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 plastic blank into the forming die, and then into the compressed air, use air pressure to make along the cavity deformation, blow to make 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 molding 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.
Rotomolding：The wall-thickness in rotomolding can never be controlled or distributed in the same way that 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 he middle of the tank!
2.Material Melting
Blow Molding：The blow molding 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 keep the smooth mould halves together.
4.Multi-Layers
Blow Molding：The blow molded tank uses intensely UV-stabilized outer layer, a black middle layer which 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.
Rotomolding：In rotomolding the material layers are separately added in each moulding process-weak bonding plus very tedious and wastage of energy, labour, material and space!
5.Energy Saving
Blow Molding：Blow molding manufacturing is fully automatic and use electricity which is safe for labor, keep the temperature low and environment clean.1 operator, 2 worker for scrap cuttingand move the tank.In blow molding it is auto material feeding & auto water circulation cooling.
Rotomolding：In rotomoulding is having many manually work than blow molding.It is using fuel which keeps the temperature very high and dangerous for workers and addingmaterials. 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.
7.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 2000L tank.
Rotomolding：Rotomolding processing is slow,the output is only 1-2 pieces per hour for 2000L tank.
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!