller will allow users to set specific ramp up and ramp down time and temperatures per their requirements up to temperatures of 550˚F while maintaining a safe external surface temperature of less than 110˚F. This functionality is crucial when curing as it allows the carbon to heat uniformly reducing the chance of warping. The vacuum pump provided by Ranshu Inc of Reno allows the use of bagged carbon layups that are used to compress a given layup onto a mold as well as assisting in pulling the resin into the fibers of the composite material. Combining these functions and components, a curing oven with all the functionality required will be at the University of Nevada’s students, staff, and clubs disposal in the hopes of allowing the integration of this advanced technology into their plans.
The fabrication of the composite oven began off site at Jensen Metal Tech, where the donated raw materials were cut to size based on the CAD drawings the team provided Jensen Metal Tech. This enabled the materials to be precision cut using commercial grade equipment which ensured that the metal sheeting for the oven walls was square and all of the supporting angle iron was the required length. Having the materials precut to the required size saved many man-hours of labor which would have been spent cutting the steel with a grinder and cut-off wheel. The provided materials can be seen in Figure 1.
Once the raw materials were delivered fabrication of the oven began. The first step was fabricating the internal frame of the oven from 1 inch angle iron and making sure that it was square. The bottom of the oven was also fabricated at this time and the first piece of sheeting was attached.
Once the internal frame was completed, the internal walls of the oven were attached and it began to look something like an oven. There were a few complications when the internal wall sheeting was attached. The main problem being that the frame was not completely square. Since the sheeting had been precision cut and was square, the team was able to shift the frame slightly to match the sheeting ensuring that everything lined up properly.
After the internal oven walls had been assembled construction of the outer part of the oven began. This consisted of creating another frame from 2 inch angle iron to support the external sheeting. Once the external frame was attached, the insulation was placed between the internal walls and the external frame. The external sheeting was then installed and the first major fabrication milestone was reached. The team had the physical structure of the oven done.
Once the main body of the oven was finished, the door frame was constructed and then attached to the main body of the oven. Once the door was attached the heating elements and the electrical system were installed. Once the electrical system was in place the heat shield for the heating elements and the fan system were added to the oven.
After everything was installed, the wiring system and the control box were installed completing the main fabrication of the oven. From this point on fabrication consisted of small tweaks to various aspects of the oven to improve the ovens performance.
Things we learned during fabrication
The fabrication process was a learning experience for the team as we assembled various parts we learned what worked and what didn’t for a project of this scale. We learned many things through trial and error. Firstly, that making a truly square frame out of angle iron is more difficult than you would think. Secondly, weight adds up quickly when making something of this size (completed oven ~3000 lbs) so more consideration could have been given in how the team is going to transport it to its final destination at UNR.
The UNR Composites oven was tested in order to verify that all design specifications were met. The test consisted of operating the oven in a way that we would be able to determine its maximum ramp up temperature rate in addition to its maximum operating temperature. The oven increased in temperature from 60°F to 550°F in 2.5 hours. The oven operated as designed and met all design specifications. The composite oven will allow for the production of many different composite projects for many years to come.
Special thanks to Jensen MetalTech, Ray Heating Mechanical Systems, and Ranshu Inc for their support of UNR Composites capstone project 2015.
Meet the Team
Tyler Toulouse is currently enrolled as a senior in the UNR mechanical engineering program. Tyler also holds a degree in Anthropology with a minor in world history from UNR. He has been involved in with the cycling team at UNR since 2012 and races primarily road bikes but has been known to race mountain bikes occasionally as well. Based on the personality test he is an INTJ with a 1% bias toward Judgment over Perceiving which means that he will have personality traits from both.
Luis Barraza is a senior level mechanical engineering student at the University of Nevada, Reno. He has an Associate’s of Science and an Associate’s of Applied Science in Renewable Energy from Truckee Meadows Community College. He has been a lifelong runner and recently competed in the Boston marathon. Balancing running with school and work has taught him how to follow a plan, time allocation, and efficiency. The results of the human metrics personality test he is an ISTJ. Individuals with these are noted for punctuality, devotion, and are most at home with just the “facts”.
Paul is currently enrolled as a senior in the mechanical engineering program at the University of Nevada Reno. He previously acquired a Bachelor’s degree in Criminal Justice from California State University Stanislaus. Based on the personality test he is an ISTJ type with 22% preference of introversion over extroversion, 38% preference of sensing over intuition, 50% preference of thinking over feeling, and 44% preference of judging over perceiving.
Devan LeBlanc is a senior standing mechanical engineering student at the University of Nevada, Reno. He spent five years in the Marine Corps as a helicopter crew chief/mechanic before pursuing a degree in engineering. As a Sergeant collateral duty inspector/aircrew instructor, and in combination with the knowledge gained at the university, he will help build a well rounded team to meet the challenges of this project.
Cameron Chappell is a senior in the mechanical engineering at the Univerity of Nevada, Reno. He spends the majority of his time tinkering with either tools or instruments. His primary interest is the piano, but has recently picked up the banjo. When not engaged with music, he enjoys hunting, and the outdoors. He scored and “INTJ” on the personality test, with a moderate preference to introversion and intuition, and a slight preference to thinking and judging. Cameron found the personality test to be helpful.