RENPIM USED FOR 40KG TRACTOR ROOF PROTOTYPES
30 June 2003 - Huntsman Advanced Materials

The size of the part was further complicated by the design, which included a series of large bosses that would be difficult to demould.

The parts were produced using Vantico epoxy tooling and RenPIM polyurethanes
and were accurate and durable enough for functional testing.

Reko started the project by using CAD data to cut a RenShape 450 model. A
fibreglass reinforced epoxy paste tool was then built and used for the mould, while a Shore 50A silicone rubber was used for the loose mould inserts.

A modified RenPIM polyurethane system was used for the prototype parts after it
became apparent there were no fast-setting materials readily available with a pot life long enough to shoot the part.

After tests, Reko technicians realised they could use RenPIM 5218 A/B polyurethane for the large parts if they used a different combination of hardeners. When the hardener was mixed with RenPIM 5219B, this slowed the pot life to seven
minutes– long enough to mould these huge parts.

Two meter/mix dispensing machines were used to shoot the tool, with the first run
determining the precise demould time. While the seven minute work life was
adequate, the demould time needed to be increased so an air ejection system was
added.

After the mould was filled with the specially formulated RenPIM material, the
prototype remained in it for several hours. More air ejectors were then added to help demoulding and enable the mould to be opened while the prototype remained in the cavity half.

The resulting parts exhibited good accuracy with virtually no warping despite their
large size. After inspecting these prototypes, Reko’s customer asked for some
design changes to be made and the mould was altered to add more ribs. Some
additional prototypes were cast before proceeding to final production parts that were moulded using structural foam.

More News:
  • For June 2003
  • From Huntsman Advanced Materials
  • For General