AAC block machines produce Autoclaved Aerated Concrete blocks for modern construction. Runding AAC can provide complete AAC block machine and production line solutions for investors wishing to build or modernize an AAC block factory.

Because the process is continuous and technical, small problems can affect block quality, efficiency, and profitability. This guide explains common AAC block machine problems, possible causes, and practical solutions for daily production.

Raw Material Preparation Problems

Raw material preparation is the first stage of AAC block production. Typically, fly ash or sand, cement, lime, gypsum, aluminum powder, and water are the primary ingredients. If raw materials are not prepared correctly, later production problems may appear during pouring, pre-curing, cutting, or autoclaving.

Common Problems in Raw Material Preparation

Problem	Possible Cause	Solution
Slurry is too coarse	The ball mill grinding time is too short	Increase grinding time and check fineness
Slurry density is unstable	Water ratio changes or poor mixing	Use accurate density control and regular testing
The lime reaction is unstable	Lime quality varies	Test lime activity before production
Sand slurry settles quickly	Poor slurry tank agitation	Check agitator speed and tank design
Raw material blockage	Moisture, lumping, or poor silo flow	Add an anti-blocking device and clean the silo regularly

Practical Solution

Factories should build a raw material testing routine. Regular checks should be made for slurry fineness, density, lime activity, cement quality, and moisture content. If raw materials change, the production formula should be adjusted before mass production.

Batching System Accuracy Problems

The batching system controls the material ratio. If the weighing system is inaccurate, the AAC block may have unstable density, poor strength, cracking, or abnormal expansion.

Common Batching Problems

Problem	Possible Cause	Production Impact
Weighing error	Load cell failure or calibration problem	Formula deviation
Cement or lime overfeeding	Valve closing delay	High strength variation
Aluminum powder dosage error	Manual error or unstable feeder	Poor aeration or collapse
Water addition inaccurate	Flowmeter failure	Slurry density changes
Material discharge delay	Blocked valve or poor control signal	Mixing cycle instability

Solutions

The weighing system should be calibrated regularly. Load cells, pneumatic valves, screw conveyors, and flowmeters should be inspected before production. For aluminum powder, the feeding amount must be especially accurate because it directly affects expansion height, pore structure, and block density.

Mixing and Pouring Problems

Mixing and pouring determine whether the raw materials are evenly blended. Poor mixing may cause uneven pores, low strength, cracks, and surface defects.

Typical Issues with Pouring and Mixing

Problem	Possible Cause	Solution
Slurry is not uniform	Mixer speed too low or mixing time too short	Adjust mixing time and blade condition
Poor expansion after pouring	Aluminum powder reaction is weak	Check aluminum quality, temperature, and formula
Slurry over-expands	Too much aluminum powder or high temperature	Reduce aluminum dosage or control slurry temperature
Cake collapse	Poor formula balance or weak green strength	Adjust lime, cement, gypsum, and pre-curing time
Uneven pore structure	Incomplete mixing	Improve mixer efficiency and feeding sequence

Practical Tips

The slurry temperature should be controlled within a suitable range. Aeration may be sluggish if the temperature is too low. A reaction that is too rapid could result in unstable expansion if it is too high. Operators should record slurry temperature, pouring time, expansion height, and pre-curing performance for each batch.

Mould and Side Plate Problems

The mould system forms the AAC green cake before cutting. Mould quality affects cake shape, demoulding performance, and cutting accuracy.

Common Mould Problems

Problem	Possible Cause	Solution
Slurry leakage	Worn sealing strips or poor mould locking	Replace seals and check locking system
Cake sticks to mould	Insufficient oiling or rough mould surface	Clean mould and apply release oil evenly
Mould deformation	Long-term use or poor steel structure	Repair or replace damaged mould
Uneven cake surface	Mould not level	Adjust mould position and track level
Side plate misalignment	Positioning device worn	Check side plate locking and alignment

Maintenance Advice

Moulds should be cleaned after each use. Release oil should be applied evenly, but not excessively. Too much release oil can affect surface quality, while too little oil can cause sticking and damage during demoulding.

Pre-Curing Problems

Pre-curing allows the poured AAC slurry to gain enough green strength for cutting. If pre-curing is too short, too long, too hot, or too cold, the cutting process may become unstable.

