1. Scorch phenomenon
(1) The temperature is too high, or the temperature control instrument fails, causing the plastic to burn at an ultra-high temperature.
(2) The glue outlet of the machine head has large smoke, strong pungent smell and crackling sound.
(3) Granular scorched matter appears on the plastic surface.
(4) There are continuous pores at the glue joint.
2. Causes of scorch
(1) High temperature control causes plastic scorch.
(2) The screw is used for a long time without cleaning, and the burnt materials are accumulated and extruded with the plastic.
(3) If the heating time is too long and the plastic deposit is heated for a long time, the plastic will be aged, deteriorated and burnt.
(4) The parking time was too long and the machine head and screw were not cleaned, resulting in plastic decomposition and scorching.
(5) Change the mold or color for many times, resulting in plastic decomposition and scorching.
(6) The head gland is not compressed, and the plastic is aged and decomposed inside.
(7) The instrument controlling the temperature failed, resulting in scorch after ultra-high temperature.
3. Method of eliminating scorch
(1) Frequently check whether the heating system is normal.
(2) Clean the screw or head regularly and thoroughly.
(3) Heat up according to the process requirements. The heating time should not be too long. If there is a problem with the heating system, find relevant personnel to solve it in time.
(4) Mold change or color change shall be timely and clean to prevent mottled or burnt glue.
(5) After adjusting the mold, press the mold sleeve gland tightly to prevent glue from entering.
(6) In case of burning, clean the head and screw immediately Poor plasticization
2、 Poor plasticization
1. Poor plasticization
(1) There is a toad skin phenomenon on the surface of the plastic layer.
(2) The temperature control is low, the temperature reflected by the instrument pointer is low, and the actual measured temperature is also low.
(3) The plastic surface is dark, with small cracks or small particles that are not plasticized well.
(4) The plastic glue is not sewn well, there is an obvious trace.
2. Causes of poor plasticization
(1) The temperature control is too low or inappropriate.
(2) There are resin particles in plastics that are difficult to plasticize.
(3) Improper operation method, screw and traction speed is too fast, and the plastic does not fully plasticize.
(4) During granulation, the plastic is mixed unevenly or the plastic itself has quality problems.
3. Methods for eliminating poor plasticization
(1) Control the temperature according to the process regulations. If the temperature is low, increase the temperature appropriately.
(2) The speed of screw and traction shall be appropriately reduced to increase the time of plastic heating and plasticization, so as to improve the effect of plastic plasticization.
(3) Use screw cooling water to strengthen the plasticization and tightness of plastics.
(4) When selecting the mold, the mold sleeve should be smaller to strengthen the pressure at the rubber outlet.
1. Produce pimple phenomenon
(1) There are small crystal dots and particles on the surface of the plastic layer, which are distributed around the surface of the plastic layer.
(2) There are burnt objects on the surface of the plastic layer, especially on the surface of the glue joint.
(3) There are impurities on the plastic surface, and there are impurities in the lumps of slices.
(4) Plastic bumps caused by poor plasticization. After slicing, it is found that there is cooked glue in the bumps.
2. Causes of pimples
(1) Due to the low temperature control, the plastic was squeezed out of the machine head before it was plasticized.
(2) The quality of plastics is poor, and there are resins that are difficult to plasticize, which are extruded without complete plasticization.
(3) During feeding, some impurities are added into the hopper, causing impurities pimples.
(4) The temperature control is too high, resulting in coke burning, resulting in coke burning pimples.
(5) The molded cover was not pressed tightly, and the rubber was aged and deteriorated, resulting in burnt pimples.
3. Methods of eliminating pimples
(1) The temperature should be properly increased for the pimples caused by the plastic itself.
(2) During feeding, strictly check whether there are sundries in the plastic. During feeding, do not add other sundries into the hopper. If impurities are found, clean the machine head immediately and run away the glue stored in the screw.
(3) If the temperature is found to be excessively high, the temperature shall be appropriately reduced immediately. If the effect is not good, the machine head and screw shall be cleaned immediately to eliminate burnt objects.
(4) In case of resin knots and knots with poor plasticization, appropriately increase the temperature or reduce the speed of screw and traction.
4、 Positive and negative out of tolerance of plastic layer
1. Out of tolerance
(1) The speed of screw and traction is unstable, and the ammeter or voltmeter swings left and right, which affects the outer diameter of cable and produces deviation of plastic layer.
(2) Quality problems of semi-finished products, such as loose wrapping of steel belt or plastic belt, uneven convex concave phenomenon, or defects such as package, edge and pit in plastic layer.
(3) The temperature control is ultra-high, resulting in the reduction of extrusion, resulting in the sudden thinning of the outer diameter of the cable and the thinning of the plastic layer, forming a negative difference.
2. Causes of out of tolerance
(1) The wire core or cable core is not round, there is snake shape, and the outer diameter changes too much.
(2) There are quality problems in semi-finished products, such as poor steel belt joint, loose steel belt sleeve, steel belt crimping, loose plastic belt sleeve, too large joint, scattered flowers, etc.
(3) During operation, the mold core selection is too large, resulting in glue pouring and plastic layer deviation.
(4) When adjusting the mold, the mold adjusting screw is not tightened, resulting in reverse buckle, which makes the plastic layer deviate from the core.
(5) The screw or traction speed is unstable, resulting in out of tolerance.
(6) The feeding port or filter screen is partially blocked, resulting in the decrease of glue output and negative difference.
3. Methods of eliminating out of tolerance
(1) Frequently measure the outer diameter of the cable and check the thickness of the plastic layer. If the outer diameter changes or the plastic layer is uneven, it shall be adjusted immediately.
