ROTATIONAL MOULDING TROUBLESHOOTING GUIDE

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Problem Possible causes Possible solution
  Air Entrapment Insufficent heating Cook to a higher peak internal air temperature
 Powder quality  Powder may too course or contains tails. Consult powder supplier
 Cycle time too short Increase heating time
  Corners do not fill Design - sharp corners or small gaps between walls Redesign mould
 Powder has poor dry flow Contact Powder supplier
  Failure during Chemical Storage Contents not compatible with container Discontinue or revise service life appropriately
 Design - Stress concentrators present Redesign mould
 Thickness insuffient Increase shot weight
 Service temperature too high Increase shot weight, reduce maximum exposure temperature
  Flashing Contamination in part line Ensure good cleaning practices
 MFI of polymer too high Change to a lower MFI grade
 Unevenly clamped mould Check clamping mechanism
 Poor venting Check vent is not blocked and is of sufficient size
  Insufficient Rigidity in Moulding Wall thickness too thin Increase shot weight
 Density of Resin too low Trial higher density resin
 Design Design stiffening features or ribs may be required
  Odour, shiny yellowish internal surface Overcuring Reduce temperature or heating time. Reduce peak internal air temperature
  Parts Stick in Mould Insufficient mould release due to inadequate application Reapply mould release
 Mould release diminished with number of shots Reapply mould release
 Design Check for undercuts
 Mould damage Inspect mould and repair if required
 Poor mould finish Inspect mould and repair if required
  Poor Impact Properties Design Review Design , minimising any sharp corners or areas of stress concentration
 Undercure - Small voids are present in wall sections Cook to a higher peak internal air temperature
 Overcure - Internal surface is shiny Cook to a lower peak internal air temperature
 Choice of Polymer Lower Density and/or lower MFI grades may enable increased impact resistance
  Wall Thickness Variation Poor powder quality. Tails and poor flowability Contact Powder supplier
 Incorrect rotation Alter rotations
 Variable heating of the mould walls Check for thickness variation of the mould wall. Check for shielding effects
  Warpage Uneven Cooling due to large thickness variations Alter rotation ratio. Review design
 Uneven Cooling due to premature separation from mould surface Reduce mould cooling or apply internal cooling. Reduce mould release
 Poor Venting Check vent is not blocked and is of sufficient size

The information contained in these guidelines is provided in good faith and may assist with problem solving and troubleshooting.

The information is offered solely for your information and is not all-inclusive – other variables or constraints may impact the ability of the user to apply them. The user should conduct its own investigations and satisfy itself as to whether the information is relevant to the user’s requirements. The user should not rely upon the information in any way. The information shall not be construed as representations of any outcome for which Qenos assumes any legal liability. Qenos expressly disclaims liability for any loss, damage, or injury directly or indirectly suffered or incurred as a result of or related to anyone using or relying on any of the information. There is no endorsement of any product or process, and Qenos expressly disclaim any contrary implication.

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