Polyether ether ketone (PEEK) plastic

PEEK, which an aromatic crystalline thermoplastic polymer material, the melting point of 334 ℃, the following is a charm features: short-term heat resistance by adding glass fiber or carbon acid after heat distortion temperature up to above 300 ℃; long-term heat resistance index for the UL 250 ℃; toughness, resistance However, up to UL-0 level, can be self-extinguishing, and smoke less; resistance to drugs of good performance, only soluble in concentrated sulfuric acid. Another good processing behavior, it also resistance to radiation, resistance to peeling, electrical properties, fatigue resistance, impact resistance wear resistance, hydrolysis resistance and other properties are very good, is a rare engineering plastics. 

Because of its good overall performance, they are widely used: 

    Extrusion: the magnet wire coating using PEEK has good machinability and good resistance to peel, good abrasion resistance and good resistance to radiation and strong, free coloring, etc. have been used as a cable, wire insulation and protection layer . Widely used in atomic energy, aircraft, ships, oil, gas, magnet wire, fiber optics and other fields; films use its moisture absorption of small, acid-resistant solder, etc., for H-class and C class insulation material widely used in motors, generators , transformer insulating film, and orbit of printed circuit board, the carrier belt, heat resistant with other drugs ring; PEEK monofilament fiber using steam-resistant, anti-drugs, wear resistance, creep resistance, toughness, etc. Paper machine drying applied to canvas, heat Shanghai cloth, racket cable, composite materials, heat-resistant woven with other drugs. Injection molding: the wear-resistant materials, its wear resistance, resistance to drugs, toughness, and can be used at 250 ℃, etc. for the manufacture of bearing cage, the metal bearing the protection lining, clutch parts, power brake vacuum parts, gasoline engines parts, wheels loader blade, copier parts, suspension bearings, engine Putters; electrical and electronic use of its resistance to solder, natural resistance, UL temperature index of high toughness and good, for the manufacture of inserts plugs, high reliability plug-ins, cable plugs, junction boxes, wiring leads to the first, the battery case, IC packaging and so on. Hot water equipment for the manufacture of hot water, chemical pump impeller and pump body and the other parts, clean the valve, oil extraction, socket connector, PH meter boiler jacket and so on.

Plastic molding operating principle and maintenance works

Plastic molding is a cyclic process, with each cycle including: dosing – molten plastics – Injection pressure – Filling the cooling – Kai-mode pickup. Remove the plastic parts and then re-closed mode, the next cycle.
    1.2 The structure of the injection molding machine
Plastics injection molding machine according to two ways of piston and screw injection molding machine injection molding machine; according to machine transmission mode can be divided into hydraulic, mechanical and hydraulic – mechanical (link) type; divided automatically by operation , semi-automatic, manual injection molding machine.


    (1) horizontal injection molding machine: This is the most common type. Its part and injection mold parts at the same level center line, and the mold is opened along the horizontal direction. Its characteristics are: body short, easy operation and maintenance; machine center of gravity is low, install a more stable; products after the top of the automatic use of gravity down, easy to implement fully automatic operation. At present, injection molding machines on the market to use more of this type.


    (2) vertical injection molding machine: its part and injection mold parts in the same vertical center line, and the mold is opened along the vertical direction. Therefore, its small footprint, easy to place inserts, more convenient loading and unloading the mold, the material from the hopper into the plastics can be more evenly. But the product is not easy automatic ejection after the fall, must be removed by hand, not easy to achieve automatic operation. Vertical injection molding machine should be used for small injection molding machine, generally less than 60 grams in the injection molding machine with more large and medium-sized machines should not be used.


 (3) angle injection molding machine: the injection direction and the interface in the same mold surface, it is particularly suitable for machining center parts of the plane not allowed to leave the gate traces of products. It covers an area smaller than the horizontal injection molding machine, but it inserts into the mold easily tilted down. This type of injection molding machine should be used for small machines.


   (4) multi-mode rotary injection molding machine: it is a special multi-station plastic molding machine operation, which is characterized by the rotary clamping device structure, mold around the shaft rotation. This type of injection molding machine injection device into full play the plasticizing ability to shorten the production cycle and improve the productive capacity of the machine, which is particularly suitable for cooling and sizing a long time or place inserts for supporting the time and need more plastic in large quantities products production, but a large clamping systems, complex clamping device clamping force tend to be smaller, so that the plastic molding machines in the production of soles and other products used more often.

How to Improve Plastic Injection Products Bubbles Issue

Bubbles issues are also know as vacuum bubbles, in which gases are very thin. In general, if the bubbles happen at the moment when you open the moulds, the bubble is a matter of gas interference. Vacuum bubbles are formed, because the plastics fillings are insufficient or pressure is low. 

Solutions
(1) Increase injection volumes; adjust injection speeds, holding pressure and temperatures of injection materials; increase the moulds’ temperature to improve short shots of the products.
(2) Place the pouring gate at the thick part of the workpiece; improve flow conditions of nozzles, runners and pouring gates; reduce consumption of flow.
(3) Improve exhaust conditions of the moulds.
(4) Avoid great differences of the products’ wall thicknesses. 
(5) Improve structures of injection molded products to avoid great differences of the cavities’ parts which can be filled with molten plastics.
(6) Reasonably adjust the molding process to avoid impacts on the plastic moulded products due to gases generated by plastic degradation.

Size changes of plastic products are caused by different shrinkage of the plastics essentially. Any variable operation of material temperatures, molds, pressure and production cycles will lead to size changes of plastic products, especially for products made of materials such as PP, PE, nylon, etc. which have larger crystallinities.

The main reasons are as follows.
1. Machines
(1) Select machines with the large plasticizing capacity if the plasticizing capacity is insufficient.
(2) Check whether voltage fluctuates, components of injection systems wear or hydraulic valves have problems or not, when feeding instability happens.
(3) Check whether motors have problems, screws and charging barrels wear, hydraulic valves are stuck, or voltage is stable or not, when instability of screw speed happens.
(4) Temperature is out of control; proportional valves and general pressure valves are not working properly; back pressure is instable.

2. Moulds
(1) Moulds should have enough strength and rigidity; we should adopt wear resistant materials for the cavities.
(2) When dimensional accuracy is high, we should try not to use a multi-cavity mould.
(3) Ejection systems, pouring systems and cooling systems should be set reasonably so as to ensure stability of production conditions.

3. Plastics
(1) A mixture of the new material and the reworked material should be consistent.
(2) Dry conditions should be consistent; particles should be uniform.
(3) Take into full account the impact of shrinkage on dimensional accuracy.

4. Processing
(1) The higher the temperature is, the smaller the changes of products’ sizes will become.
(2) The mould temperature should be lower when it comes to crystalline plastics.
(3) The moulding cycle should be stable without too much fluctuation.
(4) Shot weight of injection mold products should be stable.