US firm Submergence Group LLC specialises in the design, fabrication and operation of experimental submersible vehicles, otherwise known as UUV’s (Unmanned Underwater Vehicles). Having been asked by the US Navy to produce a large UUV for testing at sea, MSubs Ltd, under contract to Submergence Group, designed and constructed the MASTT (Mobile Anti-Submarine Training Target) vehicle in just 13 months at their base in Plymouth, Devon.
Completed in October 2011, the 60-tonne, 24-metre long UUV will be used by the US Navy for anti-submarine training at sea and is currently undergoing sea trials in Lake Pend Oreille, Idaho. It is capable of being transported unassembled in standard shipping containers and reassembled on-site, representing a new series of cost effective, low-maintenance and robust unmanned underwater vehicles.
The Design Engineers at MSubs already had several large scale models of other submersible vehicles that had been produced by professional modelmakers, but they found the cost was too high and the model too fragile. At the same time, they had little input as to how their design drawings were interpreted by the modelmaker, so accuracy of the final model was becoming an issue.
By using the plastic additive manufacturing (AM) services of 3T RPD Ltd, all these issues were resolved. The Lead Design Engineer at MSubs produced 3D data using Autodesk Inventor from renderings created during the design and construction of the actual vehicle. 3T then built five models using SLS (Selective Laser Sintering) technology in Nylon material directly from the CAD data supplied. With no potential for translation errors or misinterpretation of the data, this manufacturing process generates extremely accurate models in a fraction of the time compared to other manufacturing methods.
Each model measured just over 1.1m long but by building them in two pieces they could fit all five models into one build chamber, making the process even more time- and cost-efficient. 3T’s CAD Engineers strategically ‘cut’ the models so as not to adversely affect their functionality or strength, or indeed their aesthetic appearance. Their team of expert finishers then bonded the two parts together using specialist modelmaking techniques, making it virtually impossible to see where the actual join was.
Brett Phaneuf, President of Submergence Group, says “We got five models from 3T for the usual price of one from a modelmaker, and they are exactly as we wanted them. They were produced in a tenth of the time and are extremely robust.”
The plastic models are now being used to explain what the MASTT vehicle is to existing and future clients, demonstrating how it was designed and constructed. They are also used at trade shows and as office display models, and have proved extremely beneficial as the design team no longer have the actual vehicle to make reference to.
Brett adds, “We are considering designing a small UUV to be produced using plastic AM as much as possible for actual deployment underwater for R&D, and we will use 3T again to produce the next series of models for these new vehicles.”
Brett summarises by saying, “The service we received from 3T was flawless! They offer a cost effective, timely service and have very friendly, helpful staff. I wish every company we dealt with was as helpful and professional.”
MSubs Ltd is hoping more work will come from the US Navy as a result of this project.