A study of the staircase effect induced by material shrinkage in rapid prototyping

Abstract

Purpose

To investigate the “staircase effect”, which is one of the most significant manifestations of part inaccuracy in liquid‐based rapid prototyping (RP) processes, on multi‐layer RP parts made using a thick layer deposition and photo‐curing process in a stepless rapid prototyping (SRP) system.

Design/methodology/approach

The building of a five‐layer part is simulated layer by layer using a finite element method based on an incremental elastic model, to analyze the staircase effect due to shrinkage induced by polymerization and temperature variation. The influence of various factors such as layer thickness and intensity of incident UV light is studied. The results were verified experimentally.

Findings

Results show that the staircase amount increases 20 percent and 300 percent with light intensity increasing from 65 to 145 mW/cm² and layer thickness increasing from 0.2 to 2.0 mm, respectively. It is also found that the overall staircase is below 100 μm, which suggests that the SRP process improves surface quality greatly compared to other RP systems, and can provide enough accuracy for fabricating functional parts.

Research limitations/implications

The results apply only to the material used in the work: an acrylate‐based photopolymer resin, C123, produced by Tianjin Chemical Co., China. Also, the thickness of the layers is fixed at 6 mm.

Practical implications

Provides a method to analyze the origin and amount of the staircase effect, upon which to better control the surface finish of RP parts. New materials and different layer thicknesses can be investigated using the same method.

Originality/value

Apart from the above practical implication, this paper establishes the parameters that influence the shrinkage of the material used in SRP.

Citation

Wenbin, H., Yong Tsui, L. and Haiqing, G. (2005), "A study of the staircase effect induced by material shrinkage in rapid prototyping", Rapid Prototyping Journal, Vol. 11 No. 2, pp. 82-89. https://doi.org/10.1108/13552540510589449