A) Product name:
1．Vesicant PS resin grain for lost-foam casting (EPS);
2. Vesicant PMMA-PS co-polymerization resin grain for lost-foam casting (STMMA);
3. Vesicant PMMA resins grain for lost-foam casting (EPMMA).
Consumers could select favorite products with special type and standard to make sure that high-quality lost-foam plastic model and cast can be obtained.

B) Applied scope of products
Type 　　　 Applied scope
EPS 　　　　colored metal (aluminum, copper, etc.), gray iron and general steel cast
STMMA 　　　gray iron, sphere iron, soft steel, alloy steel cast
EPMMA　　　 Nodular iron, malleable iron, low carbon-steel, alloy steel, stainless steel etc.

C) Type and standard of products
Index 　　　　　　　　　　YATA-EPS 　　　　　　　YATA-STMMA 　　　　　　　　YATA-EPMMA
Co lour and luster 　　translucent grain 　　　translucent milky grain 　　milky grain
Apparent density (g/ml)　　0.55-0.67 　　　　　　0.55-0.67 　　　　　　　　　0.55-0.67
Pre-vesicant multiple ≥　　50 　　　　　　　　　　45　　　　　　　　　　　　　40
Volatile（%）≥ 　　　　　　6.5　　　　　　　　　　8 　　　　　　　　　　　　　10

D) Diameter of grain (mm)

1# 0.60-0.80 　　　2# 0.42-0.60 　　　3# 0.30-0.40
4# 0.25-0.30 　　　5# 0.21-0.25 　　　6# 0.18-0.21
Note: This product contains low boiling point hydrocarbon vesicant. As a result, It must be placed in airtight container with plastic membrane as inner-liner during storing and transportation, and should be stored in low temperature, ventilated site far from fire.

E) Using method:
The processing of lost-foam casting foam mould is as follows:
Pristine grain → pre-foaming → desiccation, ripe→ molding foaming → foam mould
1．Selection of pristine grain
Firstly, select the type of pristine grain according to the requirement of material and qulity of the cast, and then select the standard according to the least thickness of the wall. Generally, the diameter of the grain should be less than or equal to 1/9 - 1/10 of the least thickness of the wall.
2．Pre-foaming of the resin grain
Pre-foaming of the grain in lost-foam cast use intermittent pre-foaming machine. In the two types of intermittent pre-foaming machine, the vacuum type is superior to the pressure-loading type. Their processing parameters of pre-foaming are shown below:
a. The processing parameters of vacuum pre-foaming machine:
① Resin loading 6 seconds
② Pre-heating shown in the table below
③ Affusion under vacuum 50-75 ml/10 sec
④ Preserve under atmospheric pressure 5 sec
⑤ Preserve under vacuum 20 sec
⑥Down load 45 sec
The processing parameters of vacuum pre-foaming
Volume loaded（g）Steam pressure of Interlining sleeve（Mpa）Density of pre-foaming (g/l)
Co-polymerization resin 500　　　　3-5 　　　　　　0.15-0.18 18-20
EPMMA 500 　　　　　　　　　　　　 5-7 　　　　　　0.18-0.20 22-25
EPS 500 　　　　　　　　　　　　　 2-3　　　　　　 0.11-0.15 16-22
b. Pressure-loading of pre-foaming machine
The pre-foaming temperature of EPS is 100-105℃；
The pre-foaming temperature of co-polymerization resin is 105-115℃；
The pre-foaming temperature of EPMMA resin is 115-120℃；
The pre-foaming multiple of grain is controlled by the temperature and time of pre-foaming.
c. The desiccation, ripe of pre-foaming grain
By using vacuum pre-foaming machine, higher pre-foam multible can be achieved, and the grain produced is even-sized and dry. While in the pressure-loading condition, the grain achieved contains more water, thus must be desiccated by flow bed with 25-35℃ wind temperature to get the water-contained ratio lower than 2%.
The ripe time for EPS is as follows：
Stacking density (g/l) 　　　　15　　　　20 　　　　25　　　　30
Optimal ripping time (hour) 　48-72 　　24-48 　　10-30 　　　5-25
Least ripping time (hour) 　　10　　　　　5 　　　　2　　　　　0.5
EPMMA and vo-polymerization resin have a shorter riping time than EPS.
The optimal ripping time relate to atmosphere temperature and the flowing condition of the air. Whether the ripping process is finished can be judged by the elasticity of grain. The ripping temperature and time should be properly controlled, otherwise the quality of foaming may be harmed due to the loss of vesicant. After ripe, the grain should be place in airtight container under low temperature.
d. Molding foaming
Lost-foam plastics generally use two processing methods: streaming vat processing and pressing machine processing:
① The stream pressure in streaming vat processing (Mpa)
EPS　　　　　　　　　　　　　　　　　　　　　　0.1
Co-polymerization resin 　　　　　　　　　　0.11-0.15
EPMMA 　　　　　　　　　　　　　　　　　　　0.15-0.18
The temperature holding time should be determined according to the size and structure of the mould.
② Typical processing parameter of pressing machine (the size of mould is 50×200×200)
Density of mould (g/l) stream ventilating stream pressure in cooling time (sec)
time (sec) interlining sleeve (Mpa)
least most normal
Co-polymerization 　　13　　30　　13　　0.12-0.15 　　90
resin（20）
EPMMA（26）　　　　　 10 　 45　　25　　0.13-0.15 　　110
EPS（24）　　　　　　 3 　　15 　　9 　　0.10 　　　　130
After molding foaming, the mould should be desiccated and preserved (stabilizing) and thus shrinked in size. The contracting ratio for EPS mould is 0.4-0.8%； for EPMMA mould is 0.2-0.4%. As a result the shrink must be considered during the design of processing mould.