This article breaks down the most common defects linked to PVC jacketing compounds and explains how to diagnose and fix them for more consistent production performance.<\/p>\n
Why Does Your PVC material for cable jacket Keep Producing Bubbles and Pores?<\/span><\/h2>\nThe Moisture Menace<\/span><\/h3>\nIf you have ever sliced open a freshly extruded cable jacket and found tiny voids or pinholes scattered through the cross-section, you have encountered one of the most persistent enemies of PVC extrusion: moisture. Even a fraction of 0.1% water in your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0can vaporize under extrusion heat, creating bubbles that mar the surface and compromise the jacket’s integrity. The science is straightforward: when moisture-laden PVC enters the heated barrel, the water turns to steam. That steam expands, gets trapped in the molten polymer, and emerges as bubbles or pores as the material cools.<\/span><\/p>\nWhere does this moisture come from? PVC resin is inherently hygroscopic\u2014it attracts and absorbs moisture from the air. Poor storage conditions, extended exposure to humid environments, or simply leaving bags open overnight can introduce enough water to ruin an entire production run. One industry source notes that PVC produced more than 24 hours earlier and not preheated before use is highly likely to absorb moisture, leading to surface defects. The solution?\u00a0<\/span>Proper drying<\/span>\u00a0of your\u00a0<\/span>PVC material for cable jacket<\/span>. Industry practice recommends drying PVC at 80\u201390\u00b0C for 2\u20133 hours using a dehumidifying hopper dryer. Some specifications call for drying to a -40\u00b0C dew point to ensure complete moisture removal.<\/span><\/p>\nThermal Degradation: When Heat Becomes the Enemy<\/span><\/h3>\nNot all bubbles come from water. Excessive heat can cause the\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0to degrade thermally, releasing hydrogen chloride (HCl) gas and other volatiles that manifest as bubbles and discolouration. PVC is notoriously sensitive to overheating\u2014extrusion temperatures around 170\u00b0C are typical, but the material becomes susceptible to thermal decomposition above 200\u00b0C. Prolonged residence time in the barrel, poor screw design that creates stagnant zones, or simply running the extruder too hot can all trigger degradation.<\/span><\/p>\nThe telltale signs? A sharp, irritating odour at the die, smoke emanating from the extruder head, and\u2014most obviously\u2014bubbles and discolouration in the finished jacket. If you notice these symptoms, check your temperature profile immediately. Reduce barrel temperatures, shorten the heating time, and ensure your cooling systems are functioning properly. Remember, overheating your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0is one of the quickest ways to introduce gas-related defects.<\/span><\/p>\nFormulation Instability<\/span><\/h3>\nSometimes the problem is baked into the compound itself. Poor formulation stability\u2014whether from an inadequate stabilizer package or an imbalance between internal and external lubricants\u2014can cause gas evolution during extrusion. This is where the quality of your\u00a0<\/span>PVC material for cable jacket<\/span> truly matters. Premium compounds like the DST series from Shandong Dingshengtong are engineered with carefully balanced additive systems to minimise degradation and ensure consistent processability. Off-the-shelf compounds with insufficient stabilisation may save money upfront, but cost far more in rejected batches and production downtime.<\/span><\/p>\nSolutions to eliminate bubbles and pores:<\/span><\/strong><\/p>\n\n- \n
Install and maintain dehumidifying dryers; dry your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0at 80\u201390\u00b0C for 2\u20133 hours before processing<\/span><\/p>\n<\/li>\n- \n
Set extruder vacuum pressure at -0.08 to -0.1 MPa to discharge volatile gases<\/span><\/p>\n<\/li>\n- \n
Reduce high-temperature residence time; avoid overheating above 200\u00b0C<\/span><\/p>\n<\/li>\n- \n
Choose a PVC compound with a robust stabilizer package designed for your specific extrusion conditions<\/span><\/p>\n<\/li>\n- \n
Preheat wire cores if they show signs of dampness<\/span><\/p>\n<\/li>\n<\/ul>\n![\"PVC](\"https:\/\/www.dstpvc.com\/wp-content\/uploads\/2025\/11\/\u5fae\u4fe1\u56fe\u7247_20251127144135_115_576-300x283.jpg\" "\\"PVC")
