What are the common faults of the vermicelli cutting machine

The vermicelli cutter is a key piece of equipment in the vermicelli production line, used to precisely cut the continuously extruded vermicelli to the 

set length. Due to the high water content of vermicelli (usually 30% to 40%), its sticky and soft texture, and the fact that the equipment needs to operate 

at high speed for a long time (with hundreds of cuts per minute), it is prone to malfunctions caused by mechanical wear, material blockage or improper 

operation. The following are common faults, cause analysis and solutions of the vermicelli cutting machine, covering four major modules: transmission 

system, cutting components, electrical control and material handling:

I. Transmission system failure

The rotational speed of the cutting blade is unstable

Phenomenon: The blade rotates at different speeds, resulting in a deviation of more than 5mm in the length of the cut vermicelli 

(the standard should be ≤2mm).

Reason

The pulley is worn or the belt is slipping (the contact area between the belt and the pulley groove is less than 70%);

Fluctuations in motor speed (unstable voltage or wear of motor carbon brushes);

The gears in the reducer are worn (the tooth side clearance is greater than 0.5mm).

Solution

Replace the worn pulley or adjust the belt tension (with a deflection of 10 to 15mm when a 50N force is applied to the center point).

Check the power supply voltage (stable within the range of 380V±5%), and replace the motor carbon brushes

 (replacement is required if the contact surface wear is greater than 1/3).

Disassemble the reducer, replace the worn gears or adjust the side clearance of the teeth (by adding or removing gaskets).

2. The conveyor belt slips or deviates

Phenomenon: Uneven conveying speed of vermicelli leads to misalignment of the cutting position

 (such as normal cutting at the front end but offset at the back end).

Reason

The tension of the conveyor belt is insufficient (the adjusting bolts of the tensioning device are loose).

Powder residue adheres to the surface of the roller (the coefficient of friction decreases);

The joints of the conveyor belt have aged and cracked (resulting in local relaxation).

Solution

Rotate the tensioning device bolts to ensure that the conveyor belt does not slip on the rollers and there is no obvious sagging (sagging amount ≤20mm).

Rinse the surface of the roller with a high-pressure water gun (pressure ≤0.3MPa), or apply a food-grade anti-stick coating (such as polytetrafluoroethylene).

Re-vulcanize or mechanically connect the conveyor belt joints (ensure that the joint strength is ≥ 80% of the conveyor belt body strength).

Ii. Faults in the cutting components

1. The blade wears out quickly or breaks

Phenomenon: The blade develops a dull edge after 1 to 2 days of use, or suddenly breaks during operation (the fracture surface shows brittle characteristics).

Reason

The blade material does not match (65Mn spring steel or 9CrSi alloy steel should be selected, with a hardness of HRC52 to 56).

When cutting, the sand content in the vermicelli is high (the raw material is not thoroughly cleaned, and the hardness of the sand particles is greater 

than that of the blade).

The blade is installed too tightly (causing stress concentration) or too loosely (vibrating during cutting).

Solution

Replace the blades that meet the standards (for example, 65Mn steel needs to undergo quenching and tempering treatment);

Strictly control the raw material cleaning process (sand content ≤0.5%), and add filter screens (mesh size ≥100 mesh).

Adjust the torque of the blade fixing bolt (use a torque wrench, the standard value is usually 15 to 20N·m).

2. The cutting surface is uneven

Phenomenon: Burrs, adhesion or flattening appear on the cut surface of the vermicelli (affecting the appearance and taste of the product).

Reason

Blade Angle deviation (the standard Angle is 30° to 45°. A deviation greater than 5° will cause uneven distribution of cutting force);

The gap between the blade and the conveyor belt is too large (the gap should be ≤0.5mm; otherwise, the vermicelli will be squeezed and deformed).

The moisture content of the vermicelli is too high (when it exceeds 45%, its stickiness increases and it is prone to stick to the blade).

Solution

Use an Angle gauge to correct the installation Angle of the blade. The deviation should be ≤±2°.

