Defect 1: pimple

1、 The phenomenon of pimple

(1) The pimple produced during the plasticizing process of the resin has small crystal points and particles on the surface of the plastic layer, which are distributed around the surface of the plastic layer.

(2) The pimple produced by scorching has scorched material on the surface of the plastic layer, especially on the surface of the glue joint.

(3) Impurities: there are impurities on the plastic surface and impurities in the lumps of slices.

(4) Plastic pimples caused by poor plasticization were found to be cooked glue in the pimples after slicing.

2、 Causes of pimples

(1) Due to the low temperature control, the plastic is not yet plasticized and extruded from the head.

(2) The plastic quality is poor, and there are resins that are difficult to plasticize, which are not completely plasticized and extruded.

(3) During feeding, some impurities are added into the hopper, causing impurities pimple.

(4) The temperature control is too high, resulting in scorching, resulting in scorching lumps.

(5) The molded cover was not pressed tightly, and it deteriorated after rubber injection, resulting in burnt bumps.

3、 Methods to eliminate pimples

(1) The temperature should be appropriately raised for the pimple caused by the plastic itself.

(2) When feeding, strictly check whether there are sundries in the plastic. When feeding, do not add other sundries into the hopper. If impurities are found, immediately clean the head and remove the glue stored in the screw.

(3) If it is found that the temperature is too high, the temperature shall be reduced appropriately immediately. If the effect is not good, the machine head and screw shall be cleaned immediately to remove the burnt materials.

(4) In case of resin pimple and poorly plasticized pimple, the temperature shall be appropriately raised or the speed of screw and traction shall be reduced.

Defect 2: positive and negative deviation of plastic layer

1、 Out of tolerance

(1) The speed of screw and traction is unstable, and the ammeter or voltmeter swings from side to side. Therefore, the outer diameter of the cable is affected, resulting in the deviation of the plastic layer.

(2) The semi-finished products have quality problems, such as loose wrapping of steel strip or plastic strip, uneven convexity and concavity, or defects such as wrapping, ridge and pit in the plastic layer.

(3) The temperature control is too high, resulting in a reduction in the amount of extrusion, which makes the outer diameter of the cable suddenly thinner and the plastic layer thinner, forming a negative difference.

2、 Reasons for out of tolerance

(1) The wire core or cable core is not round, and there is snake shape, while the outer diameter changes too much.

(2) The semi-finished products have quality problems, such as poor steel strip joint, loose sleeve of steel strip, rolled edge of steel strip, loose sleeve of plastic strip, too large joint, scattering, etc.

(3) During operation, the mold core selection is too large, resulting in the plastic layer core deflection due to the glue pouring.

(4) When adjusting the mold, the mold adjusting screw was not tightened, resulting in a backoff phenomenon, which caused the plastic layer to deviate from the core.

(5) Screw or traction speed is unstable, resulting in out of tolerance.

(6) The feeding port or filter screen is partially blocked, resulting in a negative difference due to the reduction of glue output.

3、 Method of eliminating out of tolerance

(1) Regularly 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 should be adjusted immediately.

(2) The mold shall be properly selected. After the mold is adjusted, the mold adjusting screw shall be tightened and the gland shall be pressed tightly.

(3) Pay attention to the screw and the traction current and voltmeter. If any instability is found, call an electrician and fitter for maintenance.

(4) Do not add strips or other sundries into the hopper. If this situation is found, it should be removed immediately.

Defect 3: Scorching

1、 Scorching phenomenon

(1) The temperature is too high, or the instrument controlling the temperature is out of order, causing the plastic to be burnt due to ultra-high temperature.

(2) The rubber outlet of the machine head has large smoke, strong pungent smell and crackling sound.

(3) Granular scorch appears on the plastic surface.

(4) There are continuous air holes at the glue joint.

2、 Causes of scorching

(1) The temperature control is too high, causing the plastic to scorch.

(2) The screw has been 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, the plastic deposit will be heated for a long time, which will cause the plastic to age, deteriorate and scorch.

(4) The parking time is too long, and the machine head and screw are not cleaned, resulting in plastic decomposition and scorching.

(5) Change the mold or color for many times, causing the plastic to decompose and burn.

(6) The head gland is not pressed tightly, and the plastic is aging and decomposing inside.

(7) The instrument controlling the temperature failed, resulting in scorching after ultra-high temperature.

3、 Methods for eliminating scorch

(1) Frequently check whether the heating system is normal.

(2) Clean the screw or head regularly and thoroughly.

(3) The heating shall be carried out according to the process requirements, and the heating time shall not be too long. If there is a problem with the heating system, it shall be solved by relevant personnel in a timely manner.

(4) Change the mold or color in a timely and clean manner to prevent discoloration or burning of stored glue.

(5) After adjusting the mold, press the mold sleeve gland tightly to prevent glue from entering.

(6) Clean the head and screw immediately in case of scorching.

Defect 4: poor plasticization

1、 Poor plasticization

(1) The plastic layer surface has a toad skin like ground phenomenon.

(2) The temperature control is low, the pointer of the instrument reflects low temperature, and the actual measured temperature is also low.

(3) The plastic surface is black, with tiny cracks or small particles without good plasticization.

(4) The plastic glue is not sewed well, there is an obvious trace.

2、 Causes of poor plasticization

(1) The temperature control is too low or improper.

(2) There are resin particles in the plastic that are difficult to plasticize.

(3) The operation method is improper, the screw and traction speed are too fast, and the plastic is not fully plasticized.

(4) The plastic is not uniformly mixed during granulation or the plastic itself has quality problems.

3、 Methods to eliminate poor plasticization

(1) The temperature shall be controlled according to the process regulations. If the temperature is low, the temperature shall be appropriately raised.

(2) The speed of screw and traction shall be appropriately reduced to increase the heating and plasticizing time of plastics, so as to improve the plasticizing effect of plastics.

(3) The screw cooling water is used to strengthen the plasticization and tightness of plastics.

(4) When selecting the mold, the mold sleeve should be smaller to strengthen the pressure of the rubber outlet.

Defect 5: uneven thickness of cable outer diameter and bamboo shape

1、 Uneven thickness and slub shape

(1) The outer diameter of cable is uneven due to unstable screw or traction.

(2) Due to the sudden instability of the traction, the plastic that forms 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、 Reasons for uneven thickness and slub shape

(1) The speed of reeling in/out or traction is uneven.

(2) The outer diameter of semi-finished products varies greatly, and the mold selection is inappropriate.

(3) The screw speed is unstable, the main motor speed is uneven, and the belt is too loose or slipping.

3、 Methods to eliminate uneven thickness and slub shape

(1) Regularly check whether the speed of screw, traction and wire retraction and paying off is uniform.

(2) The mold shall be properly selected to prevent glue pouring.

(3) Regularly check the operation of machinery and electrical appliances, and immediately find fitters and electricians to repair problems...