PVC material for cable jacket<\/figcaption><\/figure>\nWhy Does the Surface of Your Cable Jacket Look Rough or Uneven?<\/span><\/h2>\nThe “Fish Eye” Problem<\/span><\/h3>\nNothing undermines customer confidence like a rough, pitted cable jacket surface. The causes are numerous, but one of the most common is poor dispersion of the\u00a0<\/span>PVC material for cable jacket<\/span>. When the compound contains unmelted resin particles, agglomerated fillers, or poorly dispersed additives, these defects manifest as “fish eyes”\u2014small, hard, translucent spots that disrupt the smoothness of the extruded surface.<\/span><\/p>\nFish eyes typically arise from one of three sources:<\/span><\/p>\n\n- \n
Unplasticized particles<\/span><\/strong>\u00a0in the PVC resin that fail to melt during extrusion<\/span><\/p>\n<\/li>\n- \n
Poorly dispersed fillers<\/span><\/strong>\u00a0or stabilizers that create localized areas of different melt viscosity<\/span><\/p>\n<\/li>\n- \n
Contamination<\/span><\/strong>\u00a0from foreign materials introduced during handling or feeding<\/span><\/p>\n<\/li>\n<\/ul>\nThe Roughness from Low Temperatures<\/span><\/h3>\nCounterintuitively, running your extruder too cool can be just as damaging as running it too hot. When your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0is extruded at lower temperatures, its high viscosity prevents proper flow through the die. The result? A matte, rough surface appearance caused by changes in the surface microstructure. The material simply does not have enough thermal energy to flow smoothly and fill the die geometry completely.<\/span><\/p>\nPitting and Surface Imperfections<\/span><\/h3>\nSurface pitting\u2014small depressions or craters scattered across the jacket\u2014often points to a different issue: small molecules precipitating out of the melt after vacuum venting, or insufficient external lubrication causing the PVC to stick to hot metal surfaces. When the\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0lacks adequate external lubrication, it adheres to the die lips and barrel walls, creating drag that tears the surface as the extrudate exits.<\/span><\/p>\nSolutions for surface quality issues:<\/span><\/strong><\/p>\n\n- \n
Increase kneading temperature and time to ensure full plasticizer absorption<\/span><\/p>\n<\/li>\n- \n
Balance external and internal lubricant ratios to prevent both poor plasticization and die build-up<\/span><\/p>\n<\/li>\n- \n
Adjust the temperature upwards if the surface appears matte or rough<\/span><\/p>\n<\/li>\n- \n
Use high-mesh filters to remove agglomerates and impurities from the melt<\/span><\/p>\n<\/li>\n- \n
After shutdown, discharge 50\u2013100 metres of material to remove cold residue that can cause surface defects<\/span><\/p>\n<\/li>\n<\/ul>\nIs Your Extrusion Temperature Profile Working Against You?<\/span><\/h2>\nThe Temperature Tightrope<\/span><\/h3>\nPVC extrusion is a delicate balancing act. The temperature must be high enough to melt and plasticize the\u00a0<\/span>PVC material for the cable jacket<\/span>\u00a0completely, but low enough to prevent thermal degradation. Typical temperature profiles for PVC cable jacketing start around 140\u00b0C in Zone 1, rising to 160\u00b0C in Zone 2 and 165\u2013175\u00b0C at the die. But these are starting points, not absolutes. Every batch of\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0has its own optimal processing window, and deviating from it invites defects.<\/span><\/p>\nThe Consequences of Getting It Wrong<\/span><\/h3>\nToo cold:<\/span><\/strong>\u00a0The PVC does not plasticize fully. The extrudate emerges rough, with unmelted particles scattered across the surface. The melt pressure fluctuates, leading to inconsistent thickness and poor dimensional stability. If you run your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0too cold, you are essentially wasting the compound’s potential.<\/span><\/p>\nToo hot:<\/span><\/strong>\u00a0The PVC begins to degrade. The material scorches, releasing HCl gas that creates bubbles and pores. The jacket may become brittle, discoloured, or both. In severe cases, the compound burns inside the barrel, requiring a full screw pull and cleaning. Overheating your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0is a sure path to reject piles.