Polyethylene Rotation Production Process

Polyethylene Rotation Production Process

-Raw Material: Polyethylene raw material is produced from LLDPE low density linear polyethylene with stabilizer.

-Molding: It is designed and manufactured according to the desired product from DKP sheet or aluminum.

The mold filled with raw material is placed inside the furnaces that work with electricity and natural gas.It starts rotating with a walking rail car, working at about 145 rpm.When the powdered substance becomes liquid and reaches 250 degrees heat, the mold is rotated in the oven for another 1 hour.When the time is up, the mold is taken out of the oven and left to cool.

-Demoulding:The cooled product is removed from the mold by means of a crane with suitable lifting capacity or manually.

Operator Control:The cooled product removed from the furnace is controlled by the furnace operator.If the length, diameter and thickness of the water tank is suitable, it is sent to the storage area.If it is not suitable, it is started to be used for making cover after it is sent to recycling and turned into powder.Recycling: Products that are not suitable for shipment are first crushed with jigsaws, then cut into smaller pieces with a 4-blade crusher.

Storage: The polyethylene product removed from the mold is checked by the furnace operator and sent to the storage area in desired dimensions and specifications.

Shipping: Orders placed in the storage area are shipped.

Molding Room:Material Supply:Materials such as DKP sheet / aluminum, profile, angle iron, lama are provided. Cutting: According to the required size, after the material is dimensioned by the operator,cutting is done with the help of oxygen, handsaw.Convolution:The cut material is folded on the roller manually by the operator.Mold Bottom and Top Cover:Mold bottom and top plate covers are manufactured.Moulding: The top and bottom covers produced with the curled material are combined by the operator with the help of a gas welding machine on a flat ground and the mold is created.Check: The size of the finished mold is checked. (diameter of the mold, body length, total length)Cleanness: Cleaning of the mold, which is controlled in size, is done with tools such as grinding and sanding.Production:The finished mold is put into production with the raw material prepared in the rotation section.


Characteristics of Rotation Technology

The most prominent feature of the rotation technology is the length of the production time.

For an ordinary product; It should be considered that there is 20 minutes cooking, 15 minutes cooling, 5 minutes mold preparation and 5 minutes mold removal time.This means that 1 product is taken from 1 mold in 45 minutes.This period may be even more than 2 hours depending on the difficulty / size of the product.In this respect, we are talking about a very slow process compared to injection and blow molding technologies. This low speed normally increases overhead costs on the product and the resulting product is more expensive than other technologies.Despite its’ disadvantages like low speed and high price,Rotation Technology has many advantages.

Mold cost per unit is low in products with low consumption.

Although the product price is expensive, the mold price is quite low compared to other technologies.If the product to be produced is a product with low annual consumption, rotation technology is preferred due to mold depreciation.For example, Tractor fuel tank is a product that will not be sold tens of thousands of years due to its nature.It is not logical to make a blow mold for a fuel tank, which is planned to produce 1000-2000 units per year.Besides, a new model will be made before the mold pays off.The tractor companies in Turkey have begun to prefer rotation technology to fuel tanks.

They are suitable for products that cannot be made in other technologies.

Sometimes there is no alternative to rotation technology due to the size of the product.Water tanks larger than 1 ton are the best example for this.For example, a 40-ton water tank; printed on a weight between 850 - 950 kg. No other technology is suitable for producing such a heavy product. Sometimes product geometry is monolithic and complex.In this case, rotation technology is the only solution to be applied with its flexible structure.

Rotation products are robust compared to other plastic products.

Since rotation is not shaped by pressure during production, tensions do not occur during production.This ensures that the products from the rotation are incomparably more robust than injection, blowing and polyester products, even if the same thickness and raw material are used.

Product wall thickness can be changed regardless of the mold.

In rotation technology, the product wall thickness is proportional to the raw material placed in the mold.In this way, there is no need to decide what the thickness of the product should be (except in some special cases) during the design.In addition, products of different quality can be produced from the same mold, sometimes by placing more or less raw materials in the same mold. For example, water tank manufacturer in Turkey the same molds by simply changing the product weight, produce a robust economic model.

In the rotation, double-walled products can be printed, foam can be filled in the gap during or after production.

Rotation technology is a technology suitable for printing double-walled products, called double walled. In this way, double layer water tanks not only increase the strength of the product, but also allow the inner and outer parts of the product to be molded, and the space between them can be used functionally.If desired, various raw materials that foam during the production can be placed in the gap, or polyurethane foam can be filled after production. In this way, various products (such as food carrying containers / thermobox) that can provide heat insulation can be easily produced.

Rotation; It allows adding various parts to the product during production.

Normally, parts such as flanges, nuts, screws that can be attached to the product can be attached to the product during manufacture.These attachments are very robust if designed properly.In this way, assembly workmanship after production is reduced. Some examples are flanges on diesel tanks, connecting nuts of seats used in public transport.


Since the coloring agent is added to the raw material, the resulting product does not need to be painted.

Raw material is used as powder in rotation technology.The raw material is painted with powder colorants.In this method, powder paint is thrown into the raw material in powder form and the raw material is painted by mixing.In the second method, the raw material is passed through the extruder while it is still in the granular form and at this stage it is painted with masterbach.The raw material that comes out colored from the extruder is granulated again and colored powder plastic is obtained by passing it through the powder mill.

In this method, the color; The result is of good quality as it penetrates the raw material.However, it takes longer to obtain colored powder with this method than to paint the raw material with powder paint and it is not possible to paint a small amount of raw material.


It can be produced with different colors of raw materials on the same product.

During production, different colors can be produced inside and outside.For example, by producing the inner surface of the water tanks in white, the middle part in black, the outer part in blue; Since the inner surface is suitable for food, the middle surface is resistant to impacts, and the outer surface does not pass sunlight, it prevents algae.It is also possible to produce different colors on the same surface in rotation.

An aesthetic appearance with different color transitions can be achieved in most products.

Rotation Machine Park

What kind of equipment do we need to produce with rotation?

1) Rotation Machine:Basically, a machine rotating in 2 axes is considered sufficient for production.However, for some special products other than the water tank, the machine must have some features.

2) Powder Grinder: Raw material is used as powder in rotation technology.Whereas it is possible to purchase the raw material directly in powder form, it is more convenient to take raw materials as granules and make powder with a mill.Because granular raw material is more suitable than powder raw material.In addition, if colored production is desired and  as to painting process; If dusting is not desired, finding powder in different colors is also a problem. Therefore, the powder mill is a must for a spinning mill.

3) Extruder:If colored production is desired, an extruder is essential to paint the raw material.Although dyeing can be done with powder coating, it will be the right method to dye with extruder to obtain quality results. It is necessary to have these basic components for rotation production.However, since large products are produced in rotation, a large space is required for the storage of molds and products.