{"id":66,"date":"2026-11-06T19:06:37","date_gmt":"2026-11-06T11:06:37","guid":{"rendered":"https:\/\/kerkepm.com\/knowledge\/engineering-plastics-compounding\/"},"modified":"2026-11-12T19:12:23","modified_gmt":"2026-11-12T11:12:23","slug":"engineering-plastics-compounding","status":"publish","type":"page","link":"https:\/\/kerkepm.com\/es\/knowledge\/engineering-plastics-compounding\/","title":{"rendered":"Engineering Plastics Compounding: PA, PBT, PC and ABS"},"content":{"rendered":"
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\n Home<\/a>\/<\/span>Applications<\/a>\/<\/span>Engineering plastics\n <\/div>\n\n
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Application \u00b7 Twin screw compounding<\/p>\n

Engineering Plastics Compounding: Glass-Filled PA, PC\/ABS and PBT Lines<\/h1>\n

The highest-value single-machine application in compounding \u2014 and the easiest one to ruin. Side feeding, fibre-length protection and moisture control decide the mechanical properties long before the barrel temperature does.<\/p>\n

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Updated<\/b> 5 November 2026<\/div>\n
Typical output<\/b> 60\u20131,000 kg\/h by model<\/div>\n
Barrel range<\/b> 190\u2013280 \u00b0C<\/div>\n <\/div>\n <\/div>\n<\/div>\n\n
\"Engineering<\/figure><\/div>\n\n
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Quick answer<\/h2>\n

An engineering plastics compounding line is a twin screw extruder with side feeding for glass fibre, vacuum devolatilization and a wear package<\/strong>. The resin melts first, fibre goes in after, and everything downstream of the fibre entry is designed to protect fibre length: no 90\u00b0 kneading blocks, gentle 45\u00b0 elements only, bimetallic barrel liners. PA66+GF30 runs at 240\u2013280 \u00b0C barrel with moisture below 0.1%; typical output is 60\u2013700 kg\/h for glass-filled grades and up to 1,000 kg\/h for blends on a KTE-95.<\/p>\n <\/section>\n\n

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30%<\/b>typical glass loading, up to 50% feasible<\/span><\/div>\n
<0.1%<\/b>maximum PA66 moisture before extrusion<\/span><\/div>\n
240\u2013280 \u00b0C<\/b>barrel window, glass-filled PA66<\/span><\/div>\n
3\u00d7<\/b>impact strength of long-fibre vs short-fibre PET<\/span><\/div>\n <\/div>\n\n

Three product families, one process logic<\/h2>\n

Glass-fibre reinforcement, toughening and alloying cover most engineering plastics compounding. The machine logic is identical in all three: dry the resin, melt it clean, add the modifier downstream, vacuum out the moisture, pelletize without breaking what you built.<\/p>\n\n

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Table 1.<\/b> Reference formulations. Typical industry values \u2014 validate against the target grade in a trial before production.<\/caption>\n
System<\/th>Composition<\/th>Ratio<\/th>Critical point<\/th><\/tr>\n <\/thead>\n
PA66 + GF30<\/b>
automotive, electrical<\/td>\n 		PA66 \/ E-glass chopped strand 3\u20134.5 mm \/ silane coupling \/ amide wax lubricant \/ antioxidant<\/td>\n 68 \/ 30 \/ 0.5 \/ 0.5\u20131 \/ 0.2\u20130.5 %<\/td>\n PA66 dried at 120 \u00b0C \u00d7 4 h, moisture <0.1% \u2014 hydrolysis is the number-one cause of batch variation<\/td>\n <\/tr>\n
Toughened PA<\/b><\/td>\n PA66 \/ POE-g-MAH \/ antioxidant<\/td>\n 70\u201380 \/ 15\u201325 \/ 0.3\u20130.5 %<\/td>\n Grafted POE reacts with PA end groups \u2014 compatibilized, not just blended<\/td>\n <\/tr>\n
PC\/ABS alloy<\/b><\/td>\n PC \/ ABS \/ MBS impact modifier \/ antioxidant 1076 + 168<\/td>\n 60\u201370 \/ 30\u201340 \/ 3\u20135 \/ 0.2\u20130.4 %<\/td>\n Both resins dried, PC at 120 \u00b0C \u00d7 4 h<\/td>\n <\/tr>\n
PP \/ talc bumper compound<\/b><\/td>\n PP copolymer \/ talc 1,250 mesh \/ POE \/ coupling agent<\/td>\n 70 \/ 15\u201320 \/ 5\u201310 \/ 0.5\u20131 %<\/td>\n Lower barrel window, 190\u2013220 \u00b0C \u2014 see the temperature profile page<\/td>\n <\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n

