Common problems and countermeasures of cable extrusion

　　one.electronic wire

　　1.rough surface:

　　A．The temperature is too low:adjust the temperature appropriately

　　B．Insufficient PVC baking:bake the rubber according to the operating standard(time/temperature)

　　C．The head pressure is too low:replace the outer mold with a longer section and increase the number of omentum

　　2.Dead glue coke:

　　A．PVC stays in the machine head for a long time:discharge the material with a long stay time when extruding

　　B．The extrusion temperature is too high,and the temperature should be lowered in time when the extrusion is stopped at high temperature

　　3.Tingling:

　　A．The temperature is too high:adjust the temperature of the machine head/eye mold appropriately,and increase the outer eye aperture(the bright surface is numb)

　　B．The outer mold is too large:replace the outer mold with a slightly smaller aperture and increase the extrusion temperature(the surface is foggy and numb)

　　4.There are bubbles on the extrusion surface:

　　A．The extrusion temperature is too high:reduce the extrusion temperature

　　B．Insufficient PVC Baking:Increase Baking Time

　　5.Uneven surface:

　　A．The surface of the conductor is dirty:apply a small amount of oil and preheat properly

　　B．If the extrusion temperature is too high,it becomes bubbles:reduce the extrusion temperature,and reduce the distance between the water tank and the machine head

　　6.PVC shrinkage/melt loss:

　　A．The conductor is not preheated:the temperature of the preheater should be adjusted appropriately(the copper wire will not be oxidized,but it will be hot)

　　B．The pressure of the machine head is small/the temperature is too low:use the pressurized outer mold,and the temperature of the eye mold of the machine head will rise slightly

　　C．The water tank is not overheated,and the tension of the wire storage rack is too high:when the water is overheated during extrusion,the tension of the wire storage rack should be reduced as much as possible

　　7.Insulation high temperature fragility:

　　A．Insufficient PVC baking:change the specifications and bake PVC in time

　　B．Rapid cooling during extrusion:water tank overheated

　　8.Eccentricity:

　　A．The mold aperture is too large:replace the mold(the inner mold is too small/the outer mold is too large)

　　B．The mold is not installed correctly:reinstall the mold

　　C．Improper distance between inner and outer molds:adjust the distance between inner and outer molds based on the principle of first close and then far

　　9.other

　　A．Bad appearance caused by strand skipping:replace the inner and outer molds with ones with slightly larger apertures

　　B．Insufficient mixing of PVC causes slag accumulation in the outer eye:increase the extrusion temperature,reduce the hole diameter of the outer mold and the distance between the inner and outer eyes

　　C．Scratches:scratches caused by the outer mold,replace the copper wire blocked in the middle of the inner and outer molds of the outer eye:clean the inner and outer molds by folding the mold

　　Scratches on the wire storage frame of the guide wheel of the water tank:put the wires on the guide wheel,and the wire storage frame is in a suitable position,and replace it in time if there is any damage.

　　two.Outer quilt line

　　1.The appearance shows the texture of the finished product

　　Winding pattern:A too high pressure(the distance between the inner and outer molds is too far):the distance between the inner and outer molds during production is about 2M/M.The outer mold is too small:the outer mold should be 0.1-0.3M/M larger than the OD in production

　　Weaving pattern:A.The outer mold is too small:Too small eye molds cause poor appearance due to high pressure.During production,it is advisable to choose an outer mold with a slightly larger aperture(the specific aperture size is subject to replacement in actual production).B.The distance between the inner and outer molds is too far:In production,the distance between the inner and outer molds is too far,resulting in too much pressure,which leads to obvious weaving pattern/Try to be short in production.

　　The braided wire generally requires good peeling,so if there is no special requirement,it is generally extruded with a half-empty tube.For braided wires that need to be extruded with a full type,too much or too little pressure on the head will cause poor extrusion appearance.The die aperture is adjusted to solve the appearance problem.

　　2.Poor appearance of powdered wire and aluminum foil wire

　　The quality of talcum powder directly affects the appearance of the wire,so the talcum powder must be baked and dried before use.In this way,the talcum powder can be evenly distributed on the wire.During production,the semi-finished product must pass through the middle of the brush to avoid excessive powder Too much will lead to poor appearance,too small outer mold and too close inner and outer molds will lead to poor appearance of extrusion,special attention should be paid during production.The appearance adjustment of aluminum foil wire is the same as that of braided wire.

　　3.Poor outer coat peeling and core wire adhesion

　　(1)When the pressure of the extrusion head is too high during production,it will cause poor peeling.During extrusion,try to avoid excessive pressure by increasing the aperture of the outer mold.Secondly,the closer the water tank is to the head,the better.The water volume should be the largest.Do rapid cooling.

