A composite part manufacturing mold was considered one of the most
important factors that affected a successful composite part manufacturing process
for this research. A highly durable surface was required for the mold to prevent
surface damages and increase mold life. A high surface finish quality of the mold
improved the surface quality of the composite part and lowered the demolding force.
However, the surface of additively manufactured fiber reinforced composite molds
usually had lower durability and surface finish quality compared to traditional metal
molds. To solve these issues, the author applied an additional coating on top of the
additively manufactured fiber reinforced composite mold surface. A thermal
analysis of the additively manufactured fiber reinforced composite material and the
coating material were performed to select an applicable coating technique and
coating material. The thermoset polymer coating with ceramic particles that was
applied with a liquid spray coating technique was selected as a coating material.
Various surface property tests were performed to evaluate the coated surface
compared to the non-coated surface. The additively manufactured fiber reinforced
composite test specimen manufacturing process and the coating application process
were demonstrated in this study. The surface durability of the test specimens was
tested using a surface hardness test and an abrasion resistance test. The surface
performance of the test specimens was measured using a surface roughness test and
a demolding test. The sustainability of the coating material on the additively
manufactured fiber reinforced composite was tested using coefficient of thermal expansion (CTE) test, coating adhesion test, and mold life experiment. In the mold
life experiment, the non-coated and coated mold were used for multiple composite
part manufacturing processes to investigate how the coating affected the life of the
mold. The test results showed that the coated surface had a significantly improved
surface abrasion resistance and demolding performance. However, the coating did
not significantly improved surface hardness and roughness with the coating. The
adhesion strength of the coating was not degraded even there was a coefficient of
thermal expansion (CTE) mismatch between the additively manufactured fiber
reinforced composite and the coating material. The coated additively manufactured
fiber reinforced composite mold was able to be used for multiple autoclave
composite part manufacturing cycles. The coating covered most of the small voids
on the mold surface and provided a more homogeneous surface compared to the
non-coated mold, but the voids which could not be covered with the coating caused
a chipped coating issue. Once the chipped coating occurred, the size of chipped
coating got larger each time the tool was used for a composite part manufacturing
cycle. Although the additional coating provided some improvements for the surface
properties, the coating applied in this research could not be an ultimate solution to
meet all the surface property requirements for composite part manufacturing mold.