Automotive grades are material-certification sensitive. A formulation is validated against the customer's target specification, not copied.<\/p>\n\n

Fibre length decides everything<\/h2>\n

Chopped glass enters the extruder at 3\u20134.5 mm. Published fibre-length measurements on twin screw compounded pellets show it leaves at 0.2\u20131 mm, usually below 0.7 mm<\/strong>. That is not a defect of one machine \u2014 it is what high shear does to brittle fibre, and it is why fibre length, not fibre content, is the variable that separates a good compounded grade from expensive filler.<\/p>\n

The consequence is measurable. At the same 30% glass loading in PET, long-fibre pellets beat short-fibre compounds by:<\/p>\n\n

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1.5\u00d7<\/b>tensile strength, LFT vs SFT<\/span><\/div>\n
1.4\u00d7<\/b>flexural strength<\/span><\/div>\n
3\u00d7<\/b>impact strength<\/span><\/div>\n <\/div>\n\n
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Where the line is drawn<\/h4>\n

A standard twin screw with side feeding makes short-fibre compound \u2014 0.2\u20131 mm retained fibre. Long-fibre (LFT) pellets of 11\u201325 mm cannot be made this way<\/b>: they require a continuous roving pulled through a melt-impregnation die, then cut. If an enquiry specifies LFT pellets, quote an impregnation line, not a side-feed compounding line. Quoting the wrong machine here costs the project.<\/p>\n <\/div>\n\n

Process flow for engineering plastics compounding<\/h2>\n
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  1. Dry the resin.<\/b> PA, PC and PBT at 120 \u00b0C \u00d7 4 h to below 0.1% moisture. Skipped drying shows up later as hydrolysed molecular weight and unexplained batch-to-batch scatter.<\/li>\n
  2. Main feed.<\/b> Resin pellets in by volumetric or gravimetric feeder at the main throat.<\/li>\n
  3. Melting.<\/b> Two to three barrel sections after the main feed, with staggered 45\u00b0 kneading blocks, complete the melt.<\/li>\n
  4. Glass side feeding \u2014 critical point one.<\/b> Fibre enters only after the melt is fully formed, through side feeders. For GF30, distribute the addition over 2\u20133 side ports: add at one port, disperse, add at the next.<\/li>\n
  5. Fibre protection \u2014 critical point two.<\/b> Downstream of every glass entry: large-pitch conveying elements and moderate shear \u2014 tooth-type elements beat kneading blocks. No 90\u00b0 kneading blocks after glass, ever.<\/b> Fibre length survives, and with it impact strength.<\/li>\n
  6. Vacuum devolatilization.<\/b> Standard at L\/D 40\u201344, one vent section, pulling moisture and volatiles from PA and PC.<\/li>\n
  7. Filtration.<\/b> 40\u201380 mesh. Finer screens on glass-filled melts clog fast and break fibre at the breaker plate.<\/li>\n
  8. Pelletizing.<\/b> Water-cooled strand for PA, PC and PBT; underwater hot-face on high-output lines.<\/li>\n
  9. Wear management.<\/b> Glass fibre is a continuous abrasive on flight tips and bores. D-series high-torque drives with bimetallic liners are the standard answer, not an upgrade option.<\/li>\n <\/ol>\n\n
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    Table 2.<\/b> Barrel temperature windows by system. Reference values \u2014 tune on trial.<\/caption>\n
    System<\/th>Barrel, \u00b0C<\/th>Note<\/th><\/tr>\n <\/thead>\n
    PA66 + glass fibre<\/b><\/td>240\u2013280<\/td>Die set slightly below the maximum melt temperature<\/td><\/tr>\n
    PC \/ PC-ABS<\/b><\/td>230\u2013260<\/td>Both resins dried before the hopper<\/td><\/tr>\n
    PBT \/ PET modification<\/b><\/td>240\u2013260<\/td>PET needs drying plus vacuum at the vent<\/td><\/tr>\n
    PP \/ talc<\/b><\/td>190\u2013220<\/td>Wide flat plateau, see the profile-by-material page<\/td><\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n\n