(2) The selected mold shall be appropriate. After adjusting the mold, tighten the mold adjusting screw and press the gland tightly.
(3) Pay attention to the screw and traction ammeter and voltmeter. In case of instability, find an electrician and fitter for maintenance in time.
(4) Do not add strips or other sundries into the hopper. If this situation is found, it shall be removed immediately.
5、 Uneven thickness and bamboo shape of cable outer diameter
1. Produce uneven thickness and slub shape
(1) Uneven outer diameter of cable due to unstable screw or traction.
(2) Due to the sudden instability of traction, the plastic forming the cable is bamboo shaped.
(3) The mold selection is small, and the outer diameter of semi-finished products changes greatly, resulting in uneven thickness of the plastic layer of the cable.
2. Causes of uneven thickness and slub shape
(1) Uneven speed of take-up and take-off or traction.
(2) The outer diameter of semi-finished products changes greatly, and the mold selection is inappropriate.
(3) The screw speed is unstable, the speed of the main motor is uneven, and the belt is too loose or slippery.
3. Methods of eliminating uneven thickness and slub shape
(1) Regularly check whether the speed of screw, traction, retraction and setting out is uniform.
(2) Mold selection shall be appropriate to prevent glue pouring.
(3) Regularly check the operation of machinery and electrical appliances, and immediately find a fitter and electrician to repair any problems.
6、 Bad glue joint
1. Bad glue joint
(1) On the outside of the surface of the plastic layer, the plastic is not combined well, with a black mark and cracks in serious cases.
(2) The glue joint of the plastic layer is not plasticized well, and there are pimples and small particles. In serious cases, it can be torn off by hand.
(3) The control temperature is low, especially the control temperature of the head.
2. Reasons for poor glue joint
(1) Low control temperature and poor plasticization.
(2) The machine head has been used for a long time, resulting in serious wear.
(3) The temperature control of the machine head fails, resulting in low temperature and poor plastic lamination.
3. Methods to eliminate bad glue joint
(1) Appropriately increase the control temperature, especially the control temperature of the machine head.
(2) The outside of the machine head is insulated with a thermal insulation device.
(3) Add two layers of filter screen to increase the pressure and improve the plasticization degree of plastic.
(4) Appropriately reduce the speed of screw traction to prolong the plastic plasticizing time and achieve the purpose of plastic joint.
(5) Lengthen the wire diameter of the die and increase the extrusion pressure and temperature.
7、 Other defects
1. Pores, bubbles or air holes
(1) Local control temperature is too high.
(2) Plastic is wet or moist.
(3) After parking, the excess gas in the plastic was not eliminated.
(4) The natural environment is humid.
（2） Exclusion method
(1) The temperature control shall be appropriate. If the temperature is too high, it shall be adjusted immediately to prevent local temperature from being too high.
(2) During feeding, the quality of plastics shall be strictly checked, especially in rainy seasons. In case of moisture and water, the use shall be stopped immediately, and then the wet materials shall be cleaned.
(3) A preheating device is added at the feeding place to drive away the moisture and moisture in the plastic.
(4) Take samples frequently to check whether there are pores, air holes and bubbles in the plastic layer.
2. Disjointed or broken glue
（1） Cause of occurrence
(1) There is water or oil in the conductive core
(2) The wire core is too heavy to contact with the mold core locally, resulting in temperature reduction, local cooling of the plastic, and disconnection or glue breaking due to the stretching of the plastic.
(3) The quality of semi-finished products is poor, such as loose sleeves of steel belt and plastic belt, loose or too large joints.
（2） Exclusion method
(1) The mold selection should be larger, especially the mold with sheath, which should be enlarged by 6 to 8mm.
(2) Properly reduce the length and thickness of the core nozzle.
(3) Reduce the speed of screw and traction.
(4) Properly raise the control temperature of the head.
3. Pit and eye
(1) The tightly pressed conductor core is not tightly twisted and has gaps.
(2) The wire core has water, oil and dirt.
(3) The semi-finished products have defects, such as strand expenditure, falling, crossing and bending, overlapping of steel strip and plastic strip, loose sleeve, oversized joint, etc.
(4) Low temperature control.
（2） Exclusion method
(1) The tightening of stranded conductors shall comply with the process regulations.
(2) If the semi-finished products do not meet the quality requirements, they shall be processed before production.
(3) Remove the dirt and preheat the cable core or wire core.
4. Plastic layer wrapping, edges and corners, ears, wrinkles and concave convex
(1) Quality problems caused by wrapping plastic tape and steel strip.
(2) The mold selection is too large, which is caused by vacuum pumping.
(3) Plastic glue pouring occurs after the mold core is damaged.
(4) The core is too heavy and the plastic layer cannot be cooled well.
（2） Exclusion method
(1) Check the quality of semi-finished products, and the unqualified products will not be produced.
(2) Check the mold before assembly, and handle the problems before use.
(3) Mold selection should be appropriate. Properly reduce the traction speed so that the plastic layer is completely cooled.
5. There are traces on the plastic surface
(1) The surface of die sleeve bearing wire diameter is not smooth or notched.
(2) If the temperature control is too high, the barium stearate of the plastic itself decomposes and accumulates at the die sleeve mouth, resulting in traces.
（2） Exclusion method
(1) When selecting the mold, check whether the surface of the die sleeve bearing wire diameter is smooth. If there are defects, deal with them.
(2) Reduce the temperature of the heating zone of the machine head appropriately, and remove barium stearate immediately after it is produced.