Blow molding and rotomolding are two commonly used hollow plastic forming processes. Yankang Plastic Machinery has been focusing on blow molding for 20 years. Compared with rotomolding, where is it better to blow molding?

 

What is Blow Molding?

Blow molding is out from the extruder, is still in a state of softening tube thermal plastic blank into the forming die, and then into the compressed air, use air pressure to make along with the cavity deformation, blow to make a mouth, short neck insulating products.

What is Rotomolding?

Rotomolding is a multi-purpose process for manufacturing various hollow plastic parts. A single hollow part is produced by heating and rotating along two axes. The molten plastic is injected into the rotating mould. Centrifugal force forces the molten plastic to stick to the inner wall of the mould.

Today, Yankang will make a comparison between blow molding and rotomolding.

1.Wall Thickness Control
Blow Molding：

The Blow moulding wall-thickness is controlled by a highly sophisticated electronic parison programmer 100 points.
The wall thickness in the corners you can do that better in blow molding than in rotomoulding. You can simply choose to have greater wall-thickness where you want by the parison programmer.

Large blow moulding machine and special blow molding device, ensure the wall thickness of blow molding product is uniform and the performance of the product is more stable and reliable.

Yankang blow molding machine adopt MOOG Wall thickness controller, the wall thickness of blow molding product is more stable and uniform

Rotomolding：

The wall-thickness in rotomolding can never be controlled or distributed in the same way that the blow molding process can! That means that in rotomolding the wall-thickness is the least in the most critical area, where the hoop-stress is acting, viz. along the middle of the tank!

 

2.Material Melting

Blow Molding：

The process uses a completely molten, uniformly homogenized, melt under extreme pressure and forces it through the die-head.

Rotomolding：

Rotomolding the raw material has to be first pulverized using additional energy and the powder is coated on the inside of the rotating mould at zero pressure.

 

3.Parting Line

Blow Molding：

The parting line in the blow mold plays absolutely no role at all because the extremely high clamping tonnage of the machine’s hydraulics keeps the smooth mould halves together.

 

4.Multi-Layers

Blow Molding：

The blow-molded tank uses an intensely UV-stabilized outer layer, a black middle layer that takes 100% of the recycled flash and trimmings and a virgin polymer inner layer in contact with potable water. The layers in blow molding are formed simultaneously and therefore the bonding between the layers is perfect.

Yankang Blow Moulding Machine adopts multi-layers die head technology. Achieve the production of multi-layer products. Improve the recovery utilization rate of material and reduce the material cost.

Rotomolding：

In rotomolding the material layers are separately added in each moulding process-weak bonding plus very tedious and wastage of energy, labor, material, and space!

5.Energy Saving

Blow Molding：

Blow moulding manufacturing is fully automatic and uses electricity which is safe for labor, keeps the temperature low and environment clean.1 operator, 2 workers for scrap cutting and move the tank. In blow molding, it is auto material feeding & auto water circulation cooling.

Rotomolding：I

n rotomoulding is having many manually work than blow molding. For example, in the process of rotomolding, special workers are needed to open and close the moulds. Opening and closing die belongs to heavy manual labor. It takes a lot of labor and labor costs.

It is using a fuel that keeps the temperature very high and dangerous for workers and adding materials. You heat the moulds using precious fuels and while the moulds are still very hot you are cooling it by pouring cold water on it! This is the biggest waste of energy.

 

6.Productivity

Blow Molding：

Blow molding is at least 5-8 times higher output than Rotomoulding. For example, it can produce 8-9 pieces one hour for a 2000L tank.

Blow molding usually adopts HDPE as material. Once molding.

The blow molding process is fast and sufficient. The product is molding fully.

The inner quality and performance are stable.

Rotomolding：

Rotomolding processing is slow, the output is only 1-2 pieces per hour for 2000L tank.

And the material of rotomolding must be ground and crushed. The processing cycle is longer. Improve cost. Thus, it’s not suitable for mass production. In addition, less plastic material are available.

 

The blow moulding products have the advantages of a long lifetime, wearable, strong and durable, good impact resistance, good low-temperature resistance, etc.

Here is a complete Blow Moulding Products Video

After comparison, do you know better? Tomorrow, Yankang will continue to share with you the things of the blow molding machine, please look forward to it!