Machinery XB-303

The widely used ordinary EPS, one of light material PKF-XJ expandable polystyrene products, is applicable for automatic vacuum forming machine, the traditional lift hydraulic presses and all kinds of large board machines.

PKF-XJ series belong to raw material with high foaming ratios, which can achieve lighter weight foam particles through one-time foaming. They are more suitable for multiple foaming to achieve lighter products; therefore, they are more suitable for making products under 18 g/L through one-time foaming and products under 10g/L through multiple foaming. The products are widely used in electronic products packaging, insulation materials for civil construction, float tubes for fishing, crafts, decoration materials, lost foam of castings, lightweight impact resistant apparatuses, light large boards, etc.

Specifications and features
1.Features
XJ materials have higher foaming ratio, fast foaming speed, low energy consumption, short curing time and cycle time; the products have good fusion performance, smooth surface, excellent material stability, high applicability, and resistance to shrinking or deformation.
2. Product specifications

Storage Precautions
1)EPS should be stored in a cool, well-ventilated place; in order to prevent fast escaping of the foaming agent, and maintain a moderate multiplying power, the storage temperature should be below 25 ℃, and the place should be ventilated often.
2)EPS contains flammable volatile foaming agent, which can still release slowly in the storage state; therefore, spaces for storing original foam particles or molded products should be totally free of smoke or fire, statics or sparkles to prevent dangers.
3、3) Try to use the materials following their sequences of entering the warehouse to keep them fresh, in order to obtain stable operating conditions and good products.

EPS Operating Process
A. Pre-foaming
When XJ grains and particles are heated to over 87℃ in a continuous or intermediate pre-foaming machine by steam, the particle volume will gradually be expanded to the desired magnification power or weight.
Stable magnification power is the guarantee to get the fixed molding conditions and the quality of molding. Because the pre-foaming conditions are different, it is necessary to rely on the skills and experience of the operators, who appropriately adjust the pre-foaming temperature, vapor pressure, material feed rate and the output height within the allowable foaming speed, in order to obtain satisfactory results. To obtain higher magnification power, it is allowed to conduct secondary foaming, and the appropriate temperature for pre-foaming is below 90℃.

B. Maturation
The foaming particles just produced are soft with poor flexibility due to the evaporation of the foaming agent and the vacuum state of the condensed interior of the residual foaming agent; therefore, it is important to have sufficient time to allow air to enter the pores of the foam particles, so that the inner and outer pressures are balanced to achieve the flexibility. It normally takes about four hours. In the case of multiple foaming, the time interval should be 3-5 hours.
It is better to use mesh antistatic gauze to make a maturation chamber to achieve maturation, to facilitate the dissemination of moisture attached to the foam particles and the elimination of the naturally accumulated power caused by the frictions of the foam particles. At the same time, good ventilation can increase the degree of maturation.
In order to prevent the newly expanded particles, especially those that were lightly expanded, from being deflated during air-assisted spraying, or being shrunk due to cold air, which can increase the maturation time, it is best to allow foam particles to fall freely into the chamber; if conditions permit, wait till the particles get mature before use air spray or suction to send them to the chamber, in order to get plump particles and reduce the time for maturation.

C. Molding
After the maturation, the foam particles are heated by steam to fuse into the molded product with a fixed shape after the mold is filled to a certain extent. The products are featured by tough, light and tight fusion, and closed foam pores with non-absorbent properties.
Improper molding conditions or operations will result in the contraction, uneven surface, difficulty in stripping, bad fusion, brittleness, high scrap rate and other negative phenomena of the finished products.
Steam, cooling water, and the compressed air supply conditions are the basis to ensure good product release, good conjunction, nice surface nice and shortened molding cycles; therefore, it must be stable.
Main steam pressure: 0.4-0 .7 Mpa
Cooling water pressure: 0.3-0 .5 Mpa
Compressed air: 0.45-0 .7 Mpa
Degree of vacuum: -600 ~ 650mmHg
The operator’s experience is the key to produce good products, which can develop appropriate operating parameters for a certain product and make appropriate parameter adjustments according to the conditions of the product, in order to achieve the perfect product.

D. Product curing
The surface of stripped products is attached with moisture, and the vapor condensed on the particles needs evaporation; at the same time, the particles are in the vacuum state and greater contraction is generated due to cold reduction pressure. Products with higher magnification power may produce contraction in the thin-walled section, which requires curing. The hardness and strength of finished products will increase after being placed in warehouses or exposed under the sun light. It is even better if they are cured in a dry room with the temperature of 50 ~ 60℃.