Several Problems Occurring in the Production of EPS Foam Plastic Materials

EPS-expandable polystyrene foaming materials have been widely known as buffer packaging materials for household appliances such as televisions, refrigerators, washing machines, and meters. The author talks about the design of molds in production and the control of key processes.
First, the design of EPS molding mold EPS molding mold is an essential process equipment in production, design should consider the following points:
1. Product redesign. Because some customers are not familiar with the EPS production process, according to their packaging products only, the design often has problems such as too large or too small, deep groove is too deep, excessive fillet, uneven thickness, or the buffer pad is too thick or too thin In such cases, professional and technical personnel shall re-design the product in conjunction with the production process of the factory and obtain the customer's consent.
2. The draft angle and size extension in the mold design. Considering the convenience of demoulding in the forming and processing of EPS products, and taking into account drainage and other factors, in the design and manufacture of EPS molding molds, there is a certain draft angle both inside and outside, generally taking 1 to 1.5°. In addition, due to the shrinkage and deformation of EPS formed after demoulding, generally consider the size of the mold to be properly added, and the ratio of addition and discharge is 1 to 5 turns.
3. The mold design should also take into account that the wall thickness of the mold should be reduced as much as possible on the basis of the strength to accelerate the production cycle. In addition, stagnant water should also be prevented inside the mold.
4. Feeding port selection. According to the thickness, size, different material caliber of different moldings. The position of the feeding port should be selected properly, and the back feeding material port should be selected as far as possible to provide a thicker part or center position in the product. The side feeding material port should be located on the thin side of the product, and the position of the feeding material should be smooth. If the feeding is difficult and the product volume is large, the feeding port may be appropriately increased.
5. Certain roughness and precision processing requirements should be selected in the mold design.
Second, the key process control EPS molding products production process is roughly as follows:
Raw materials → pre-expansion → aging → forming → cutting → drying → finishing → factory In the production process, pre-foaming process is the key process. In the pre-foaming process should pay attention to:
1. According to the requirements of different products, select different pre-issued capacity, usually expressed as a multiplier. Magnification is the reciprocal of the weight value of the foaming particles per unit volume and is a dimensionless unit. Since the proportion of water is "1", it can also be expressed by the following formula:
Magnification = weight per unit volume of water / weight per unit volume of foamed plastic particles EPS foaming rate is too low, will increase the consumption of molded products, increase production costs; too high, it will cause pre-expanded foam shrinkage, affect the shape of the mouth quality. Therefore, each batch of materials requires advanced small batch pre-test. In the pre-test, according to the quality of raw materials, try to pre-test magnification. Raw materials that have never been used should start from a low magnification, and gradually increase in advancement and molding conditions until the desired effect.
Especially noteworthy here is that when signing a processing contract between a foam-molded product processing factory and a customer, the foamed foam product is generally priced based on the weight of the sample, while the raw material, that is, the plate is priced by volume, so the foam-molded product processing manufacturer wants to increase Benefits can be achieved by appropriately increasing the pre-production rate and reducing product consumption.
2. During the production process, ordinary materials and self-extinguishing materials should be separated to prevent the pre-expansion or feeding materials from blending in order to avoid leaving fire.
3. To prevent the steam pressure from rising to low, maintaining stability, the raw materials stay in the machine for a suitable time, the feeding and discharging speed are evenly distributed, and the granularity specification is suitable for selection.
The maturation process has sufficient maturation time, generally about 8 to 48 hours.
The basic process of the molding process is:
Clamping → Feeding → Heating → Cooling → Molding → Stripping. It should be noted that according to the specifications of different products, size, thickness control heating, water cooling time, the general process of molding, the water cooling time accounted for half of the total molding cycle time.