I Feed cannot enter the ring die.

Cause

1. Bridged inlet of the feeder  

2. Clogged conditioner    

3. Failure of the feeder’s driving device

Solution

1. Clean the inlet.

2. Clean the conditioner.

3. Check the driving device for feeder.

II Material can enter the ring die, but cannot be pelletized.

Cause

1. Worn-off of press rollers and ring die 

2. Too many die holes are clogged.  

3. The feed formula is changed. 

4. The clearance between the press rollers and ring die is too large. 

5. Improper water content in feed

Solution

1. Replace the press rollers and ring die.

2. Remove the feed and impurity from the die holes.

3. Install the ring die properly for the feed formula to be processed.

4. Readjust the clearance between the press rollers and ring die.

5. Adjust steam amount correctly.

III The pellet mill cannot be started up.

Cause

1. The press rollers and ring die in pelletizing chamber are clogged. 

2. Limit switches cannot touch the brake plate or the operation bar, or have been damaged.

3. Circuit failure

Solution

1. Remove the feed from the pelletizing chamber.

2. Check the limit switches for mounting status.

3. Check the circuit.

IV Load of pellet mill fluctuates unreasonably or the pellet quality is uneven.

Cause

1. Steam supply is not enough or the pressure changes sometime. 

2. Unstable conveying of material

3. Deflecting plate scrapers are worn which causes uneven feeding.

Solution

1. Check the steam pipelines.

2. Adjust the feeding rate.

3. Replace the deflecting plate scraper.

V Pellet mill stops during working

Cause

1. V-belts are not tensioned enough, which makes the speed controller actuate. 

2. The parameter of speed controller is not reasonable. 

3. V-belts are seriously worn off partially or completely or broken.

4. The main shaft rotates and limit switch escapes because of overload or a foreign matter is entrapped between the press rollers and ring die.

5. Circuit failure

Solution

1. Readjust the tension of V-belts or check the pressure value on the pressure gauge of hydraulic system, reset the pressure value if necessary (Be careful when adjusting). 

2. Reset the parameter.

3. Replace the V-belts completely, not partially.

4. Reset the main shaft and limit switch. 

5. Check the circuit.

VI The pellet mill is clogged frequently

Cause

1. Deflecting plate scrapers are worn and material is distributed unevenly. 

2. Press rollers are worn off. 

3. A press roller gets stuck. 

4. The installation positions of the deflecting plate scrapers are incorrect. 

5. The moisture content in feed is too high.

Solution

1. Replace with new deflecting plate scrapers. 

2. Replace with new press rollers. 

3. Check the press rollers. 

4. Reassemble the deflecting plate scrapers.

5. Decrease the moisture content.

VII  Pellet mill is smoking

Cause

1. The scrapers are worn off and there is a layer of hard material formed between the supporting plates of the rotors and the press rollers. 

2. Tension of V-belts is not enough. 

3. Hard material deposited behind the back supporting plate, which makes the main shaft lack of lubrication.

Solution

1. Install a new scraper.

2. Tighten the V-belts.

3. Clear away hard material and lubricate the main shaft till lubricating grease overflows from the back.

VII  Ticks are heard when the pellet mill makes each rotation.

Cause

Tramp metal in the ring die

Solution

Check the inner surface of the ring die and clear away the tramp metal.

IX V-belts are slipping when they are under full loading or overload a bit.

Cause

1. Tension of V-belts is not enough 

2. The length of V-belt in a group is different.

3. V-belt is contaminated by grease.

4. Wrong location of V-belt

5. The external form of V-belt is incorrect

Solution

1. Readjust the tension of V-belts.

2. Replace with a complete set of belts of the same size.

3. Clean the V-belts and pulley.

4. Calibrate the motor and middle pulley.

5. Use qualified V-belts

X  Output of the pellet mill is not enough, while the main motor works under full load.

Cause

1. Too much steam added (only for materials sensitive to temperature and humidity)

2. The ring die is too thick

3. Bad steam quality and too much water content

4. Material is not sufficiently conditioned

5. The clearance between the press roller and ring die is too big

6. The press roller and ring die are over worn

7. Bad formula or too big grinding pellet

Solution

1. Reduce the steam adding amount.

2. Use the ring die with a depth proper for the material to be processed. 

3. Readjust the steam supply system. 

4. Increase the steam amount or the extend the conditioning time. 

5. Readjust the clearance. 

6. Replace the press rollers and ring die.

7. Adjust the formula or replace with a sieve with smaller apertures in the hammer mill.

XI  The ring die is broken when worn to a certain extent.

Cause

1. Foreign matters in the die   

2. Ring die is too thin.   

3. Fixing of the ring die is out of order.

Solution

1. Perfect the material cleaning operation.  

2. Use a thicker ring die with holes with step relieves.

3. Check whether the driving rim of the ring die and the fixing bolts are locked sufficiently or not, and replace the driving rim of the ring die if necessary.

XII  The bearings of the press rollers are vulnerable.