Pre-Curing Problems and Solutions

Problem	Cause	Solution
Green cake too soft	Pre-curing time too short or temperature too low	Extend pre-curing time and control room temperature
Green cake too hard	Pre-curing time too long	Shorten pre-curing cycle
Cracks appear before cutting	Fast temperature change or formula issue	Stabilize curing temperature and adjust formula
Cake surface dries	Poor humidity control	Maintain suitable humidity
Uneven hardness	Uneven pre-curing room temperature	Improve air circulation and heating control

Key Control Points

The green cake should be just solid enough to cut without being overly so. If the cake is too soft, cutting wires may drag and deform it. If it is too hard, cutting wires may break or create rough surfaces.

Cutting Machine Problems

One of the most crucial components in the manufacturing of AAC blocks is the cutting machine. It controls block size, surface smoothness, and finished product appearance.

Common Cutting Problems

Problem	Possible Cause	Solution
Block size is inaccurate	Wire spacing error or frame misalignment	Adjust wire spacing and cutting frame
Cutting surface is rough	Worn or loose cutting wire	Replace wire and adjust tension
Wire breaks frequently	Green cake too hard or wire tension too high	Adjust pre-curing time and wire tension
Block edge damage	Cake too soft or cutting speed unstable	Improve green strength and control cutting speed
Horizontal cut uneven	Wire sagging or poor levelness	Check horizontal wire tension and alignment

Vertical Cutting vs Horizontal Cutting Issues

Cutting Section	Common Issue	Main Solution
Vertical cutting	Uneven width or poor side edges	Check vertical wire position and frame stability
Horizontal cutting	Uneven block thickness	Adjust wire levelness and tension
Cross cutting	Length deviation	Check cutting trolley positioning
Side trimming	Waste edge is not clean	Adjust side trimming wire and cutting path

A high-quality AAC cutting machine should have a rigid frame, accurate positioning, stable wire tension, and easy size adjustment. Regular cleaning is also necessary because slurry residue can affect movement accuracy.

Autoclave Curing Problems

Autoclaving is the process that gives AAC blocks final strength. The blocks are cured using high-temperature, high-pressure steam. Autoclave problems can lead to low strength, cracking, incomplete curing, or safety risks.

Common Autoclave Problems

Problem	Possible Cause	Solution
Block strength is low	Insufficient pressure or curing time	Check steam pressure and extend curing cycle
Blocks crack after curing	Temperature rise or pressure release too fast	Control heating and pressure release speed
Uneven curing	Poor steam distribution	Check steam pipes and trolley arrangement
Autoclave door leakage	Seal aging or poor locking	Replace sealing ring and inspect locking device
Condensate accumulation	Drainage system blocked	Clean condensate drain regularly

Safety Reminder

Autoclaves are pressure vessels. Operators must follow safety procedures strictly. Regular inspections are necessary for pressure gauges, safety valves, door locks, seals, and control systems. Never open the autoclave before pressure is fully released.

Separating and Packing Problems

After autoclaving, AAC blocks need to be separated, stacked, and packed. Poor handling can damage finished blocks and reduce the qualified product rate.

Common Finished Product Handling Problems

Problem	Cause	Solution
Blocks stick together	Cutting gap too small or insufficient separation	Improve cutting accuracy and use separator
Corners break during handling	Weak strength or rough handling	Improve curing quality and adjust gripper pressure
Stack is unstable	Uneven block size or poor palletizing	Improve cutting accuracy and stacking program
Packing is loose	Poor packing tension	Adjust packing machine
High breakage rate	Forklift or conveyor impact	Train operators and optimize transfer speed

Solution

Finished AAC blocks should be handled with stable lifting devices, suitable clamps, and controlled transfer speed. Packing should keep blocks stable during storage and transportation.

Electrical and Control System Problems

Modern AAC block machines often use PLC control, sensors, motors, pneumatic components, and electrical cabinets. Electrical problems can stop production quickly.

Common Control System Problems

Problem	Possible Cause	Solution
Machine does not start	Power failure or emergency stop activated	Check power supply and safety switches
Sensor signal missing	Sensor damaged or dirty	Clean or replace sensor
Motor overload	Mechanical blockage or high load	Check mechanical parts and motor current
PLC alarm appears	Program or component error	Check alarm code and electrical wiring
Pneumatic valve not working	Low air pressure or valve failure	Check air compressor and valve condition

Maintenance Tips

Electrical cabinets should be kept clean and dry. Operators should not randomly change PLC settings. Sensors, cables, terminals, and control buttons should be checked regularly to avoid unexpected shutdowns.

Hydraulic and Pneumatic System Problems

Mould movement, cutting machine placement, lifting, clamping, and material handling are all common applications for hydraulic and pneumatic systems.

Common Problems

Problem	Cause	Solution
Cylinder moves slowly	Low pressure or oil leakage	Check pump, seals, and pressure setting
Pneumatic action is weak	Low air pressure	Check the compressor and air pipeline
Oil leakage	Seal wear or loose joint	Replace seals and tighten joints
Abnormal noise	Air in hydraulic system or pump wear	Exhaust air and inspect the pump
Unstable movement	Valve blockage or poor lubrication	Clean the valve and maintain the system

Regular inspection of oil level, air pressure, seals, hoses, and valves can reduce machine failure.

Boiler and Steam System Problems

The boiler provides steam for autoclave curing. If steam supply is unstable, production quality and cycle time will be affected.

Steam and Boiler Issues

Problem	Possible Cause	Solution
Steam pressure unstable	Boiler capacity insufficient	Match boiler capacity with autoclave demand
Slow pressure rise	Poor combustion or heat transfer	Clean boiler and check fuel system
High fuel consumption	Low boiler efficiency	Improve insulation and maintenance
Steam leakage	Pipe or valve leakage	Repair steam pipeline
Water quality issue	Poor water treatment	Use proper water softening system

Steam system design should match AAC plant capacity. An undersized boiler can become a production bottleneck.

Common AAC Block Quality Problems

Many machine problems finally appear as product quality problems. Operators should use finished block defects to trace possible machine or process causes.

AAC Block Quality Troubleshooting Table

Block Problem	Possible Machine or Process Cause	Solution
Low strength	Poor raw material ratio, weak curing	Adjust formula and autoclave cycle
High density	Poor aeration or low aluminum dosage	Check aluminum powder and slurry temperature
Cracks	Poor pre-curing or fast autoclave pressure change	Control curing schedule
Uneven size	Cutting machine error	Adjust the cutting wires and frame
Rough surface	Worn cutting wires	Replace wires
Broken corners	Poor handling or low green strength	Improve handling and pre-curing
Blocks sticking	Poor cutting gap or separation system issue	Improve cutting and separating process

Preventive Maintenance Schedule

A preventive maintenance system is better than emergency repair. AAC block plants should create daily, weekly, and monthly maintenance plans.

Maintenance Schedule

Frequency	Maintenance Tasks
Daily	Clean cutting wires, check sensors, inspect moulds, check air pressure
Weekly	Lubricate guide rails, check bolts, inspect conveyors, and test the weighing system
Monthly	Calibrate batching system, inspect hydraulic system, check autoclave seals
Quarterly	Inspect the boiler, motors, reducers, electrical cabinet, and control system
Yearly	Full production line inspection, replace worn parts, and safety inspection

Good maintenance reduces downtime and extends machine service life.

How Runding AAC Helps Solve AAC Machine Problems

For long-term production consistency, selecting a trustworthy AAC block machine provider is crucial. A professional manufacturer should not only provide machines, but also offer plant design, installation support, operator training, spare parts, and troubleshooting guidance.

Runding AAC provides complete AAC block machine and production line solutions, including raw material preparation systems, batching systems, mixers, moulds, cutting machines, autoclaves, separating systems, packing systems, and control systems. For investors and factory owners, working with an experienced supplier can help reduce equipment matching problems and improve production efficiency.

Runding AAC can also support customers with customized equipment configuration based on plant capacity, raw materials, factory layout, automation level, and local production needs.

Common AAC block machine problems can result from unstable raw materials, inaccurate batching, poor mixing, mould leakage, weak pre-curing, cutting errors, autoclave issues, or poor maintenance. These may cause cracks, uneven sizes, low strength, breakage, and downtime.

Stable production needs raw material testing, regular maintenance, operator training, process records, and inspections.