Problems encountered in the extrusion process of wires and cables and their solutions
1. The plastic layer is positive and negative
1. Out of tolerance
(1) The speed of the screw and traction is unstable, and the ammeter or voltmeter swings from side to side, which affects the outer diameter of the cable and produces a deviation of the plastic layer.
(2) The quality of semi-finished products is problematic, such as loose steel or plastic belts, uneven unevenness or defects in the plastic layer, such as packages, ribs, and pits.
(3) The temperature control is super high, which reduces the extrusion volume, which makes the outer diameter of the cable suddenly thinner, and the plastic layer becomes thinner, forming a negative difference.
2. The reason for the out of tolerance
(1) The core or cable core is not round or has a serpentine shape, and the outer diameter changes too much.
(2) Semi-finished products have quality problems, such as: bad steel strip joints, steel strip loose sleeves, steel strip crimping, plastic strips loose sleeves, excessive joints, scattered flowers, etc.
(3) During operation, the mold core selection is too large, causing the glue to be poured and the plastic layer to be eccentric.
(4) When the mold is adjusted, the mold adjustment screw is not tightened, resulting in an undercut phenomenon and eccentricity of the plastic layer.
(5) The screw or traction speed is unstable, resulting in over-tolerance.
(6) The feeding port or the filter screen is partially blocked, resulting in a decrease in the amount of glue and a negative difference.
3. Ways to eliminate out of tolerance
(1) Always 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 matching mold should be suitable, and after the mold is adjusted, the mold adjustment screw must be tightened to press the gland tightly.
(3) Pay attention to the screw and traction current and voltmeter. If it is unstable, please find an electrician and fitter for repair.
(4) Do not add strips or other sundries into the hopper. If this is found, remove it immediately.
2. Uneven thickness of cable outer diameter and bamboo joint shape
1. The phenomenon of uneven thickness and bamboo joints
(1) The diameter of the cable is uneven due to the unstable screw or traction.
(2) Due to the sudden instability of traction, the plastic forming the cable is in a bamboo shape.
(3) The mold selection is small, and the outer diameter of the semi-finished product changes greatly, resulting in uneven thickness of the plastic layer of the cable.
2. Reasons for uneven thickness and bamboo joints
(1) Uneven speed of retracting and unwinding or traction.
(2) The outer diameter of the semi-finished product changes 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 bamboo joints
(1) Always check whether the speeds of the screw, traction, and retracting lines are uniform.
(2) The mold selection should be appropriate to prevent the phenomenon of glue pouring.
(3) Regularly check the operation of machinery and electrical appliances, and find a fitter or electrician to repair any problems.
Third, the glue seam is not good
1. The phenomenon of bad glue joints
(1) On the outside of the surface of the plastic layer, the plastic is not well merged, there is a black mark, and sometimes there are cracks.
(2) The glue of the plastic layer is not well plasticized, and there are lumps and tiny particles, which can be opened by hand in severe cases.
(3) The controlled temperature is low, especially the control temperature of the machine head is low.
2. Reasons for bad glue seams
(1) The control temperature is low and the plasticization is poor.
(2) Long-term use of the machine head causes severe wear and tear.
(3) The temperature control of the machine head fails, resulting in low temperature, which makes the plastic laminate bad.
3. Eliminate bad glue joints
(1) Increase the control temperature appropriately, especially the control temperature of the machine head.
(2) The outer side of the machine head adopts a heat preservation device for heat preservation.
(3) Add two layers of filters to increase the pressure and increase the degree of plasticization of the plastic.
(4) Appropriately reduce the traction speed of the screw and increase the plasticization time of the plastic to achieve the purpose of plastic seaming.
(5) Lengthen the wire diameter of the die and increase the extrusion pressure and temperature.
Four, other defects
1. Stomas, bubbles or air holes
(1) the reason
(1) The local control temperature is extremely high.
(2) The plastic is damp or has moisture.
(3) The excess gas in the plastic is not eliminated after parking.
(4) The natural environment is humid.
(2) Elimination method
(1) The temperature control should be appropriate. If the temperature is too high, it should be adjusted immediately to prevent the local temperature from being too high.
(2) Strictly check the quality of the plastic when adding materials, especially in rainy seasons, if there is water in the wet, stop using it immediately, and then run away the wet material.
(3) A preheating device is added at the feeding place to drive away moisture and water in the plastic.
(4) Regularly take samples to check whether the plastic layer has pores, holes and bubbles.
2. Disjointed or broken glue
(1) The reason
(1) The conductive wire core has water or oil
(2) The wire core is too heavy to locally contact the mold core, causing the temperature to drop, and the plastic is locally cooled, and the plastic is stretched to cause disconnection or breakage.
(3) The quality of semi-finished products is poor, such as loose steel belts and plastic belts, and the joints are weak or too large.
(2) Elimination method
(1) The mold matching should be larger, especially the mold matching the sheath, which should be enlarged by 6 to 8mm.
(2) Appropriately reduce the length and thickness of the core nozzle.
(3) Reduce the speed of screw and traction.
(4) Increase the control temperature of the machine head appropriately.
3. Pit and eye
(1) the reason
(1) The tightly pressed conductive core is not twisted tightly and there is a gap.
(2) There is water, oil, and dirt in the wire core.
(3) Semi-finished products are defective, such as stranding, falling, crossing, bending, overlapping of steel and plastic belts, loose sleeves, oversized joints, etc.
(4) The temperature control is low.
(2) Elimination method
(1) The tight pressure of the stranded conductor must comply with the process regulations.
(2) The semi-finished product does not meet the quality requirements and should be processed before production.
(3) Remove dirt, and preheat the cable core or wire core.
4. Plastic layers, edges and corners, ears, wrinkles and bumps
(1) Quality problems caused by plastic wrapping tape and steel tape wrapping.
(2) The mold selection is too large, caused by vacuuming.
(3) Plastic pouring occurs when the mold core is damaged.
(4) The core is too heavy and the plastic layer is not cooled well.
(two) elimination method
(1) Check the quality of semi-finished products, and non-conforming products will not be produced.
(2) Check the mold before assembling, and solve the problem before using it.
(3) The mold selection must be appropriate. To properly reduce the traction speed, the plastic layer is completely cooled.
5. Traces appear on the plastic surface
(1) The surface of the die sleeve bearing wire diameter is not smooth or has gaps.
(2) If the temperature is controlled too high, the barium stearate in the plastic will decompose, and it will accumulate at the mouth of the die sleeve and cause marks.
(2) Elimination method
(1) When selecting the mold, check whether the surface of the mold sleeve is smooth or not, and deal with any defects.
(2) Lower the temperature in the heating zone of the machine head appropriately, and remove it immediately after producing barium stearate.