How to Reduce Flash in Injection Molding?

May 13, 2022

How to reduce flash in injection molding?
Plastic injection molding equipment is in demand in various industries. In addition, the casting method uses to produce toys and stationery, car parts, polymer pipes, various containers, and profiles for plastic windows..

Types of plastics and raw materials

The following materials are used for the production of plastics:

  • Polyvinyl Chloride;
  • Polyethylene of high and low pressure;
  • Polyethylene Terephthalate;
  • Polystyrene;

Plastic injection molding: readjusted with every change of raw material

One of the features of the material is the possibility of its processing and creation of a secondary product. In addition, the latest technologies used in the processing and disposal of industrial waste make it possible to turn recycled materials into new materials that are used in subsequent production.

The recycling of polyethylene makes it possible to obtain products with the same properties and technical characteristics as the material from primary granules.

How to reduce flash in injection molding? Production features

The raw material for the production of such a synthetic polymer is LDPE granules of the highest quality. In addition, on its basis, a film is made that complies with GOST. The product does not have an unpleasant odor, it is durable, elastic, and colorless. The only drawback compared to the secondary counterpart is the high cost due to the fact that the feedstock is more expensive.

Production technology

The production of plastic products is carried out in a certain sequence:

  1. PVC materials for the production of plastic products crush and load into the hopper of the injection molding machine.
  2. Solid polymers are heated to the required temperature. The screw feeds the melt into the plasticizing unit.
  3. In addition, under high pressure, the polymer mass is injected into the injection mold. Plastic uniform layers cover the walls of the form, exactly repeating its shape.
  4. During the cooling process, the pressure in the mold decreases, and the cooling parts are removed outside.

The speed and volume of injection, as well as temperature parameters, are set individually for each type of product.

There are different ways of molding plastics:

  • Extrusion – the creation of plastic products by extrusion;
  • Casting – molding products in injection molds;
  • Compression molding, when the molten mass compresses under the action of mechanical loads;
  • Blowing – a heated polymer blank acquires the exact shape of an injection mold by blowing;
  • Compression molding occurs when injection molds compress.

Equipment for the production of plastic products

In addition, for the manufacture of plastic products, various machines, and equipment for injection molding use:

  1. Extruders

Extrusion means extrusion or extrusion. The production of plastic products occurs by extruding the molten polymer mass through a matrix that forms a certain shape.

The extrusion method creates window profiles, polymer sheets and films, plastic roofing, and plastic pipes.

How to reduce flash in injection molding? The installation includes the following components and mechanisms:

  • Extruder;
  • Pneumo-loader;
  • Inflating heads with a cooling system;
  • Calibration mechanisms;
  • Pulling and turning devices;
  • Stacking and winding modules.

The operation of mechanisms is controlled automatically

In addition, they are injection molding machines for the production of mass-produced plastic parts in molds by injection under pressure.

They include various functional units:

  • Plasticization module, where the raw material heats to the required temperatures;
  • An injection mold for plastic injection, where polymers inject and products form;
  • A locking unit that provides closing and opening of molds;
  • A special pusher removes finished castings from the machine.

An automatic CNC unit with a foreign-language interface and an LCD display ensures the management and control of the production of all plastic products.

In addition, the operation of the mechanisms provides by an electric, hydromechanical or electromechanical drive.

Depending on the location of the polymer injection system, injection molding machines are divided into:

  1. Vertical – with vertical injection and horizontal split molds.
  2. Horizontal – with a horizontal injection system and vertically arranged connectors.
  3. Corner – for products of complex configurations with the location of the injection in different places.

The production of plastic products in injection molding machines involves heating polymers to a liquid state, feeding them under high pressure into molds, cooling, and removing finished parts.

Blow molding machines

With the help of blow molding machines, various thin-walled containers produce canisters, bottles, and barrels.

In addition, the production of bottles from blanks (preforms) pre-made in injection molding machines is carried out in the following order:

  1. The performs heat in a special oven.
  2. Hot blanks are placed in a mold, where the bottles pull and inflate through a special rod.
  3. When in contact with the metal of the injection molds, the polymer hardens and becomes rigid.
  4. The mold opens, and the finished bottles remove using a special manipulator.

How to reduce flash in injection molding? Extrusion blow molding machines


In addition, devices are used for the manufacture of volumetric hollow products by blow molding.

Used in various industries:

  • Food production – production of bottles, cans, and containers;
  • Pharmaceuticals – containers for medicines;
  • Mechanical Engineering – fuel tanks, pipes, bumpers;
  • Construction – pet packaging, containers for paints, and varnishes.

Extrusion blow molding machines consist of several main components:

  1. Extruder with a screw mechanism and heating generator.
  2. Head with a mouthpiece for forming tubular blanks or sleeves. It can be single, multi-strand, direct-flow, or angular.
  3. Metal molds for plastic injection molding.

How to reduce flash in injection molding? The receiving-inflatable device consists of several mechanisms:

  • Moving blanks to the mold;
  • Closing, opening, and locking forms;
  • Billet blowing;
  • Flash cutting;
  • Ejection of finished products.

In addition, the complete set of the machine includes the compressor and a cooler.

Thermoforming machines

Devices for thermal molding of products made of polyethylene film of various thicknesses: disposable thin-walled cups, plates, and containers.

Machines are single or multi-position rotary, revolving, or belt types.

For simple products, belt-type machines are suitable; for products of complex configuration, turret or rotary machines are suitable.

How to reduce flash in injection molding? Optional equipment

Auxiliary equipment for the production of plastic products can reduce manual labor and facilitate the production process.

This category includes:

  • Various conveyors and belt conveyors;
  • Mixers, loaders, dispensers;
  • Crushers and drying bins;
  • Robotic manipulators.

Mini plastic injection molding machines

Desktop machines for the manufacture of plastic products are widely in demand in small industries in the manufacture of limited quantities of goods. In addition, they easily place in small workshops, laboratories, or service stations.

Mini plastic injection molding machines can be made by hand. For this you will need:

  1. Steel rod with the piston.
  2. Cylinder from a metal pipe trim.
  3. The adapter is 0.5 inches.
  4. Thermostat and heater for 600 watts.
  5. Fitting and fasteners.

With little engineering skills and instructions on the internet, you can build a machine to make simple plastic shapes.


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