<\/span><\/p>\nZone-by-Zone Control Matters<\/span><\/h3>\nModern extruders feature multiple heating zones, each with independent temperature control. A typical profile might look like this:<\/span><\/p>\n\n\n\n\nZone<\/span><\/th>\n Temperature Range (\u00b0C)<\/span><\/th>\n Purpose<\/span><\/th>\n<\/tr>\n<\/thead>\n\n\nZone 1 (Feed)<\/span><\/td>\n 140\u2013150<\/span><\/td>\n Gradual heating avoids premature melting that can cause feeding issues<\/span><\/td>\n<\/tr>\n\nZone 2 (Compression)<\/span><\/td>\n 155\u2013165<\/span><\/td>\n Primary melting and plasticization<\/span><\/td>\n<\/tr>\n\nZone 3 (Metering)<\/span><\/td>\n 160\u2013170<\/span><\/td>\n Homogenisation ensures a consistent melt temperature<\/span><\/td>\n<\/tr>\n\nZone 4 (Head)<\/span><\/td>\n 165\u2013175<\/span><\/td>\n Final temperature adjustment before die entry<\/span><\/td>\n<\/tr>\n\nDie<\/span><\/td>\n 165\u2013175<\/span><\/td>\n Maintains flow consistency through the die opening<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\nData compiled from industry extrusion guides<\/span><\/p>\nThe key insight? Every zone matters. If Zone 1 is too hot, the\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0melts too early, creating a “screw slippage” condition that reduces output and causes surging. If the die is too cold, the melt cools prematurely, creating a rough, “shark skin” surface.<\/span><\/p>\nWhy Does Your PVC material for cable jacket fail to Plasticize Properly?<\/span><\/h2>\nIncomplete Plasticization: The Hidden Defect<\/span><\/h3>\nPlasticization is the process by which the PVC resin absorbs plasticizer molecules, transforming from a rigid, granular powder into a flexible, homogeneous melt. When this process is incomplete, the extruded jacket contains unplasticized particles that appear as hard spots, rough patches, or\u2014in the worst cases\u2014stress concentrators that weaken the jacket.<\/span><\/p>\nWhy does incomplete plasticization happen? There are several common culprits:<\/span><\/p>\n\n- \n
Insufficient temperature:<\/span><\/strong>\u00a0The melt never reaches the temperature needed for full plasticizer absorption<\/span><\/p>\n<\/li>\n- \n
Inadequate mixing:<\/span><\/strong>\u00a0The screw design does not provide enough shear or distributive mixing to break down the resin and distribute the plasticizer uniformly<\/span><\/p>\n<\/li>\n- \n
Wrong screw design:<\/span><\/strong>\u00a0A general-purpose screw may not generate enough pressure or shear for your specific\u00a0<\/span>PVC material for cable jacket<\/span><\/strong><\/p>\n<\/li>\n- \n
Short residence time:<\/span><\/strong>\u00a0The material does not spend enough time in the heated barrel to complete the plasticization process<\/span><\/p>\n<\/li>\n<\/ul>\nThe Role of Screw Design<\/span><\/h3>\nYour extruder screw is not just a conveyor\u2014it is a precision mixing and melting device. For PVC cable jacketing, single-screw extruders with an L\/D (length-to-diameter) ratio of at least 20:1 are recommended. The screw should feature a compression ratio appropriate for your\u00a0<\/span>PVC material for cable jacket<\/span>\u2014typically 2.5:1 to 3.5:1\u2014and a barrier or BM-type design that enhances melting and mixing.<\/span><\/p>\nIf your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0consistently fails to plasticize, consider these adjustments:<\/span><\/p>\n\n- \n
Increase barrel temperatures in 5\u00b0C increments until full plasticization is achieved<\/span><\/p>\n<\/li>\n- \n
Install a screw with a higher compression ratio or a barrier flight design<\/span><\/p>\n<\/li>\n- \n
Reduce the line speed to increase residence time<\/span><\/p>\n<\/li>\n- \n
Check that your screw and barrel are clean and free from degraded material buildup<\/span><\/p>\n<\/li>\n<\/ul>\nWhen Does Your PVC Compound Cause Scorching and Burning?<\/span><\/h2>\nThe Scorch Cycle<\/span><\/h3>\nScorching\u2014also known as “burning” or “coking”\u2014occurs when the\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0degrades inside the extruder barrel or die. The symptoms are unmistakable: black or brown specks scattered through the extrudate, a pungent, acrid odour, and smoke emerging from the die. In severe cases, the degraded material forms hard deposits that clog the die or create surface defects that render the cable unusable.<\/span><\/p>\nWhy Scorching Happens<\/span><\/h3>\nThe root cause is almost always excessive heat history. Your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0has been exposed to high temperatures for too long, either because:<\/span><\/p>\n\n- \n
The extruder is running too hot (above 200\u00b0C)<\/span><\/p>\n<\/li>\n- \n
The material is stagnant in the screw channels or crosshead, creating “dead spots” where residence time is extended<\/span><\/p>\n<\/li>\n- \n