    Equipment configuration<\/h2>\n
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    Table 3.<\/b> Line configuration for glass-filled engineering plastics.<\/caption>\n
    Section<\/th>Recommendation<\/th>Why<\/th><\/tr><\/thead>\n
    Main extruder<\/b><\/td>KTE-50 to KTE-95, D series for high glass loading and high output<\/td>D-series gearboxes carry roughly 1.7\u20132\u00d7 the torque of the same-size B series at equal diameter<\/td><\/tr>\n
    L\/D ratio<\/b><\/td>40\u201344<\/td>Long enough for melt, side feed, dispersion and vacuum; short enough to limit fibre attrition and PA residence time<\/td><\/tr>\n
    Feeding<\/b><\/td>Gravimetric main feed + 2\u20133 twin-screw side feeders<\/td>Splitting the glass addition over several ports disperses each dose before the next arrives<\/td><\/tr>\n
    Screw elements after glass<\/b><\/td>Large-pitch conveying + tooth-type mixing, 45\u00b0 kneading only<\/td>90\u00b0 blocks after the glass entry shred fibre and tank impact strength<\/td><\/tr>\n
    Barrel and screw material<\/b><\/td>Bimetallic liners, W6Mo5Cr4V2 elements<\/td>Glass is abrasive; liners turn a screw replacement into a liner replacement<\/td><\/tr>\n
    Vacuum<\/b><\/td>One vent section, standard<\/td>Removes moisture and volatiles; PA and PC both demand it<\/td><\/tr>\n
    Pelletizing<\/b><\/td>Water-cooled strand (PA\/PC\/PBT) or underwater hot face at high output<\/td>Sample catalogue recommendation for all three resin families<\/td><\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n\n

    Output by model<\/h2>\n
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    Table 4.<\/b> Catalogue reference output, kg\/h. Trial on your own material before contract commitment.<\/caption>\n
    Process<\/th>KTE-50<\/th>KTE-65<\/th>KTE-75<\/th>KTE-95<\/th><\/tr>\n <\/thead>\n
    Engineering resin blends<\/b>
    PP+PE, PBT+PET, PA\/PC\/TPU+ABS<\/td>    		80\u2013180<\/td>160\u2013250<\/td>300\u2013400<\/td>600\u20131,000<\/td><\/tr>\n
    Glass \/ carbon fibre reinforced<\/b>
    PE, ABS, PBT, PET, PA, PC, PPS<\/td>    		60\u2013140<\/td>140\u2013200<\/td>220\u2013300<\/td>500\u2013700<\/td><\/tr>\n
    Long \/ short glass fibre<\/b>
    same resins + PPO<\/td>    		80\u2013140<\/td>180\u2013260<\/td>280\u2013360<\/td>550\u2013750<\/td><\/tr>\n <\/tbody>\n <\/table>\n <\/div>\n

    Fibre-reinforced grades run below blend outputs at equal machine size: dispersion and fibre protection cost throughput. Quote from the lower third of the range and confirm with a material trial.<\/p>\n\n

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