Difference Between Blow Molding Machine & Roto Molding Machine

Difference Between Blow Molding Machine & Roto Molding Machine

Since the birth of plastic processing technology, rotational molding machines, injection molding machines and blow molding machines have been born one after another, and have their own production processes and application areas. Of course there are areas of overlap, but each plastic processing process has its own characteristics.

This issue focuses on the advantages and disadvantages of rotational molding machines and blow molding machines and their plastic products.

First of all, it is clear that the rotational molding process also has its own advantages, mainly including the following 8 points:

1. Low cost of roto molding molds—for products of the same size, the cost of roto molding molds is about 1/3 to 1/4 of the cost of blow molding and injection molds, which is suitable for molding large plastic products;

2. Good edge strength of roto molding products - roto molding can achieve a thickness of more than 5 mm at the edge of the product, which completely solves the problem of thin edges of hollow products;

3. Roto molding can place various inserts;

4. The shape of the roto molded product can be very complex, and the thickness can exceed 5 mm;

5. Roto molding can produce fully enclosed products;

6. Roto molding products can be filled with foam materials to achieve thermal insulation;

7. There is no need to adjust the mold, and the wall thickness of the roto molded product can be adjusted freely (above 2mm); the maximum can be 3cm.

8. The product is hollow and seamless, but the wall thickness can be adjusted to make the product with high strength.

Of course, each process has its advantages and disadvantages.

 The disadvantages of roto molding are many:

1. The processing cycle is long, which is not suitable for mass production;

2. The energy utilization rate is low, the liquefied oil is heated, and a large amount of heat loss causes energy waste;

3. The choice of molding materials is limited. At present, there are only a small number of materials used for rotational molding. 99% of the rotational molding products in my country are made of PE, and 95% of them are rotational molding grade LLDPE suitable for rotational molding. Although nylon, polycarbonate, ABS and other plastics are also formed by rotational molding, the application area is very narrow;

4. The material cost is high, and special additives need to be selected and made into fine powder. Due to the particularity of roto molding, in order to facilitate heat transfer, the material must be powder, and the particle size of the powder has a great influence on the quality of the product. There are very few domestic producers of roto molding. At present, the raw materials are mainly imported. Therefore, relatively high cost;

5. It is difficult to mold some shaped products (such as rib-shaped products)

6. Compared with injection molding and blow molding, each time unloading products and loading raw materials is troublesome, and the labor intensity of workers is relatively high.

In contrast, blow molding machines solve some of the shortcomings of roto molding machines and roto molding products from many aspects, and gradually replace roto molding machines in a considerable field.

 The following takes IBC tons of barrels as an example to analyze them one by one.

1. Material

Material for rotational tank is LLDPE, blow molded tanks are using HDPE material, HDPE is 

more stronger than LLDPE.Of course,as the different production,can used the different extruder screw,for example,IBC tank use the HWMHDPE.

2. High Output

For example,the cycle time for IBC roto tanks is four piece one hour, but for blow molding 

machine can produce 20-25 pieces per hour  for IBC tank.

3. Weight

Roto tanks weight for IBC is 22 kg , for blow molding IBC tank it it only 14~16 kg.

4.  Environment protection is very clean for blow molding machine, all are using electricity.

But the roto used the liquefied gas,can not protect the environment.

5. Labour saving, maximum 2~ 3 operators for one blow molding machine running is enough,

 all is automatic and intelligent.even for the scrape also can used the machine.

6. About the craft ,multi-layered die head design for the blow molding,can produce the multi layers IBC tank directly .but for the roto ,need one by one layer to make.the product time is too long .so the blow molding machine is more integrated,operation is more easy than roto.

7. consumption

For example:IBC double layers blow molding machine

the consumption is 234KW,the IBC tank output is 20-25PCS/H,the tank weight is 15KG,the price of raw material is $170/tons,the cost of blowing tank is lower than Roto tank.

As followed the comparison table: