The usage methods, steps, precautions and application fields of shot blasting tank.
I. Working Principle of Shot Blasting Tank
Shot blasting tank (sandblasting tank, pressure sandblasting tank) is a sealed pressure vessel. Its core principle is:
Pressurization and mixing: Compressed air simultaneously enters the top of the tank (applying pressure to the abrasive) and the spray gun valve.
Conveying: Under the pressure inside the tank, the abrasive enters the mixing chamber through the valve at the bottom and mixes with the high-speed flowing compressed air.
Spraying: The mixed abrasive - air two-phase flow is conveyed to the spray gun through the sandblasting hose and finally ejected at high speed from the nozzle to impact the surface of the workpiece.
Compared with suction sandblasting machines, pressure shot blasting tanks have higher efficiency and are suitable for large-scale continuous operations and heavy-duty cleaning.
Ii. Typical Usage Steps of Shot Blasting Tanks (sandblasting tanks, pressure Sandblasting tanks)
(1) Preparation before assignment
Safety inspection
Personal protection: Full set of protective equipment must be worn, including:
Sandblasting helmet: Offers breathing filtration to protect the head and face.
Protective clothing: Thick cowhide or rubber canvas clothing to prevent abrasive impact damage.
Thick gloves and safety shoes.
Inspection of shot blasting tanks (sandblasting tanks, pressure sandblasting tanks) :
Pressure vessel safety: Check the tank body for obvious rust, depressions or cracks. Make sure the safety valve is working properly and the pressure gauge reading is accurate.
Sealing performance: Check whether the sealing ring of the can lid is intact and free from aging to ensure a complete seal.
Pipelines and joints: Check whether the air hose and sandblasting pipe are worn or leaking, and whether all joints are tightened.
Nozzle: Check if the nozzle is excessively worn (wear can lead to reduced efficiency and increased gas consumption), and replace it if necessary.
Environmental preparation
The operation should be carried out in a dedicated sandblasting room or a closed area.
Ensure that the working area is well-ventilated, the ground is flat and free of oil stains.
Fix or place the workpiece to be processed in an appropriate position.
Shot blasting tank (sandblasting tank, pressure sandblasting tank) preparation:
Feeding: Cut off the gas supply, open the exhaust valve, and release the residual pressure inside the tank. The can lid can only be opened after confirming that the pressure has dropped to zero. Add the selected, dry and clean abrasive to the specified volume (usually 2/3 to 3/4 of the tank's volume), and be careful not to mix in any foreign substances.
Sealing: Clean the sealing surfaces of the tank lid and the tank body thoroughly, confirm that the sealing ring is in place, and then apply even force to close and lock the tank lid.
Connection: Connect the air intake pipe, sandblasting pipe and spray gun properly.
(2) Operation process of shot blasting tanks (sandblasting tanks, pressure sandblasting tanks)
Start the air compressor: Start the air compressor and wait until it reaches the rated working pressure (usually 0.6-0.8 MPa).
Adjust the pressure: Slowly open the main air line valve to allow compressed air to enter the tank. Observe the pressure gauge and adjust the pressure inside the tank to the value required by the process through the pressure regulating valve (different abrasives and process requirements require different pressures).
Start shot blasting: Hold the spray gun, aim it at the surface of the workpiece, and press the trigger of the spray gun to start the operation.
Maintain an appropriate distance (usually 15-30 centimeters) and Angle (usually 70-90 degrees) between the nozzle and the surface of the workpiece.
Move the spray gun evenly to avoid staying in a local area for too long, which may cause excessive removal or deformation of the material.
Monitoring process: During the operation, always pay attention to the pressure gauge reading and shot blasting effect. If the discharge is not smooth or the pressure drops abnormally, the inspection should be stopped immediately.
(3) Cleaning and maintenance of shot blasting tanks (sandblasting tanks, pressure sandblasting tanks) after operation
Emptying and pressure relief: After completing the work, release the trigger of the spray gun first, and then close the main gas line valve. The most important step: Open the exhaust valve on the tank to completely release the residual pressure inside the tank to zero.
Clean the equipment
Open the can lid and clean the remaining abrasives and dust inside the can (if the abrasives are recyclable, they need to be screened and reused).
Clean the dust and waste inside the sandblasting chamber.
Wipe the inside and outside of the equipment clean.
Inspection and maintenance
Check the wear of vulnerable parts such as nozzles, sealing rings and pipelines, and replace them in time.
Drain the condensate water from the air compressor and the water-gas separator.
Proper storage: Organize all the equipment and store it in a dry and clean environment.
Iii. Safety Precautions for Shot Blasting Tanks (Sandblasting Tanks, Pressure Sandblasting Tanks)
Pressure safety: It is strictly prohibited to attempt to open the tank lid or carry out maintenance when there is pressure inside the tank! This is the most dangerous operation, which may cause the can lid to fly out and result in a fatal accident. Be sure to release the air first before opening the lid.
Dust hazard: Shot peening generates a large amount of harmful dust. Work must be carried out in a well-ventilated environment, and a qualified sandblasting helmet must always be worn to provide clean breathing air.
Noise hazard: Shot blasting operations generate extremely high noise levels. It is essential to wear noise-proof earplugs or earmuffs.
Rebound hazard: After high-speed abrasive impacts the workpiece, it will rebound. Unprotected personnel are strictly prohibited from entering the operation area.
Electrical safety: Ensure that all electrical equipment is properly grounded to prevent static sparks.
Iv. Common Problems and Countermeasures of Shot Blasting Tanks (Sandblasting Tanks, Pressure Sandblasting Tanks
Poor discharge or no abrasive ejection
Reasons: The abrasive has run out, the abrasive is damp and has formed lumps, the nozzle is clogged, and the bottom valve is faulty.
Countermeasure: Check the abrasive quantity; Replace the dry abrasive; Clean or replace the nozzle; Inspect and repair the valve.
The pressure dropped too quickly
Reasons: Air pipeline leakage, damage to the sealing ring causing air leakage, excessive wear of the nozzle.
Countermeasure: Inspect and tighten all joints; Replace the sealing ring; Replace the new nozzle.
The shot blasting effect is uneven
Reasons: Uneven movement of the spray gun, unstable distance/Angle, uneven mixing of abrasive or presence of impurities.
Countermeasure: Maintain a stable operation method; Screen or replace the abrasive.
V. Application Fields of Shot Blasting Tanks (sandblasting Tanks, Pressure Sandblasting Tanks)
Surface cleaning: Remove oxide scale, welding slag and old paint from castings, forgings and welded parts.
Surface strengthening/shot peening strengthening: In the automotive and aerospace fields, compressive stress is introduced into the metal surface through impact to enhance the fatigue strength of parts.
Surface finishing: Remove burrs to achieve a matte or uniform decorative surface.
Pretreatment: Before spraying, electroplating or bonding, the surface is roughened to increase the adhesion of the coating.
In summary, shot blasting tanks are highly efficient but potentially dangerous industrial equipment. Successful and safe use depends on strict adherence to operating procedures, comprehensive personal protection, and regular maintenance of the equipment. For beginners, it is essential to operate under the guidance of experienced personnel.