Prototyping
Traditional prototyping techniques were used to manufacture the parts. Machining and 3D printing for creating masters and silicone tooling and vacuum casting of various materials for manufacturing the large quantity of test parts. Challenges of high heat and high tolerances were all met through the careful selection and testing of materials. Certain parts required combinations of materials, including hard metal inserts. The water pipe was unique in that a complex core was made to carry the support of the pipe in the moulding process, in order to prevent kinking on severe bending.
2. ECU Cover:
This part mounts on the outside of the propulsion system and covers the engine control unit. The CAD files were provided by the client. We used our CAD system to split the part in two in order to 3D print the graphic in high quality and the body in high speed mode on our Eden 350V. This allowed us to have a lower cost print with a high quality graphic. The two parts were glued together, finished off cosmetically, silicone tooled and the 30 parts were vacuum cast in high temperature polyurethane.
3. Trim Button:
This part needed to be functional and highly cosmetic as it was mounted on the outside of the propulsion system and highlighted by its stainless steel housing. The part was 3D printed in high quality and hand finished with a light spark effect. A silicone mould was made into which we cast polyurethane resin to create a durable part.
4. Water Pick-up:
Various versions of this were requested by our client. This part was assembled on the outside of the gearbox and was meant to take water into the system whilst filtering out solid debris. Various versions were made in order to test the volume of water picked up and flowrate into the system. The parts were 3D printed at high quality and then worked off to a gloss finish by hand. They were then silicone tooled and vacuum cast in a very strong 82D shore polyurethane that could withstand salt water and impact from debris in the water.
5. Oil Cap:
This part was 3D printed in high quality in order to get the best quality graphics. It was hand finished and silicone tooled. A chemically resistant polyurethane was used to vacuum cast the final parts.
6. Oil Pick-up:
Geometry for this part was supplied by our client. The part needed to be made from a chemically resistant material and it needed aluminium inserts. The master was CNC milled and whilst it was being hand finished and silicone tooled, the CNC lathe was used to make all the various aluminium inserts. These inserts were loaded into the silicone mould and an appropriate polyurethane resin was cast around them.
7. Water Pipe:
The client provided the CAD files for the pipe. We used our CAD software to split the part in two along the length. We also designed a core for the part that was machined out of acetyl on our CNC mill. After machining the core we assembled the two pipe halves around the core and finished the outsides. The acetyl core with the printed part was used to create the silicone mould. The acetyl core ensured easy release of the cast part as well as accurate internal geometry.
The pipe was tested by the client thereafter they provided us with a new version of the pipe which was designed to eliminate "kinking" that occurred in assembly. The new part had a coiled design instead of the original concentric ring design. This was meant to prevent the pipe from collapsing on itself when bent as it would sit in the assembly. The same process used in the first iteration was used here to create this part. The only difference was that we co-moulded a spring into the part to aid in the prevention of collapse in the assembly. Both versions of the pipe were vacuum cast using a polyurethane casting system wherein we could adjust the shore hardness from 40 to 90 A shores.
PBH Seal:
This was 3D printed in high quality as the part had fine ribs all around that formed a seal when the parts were assembled. The part had to be finished very carefully in order to keep to the strict tolerances. The finished part was used as a master for the silicone tool. A range of different A shore polyurethanes were cast into this mould in order for the client to determine the correct shore hardness for the part. The part was altered in CAD and a second version of the part was prototyped using the same method. Thereafter 30 units were made.
