Plastics Technology pressing at a high pressure (1968)

Plastic processing workshop.

During processing, the mass loses its plasticity, hardens and becomes durable.

Such plastics are called reactoplasts.

A sample of such a product.

A document explaining plastic recycling methods.

Enumeration of the most common methods of plastic processing.

The most used method is pressing in hot closed forms.

Samples of products obtained in this way.

Samples of press materials.

Phenoplast is used in the production in the form of powder or tablets.

A cartoon explaining the processes occurring in the material during such pressing.

The process of preparing the initial phenoplast tablets.

Samples of tablets.

Presses and molds.

The main parameters of pressing are temperature, pressure and the time or duration of the stay of the material in the mold, fixed by a time relay.

A cartoon explaining the pressing process.

Removal of the product from the mold.

A cartoon explaining the physico-chemical phenomena occurring during the pressing process.

Chemical formula of the material.

A cartoon explaining the process of pressing tablets.

Product quality control.

The most important technological property is fluidity.

Checks are carried out by different methods.

For example, a check by the Rashig method.

The Iconoclast method.

A cartoon explaining the operation of the Icon's device.

A cartoon explaining the principle of choosing the pressing temperature of the material to obtain the best quality of the finished product.

The holding time of the product in the mold should be sufficient to achieve a shear stress of 25 kg / cm2.

If the shear stress is less, the product may be destroyed by the internal pressure of gases during decompression.

A sample of a defective product.

A longer exposure time is needed for products whose quality is subject to increased requirements.

If a preheated material is loaded into the Konavets device, the kinetics of curing will change.

A cartoon explaining the process.

When the press material overheats, it loses its viscous state, cures quickly, and the strength index drops sharply.

The product does not have time to take shape.

Preliminary high-frequency heating is usually carried out on a tableted material.

The heating mode is strictly controlled.

A cartoon explaining the processes taking place during heating.

Mathematical formula of dielectric losses.

The mathematical formula is the amount of heat generated.

The optimal curing temperature of preheated novolac press powders on existing presses is 180 degrees.

If the temperature is exceeded, curing may occur before the part is fully formed.

This will lead to deterioration of the properties of the finished product.

Samples of defective products.

The pressing temperature and curing speed should not be low, because this lengthens the curing process.

A cartoon explaining this process.

A cartoon explaining the process of orientation in the material in the direction of its flow.

The specific pressure value is selected depending on the pressed material and the mold configuration.

Materials with low viscosity or molds with a simple configuration do not require high pressure.

A material with high viscosity and a complex mold of a product with thin walls requires high pressure.

Samples of materials with high viscosity.

Pressing in single-socket and multi-socket forms.

A cartoon explaining pressing in multi-nest forms.

A cartoon explaining the disadvantages of pressing tablets in multi-socket forms.

Presslitje.

A cartoon explaining the presslitya process.

A sample of the product obtained by pressing.

Pressing in hot stitched forms.

A cartoon explaining the pressing process in hot stitched forms.

The method of pressing in cold closed forms with subsequent heat treatment in the production of abrasive products.

The main components of the pressed mass are abrasive and phenolic-formaldehyde resin.

The prepared mass is loaded into the mold.

Under the press, the mass is compacted and molded.

The formed product enters the bakelizer, where it is heated and cured.

Heating and curing of products is carried out slowly, in a stepwise mode for 12 hours.

Heating table.

This mode ensures complete curing of the resin, prevents cracks when removing the formed gases, reduces stress and the number of shrink shells.

The resulting products are mechanically high-strength.

Packages of sheet fillers impregnated with carbamide or resin resins are pressed on hot plates.

Samples of fillers.

Bags of impregnated filler are placed between metal polishing sheets lubricated with anti-adhesive substances.

After the packages are assembled, pressing is carried out between the hot plates of the floor hydraulic press.

The end sides of the package are not limited by the walls of the mold and with a low viscosity of the resin, its leakage is possible.

A cartoon explaining this method and its disadvantages.

Decompression of packages.

Very valuable plastic materials are produced by pressing on hot plates, for example, textolite, decorative laminated plastics, fiberglass, chipboard and other materials.