Adjust the blade height adjustment bolt to make the gap meet the standard.

Control the degree of gelatinization of vermicelli (starch gelatinization degree ≥85%), and reduce the moisture content to 38% - 42%.

Iii. Electrical Control Faults

1. The cutting length error is large

Phenomenon: The cutting length is set at 20cm, but the actual length fluctuates between 18 and 22cm.

Reason

Encoder failure (loss or interference of pulse signals);

PLC program logic error (such as improper setting of counter parameters);

The sensor position is offset (the distance between the photoelectric sensor and the vermicelli is greater than 5mm, resulting in detection delay).

Solution

Check the encoder connection lines (with the shielding layer grounded), and replace the damaged encoder (with a resolution of ≥1000 pulses per revolution).

Re-debug the PLC program (ensure that the cut-off signal is synchronized with the blade rotation period);

Adjust the sensor position (2 to 3mm away from the edge of the vermicelli, and set the sensitivity to medium).

2. Frequent equipment shutdowns

Phenomenon: It suddenly stops during operation, and the control panel shows "Overload protection" or "Emergency stop trigger".

Reason

Motor overload (cutting resistance > 120% of the motor's rated torque);

Aging of electrical components (such as erosion of contactor contacts, misoperation of thermal relays);

The operator accidentally touched the emergency stop button (the button was stuck or there was a short circuit in the circuit).

Solution

Reduce the cutting speed (by adjusting the speed through a frequency converter) or check if the blade is blunted.

Replace the contactor (contact capacity ≥ 1.5 times the motor rated current) and the thermal relay (operating current setting value = motor rated current ×1.1).

Check the circuit of the emergency stop button (use a multimeter to measure the continuity and repair the short circuit points).

Iv. Material handling failure

1. The vermicelli blocks the cutting edge

Phenomenon: Vermicelli accumulates under the blade, causing the equipment to get stuck (manual cleaning is required before restarting).

Reason

Uneven ripening of vermicelli (with local hard cores or soft lumps);

The cutting speed is too fast (the rotation frequency of the blade is greater than 1.2 times the extrusion speed of the vermicelli);

Insufficient cooling (the stickiness of the vermicelli increases when the temperature exceeds 40℃).

Solution

Adjust the cooking process (steam pressure 0.2-0.3MPa, time 3-5 minutes);

Reduce the blade speed through a frequency converter (to match the extrusion speed);

Increase the cooling air volume (wind speed ≥3m/s) or extend the length of the cooling conveyor belt (≥5m).

2. There are too many pieces of vermicelli

Phenomenon: A large amount of debris is produced after cutting (debris rate >5%, affecting the yield of finished products).

Reason

Blade blunting (tearing the vermicelli during cutting rather than shearing);

The conveyor belt is too fast (the vermicelli breaks after being stretched).

The design of the cutting edge is unreasonable (such as excessive gap between the blade and the support plate).

Solution

Regularly sharpen the blade (use an oilstone to polish the cutting edge after each shift to keep it sharp);

Reduce the speed of the conveyor belt (in sync with the rotation period of the blades);

Optimize the cutting edge structure (using a combination of "blade + support plate", with the support plate material being food-grade stainless steel).

V. Suggestions for Fault Prevention and Maintenance

Daily inspection

Before each shift, check the blade fastening bolts, belt tension and sensor position.

During operation, the cutting length, motor temperature (≤70℃) and noise (≤75dB) should be recorded every two hours.

Regular maintenance

Change the lubricating oil of the reducer every 200 hours (it is recommended to use 320 # industrial gear oil).

Clean the electrical cabinet every 500 hours (blow off the dust with compressed air and check the tightness of the terminal blocks).

Spare parts management

Reserve key spare parts (such as blades, belts, encoders) to ensure that production can resume within 2 hours after a failure.

Establish a spare parts life file (for example, if the average life of a blade is 800 hours, prepare for replacement 100 hours in advance).