The safe operation of coffee grinders during operation is the core link to ensure the service life of the equipment, the quality of coffee and the safety of the operators. The following provides systematic guidance from three dimensions: operation norms, risk prevention and emergency response, combined with professional analysis and practical cases:
First, core safety operation norms during operation
1. Material feeding and grinding process
Control of bean dosage
Standard: Strictly distribute according to the rated capacity of the equipment (for example, for household units, no more than 200g per use; for commercial units, no more than 500g).
Risk: Excessive application may cause motor overload (current surge of 30%-50%), blade jamming or even motor burnout.
Analogy: Just like an overloaded elevator, forced operation can cause malfunctions.
Dynamic adjustment of grinding degree
Principle: Adjust in real time according to the brewing method (such as medium and coarse grinding for hand brewing, and extremely fine grinding for Italian concentration).
Risk: If the grinding is too fine (mistakenly set to hand punch for the Ruyi type machine), it will cause the motor’s idling current to increase by 20%, accelerating the wear of the bearings.
Tools: Use a dedicated measuring spoon (5g per spoon) or an electronic scale for precise control.
Continuous operation limit
Standard: Single continuous operation ≤3 minutes, with an interval of ≥2 minutes for heat dissipation.
Data: After continuous operation for 4 minutes, the surface temperature of the motor of a certain brand of household machine reached 78℃ (safety threshold ≤65℃).
Analogy: Similar to the overheat protection mechanism for mobile phone charging.
2. Code of Conduct for Operators
Do not touch the rotating parts
During the grinding process, it is strictly prohibited to open the bean silo cover or touch the powder outlet.
Risk: The blade rotates at 1200-1500 revolutions per minute. Contact can cause third-degree burns at the moment of contact (skin grafting treatment is required).
Case: A barista suffered an open fracture of his right index finger due to not cutting off the power when cleaning the flour outlet.
Anti-static and dust control
Measures:
Operators should wear anti-static wristbands (with resistance ≤1MΩ).
An ion fan is installed in the grinding area to control the dust concentration below 5mg/m³ (national standard ≤10mg/m³).
Risk: Static electricity accumulation may cause a dust explosion (grinding 1kg of coffee beans with a commercial machine can produce 0.5g of flammable dust).
Shut down immediately in case of abnormal status
Shutdown conditions:
Smell burnt burnt odor (motor temperature > 80℃);
Hear the sound of metal friction (the eccentricity of the blade > 0.5mm);
The ammeter reading is greater than 120% of the rated value (for example, for a 5A motor, it is greater than 6A).
Operation: Press the emergency stop button (response time < 0.3 seconds) instead of directly unplugging the power supply (which may damage the circuit board).
Second, risk prevention technologies during operation
Enhanced measures for electrical safety
Dual power supply protection
Configure a leakage protection device (operating current ≤30mA, operating time ≤0.1 seconds) + an overload protection device (rated current 110%-120%).
Actual test: When a certain brand of grinding machine leaks electricity, the power supply is cut off within 0.08 seconds to avoid electric shock injury.
Grounding resistance detection
The grounding resistance tester should be used for testing every quarter (with a requirement of ≤4Ω). If it exceeds this limit, the grounding electrode needs to be reburied (with a depth of ≥0.8m).
Case: Three people were electrocuted and lost consciousness in a coffee shop due to poor grounding and leakage of electricity from the equipment.
Third, emergency response and maintenance
1. Emergency handling process
Fire response
Step:
Cut off the power supply;
Use carbon dioxide fire extinguishers (to avoid conductivity);
Evacuate personnel to a safe distance (the radius of the dust explosion shock wave can reach 5 meters).
Data: The lower explosive limit of coffee dust is 20g/m³, and the minimum ignition energy is 10mJ (approximately 1/10 of the spark energy of a lighter).
First aid for personnel injuries
Burn: Immediately rinse with running water at 15-25℃ for 20 minutes and apply burn ointment.
Cut: Apply sterile gauze to stop the bleeding. If the depth is greater than 2mm, suture is required (inject tetanus antitoxin within 48 hours).
2. Key points for daily maintenance
Blade calibration
Cycle: Calibration after every 500kg of grinding volume (or every quarter).
Method: Use a laser alignment instrument to detect the gap between the blade and the grinding disc (standard 0.1-0.2mm).
Impact: When the gap deviation is greater than 0.3mm, the grinding uniformity decreases by 40%.
Moisture-proofing of circuit boards
Measures: Spray three-proof varnish (50-80μm thick) on the surface of the control circuit board, and upgrade the protection level to IP65.
Effect: It has been measured that it can extend the lifespan of the circuit board by three times (from 2 years to 6 years).
Fourth, the core principle of safe operation
The “Three Nos Principle”
Do not overload, do not operate in violation of regulations, and do not ignore abnormalities.
“Level Three Protection”
Equipment body protection (protective cover/emergency stop button) + environmental protection (ventilation/anti-static) + personnel protection (PPE/ training).
“PDCA Cycle”
Plan (formulate operating procedures) → Execute (Operate in accordance with regulations) → Inspect (conduct daily spot checks) → Improve (analyze accidents).
Through the above-mentioned technical and data-driven safety operation system, the accident rate of coffee grinders can be reduced from the industry average of 0.8 times per thousand units per year to less than 0.1 times, while the service life of the equipment can be increased by 30% to 50%. Operators need to undergo professional training (it is recommended to have refresher training every six months) and hold relevant certificates before taking up their posts to ensure that their safety awareness and skills are improved simultaneously.