1、 Preparation before operation

1. Equipment inspection

• mechanical parts：
  • Check whether the vulnerable parts such as screws, screw sleeves, and mold heads are worn or cracked, and replace them in a timely manner if necessary (adjust or replace if the gap between the screw and screw sleeve exceeds 0.5mm).
  • Confirm that the tension of the drive belt is moderate (press with fingers to sink 5-10mm), to avoid slipping or breaking.
  • Check the lubricating oil level of bearings and gearboxes, and replenish food grade lubricating oil (such as NSF H1 grade) when it is below the scale line.
• Electrical system：
  • Check if the insulation layer of the power and control lines is damaged, and if the plug connection is secure.
  • Test the sensitivity of safety devices such as emergency stop buttons, temperature controllers, and pressure sensors.
• heating system：
  • Check if the heating tube and thermocouple are intact to ensure accurate temperature display (error ≤ ± 5 ℃).
  • Preheat the equipment to the set temperature (usually 150-200 ℃) to avoid material gelatinization caused by cold machine start-up.

2. Material preparation

• Raw material selection：
  • Use dry and impurity free raw materials (such as corn flour and big Rice noodles), and control the moisture content at 12% -14% (too high will lead to insufficient expansion, and too low will lead to easy burning).
  • Avoid using raw materials that are clumped, moldy, or contain metallic foreign objects to prevent clogging of the screw or damage to the mold head.
• formula adjustment：
  • Adjust the amount of puffing agent according to the characteristics of the raw materials, usually 0.5% -2% of the weight of the raw materials.
  • When producing a new formula, first conduct small-scale trial production to confirm the puffing effect before mass production.

2、 Monitoring during operation

1. Parameter control

• temperature：
  • Feeding area temperature: 80-100 ℃ (to prevent material clumping).
  • Compression zone temperature: 120-150 ℃ (promotes starch gelatinization).
  • Expansion zone temperature: 160-200 ℃ (to instantly vaporize water and form an expanded structure).
  • When the temperature fluctuation exceeds ± 10 ℃, the heating system needs to be shut down for inspection.
• pressure：
  • The pressure in the expansion chamber is usually 0.8-1.5MPa. If the pressure is too low, the expansion rate may be insufficient, and if it is too high, it may cause the die head to burst.
  • Regularly clean the exhaust valve to prevent blockage and abnormal pressure.
• screw speed：
  • Adjust the speed according to the characteristics of the material (usually 100-300r/min). If the speed is too fast, it will cause excessive shearing of the material, while if it is too slow, it will result in insufficient puffing.

2. Observation of material status

• Feeding speed：
  • Maintain uniform feeding and avoid material breakage or accumulation. Cutting materials can cause the screw to slip and wear, and material accumulation may lead to local overheating.
  • When using a variable frequency feeder, set low and maximum feeding limits to prevent overloading.
• Puffing effect：
  • Observing the shape of the product at the discharge outlet: Ideal puffed food should have a smooth surface, uniform pores, and no burnt or unexpanded particles.
  • If the expansion rate of the product is insufficient, the temperature or screw speed can be increased; If it is burnt, the temperature or feeding speed needs to be reduced.

3、 Security protection

1. Personal protection

• operator：
  • Wear heat-resistant gloves (temperature resistance ≥ 200 ℃), goggles, and dust masks to avoid injury from high temperature steam or splashes.
  • Do not wear loose clothing or jewelry to prevent entanglement with transmission components.
• Equipment Protection：
  • Ensure that the protective cover and safety door are closed to prevent hands or tools from coming into contact with high-temperature and high-speed components such as screws and molds.
  • Install a splash guard at the die exit to prevent high-temperature materials from splashing.

2. Emergency response

• Material blockage treatment：
  • Immediately stop the machine and cut off the power supply. After the equipment cools down, disassemble the mold head and clean the materials. Do not stab with hard objects at high temperatures.
• fire prevention：
  • Keep the area around the equipment free of flammable materials and equip it with fire extinguishers (dry powder or carbon dioxide type).
  • If material spontaneous combustion occurs, immediately turn off the heating system, extinguish with a fire extinguisher, and do not pour water.

4、 Shutdown and maintenance

1. Normal shutdown

• step：
  1. Stop feeding and turn off the heating system after no material is discharged from the discharge port.
  2. Continue running the screw for 5-10 minutes to remove residual materials and prevent hardening and blockage after cooling.
  3. Turn off the power and clean the device after it has cooled down.
• clean：
  • Clean the inner walls of the screw and screw sleeve with a soft bristled brush to avoid scratching with steel wire balls.
  • After disassembling the mold head, soak it in neutral detergent, wipe it with a soft cloth, and air dry it.

2. Long term shutdown maintenance

• rust prevention treatment：
  • After cleaning, apply food grade rust proof oil (such as mineral oil) to protect metal parts such as screws and molds.
  • Disassemble vulnerable parts (such as sealing rings) and store them separately to avoid deformation under pressure.
• Environmental Requirements：
  • Store in a dry and ventilated room, with temperature controlled between 5-35 ℃ and humidity ≤ 70%.
  • Power on and run for 10 minutes every month to prevent components from getting stuck or getting damp.

5、 Common Problems and Solutions