The screw is dirty, with degraded material from previous runs acting as a nucleation site for further degradation<\/span><\/p>\n<\/li>\n- \n
The stabilizer package in the compound is inadequate for the processing conditions<\/span><\/p>\n<\/li>\n<\/ul>\nPreventing Scorch<\/span><\/h3>\n
If you have ever sliced open a freshly extruded cable jacket and found tiny voids or pinholes scattered through the cross-section, you have encountered one of the most persistent enemies of PVC extrusion: moisture. Even a fraction of 0.1% water in your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0can vaporize under extrusion heat, creating bubbles that mar the surface and compromise the jacket’s integrity. The science is straightforward: when moisture-laden PVC enters the heated barrel, the water turns to steam. That steam expands, gets trapped in the molten polymer, and emerges as bubbles or pores as the material cools.<\/span><\/p>\n Where does this moisture come from? PVC resin is inherently hygroscopic\u2014it attracts and absorbs moisture from the air. Poor storage conditions, extended exposure to humid environments, or simply leaving bags open overnight can introduce enough water to ruin an entire production run. One industry source notes that PVC produced more than 24 hours earlier and not preheated before use is highly likely to absorb moisture, leading to surface defects. The solution?\u00a0<\/span>Proper drying<\/span>\u00a0of your\u00a0<\/span>PVC material for cable jacket<\/span>. Industry practice recommends drying PVC at 80\u201390\u00b0C for 2\u20133 hours using a dehumidifying hopper dryer. Some specifications call for drying to a -40\u00b0C dew point to ensure complete moisture removal.<\/span><\/p>\n Not all bubbles come from water. Excessive heat can cause the\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0to degrade thermally, releasing hydrogen chloride (HCl) gas and other volatiles that manifest as bubbles and discolouration. PVC is notoriously sensitive to overheating\u2014extrusion temperatures around 170\u00b0C are typical, but the material becomes susceptible to thermal decomposition above 200\u00b0C. Prolonged residence time in the barrel, poor screw design that creates stagnant zones, or simply running the extruder too hot can all trigger degradation.<\/span><\/p>\n The telltale signs? A sharp, irritating odour at the die, smoke emanating from the extruder head, and\u2014most obviously\u2014bubbles and discolouration in the finished jacket. If you notice these symptoms, check your temperature profile immediately. Reduce barrel temperatures, shorten the heating time, and ensure your cooling systems are functioning properly. Remember, overheating your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0is one of the quickest ways to introduce gas-related defects.<\/span><\/p>\n Sometimes the problem is baked into the compound itself. Poor formulation stability\u2014whether from an inadequate stabilizer package or an imbalance between internal and external lubricants\u2014can cause gas evolution during extrusion. This is where the quality of your\u00a0<\/span>PVC material for cable jacket<\/span> truly matters. Premium compounds like the DST series from Shandong Dingshengtong are engineered with carefully balanced additive systems to minimise degradation and ensure consistent processability. Off-the-shelf compounds with insufficient stabilisation may save money upfront, but cost far more in rejected batches and production downtime.<\/span><\/p>\n Solutions to eliminate bubbles and pores:<\/span><\/strong><\/p>\n Install and maintain dehumidifying dryers; dry your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0at 80\u201390\u00b0C for 2\u20133 hours before processing<\/span><\/p>\n<\/li>\n Set extruder vacuum pressure at -0.08 to -0.1 MPa to discharge volatile gases<\/span><\/p>\n<\/li>\n Reduce high-temperature residence time; avoid overheating above 200\u00b0C<\/span><\/p>\n<\/li>\n Choose a PVC compound with a robust stabilizer package designed for your specific extrusion conditions<\/span><\/p>\n<\/li>\n Preheat wire cores if they show signs of dampness<\/span><\/p>\n<\/li>\n<\/ul>\n Nothing undermines customer confidence like a rough, pitted cable jacket surface. The causes are numerous, but one of the most common is poor dispersion of the\u00a0<\/span>PVC material for cable jacket<\/span>. When the compound contains unmelted resin particles, agglomerated fillers, or poorly dispersed additives, these defects manifest as “fish eyes”\u2014small, hard, translucent spots that disrupt the smoothness of the extruded surface.