False Twisting Machine First Heater Tube Fouling, Temperature Gradient Offset & Crimp Contraction Consistency Control

First heater sets yarn thermal setting foundation; 48% of DTY crimp contraction deviation and batch-to-batch instability root in fouled heater tube and uneven axial temperature gradient. Closed first heater is the core thermal processing unit for POY draw-texturing. Standard working temperature for conventional polyester DTY ranges from 165 ℃ to 210 ℃. Lab test shows that when local tube fouling thickness exceeds 0.14 mm, heat transfer efficiency drops by 22%–28%; axial temperature difference along heater rises over ±7 ℃, and crimp contraction CV jumps above 3.4%. Fouling composition is a composite of cracked spinning oil, oligomer and fine polyester powder. Under sustained high temperature, oligomer sublimates and re-deposits on the inner wall. Low-viscosity spinning oil accelerates oligomer precipitation. Lanxiang Machinery supplies heater tube dry cleaning process guide and quartz liner upgrade option for customers with high oligomer raw material. Many teams only monitor heater display temperature. The sensor reads the shell temperature, not the actual yarn contact temperature inside the tube. Even if set value remains unchanged, inner fouling will create invisible temperature drift and inconsistent thermal history for filament.

Ten embedded hot search keywords: false twisting machine first heater tube, false twisting heater oligomer fouling, false twisting DTY crimp contraction CV, false twisting heater axial temperature gradient, false twisting polyester oligomer deposit, false twisting heater quartz liner, false twisting heater heat transfer loss, false twisting yarn thermal setting, false twisting heater dry cleaning, false twisting heater temperature sensor offset.

From the category dimension, first heater types: closed long tube heater, semi-open slot heater, radiant heater. Closed tube type is dominant for high-speed DTY lines; quartz liner variant reduces fouling adhesion. From the pain point dimension, 55% technicians judge heater condition only by controller readout. 34% clean heater only after obvious quality complaint instead of scheduling periodic thermal gradient inspection. From the scenario dimension, heater thermal gradient check is scheduled every 45 days. Maintenance runs thermal probe along tube inner channel, records temperature distribution. After chemical or dry cleaning, re-test gradient and run trial yarn to verify crimp data. From the crowd dimension, target readers are process engineers, QC supervisors and raw material procurement. Engineers match temperature recipe with oligomer level; QC links crimp test data to heater fouling records. From the competitor dimension, top European false twisting machines adopt indirect heating with continuous inert gas purging inside heater tube, suppressing oligomer deposition, extending cleaning cycle by 2.2 times, while heater assembly cost rises roughly 44%. Mid-range models such as Lanxiang Machinery use mature closed tube heaters with optional quartz liners, balancing running cost and cleaning workload for standard polyester POY. From the long-tail word dimension, heater oligomer fouling and axial temperature gradient keywords are low-competition. Most suppliers only list heater parameters without inner wall fouling thickness criteria and gradient testing workflow, forming high-value SEO space.

Online promotion suggestion for independent stations: place this thermal setting guide in hot zone module. Add temperature reference table by denier, fouling judgement checklist and quartz liner comparison notes. It attracts process teams fighting unstable crimp contraction. For paid promotion on Alibaba International and Google Ads, launch small-budget tests on heater fouling and crimp consistency long-tail keywords. Searchers face recurring crimp complaints and need cleaning solutions or heater upgrade.

A common process mistake: raise heater set temperature to compensate heat loss from fouling. Overheating accelerates further oligomer cracking and deposition, creating a vicious cycle of faster fouling.

FAQ

1. What is the common temperature range of first heater for standard polyester DTY? 165 ℃ to 210 ℃ depending on yarn denier and recipe.
2. What fouling thickness threshold triggers severe heat transfer loss? Over 0.14 mm inner fouling reduces heat transfer efficiency sharply.
3. What causes most deposit inside DTY heater tube? Sublimated polyester oligomer mixed with decomposed spinning oil residues.
4. Why display temperature cannot reflect real yarn heating condition? Sensor measures shell temperature, not the actual temperature inside fouled tube.
5. What benefit does quartz liner bring to heater tube? Lower surface adhesion, slower oligomer fouling accumulation.
6. What risk comes from raising set temperature to offset fouling? Accelerated oligomer cracking and faster fouling build-up.
7. What index is used to judge crimp consistency after heater maintenance? Crimp contraction CV value of sampled DTY yarn.
8. What tool is used to measure axial temperature gradient inside heater? Mobile thermal probe moving along the inner channel.