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Injection moulding machines

A world without plastics is hard to imagine: from pens, screw caps for bottles and dustbins right up to the bumper on your own car. Plastic components come in countless colors and shapes everywhere in daily life and these plastic parts are usually produced by injection molding. Injection moulding is one of the so-called forming process and the basis of injection-moulded plastic part usually starts as a plastic granule. The initially solid granules are heated and injected under pressure into a mould. This process is however much more complicated than it first sounds. Because, the finished product needs to be precise to the relevant specifications regarding colour, measurements and surface and at the same time be durable and high quality as possible. The first machine that operated on this principle was made ​​in 1919 for the processing of soft cellulose acetate.

Assembly of plastic injection moulding machine  
Machine bed, injection unit, clamping unit - How is the plastic injection molding machine built?

Injection moulding machines generally consist of three units: the machine bed, the injection unit and clamping unit. The energy chain systems and highly flexible igus® cables can safeguard high holding times in all the units in the plastic injection moulding machine. Particularly in applications with heat generation and high dynamics, energy chains protect cables and hoses.
 

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energy chain, various cables like data cables and media cables in injection unit

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energy chain, different cables in "picker" unit

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Linear guides in sliding door of the clamping unit

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energy chain, various cables like data cables and media cables in the clamping unit

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Machine bed

The machine bed is the base or the foundation of the machine. The switch cabinets are located here and a drive can also be integrated here depending on the machine. The other units that often can also move are located on the machine bed.

The initial part of the original forming process takes place in the injection unit. The plastic is heated and liquefied. This takes place in the so-called screw.

The clamping unit is the tool that determines the shape of the plastic product. It is called clamping unit, because the supply of the material from the injection unit can be closed and opened in the meantime. In the clamping unit are two mounting plates (one fixed and one moving) as well as a front plate. These plates are fixed vertically on one axis.

How does a plastic injection moulding machine work?

First of all, the injection moulding machine is set up, i.e. it is first filled with material (plastic granules), then equipped with the relevant tool. The tool determines which plastic product is produced and is replaceable. Therefore a plastic injection moulding machine can produce virtually any number of different parts.

When the machine runs, the screw rotates and thereby moves the plastic granules to the front of the machine, where a heater heats the material to liquid form (but this cannot be compared to the liquidity of water; the mass becomes more viscous). The movement in the screw builds up pressure. As soon as the pressure necessary for the production is reached, the material is injected into the tool in the clamping unit.

The tool is usually made of steel and is split in two. One part is installed on a fixed mounting plate, the other one on the moving mounting plate. Once both parts are joined, a hollow space is created inside, the so-called cavity. The material now enters this hollow space from the injection unit through a nozzle in the mounting plate. The pressure of the screw should completely fill the cavity. The injection speed is important here, it influences how the material is distributed in the tool; finally, no hollow spaces should be formed. Once the sealing point is reached, the clamping unit shuts off the flow of the material from the tool and the material starts to cool down in the tool. Afterwards, the tool is opened and the completed plastic parts can be removed. There will also be a projected left over part called because of the liquid material going into the tool through an opening. This projecting part is then removed by a gate picker.

Depending on the size of production and degree of automation, the injection moulding machines can have widely varying dimensions. There are injection moulding machines that have to be manually filled with granules as well as machines that suck the material from large tanks through pipe systems.
There are also machines where personnel remove the completed plastic parts from the tool and others, which automatically take them with grippers and transport them further through conveyor systems.

The advantage of igus® for the injection moulding machine

chainflex® control cables, servo cables and motor cables as well as hydraulic hoses are suitable for the energy supply system of the machine. In the clamping unit, for instance, a relatively frequent movement with a low cycle time occurs. The particular structure of the chainflex® cables with their strain-relief core, braiding in bundles and with high pressure extruded exterior jacket materials like PVC or TPE, are ideal for highly dynamic requirements.
The movements of the cables in the machine can be safely guided with igus® e-chain systems®. The strokes are mostly short, horizontal movements. To support these strokes, e-chains® can be used here. Depending on the nature of the machine, a different arrangement of the e-chain® is possible, for instance side-mounted or unsupported. The e-chains® have a long service life, so that high holding times can be expected.
The flexible structure and the easy installation makes it possible to adapt the filling of the e-chain® anytime, if something needs to be changed on the machine.

Diverse handling processes also exist for the plastic injection moulding machine: The igus® e-chain systems® can also be used for material supply and the removal of the completed moulded parts as well as the gate and tools.

The igus® plain bearing products can also be installed with drylin® linear guides. The safety doors of the clamping unit can for instance be guided with the lightweight, lubrication-free rail-carriage combination.

By the way, most igus® products are produced with injection moulding machines.

Products for use in injection molding machines

 

Energy supply chains

Protection of cables and hoses

Large unsupported lenghts or additional loads possible

High tensile strength

easy assembly through fast opening and separating of links

low wear through special optimized igus® polymers

stable, cable friendly rounded cross bars

Interior separation kit for higher service life

Wide variety of products possible for almost any application and special materials for particular application areas

Available from stock with many accessories

 

Cables

Over 950 cable types from stock

No minimum order

No cutting costs.

Special construction for the movement in e-chains®

various jacket materials

 

Linear slide bearings

Small cross section

Lubricant free

Replaceable plastic gliders

Lightweight

Typical igus® products in injection moulding machines

Already implemented customer applications

Injection-molding machine

Pivot arm in injection-molding machines mounted with plastic plain bearings: With the simple plug-in installation and the adjustable collar, it was possible to abandon the highly complex bonding mechanism.

Injection-molding machine    

Injection moulding tool

Thee-chain® was installed on an injection moulding tool so thatno additional space is necessary in horizontal direction forthe unreeling movement.

Injection moulding tool    

Injection molding machine

drylin® copes with long distances and offers a high cost reduction.

Injection molding machine    

Pillar cleaning facility

The bearings have been installed about a year ago and since then operate free of troubles in the manufacturing.

Pillar cleaning facility    
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