Cause

1. There are hard foreign matters in the feed.

2. The clearance between the press roller sand ring die is too small.

3. Improper lubricating grease is used.

4. Lubricating grease applied for the press rollers is insufficient.

5. Bad bearing end cover and seal ring are used.

6. Unqualified press roller bearings provided by other suppliers are used.

Solution

1. Improving material cleaning performance.

2. Adjust the clearance between the press rollers and ring die.

3. Apply lubricating grease as designated.

4. Apply enough lubricating grease as designated.

5. Replace the end cover of bearing and seal ring.

6. Use the bearings provided by normal manufacturers

I Temperature of expansion chamber cannot reach to rated temperature

Causes

1. Jacked steam line is blocked

2. The inlet steam line of expansion chamber is blocked

Solutions

1. Clean the jacked steam line

2. Clean the inlet steam line of expansion chamber

II Conditioning temperature cannot reach to requirement

Causes

1. Steam pressure is not sufficient

2. Steam line is blocked

Solutions

1. Check steam pressure, adjust it normally to 4bar

2. Clean the steam line

III Materials surface is coarse with different length after expansion

Causes

1. Poor conditioning

2. Part of die plate holes blocked

3. Insufficient particle size

4. Die plate is in bad quality

Solutions

1. Condition the materials

2. Stop to clean the die plate

3. Increase particle size

4. Use die plates manufactured from qualified works

IV Throughput reduced

Causes

1. Shearing block is worn

2. Sever wearing to screw head

Solutions

1.Replace shearing block

 2. Replace screw head

V Do not discharge after normal operation

Causes

1. Excessive short-time feeding or material cut-off;

2. Die holes are blocked.

Solutions

1. Stop the machine and check.

VI Wave type intermittent discharge

Causes

1. The fullness of expansion chamber is insufficient.

Solutions

1. Increase throughput.

VII Insufficient expansion

Causes

1. Ripeness of materials is insufficient.

Solutions

1. Increase throughput;

2. Raise conditioning temperature;

3. Raise jacket heating temperature;

4. Increase rotating speed of principal machine.

VIII Excessive expansion

Causes

1. Over-high temperature;

2. Over-high rotating speed of principal machine;

3. Die plate hole area is not matched with the throughput.

Solutions

1. Reduce temperature;

2. Reduce rotating speed;

3. Change the die plate hole area or adjust throughput.

IX Over long or over short expanded pellet

Causes

1. Over high or over low cutting speed.

Solutions

Adjust rotating speed of the cutting drive.

X Poor product forming

Solutions

1. Improper formula of raw materials;

2. Over high or over low processing temperature;

3. Unstable feeding;

4. Over high or over low moisture content in product;

5. Improper cutting speed;

6. Blade is worn;

7. Too large grinding particle size.

Solutions

1. Change formula of raw materials;

2. Recombine the components in machine barrel;

3. Adjust to even feeding;

4. Reduce or increase moisture or steam addition volume;

5. Adjust to a proper rotating speed;

6. Replace blade;

7. Grind the raw materials further to reach a finer particle size.

I Abnormal noise in the machine.

Causes

1. Foreign matters entering.

2. Fixing screws of the hammer blades are loose.

3. The toothed ring or stream splitting cover is loose.

4.There is collision between the grading impeller and convex shape cover.

Solutions

1. Open the operation gate or grading system and remove impurities.

2. Fasten the fixing screws.

3. Check for that the clearance between the impeller and its surroundings is 1.5 mm.

II Abnormal noise, vibration or overheat of bearings

Causes

1. Foreign matters exist in the bearing chamber.

2. Damaged bearings

3. Deformed main shaft

Solutions

1. Dismount it and clean and dry it.

2. Replace the bearings. 

3. Find out the causes and replace the main shaft. 

III Decreased production capacity

Causes

1. Mash adheres to the toothed ring or grading impeller. 

2. The hammer blades or geared ring are worn.

3. Reduced air volume.

Solutions

1. Remove foresight matters adhering on to the toothed ring or grading impeller. 

2. Replace the hammer blades and toothed ring. 

3. Check the fan, filter bags of the dust collector, and adjust the air volume.

IV Uneven ground particle size, and averagely increased particle size.

Causes

1. The toothed ring or hammer blades are worn, and the clearance increases.

2. The blades of the grading impeller are worn.

3. The blades of the grading impeller are adhered by mash.

4. Pipeline air leakage and unstable air volume.

Solutions

1. Replace the toothed ring and  hammer blades. 

2. Replace grading impeller. 

3. Clear the mash adhering on to the blades of the grading impeller.

4. Check the pipeline and seal it.

V Violently increased noise and vibration

Causes

1. The grinding disc losses its dynamic balance.

2. Mash adheres to the toothed ring. 

3. Damaged bearings.

4. Too loose triangular belts

Solutions

1. Check and rectify the dynamic balance.

2. Remove mash adhesion on the geared ring. 

3. Replace the bearings. 

4. Tighten the triangular belts.

VI Current overload

Causes

1. Too high feeding rate

2. Increased adhesion in the grinding chamber 

3. Clogged materials 

Solutions

1. Lower the feeding rate.

2. Remove thoroughly adhesive substance.

3. Properly increase suctioned air volume.

VII The motor can’t be started up.

