Product design guide

Product grade and density

Select raw material based on the density of finished product you wish to have using the table below.
Our product variations are from high-strength grade (3.5x times expansion, 285g/L) to light-Weight grade. (10x times expansion, 100g/L)
You may also contact us for details on how to select the right grade for your products.

SunForce material grade Molded products
Grade Bulk density Expand ratio Molding crack Product density
g/L pcf g/L pcf
BE265 265 16.5 x3.5 7% 285 17.8
BE180 180 11.2 x5 7% 200 12.5
BE130 130 8.1 x7 7% 140 8.7
BE90 90 5.6 x10 7% 100 6.2

Please take into consideration that the density of the finished product may be lower in hard-to-fill areas of the mold.

Product density and flammability

Thickness of product to achieve UL-94 V-0 flame retardancy is listed in the table below.

Product density (g/L) Expand ratio Flame retardancy
285 x3.5 UL94-V0 3mmt and more
200 x5 UL94-V0 3mmt and more
140 x7 UL94-V0 3mmt and more
100 x10 UL94-V0 5mmt and more

Shape of product

As the bead size of SunForce is small, filling of mold becomes easy, thus enabling various designs.
Here are a few points to take note of to ensure even filling of SunForce during molding.

Design advice

1. Protrusions

Filling of mold during production is difficult in small areas.
Design your drawing by referring to the graph of height of protrusion versus minimum required width for each SunForce grade.
For example, if you are using 10x expansion beads, the minimum width you should use for a 36mm high protrusion is 6mmt (based on the ratio of 6:1 as shown in graph below).

Protrusion height ratio and minimum thickness
Protrusion height ratio and minimum thickness
Protrusion height ratio and minimum thickness

2. Corners

Straight corners can result in insufficient mold filling. By giving a ‘R’ shape to the corner (labelled as ‘a’ in the diagram above), you will be able to achieve a smoother and better-filled corner. The recommended minimum width for ‘R’ is 2mm.

3. Draft angles

To facilitate demolding of SunForce parts from the mold, we recommend that the minimum draft angle, or degree of taper to be 1°(use 3 degrees or more for areas that are hard to demold).

4. Gaps

Ensure that the gaps (also width of mold) are no less than 3mmt as the pressure from surrounding material may alter shape of mold. On the other hand, mold width that is too wide will cause improper fusion of material. Install core vents to ensure proper flow of steam and sufficient heating of material.


Design guide for mold

Similar specifications to EPP molding dies

Mold shrinkage 7 / 1000
Draft angle
1deg. and more for better ejection
Recommended angle: 3-5 degrees (Effects on cooling time and defect rate)
Through hole part needs 3deg and more.
Thickness of mold cabity Evenly EPP (15mmt recommended)
Core-vent pitch Evenly EPP (Slit Pitch: 20-30mm)
Mold material #AC2B (JIS)
Range of possible thickness 3〜60mm (In case of product density: 140g/L)

NC milling process is recommended if flatness and dimensional accuracy are necessary.

Example of standard molding tool

(Filling & steam heating & cooling)

Clamping (Filling & Steam heating & Cooling)

(Molding release)

Clamping (Filling & Steam heating & Cooling)

Cavity mold

Clamping (Filling & Steam heating & Cooling)

Core mold

Clamping (Filling & Steam heating & Cooling)