Relationship between Contact Condition and Roughness Sensation of Plastic Texture for Injection Mold Design

Abstract

The purpose of this study is to reveal influence of dot height in roughness sensation of the dot pattern. We evaluated roughness sensation of 9 kinds of injection molded dot pattern samples made from combinations of protrusion height (7-45μm) and space (0.4-0.6mm). As a result, only on wide space and low height samples, correlation between the roughness sensation and dot height was observed. By more detailed sensory test, the limit height that dot height affects were found to be about 25μm for dot spacing 0.6mm. We measured the displacement of the skin and contact force in contact with the dot pattern. In strong contact force, the skin was displaced about 37μm on average for dot spacing 0.6mm. Quantitative relationship between the contact condition and the roughness sensation was found. Effect of dot height is considered to appear by contacting the skin of the finger to the plane between the dots.