Publish Time: 2022-04-14 Origin: Site
In the process of Rotational Moulding, many factors need to be considered, including the fluidity, specific volume, and compressibility of the plastic. Next, let us take a look at these factors considered when Rotational Moulding.
This is the content list:
l Fluidity
l Specific volume and compression ratio
The ability of Rotational Moulding's plastic to fill the cavity under a certain temperature and pressure is called fluidity. This is an important process parameter that must be considered in the design of Rotational Moulding. Rotational Moulding fluidity is easy to cause excessive overflow, incomplete filling cavity, loose structure of plastic parts, accumulation of resin and filler separately, easy mold sticking, difficult molding and cleaning, and premature hardening. However, if the fluidity is small, the filling is insufficient, forming is not easy, and the forming pressure is high. Therefore, the fluidity of the Rotational Moulding plastic must be adapted to the requirements of the plastic part, the forming process, and the forming conditions. Rotational Moulding mold design should consider the pouring system, parting surface, and feed direction, etc. according to the flow performance. Rotational Moulding thermosetting plastic fluidity is usually expressed by Raschig fluidity. Larger values mean good fluidity. Generally, plastic parts with a large area, many inserts, thin cores and inserts, and complex shapes with narrow deep grooves and thin walls are not good for filling. Plastics with better fluidity should be used. Rotational Moulding should use plastics with a Raschig fluidity of more than 150mm during extrusion molding and use plastics with a Raschig fluidity of more than 200mm during injection molding. To ensure that each batch of Rotational Moulding plastics has the same fluidity, the batch method is often used in practice to adjust, that is, to mix the same variety of plastics with different fluidity so that the fluidity of each batch of plastics can compensate each other to ensure that the plastics Piece quality. But it must be pointed out that in addition to the plastic's fluidity, Rotational Moulding is often affected by various factors when filling the cavity, which changes the ability of the plastic to fill the cavity. Such as fine and uniform particle size, high humidity, high water content, and volatile matter, proper preheating and forming conditions, the good surface finish of Rotational Moulding, and proper mold structure are all conducive to improving fluidity. Conversely, poor preheating or molding conditions, poor mold structure, high flow resistance, or long plastic storage period, overdue, high storage temperature, etc. will cause the actual flow performance of the plastic to decrease when filling the cavity and cause poor filling.
Rotational Moulding specific volume is the volume occupied by each gram of plastic. The Rotational Moulding compression ratio is the ratio of the volume or specific volume of the plastic powder and the plastic part. They can all be used to determine the size of the die loading chamber. The large value of Rotational Moulding requires a large volume of the charging chamber, and at the same time, it shows that the plastic powder is filled with a lot of air, it is difficult to exhaust, the forming cycle is long, and the productivity of Rotational Moulding is low. Rotational Moulding has a smaller specific volume and vice versa, and it is good for ingot pressing and pressing. However, the specific volume of Rotational Moulding often has errors due to the particle size and unevenness of the plastic.
Shanghai Jingyao Industrial Co., Ltd. is committed to producing more high-quality products. Through Rotational Moulding, we design accessories that satisfy military equipment, enterprises, hotels, medical care, transportation, stadiums, outdoor venues, and special requirements. If you are interested in Rotational Moulding is interested, you can contact us. Our website is www.shanghai-rotomolding.com/.