<\/span><\/p>\n Fish eyes typically arise from one of three sources:<\/span><\/p>\n Unplasticized particles<\/span><\/strong>\u00a0in the PVC resin that fail to melt during extrusion<\/span><\/p>\n<\/li>\n Poorly dispersed fillers<\/span><\/strong>\u00a0or stabilizers that create localized areas of different melt viscosity<\/span><\/p>\n<\/li>\n Contamination<\/span><\/strong>\u00a0from foreign materials introduced during handling or feeding<\/span><\/p>\n<\/li>\n<\/ul>\n Counterintuitively, running your extruder too cool can be just as damaging as running it too hot. When your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0is extruded at lower temperatures, its high viscosity prevents proper flow through the die. The result? A matte, rough surface appearance caused by changes in the surface microstructure. The material simply does not have enough thermal energy to flow smoothly and fill the die geometry completely.<\/span><\/p>\n Surface pitting\u2014small depressions or craters scattered across the jacket\u2014often points to a different issue: small molecules precipitating out of the melt after vacuum venting, or insufficient external lubrication causing the PVC to stick to hot metal surfaces. When the\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0lacks adequate external lubrication, it adheres to the die lips and barrel walls, creating drag that tears the surface as the extrudate exits.<\/span><\/p>\n Solutions for surface quality issues:<\/span><\/strong><\/p>\n Increase kneading temperature and time to ensure full plasticizer absorption<\/span><\/p>\n<\/li>\n Balance external and internal lubricant ratios to prevent both poor plasticization and die build-up<\/span><\/p>\n<\/li>\n Adjust the temperature upwards if the surface appears matte or rough<\/span><\/p>\n<\/li>\n Use high-mesh filters to remove agglomerates and impurities from the melt<\/span><\/p>\n<\/li>\n After shutdown, discharge 50\u2013100 metres of material to remove cold residue that can cause surface defects<\/span><\/p>\n<\/li>\n<\/ul>\n PVC extrusion is a delicate balancing act. The temperature must be high enough to melt and plasticize the\u00a0<\/span>PVC material for the cable jacket<\/span>\u00a0completely, but low enough to prevent thermal degradation. Typical temperature profiles for PVC cable jacketing start around 140\u00b0C in Zone 1, rising to 160\u00b0C in Zone 2 and 165\u2013175\u00b0C at the die. But these are starting points, not absolutes. Every batch of\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0has its own optimal processing window, and deviating from it invites defects.<\/span><\/p>\n Too cold:<\/span><\/strong>\u00a0The PVC does not plasticize fully. The extrudate emerges rough, with unmelted particles scattered across the surface. The melt pressure fluctuates, leading to inconsistent thickness and poor dimensional stability. If you run your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0too cold, you are essentially wasting the compound’s potential.<\/span><\/p>\n Too hot:<\/span><\/strong>\u00a0The PVC begins to degrade. The material scorches, releasing HCl gas that creates bubbles and pores. The jacket may become brittle, discoloured, or both. In severe cases, the compound burns inside the barrel, requiring a full screw pull and cleaning. Overheating your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0is a sure path to reject piles.<\/span><\/p>\n Modern extruders feature multiple heating zones, each with independent temperature control. A typical profile might look like this:<\/span><\/p>\n Data compiled from industry extrusion guides<\/span><\/p>\n The key insight? Every zone matters. If Zone 1 is too hot, the\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0melts too early, creating a “screw slippage” condition that reduces output and causes surging. If the die is too cold, the melt cools prematurely, creating a rough, “shark skin” surface.<\/span><\/p>\n Plasticization is the process by which the PVC resin absorbs plasticizer molecules, transforming from a rigid, granular powder into a flexible, homogeneous melt. When this process is incomplete, the extruded jacket contains unplasticized particles that appear as hard spots, rough patches, or\u2014in the worst cases\u2014stress concentrators that weaken the jacket.