The Ultimate DIY Guide to Cabinet Dryer 2022

Firstly, cabinet drying is an important stage in the preparation of raw materials for processing. Thermoplastic polymers are hygroscopic. Secondly, they tend to absorb moisture from the surrounding air, which ultimately affects the quality of molded plastic products.

All cabinet dryer models are equipped with

• fans supplying heated air
•   timers for automatic start
• temperature controllers and thermostats that protect the device from overheating
• air filters and magnetic separators for cleaning the outgoing air;

Moreover, management exercises by means of the microprocessor with the digital display. Eventually, the parameters are set individually for each polymer: air flow rate, temperature and drying time.

At the request of the customer, the unit comes with dust and metal trapping devices.

Further, HHD cabinet dryers characterize by low maintenance costs and high efficiency.

What is it and how it works?

Cabinet dryer for polymers designs for drying crushed or granulated raw materials.

As well as, it consists of a cylindrical container with a cone-shaped base. Further, the hoppers come with a lid and sight glass. The cylindrical shape of the hopper ensures the uniformity of the air flow and the free movement of the granules inside the unit, Ensures quality drying of the material.

Subsequently, the dryer installs directly on the mouth of the extruder or injection molding machine, thereby saving space. It is easy to place on a movable frame, next to the processing machine.

The plastic granulate loads into the machine from above. From below, air heated in heater supplies, which removes moisture from the surface of the granules.

Main components of Cabinet dryer are made of high quality stainless steel

In addition, the air stream that passes through the cabinet dryer cleans of dust, removed to the outside or enters the refrigerator, where the moisture condenses. The cooled air enters the heater again for heating and returning to the recycle.

Dry granules are moved to an injection molding machine or extruder for further processing. Simultaneously with the unloading of the dried granulate, subsequently, a new portion of the raw material loads into the upper part of the device manually or using a vacuum loader.

As well as, the hopper and all the main components are made of high quality stainless steel, which prevents contamination of the original product, ensuring a long service life of the machine.

The moisture content of the polymer raw material can lead to the following consequences

• decrease in physical and mechanical parameters clouding or discoloration of the plastic;
• decrease in strength
• the formation of voids and pores
• Foaming during casting.

In fact, the air temperature during drying should not exceed 70-80°C, in order to avoid damage to the structure of the polymers.

Main technical characteristics

Furthermore, the cabinet dryer for polymers characterize by high efficiency, minimal power consumption, fast drying, and easy operation.

Main characteristics:

• the diameter of the granules of the loading raw material is from two to five millimeters
• power of heating elements – from 2.1 to 27 kW
• fan power 100-750 W
• weight of drying units from 30 to 300 kilograms
• Device capacity – from 12 to 600 kilograms.

Maintenance costs for cabinet dryers are minimal.

As well as, when using dried polymer granules, the rate of injection of molten raw materials into molds increases.

Varieties and models

Bunker-dryers for polymer raw materials can be continuous or cyclic.

Models differ in drying technology:

Drying with hot air, through desiccants built into the unit

Furthermore, air takes moisture from the polymer raw materials, passes through regenerating filters, where it gets rid of moisture, and leaves for the next cycle. Cabinet dryers operate on the principle of convection. In addition, it’s effective for removing surface moisture, economical and easy to operate. Not suitable for polymers with internal moisture.

Cabinet drying with compressed air that absorbs moisture from the material as it expands inside the hopper. Eventually, compressed air pre-dried and heated to the required temperature is supplied to the bunker. Outgoing air together with moisture removes outside. 

Compressed air tends to absorb moisture from raw materials more efficiently than uncompressed air. Compressed air treatment is suitable for material preparation with high quality requirements.

Drying with heated air

Thirdly, this method is the least effective, since air from the room uses, which may have high humidity. Eventually, heated and saturated with moisture air, passing through polymer granules, is thrown into the room.

 This increases the humidity and temperature of the environment. Large heat losses lead to inefficient energy consumption. The cabinet dryer technology is suitable for polymers with low drying quality requirements.

• According to the method of heat supply
• convection, when drying occurs with a stream of preheated air
• contact – the material dries from contact with a heated surface
• Infrared dryers are suitable for non-flowing polymeric materials (flakes extruded or shredded plastic).

The most popular models on the market

1. Resin Cabinet dryers

Secondly, it is one of the most efficient and economical models for plastic raw materials. Cabinet drying with hot air allows processing from 12 to 1000 kilograms of polymer granules.

• Hopper-dryer for polymers

The volume of processed material is from 12 to 300 kilograms. Drying takes place with hot air.

Models with the “M” index are additionally equipped with a magnetic base, those with the “T” index equip with a 24-hour timer, and those with the “I” index have a thermally insulated case.

• Cabinet dryer with PDD desiccant

Moreover, it makes in the form of a mono block of a drying device and a desiccant with a built-in heater. The closed cycle of drying allows achieving high quality of raw materials.

  Selection Tips

When choosing drying units, it is worth considering

• bunker capacity
•  drying time and temperature
•  Type of polymer raw material.

If the Cabinet dryer is not equipped with such a function, a dust collector should order additionally.

Hopper dryer – technological advantages

Their development combines innovative design approaches and traditional design solutions. At, the production stage, highly automated equipment and modern conveyor lines use. An important factor in improving the technical characteristics of bunker dryers is the use of high-tech materials. 

A multi-stage quality control of the manufactured equipment allows guaranteeing a high level of these products. Each cabinet dryer has a number of advantages:

• high technical characteristics;
• reliable, durable and ergonomic design;
• increased productivity;
• ease and convenience in operation;
• the presence of protective automation;
• economy;
• ease of installation, connection and maintenance;
• low noise;
• Balanced ratio of cost and quality.

Lastly, when buying a cabinet dryer, you should pay attention to the presence of a cyclone dust collector, which prevents granules or dust from blowing out through the ventilation pipe of the machine.