Inside EPS raw beads, there’s the blowing gas called pentane. After steaming, pentane starts to expand so the bead size also grows bigger, this is called expanding. EPS raw beads cannot be used to make blocks or packaging products directly, all beads need to be expanded first then make other products. Product density is decided during Preexpanding, so density control is done in Preexpander.

Continuous expanded polystyrene pre-expander is functioned to expand EPS raw material to required density, machine works in continuous way both in taking raw material and discharging expanded material. Continuous expanded polystyrene pre-expander can do second and third expansion to get low density.

Continuous expanded polystyrene pre-expander complete with Screw Conveyor, First and second expansion loader, Expansion Chamber, Fluidized bed Drier

Continuous expanded polystyrene pre-expanderis a kind of EPS Machine working with mechanical control. EPS raw material is first filled from screw conveyor to expansion loader. At the bottom of loader is the screw, to move material from loader to expansion chamber. During steaming, agitating shaft is moving constantly to make the material density even and uniform. Raw material move to chamber continuously, and after steaming, material level continuously move up, till the material level comes to same level of discharging opening port, then material will automatically flow out. The higher the discharge opening is, the longer the material stays in the barrel, so the lower the density is; the lower the discharge opening is, the shorter the material stays in the barrel, so the higher the density is. The control of the continuous pre-expanding machine is very simple. Whether the steam pressure is stable or not has a great influence on the density of expanding. Therefore, our continuous pre-expanding machine is equipped with a Japanese pressure reducing valve. In order to make the steam pressure in the machine more stable, we use the screw to feed the material at a uniform speed, and the uniform steam and uniform feed are as uniform as possible.