<\/span><\/p>\n Why does incomplete plasticization happen? There are several common culprits:<\/span><\/p>\n Insufficient temperature:<\/span><\/strong>\u00a0The melt never reaches the temperature needed for full plasticizer absorption<\/span><\/p>\n<\/li>\n Inadequate mixing:<\/span><\/strong>\u00a0The screw design does not provide enough shear or distributive mixing to break down the resin and distribute the plasticizer uniformly<\/span><\/p>\n<\/li>\n Wrong screw design:<\/span><\/strong>\u00a0A general-purpose screw may not generate enough pressure or shear for your specific\u00a0<\/span>PVC material for cable jacket<\/span><\/strong><\/p>\n<\/li>\n Short residence time:<\/span><\/strong>\u00a0The material does not spend enough time in the heated barrel to complete the plasticization process<\/span><\/p>\n<\/li>\n<\/ul>\n Your extruder screw is not just a conveyor\u2014it is a precision mixing and melting device. For PVC cable jacketing, single-screw extruders with an L\/D (length-to-diameter) ratio of at least 20:1 are recommended. The screw should feature a compression ratio appropriate for your\u00a0<\/span>PVC material for cable jacket<\/span>\u2014typically 2.5:1 to 3.5:1\u2014and a barrier or BM-type design that enhances melting and mixing.<\/span><\/p>\n If your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0consistently fails to plasticize, consider these adjustments:<\/span><\/p>\n Increase barrel temperatures in 5\u00b0C increments until full plasticization is achieved<\/span><\/p>\n<\/li>\n Install a screw with a higher compression ratio or a barrier flight design<\/span><\/p>\n<\/li>\n Reduce the line speed to increase residence time<\/span><\/p>\n<\/li>\n Check that your screw and barrel are clean and free from degraded material buildup<\/span><\/p>\n<\/li>\n<\/ul>\n Scorching\u2014also known as “burning” or “coking”\u2014occurs when the\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0degrades inside the extruder barrel or die. The symptoms are unmistakable: black or brown specks scattered through the extrudate, a pungent, acrid odour, and smoke emerging from the die. In severe cases, the degraded material forms hard deposits that clog the die or create surface defects that render the cable unusable.<\/span><\/p>\n The root cause is almost always excessive heat history. Your\u00a0<\/span>PVC material for cable jacket<\/span>\u00a0has been exposed to high temperatures for too long, either because:<\/span><\/p>\n The extruder is running too hot (above 200\u00b0C)<\/span><\/p>\n<\/li>\n The material is stagnant in the screw channels or crosshead, creating “dead spots” where residence time is extended<\/span><\/p>\n<\/li>\n The screw is dirty, with degraded material from previous runs acting as a nucleation site for further degradation<\/span><\/p>\n<\/li>\n The stabilizer package in the compound is inadequate for the processing conditions<\/span><\/p>\n<\/li>\n<\/ul>\nThermal Degradation: When Heat Becomes the Enemy<\/span><\/h3>\n
Formulation Instability<\/span><\/h3>\n
\n
Why Does the Surface of Your Cable Jacket Look Rough or Uneven?<\/span><\/h2>\n
The “Fish Eye” Problem<\/span><\/h3>\n
\n
The Roughness from Low Temperatures<\/span><\/h3>\n
Pitting and Surface Imperfections<\/span><\/h3>\n
\n
Is Your Extrusion Temperature Profile Working Against You?<\/span><\/h2>\n
The Temperature Tightrope<\/span><\/h3>\n
The Consequences of Getting It Wrong<\/span><\/h3>\n
Zone-by-Zone Control Matters<\/span><\/h3>\n
\n\n
\n Zone<\/span><\/th>\n Temperature Range (\u00b0C)<\/span><\/th>\n Purpose<\/span><\/th>\n<\/tr>\n<\/thead>\n\n \n Zone 1 (Feed)<\/span><\/td>\n 140\u2013150<\/span><\/td>\n Gradual heating avoids premature melting that can cause feeding issues<\/span><\/td>\n<\/tr>\n \n Zone 2 (Compression)<\/span><\/td>\n 155\u2013165<\/span><\/td>\n Primary melting and plasticization<\/span><\/td>\n<\/tr>\n \n Zone 3 (Metering)<\/span><\/td>\n 160\u2013170<\/span><\/td>\n Homogenisation ensures a consistent melt temperature<\/span><\/td>\n<\/tr>\n \n Zone 4 (Head)<\/span><\/td>\n 165\u2013175<\/span><\/td>\n Final temperature adjustment before die entry<\/span><\/td>\n<\/tr>\n \n Die<\/span><\/td>\n 165\u2013175<\/span><\/td>\n Maintains flow consistency through the die opening<\/span><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div>\n Why Does Your PVC material for cable jacket fail to Plasticize Properly?<\/span><\/h2>\n
Incomplete Plasticization: The Hidden Defect<\/span><\/h3>\n
\n
The Role of Screw Design<\/span><\/h3>\n
\n
When Does Your PVC Compound Cause Scorching and Burning?<\/span><\/h2>\n
The Scorch Cycle<\/span><\/h3>\n
Why Scorching Happens<\/span><\/h3>\n
\n
Preventing Scorch<\/span><\/h3>\n