Processing procedure Common issues  Causes  Solutions
A. Pre-expansion a. Lumping of material to be expanded 1. Quality issues with material 1. Reapply coating agent
2. The material was stored for too long 2. Use new material or reduce expansion ratio
3. Too much water in pre-expansion chamber and material cannot be easily drained 3. Add a stream trap to the steam hose to unblock the drainage pipe
b. The material to be expanded is moist 1. Excessive water vapor 1. Increase heat preservation and add a steam hose
2. Excessive water in pre-expansion chamber 2. Clear condensed water from the drainage pipe
3. Poor heat preservation in pre-expansion chamber 3. Increase heat preservation
c. Shrinkage of material to be expanded 1. Expansion ratio is too high 1. Decrease expansion ratio and re-expand
2. Environmental temperature is too low 2. Increase environmental temperature, add a fluidized bed, and increase the temperature of the fluidized bed
3. Material to be expanded does not easily discharge and has remained in the pre-expansion chamber for too long 3. Adjust exit baffle plate
d. Expansion ratio is unstable 1. Irregular feeding speed 1. Dry the wet material and unplug the feeder
2. Irregular steam pressure 2. Adjust steam pressure
3. Mixing of different batches 3. Use material from one batch to the extent possible
e. Material to be expanded contains a dead mass 1. High expander speed 1. Decrease expander speed
2. Feed speed is too high 2. Adjust feeding speed to a reasonable level
3. Expansion temperature is too low 3. Increase expansion temperature to a reasonable level
f. Ratio not reached after multiple expansions 1. Factors relating to product quality 1. Replace material
2. Low expansion ratios attained during first and second expansion 2. Control the expansion ratio for each expansion, and do not allow the material to shrink
3. Incorrect time intervals between expansions 3. Shorten or lengthen time intervals between expansions
B. Movement of material to be expanded a. Deformation or increase in density of material 1. Material hit by fan blades when passing fan 1. Use a venturi tube to feed material
2. Small pipe diameter and high flow speed 2. Use a pipe with a diameter of more than 150 mm
3. Pipe angles are too small or tube walls are not smooth 3. Decrease number of pipe angles, increase angles of pipe, and eliminate very small angles
b. Moved material causes blockage 1. Small diameter of pipe 1. Increase pipe diameter and air flow
2. Beads are too wet 2. Add a fluidized bed
3. Too much static electricity among beads 3. Remove the static electricity and use a metal pipe
4. Issues with operation 4. Stop operation of fan when there are no beads in the pipe
C. Curing a. Poor curing 1. Low curing temperature 1. Improve ventilation and increase curing temperature
b. Excessive static electricity in curing storage hopper 1. Incorrect storage hopper material 1. Use a conductive material for storage hoppers
2. Storage hoppers are not grounded 2. Have the conveyor pipe and storage hopper make contact with the ground
c. Beads do not come out of the storage hopper 1. Incorrect orientation of hopper 1. Increase angle with respect to the bottom
2. Static in the storage hopper 2. Use a conductive material for storage hoppers
D. Molding a. Poor fusion 1. Insufficient heating 1. Increase heating time
2. Curing time is too long 2. Shorten curing time to no more than 24 hours
3. Curing time is too short 3. Increase curing time to no less than 4 hours
4. High steam pressure and fast heating speed 4. Use proper steam pressure and the correct heating time and do not use steam that’s too hot
5. Low steam pressure 5. Increase steam pressure to an appropriate level
6. Quality issues with material (incorrect coating agent) 6. Replace material
7. Mold issues
 7.1 Insufficient steam lock power  7.1 Increase steam lock pressure or clean steam lock apparatus
 7.2 Excessive limescale within the mold  7.2 Clean limescale within mold
 7.3 Seal is too weak and amount of escaping steam is too large  7.3 Replace sealing strap
b. Issues with discharging from mold 1. Material sticks to mold due to overheating 1. Shorten heating time
2. Insufficient cooling 2. Increase amount of cooling water or increase cooling time
3. Mold issues
 3.1 Incorrect orientation  3.1 Increase angle for molding discharge
 3.2 Rough mold surface  3.2 Clean the mold surface
 3.3 New mold  3.3 Use mold release agent properly
 3.4 Incorrect ejector pin position  3.4 Properly position the ejector pin in order to evenly distribute force
4. Insufficient ejection force 4. Adjust air pressure
c. Surface on material produced shrinks 1. Overheating 1. Lower steam pressure or shorten heating time
2. Cooling speed is too high 2. Increase cooling water temperature or reduce water volume
3. Insufficient feeding of material  3.1 Check for any blockages in feeder
 3.2 Increase feeding pressure
 3.3 Increase time in mold
 3.4 Use material of appropriate fineness
4. Poor curing of material 4. Increase curing time to 4-24 hours
5. Expansion ratio is too high 5. Adjust expansion ratio
d. Product becomes deformed or swells 1. Poor curing 1. Increase curing time
2. Expansion ratio too high 2. Adjust expansion ratio
3. Certain regions are too hot 3. Check distribution of steam lock pressure
4. Insufficient cooling time 4. Increase cooling water volume or lengthen cooling time
5. Environmental temperature is too low 5. Increase temperature or use a drying room
e. Board becomes deformed or shrinks 1. Curing time is too long or too short 1. Adjust curing time
2. Heating time is too long or temperature is too high 2. Adjust time or temperature
3. Expansion ratio is too high 3. Increase density
f. Product density is uneven 1. Different grades of material are mixed together 1. Use material from the same batch and the same grade
2. Pre-expansion expansion ratios vary throughout material 2. Adjust expansion so as to make expansion ratios consistent
3. Fineness of material varies 3. Use material with consistent fineness
4. Presence of residual material or waste 4. Feed material with a consistent expansion ratio to the extent possible
E. Drying a. Product is moist 1. Products are too close together 1. Arrange products properly
2. Inadequate drying temperature or drying time 2. Increase drying temperature or drying time
b. Deformation of product 1. Product is too close to the radiator 1. Place products away from the radiator and arrange them properly
F. Cutting of blocks a. Heating wire breaks 1. Board contains impurities that cannot be fused 1. When processing, ensure material is free of impurities
b. Heating wire produces corrugations 1. Board contains a lump or hard beads 1. During pre-expansion, ensure the material is free of dead lumps and use material with a consistent density to the extent possible
c. Cut surface is often uneven 1. Blocks contains too much moisture 1. Lengthen drying time or increase drying temperature
2. Expansion ratio varies greatly or low-density expanded material is present 2. Adjust pre-expansion to make the expansion ratio and density even
e. Combustion during cutting procedure 1. Time spent drying is too short or blocks are cut too soon 1. Generally, blocks require at least 24 hours of drying and need to sit for at one week before they can be cut