Basic molding die design standard

The manufacturing process of SunForce is similar to that of foamed beads.

Basic molding die design standard

1Material selection

Select a grade of SunForce based on the density of product you wish to achieve. (Refer to Product design guide for selection)


Before molding, internal cell pressure of SunForce beads of more than 0.3MPa is required. This can be achieved by the following method:

  • Fill SunForce beads into a pressuring tank
  • Insert pressurizing gas and keep internal tank pressure at 0.4MPa.
  • Leave beads in pressurized tank for a certain amount of time. The length of time depends on temperature and pressure set.
  • Release pressure and proceed with the molding process.

Pressure opreration for impregnation

Pressure opreration for impregnation

Life time of ICP

Life time of ICP


1. Filling of SunForce beads

Fill the beads into a closed mold.

Filling of SunForce beads

2. Mold heating

Preheat the mold. Insufficient heating of mold will limit the generation of steam required for heating of beads, causing improper expansion and fusion of beads.

Mold heating

3. One-sided heating

Allow steam to flow in from one side of mold to ensure all air space in between beads is replaced by steam. This ensures proper fusion of beads at all parts of mold.

One-sided heating

4. Two-sided heating

Continue with heating from both sides of mold until it reaches the molding temperature. Be sure to maintain balance as overheating causes beads to shrink and stick to the mold.

Two-sided heating

5. Cooling of mold

After heating is complete, proceed with spraying of water to cool the mold.

Cooling of mold

6. Cooling of product

Cool product by vacuuming. By utilizing the latent heat of vaporization, we can quickly reduce the water content in product.

Cooling of product

7. Mold release

Eject product from mold by ejector pins or air pressure. Unlike olefin based molded products, products made using SunForce do not undergo shrinkage after molding. The measurements of product are constant after molding.

Mold release


About 0.5wt% of moisture content is present in the molded product. The percentage will be lower if vacuum was used during cooling stage (which in this case, drying is not necessary).
To remove most of moisture after molding, keep products in a room under 80℃ for 1 to 6 hours. The drying time depends on thickness of product.

Standard molding conditions

Representative figure, mold products density at 100~200g/L
(1) Equipment
Impregnation system + EPP-molding machine
(Feeding hopper with pressurization system)
Surface pressure: More than 0.4MPa
Steam pressure should be controlled by electric-pneumatic converting diaphragm valve manipulated by PIC
Pressure inside hopper: 0.15-0.30MPa recommended (effects to beads lifespan)
(2) Impregnation
Target inner cell pressure
Pressure increasing condition
Pressurization 0 to 0.4MPa/4hr
Holding pressure 0.4MPa
(3) Molding conditions
Cross steaming1
Cross steaming2
Water cooling
depend on max. thickness
Vacuum stabilizing
Recommended using better to dehumidification
Vacuum ejection
Recommended (Effects on cycle-time and efficiency in case of complex shapes)

Standard molding cycle time

The cycle time depends on grade of SunForce used and the thickness of product. SunForce beads of higher expansion ratio (low density), thinner products = shorter cycle time.
Below is a graph of standard molding time of SunForce

Standard molding cycle time