Causes

1. Damaged motor 

2. Circuit trouble.

Solutions

1. Replace the motor. 

2. Remove circuit trouble.

1 In case the machine stops while it is working, the discharge gate should be opened to clear off all materials prior to restarting the motor;

2 If material leakage occurs at the discharge gate, it is necessary to check the contacting condition of the discharge gate with the housing. If the discharge gate cannot be closed tightly, loosen the nuts on both ends of the connecting lever firstly, and then adjust the length of the connecting lever to a proper position; if it is caused by an aged seal strip, the seal strip should be replaced;

3 When the discharge gate is closed with no signal given out, that means the limit switch is at incorrect position or the circuit is broken, so the position of the limit switch should be adjusted and checks should be made on the circuit;

4 If the discharge mechanism cannot work normally, it is necessary to check the cylinder and air supply system for any failure, and check the pipe connection for its conformity to the requirements;

5 If material leakage at shaft ends during operation is caused by the loose bolts on the sealing cover, it is necessary to screw them up tightly; if it is caused by aged sealing members, it is necessary to replace them timely. If there is not enough space for replacing the sealing members, the sprocket and bearing pedestal should be disassembled firstly, then the sealing gland, finally the sealing members should be replaced

6 If light friction noise occurs during the operation of the machine, the position of rotors can be properly readjusted, and the paddles can be ground if necessary.

I Motor unable to be started

Cause

1. Circuit problem

2.Malfunction of the safety switch of the access door

Solution

1. Check and repair the wiring

2. Check and repair or replace the safety switch

II Motor hard to be started

Cause

1. Too low voltage

2.Too small section area of the wires

3. Too small starting compensator

4. Fuse liable to burn out.

Solution

1. Avoid the power consumption peak and re-start

2. Replace with appropriate wires

3. Replace with a bigger compensator

4. Replace with a new fuse mating the motor load

III Motor overheated and not powerful

Cause

1. Motor running in two phases

2. Short circuit of motor coil

3. Long-term overloading

Solution

1.Connect another phase, keep running in 3 phases

2. Repair the motor

3. Running under rated load

IV Hammer mill vibrating violently.

Cause

1. Improper hammer arraying

2.Excessive difference between the weight of the two hammer groups

3. One or two hammers are jammed,  or not sensitive to be thrown apart

4.Other parts on the rotor not in balance

5. Main shaft bended

6. Bearings worn

7. Hammer’s pin-shafts worn off.

8. No gap between the two halves of coupling

9. Coupling parts not concentric

10. Anchor bolts not strong enough

Solution

1. Install them according to the hammer arraying plan

2. When replacing hammers, keep the weight difference within 2 g.

3. Free the hammers

4.Balance the rotor

5.Straighten the shaft or replace with a new one

6. Replace the bearings

7. Renew all the pin-shafts

8. Adjust the gap to 3-5 mm

9. Re-adjust, keep the level difference within 0.2mm, and non-concentricity<1°

10、Reinforce the anchor bolts

V Abnormal noise from inside of the hammer mill

Cause

1.Iron impurities or stones inside the machine

2. Inner component parts come off or broken

3. Too little gap between hammers and screen

4. Offset rotor

Solution

1.Stop machine to remove rigid foreign matters

2. Stop to check up, replace the parts

3. Keep a proper gap

4. Check and adjust

VI Lower productivity

Cause

1. Insufficient power of motor

2. Hammers worn severely

3. Material fed unevenly

4. High moisture in raw materials

5. Wrong screen used

6. Blocked dust filter bags of the air assist system

7. Low percentage of the opened screen area

Solution

1. Check and repair the motor

2. Shift the hammer tips or replace with new hammers

3. Make the feeding even

4. Dry raw materials

5. Replace the screen

6. Clean or replace the filter bags

7. Choose a screen with a high opening rate

VII Material regurgitation from inlet

Cause

1. Blocked conveying pipe

2. Blocked screen holes

3. Position of the guiding plate not in accordance with the rotation direction of rotor

Solution

1. Eliminate the blockage

2. Dredge the screen holes or replace with a new screen

3.Shift the guiding plate position or change the motor running direction

VIII Too coarse mash product

Cause

1. Screen worn severely or broken

2.Screen improperly fitting with its supporting frame or too big side gap

Solution

1. Repair or replace the screen

2. Stop to check and repair, tighten the screen on to the frame

IX Overheat of bearings

Cause

1. The centers of main shaft and motor are not concentric with each other

2. Too much or too little or poor lubricant

3. Damaged bearings

4.Bended main shaft or unbalanced rotor

5. Long-term overloaded operation

6. Wrong lubricant No.

Solution

1.Adjust the motor to make it concentric with the main shaft

2.Change the lubricant and refill it as per regulations

3. Renew the bearings

4.Straighten the main shaft and balance the rotor

5. Reduce feeding amount

6. Reselect the Molybdenum Disulfide Lithium-based Grease