| No | PROBLEM | REASON | SUGGESTION |
|---|---|---|---|
| 1 | Fails to blow up. | 1. Preform temp. too low. (Preform curing time or injection time too long). 2. Blow air pressure too low. Note: Some times first blow fails. Hence, wait for few shots before taking any action. | 1. Shorten curing time. 2. Check blow air pressure ( min. 25 kgf/cm2 ) 3. Check moulding conditions. 4. Check all temperatures for correctness 5. Check cooling water for temp. and pressure. 6. Check dryer for drying time and drying temp. 7. Check dryer is operating correctly. |
| 2 | Bottom comes away on blowing (Stretch rod goes through preform upon blowing). | 1. Temperature of pre form body is lower than bottom. Note: First blow fails sometimes, wait for few shots before taking action. | 1. Decrease overall temperature 2. Shorten curing time. 3. Improve cooling of bottom. 4. Check dryer for drying temp. and drying time. 5. Check dryer is working correctly. 6. Try with material from other bag. |
| 3 | Whitening of parts spread across the container “Pearl-essence” | 1. Preform temperature too low. 2. Material temperature low. Note: Occasionally this kind of trouble will arise when there is thermal imbalance in the injection core pins and injection cavities when starting. | 1. Shorten curing time. 2. Change cushion. 3. Lengthen heating time. 4. Increase heating temperature. 5. Restrict water to individual cavity. 6. Check residence time of material in the dryer. 7. Check dryer is working correctly. |
| 4 | Whitening of part of the product ( no gloss and transparency ) | Preform temp. too high. Note: Crystallisation occurs if stretch temp. is not between 85 ~ 100°C (185-212°F) | 1. Lengthen preform-cooling time. 2. Decrease barrel temperature. 3. Decrease screw RPM. 4. Decrease injection speed. 5. Lower cooling water temp. 6. Check cooling water temp. and pressure. 7. Check dryer for drying time and drying temperature. 8. Check dryer is working correctly. |
| 5 | Gate not forming in the center | 1. Secondary blowing taking place too early. 2. Primary blow air pressure too high. 3. Temperature of lower part of preform too high. Longitudinal stretch speed too low. | 1. Delay secondary blowing. 2. Reduce primary air pressure to 3 ~ 6 kgf/cm2. 3. Lower temp. of this part. 4. Increase speed. |
| 6 | Depression below the neck area | Collapsing due to vacuum creation | Introduce primary pressure early i.e. reduce delay or increase primary pressure till gate is not disturbed |
| 7 | Excess material at the base “Crater” | 1. Preform temperature too high. 2. Uneven preform wall thickness. | 1. Keep preform temp. as low as possible through increasing curing time or by decreasing inj. Speed 2. Check core pins for straightness or clean / replace lip cavities. |
| 8 | Unsatisfactory contours. (Longitudinal direction) | 1. Preform temperature low. 2. Blow air pressure too low. 3. Insufficient air flow | 1. Raise preform temperature. 2. Increase air pressure. 3. * Increase air flow volume. * Provide adequate air vents / clean air vents. |
| 9 | Unsatisfactorycontours(Circumferentially) | 1. Uneven preform temperature & wall thickness. 2. Preform sticking to core pins due to condensation | 1. Refer to “troubleshooting procedures for preform moulding. 2. Refer note on mould sweating |
| 10 | Streaks. | 1. Due to stretching of milky (hazy) portion. 2. Uneven preform temperature. 3. Stretch rod tip may be damaged 4. Due to stretching of milky (hazy) portion. 5. Uneven preform temperature. 6. Stretch rod tip may be damaged | 1. See “troubleshooting procedures for preform moulding”. 2. See “troubleshooting procedures for preform moulding”. 3. Check for possible damage / loose pieces 4. See “troubleshooting procedures for preform moulding”. 5. See “troubleshooting procedures for preform moulding”. 6. Check for possible damage / loose pieces |
| 11 | Low impact strength. | 1. Material has deteriorated. 2. Not oriented or insufficiently oriented. | 1. Moisture level in the material should not be more than 0.004% * Lower resin temperature. * Decrease drying time and drying temperature of material 2. Orient adequately. |
| 12 | Small lumps present. | 1. Water in the blow air. 2. Dust or dirt in the blow air. 3. Dirt in blow cavities. | 1. Check air system dryer 2. Check air filters. 3. Clean blow cavities. |
| 13 | AA Content | 1. Dry resin adequately. | 1. Check drying time and drying temperature. Moisture content in material should be < 0.004% 2. Process the material in lowest possible process window. 3. Minimum Back Pressure, screw rpm, barrel temperature etc. |
| 14 | Low side walk stiffness | Preform temperature too high. | Keep preform temperature as low as possible. |
| 15 | Top load of empty bottle too low (Look at sample bottle after top load test). | 1. Preform temperature too high. 2. Distribution of wall thickness was changed. 3. Material deteriorated 4. Wrong primary blow time 5. Unstable cooling water temp. and pressure | 1. Keep preform temperature as low as possible. 2. Adjust moulding conditions. 3. Check dryer for drying time / temp. * Check dryer is working correctly. 4. Correct primary blow timer. 5. Check cooling water for temperature and pressure. Note: Blowing at lower temperature gives better rigidity, but gives less thermal stability. |
ROYAL PET PREFORM has been a trusted manufacturer of PET PREFORM With state-of-the-art facilities and over 35 years of expertise, we ensure uncompromising quality. Our commitment to innovation and excellence has earned us a strong reputation in the industry.
UMIYA CABLE PVT LTD
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Opp. New Arvind Mills, Nr. Khatraj Cross Road
At & Village - Khatraj, Taluka - Kalol
District - Gandhinagar, Gujarat, India Pin Code -382721
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