　　(2)Poor isolation leads to poor peeling,winding offset,loose weaving,etc.cause the outer cover to be attached to the core wire,resulting in poor peeling.During production,it is necessary to pay attention to the selection of the inner mold not to be too small(the semi-finished product can easily slide through the eye mold as a result)should)

　　(3)Too little powder will cause poor peeling.During production,wet talcum powder and too little powder will cause peeling difficulties.Dry the talcum powder in time before production.Add talcum powder in time during extrusion,and the distance from the mold when accelerating make adjustments(decrease)

　　(4)Core wire adhesion:The core wire adhesion is generally because the melting point of the rubber is too low and the outer cover is melted and glued together at high temperature.During production,the water tank in the first stage should be filled with the largest amount of water to achieve rapid cooling.Forming agent or powder.When pressing the outer quilt,it is also possible to use the release agent first and then powder.

　　(5)Some customers require high wire stripping strength.In actual operation,the extrusion conditions can be adjusted according to customer requirements.

　　4.abnormal surface appearance

　　(1)rough:

　　A.The outer mold is too large.During production,the outer mold is too large or the appearance is rough.At this time,it is necessary to replace the outer mold with a smaller aperture.

　　B.PVC is wet,dry the talcum powder in advance according to the operating standard before starting the machine

　　C.Poor mixing of PVC,increase the omentum,increase the temperature,and choose a pressurized outer mold to solve the problem

　　(2)Stripes:

　　A.Bright stripes,the temperature of the first/second stage is too high to cause bright stripes on the extrusion surface,lower the temperature of the first/second stage

　　B.Fog streaks,the temperature of the third/fourth section is too high to cause foggy streaks on the extrusion surface,lower the temperature of the third/fourth section

　　(3)Side bright and foggy:the temperature of the machine head/eye mold is too high and the heating of the machine head/eye mold is uneven,causing the extruded surface to be bright and foggy at the same time.When this phenomenon occurs,reduce the temperature of the machine head and eye mold in time,and replace the filter.(The number of pieces is reduced)The outer mold can be improved by using a slightly smaller outer mold without corridors.

　　(4)Numbness:

　　A.The temperature of the machine head/eye mold is too high,and the temperature should be lowered appropriately.

　　B.PVC is wet,dry PVC in time before starting up

　　5.Eccentric

　　(1)The inner mold is too large:when the outer mold is extruded,an inner mold with a slightly larger aperture is generally used to make the appearance better,but if the inner mold is too large,intermittent core eccentricity or core eccentricity may occur during high-speed extrusion,and the inner mold should be avoided as much as possible during the production process.too big

　　(2)The mold adjustment screws are not locked.After the center adjustment is OK,fasten the four mold adjustment screws in time and then start the machine normally.

　　(3)In other aspects,material leakage from the machine head and debris in the conduit will also cause eccentric production.Adjustments should be made according to the actual situation.For eccentricity,self-inspection should be carefully implemented to prevent batch defects.

　　three.other bad controls

　　1.Uneven size of D:Improper human control,pay attention to abnormal acceleration and deceleration,tension of pay-off frame and take-up tension,abnormal measurement tools,etc.

　　2.Bad printing shall be adjusted according to the bad printing situation and countermeasures

　　3.Scratches:If the eye mold is scratched,replace the eye mold in time

　　Due to the scratches of the wire passing guide wheel and the wire storage rack,timely adjustment can solve the problem

　　Slag accumulation on the outer eye will also cause scratches.The material should be replaced fundamentally.Secondly,the problem of scratches caused by slag accumulation on the outer eye can be solved by increasing the extrusion temperature and replacing the outer mold with a slightly smaller aperture(without corridor).

　　4.Plastic scorch

　　Plastic scorch is a common quality defect in the plastic extrusion process.Its attention is manifested as:the temperature display is super high;there is a lot of smoke and strong irritating smell at the die mouth of the machine head,and there is a popping sound when it is serious;there are burnt particles in the extruded plastic layer;There are continuous air bubbles at the glued seam;the main reasons for the injection are:

　　1),the temperature control is ultra-high to reach the thermal degradation temperature of plastic;

　　2)The screw has not been cleaned for a long time,and the accumulated scorched matter is extruded with the molten plastic;

　　3)If the heating or shutdown time is too long,the plastic in the barrel will be decomposed by long-term heating;

　　4)The temperature control instrument is out of control or inaccurate,resulting in pyrolysis;

　　5)The cooling system of the extruder is not turned on,causing the material to overheat due to shear friction.

