Today, this paper focuses on the experimental analysis of the influence of SMC molding process parameters on its curing shrinkage, so as to share with relevant friends:

SMC(Sheet Molding The invention and development of cornbond is one of the outstanding achievements of FRP industry in the past 40 years. Because of its advantages of low raw material cost, high productivity, stable and reliable product quality, low environmental pollution and mechanized automatic production, it has been widely used in automobile transportation, construction, shipbuilding, electrical, chemical industry and other fields. In developed countries in Europe and America, the annual growth rate of SMC products is in F RP industry has been in the forefront of various molding products, but due to the high curing shrinkage of unsaturated polyester resin, the main matrix material of SMC, the apparent quality of SMC products is reduced. In general, LPA (low prolile additive) is used as a technical measure. In this paper, the effect of molding parameters on curing shrinkage of SMC is analyzed.

Experimental methods

The influence of molding temperature and two-stage pressing system on the shrinkage property of products was analyzed. The first mock exam is to establish a two stage pressing system to first determine a molding pressure to make the molding plastic flow at high pressure and fill the mold cavity. However, the high pressure is not maintained throughout the curing cycle, but is reduced to a lower value in a period of time before the molding compound is fully cured.

The linear shrinkage of SMC cured products was determined by the difference between the diameter of die (disc type) and the diameter of molded specimen at room temperature. SMC sheet from Dongfeng Chemical Plant of Jilin Province was used in the experiment.

Molding process parameters:
1. The effect of molding temperature on curing shrinkage of SMC: the molding pressure was iompa and the holding time was 3min.
2. The effect of two-stage pressing system on curing shrinkage of SMC was studied:
(1) In the second stage, the pressure was 15MPa, the holding time was 60s, the molding temperature was 1500C, and the total pressing time was 3min.
(2) The influence of holding time in the first stage on curing shrinkage of SMC was studied. The first stage pressure was 15MPa, the second stage pressure was 5MPa, the molding temperature was i500c, and the total pressing time was 3min.