　　Therefore,during the extrusion process,it is necessary to strengthen the inspection of whether the heating and cooling systems are working normally;the extrusion temperature should be set according to the process requirements and the screw speed;the heating time should be reasonably controlled,and the extrusion system should be cleaned regularly.

　　5.Poor plasticization of the extruded product

　　The problem of plasticization has been mentioned in the temperature control requirements mentioned above.Generally,the main manifestations of poor plasticization are:the extruded cladding has toad skin-like appearance;the surface of the plastic is black,dull,and has small cracks;There are obvious seams at the glue;the main reasons are:

　　1)The temperature control is too low,especially at the head part;

　　2)Other plastic particles with different properties are mixed in the insulation or sheath material;

　　3)The screw rotates too fast,and the plastic is not fully plasticized;

　　4)Plastic itself has quality problems.

　　In view of the above reasons,attention should be paid to the rationality of extrusion temperature control;the quality and product name of the materials used should be confirmed;the extrusion speed cannot be increased blindly in pursuit of output;the storage of raw materials should be strengthened,especially in the plastic drying process;reasonable mold matching,To enhance extrusion pressure and screw return.

　　6.There are air holes or air bubbles in the extruded cladding section,the main reasons are:

　　1)The temperature control is too high(especially in the feed section);

　　2)The plastic is damp and has moisture;

　　3)After parking for a long time,the decomposed plastics have not been removed;

　　4)The natural environment has high humidity;

　　5)There is water or vapor content in the cable core is too high.

　　In view of the above reasons,the temperature of each section of the screw should be reasonably controlled;the materials used should be pre-dried in advance;the requirements for process operation should be strict,and the ability to judge the degree of plasticization of plastics should be improved;attention should be paid to the production environment and material storage and storage conditions.

　　7.The size of the extruded package is unqualified,mainly manifested as eccentricity;the thickness or outer diameter of the sheath is out of tolerance;the main reasons are:

　　Unstable extrusion and pulling speed;

　　1)The outer diameter of the cable core changes too much;

　　2)The extrusion temperature is too high to reduce the extrusion volume;

　　3)Excessive impurities in the plastic block the filter to reduce the plastic flow rate;

　　4)The tension of the take-up and pay-off line is unstable;

　　5)The mold core selection is too large(extrusion type)or the length of the mold core wire bearing area is too short and the core is eccentric;

　　6)The choice of mold spacing is not appropriate;

　　7)The temperature of the extrusion head is uneven;

　　8)The concentricity of the extrusion die is not adjusted properly;

　　9)The temperature of the feed inlet is too high to make the feed difficult and affect the material flow;

　　In view of the above reasons,the outer diameter of the sheath should be measured frequently and adjusted in time;reasonable selection and adjustment of the extrusion die;attention should be paid to the tension change of the take-up and release line and timely adjustment;the temperature control should be consistent with the specified requirements;

　　8.The bonding strength of the longitudinal tape is unqualified,the main reasons are:

　　1)Extrusion temperature is too low;

　　2)Too much ointment overflows;

　　3)The speed of the production line is too fast,so that the sheath is rapidly cooled;

　　4)The temperature of the hot water tank is too low and it is close to the die opening;

　　5)The drawing ratio of the mold matching is too small,or the mold matching is unreasonable,so that it forms a loose bag;

　　6)The melting point of the longitudinal tape composite film is too high;

　　According to the above reasons,attention should be paid to the mold matching requirements,and adjusted according to the cable core if necessary;the sheath should not be cooled rapidly to improve the bonding ability;the temperature of the machine head should not be excessively reduced to improve the sheath shaping ability;pay attention to the filling of ointment It is better to scrape off a thin layer by lightly touching the cable core with your fingers.

　　9.The appearance of the extruded package is unqualified.The unqualified appearance of the extruded package is mainly manifested by scratches on the surface of the extruded cladding;roughness,trachoma or microcracks;any defects caused by insufficient plasticization.The main reasons are:

　　1)The selection of extrusion die sets is unreasonable.If it is too small,it will cause hemp patterns;if it is too large,it will cause disjoint or extrusion looseness;

　　2)Impurities in the extrusion die sleeve are stuck and scratch the surface of the sheath.

　　3)The extruder head heating temperature is too high to cause roughness,or the temperature is too low to cause microcracks;

　　4)There is damage in the sizing area of the mold sleeve;

　　5)The sheath is scratched in the sink;

　　For the above reasons,defects can be eliminated or prevented in production.

　　In actual production,in addition to the above-mentioned defect phenomena and causes,there are also problems such as cable arrangement,overlapping width of longitudinal packages,and slub-shaped appearance.We observe and summarize more in production,grasp the main and essence of the problem,and we will solve it easily and improve the quality level of the cable.