Method for adjusting the weighing accuracy of quartz sand packaging
equipment: practical tips for achieving accuracy to ±0.5%
Industry standard requirements: Accuracy error for 25kg bags ≤125g, for 50kg
bags ≤250g (based on GB/T 7724-2020)
1. Mechanical structure calibration (to solve 80% of the basic errors)
1. Sensor installation and calibration
- Horizontal positioning: Use a level meter with a precision of 0.02mm/m to
inspect the scale platform. If the inclination is greater than 0.5°, shims
should be added for adjustment
- Force balance: The diagonal load difference of the four-sensor platform is
less than 3% (tested with a 25kg standard weight)
- Shockproof isolation: Install rubber shock absorbers (with a hardness of
Shore A60±5) to reduce equipment vibration interference
2. Optimization of force transmission mechanism
- Lever cleaning: Remove sand buildup at the hinge points monthly (residual
sand particles increase error by 1.2%)
- Blade maintenance: Use red lead powder to inspect the contact surface of
the blade. If the contact area is less than 80%, it needs to be polished
- Gas path sealing: For cylinder-driven models, it is necessary to test the
stability of gas pressure (fluctuation ≤ 0.05 MPa)
II. Fine adjustment of electrical system (achieving ±0.3% accuracy)
1. Sensor calibration process
- Preheating treatment: No-load energization preheating for ≥30 minutes (to
eliminate the influence of temperature drift)
- Third-level weight calibration:
1. Zero point calibration (empty scale platform)
2. 50% span calibration (e.g., a 12.5kg weight corresponds to a 25kg
scale)
3. 100% span calibration (with a 25kg weight)
- Non-linear correction: Verify by loading 10kg/15kg/20kg weights. If the
error is >0.2%, reset the segmented compensation
2. Signal anti-interference measures
- Independent grounding: grounding resistance <4Ω (isolated from power
cables)
- Shielded twisted pair: A signal amplifier is required when the distance
from the sensor to the instrument exceeds 10 meters
- Filter parameter setting: Set the dynamic filter value to level 3-5 when
quartz sand falls
III. Material characteristic compensation (exclusive scheme for quartz
sand)
1. Precise setting of drop height
- Coarse adjustment method: Quickly add material to 90% of the target value
and then slow down the addition (drop amount = slow addition flow rate ×
0.3s)
- Fine adjustment method: Measure the difference in material discharge 10
times and take the average (for example, if the average over-tolerance of a 50kg
bag is 180g, then the drop compensation is set to +180g)
2. Elimination of electrostatic interference
- Humidity control: Packaging environment humidity ≥ 60% (error increases by
0.8% when below 40%)
- Installation of ion fan: wind speed at a distance of 1.2 meters from the
scale platform is ≥8m/s
- Antistatic additive: spraying 0.01% quaternary ammonium salt solution on
the surface of quartz sand
3. Flow adaptive control
- Speed ratio:
- Coarse sand (20-40 mesh): 60% quick addition → 40% slow addition
- Fine silt (200 mesh+): quick addition 50% → slow addition 50%
- Optimization of vibrating feeder: amplitude of fine silt <2mm, amplitude
of coarse sand 3-5mm
IV. Daily maintenance and verification
1. Precision inspection procedure
- Pre-shift inspection: Verify with standard weights of 5kg and 25kg
(tolerance ±25g/±125g)
- Weekly maintenance:
- Clean the residual sand on the weighing platform (blow with compressed air
at a 45° angle)
- Check the sensor impedance (350Ω±1Ω is normal)
- Monthly calibration: Perform full-range verification according to JJG
564-2019
2. Quick Fault Diagnosis Table
| Phenomenon | Main cause | Solution |
|--------------------|---------------------|-------------------|
| Continuous positive deviation | Insufficient drop compensation | Increase
compensation value by 5-10g/time |
| Irregular fluctuation | Airflow interference | Installing a windshield
|
| Display value drift | Sensor affected by moisture | Baking with hot air at
60℃ |
V. Precision improvement case of a company in Jiangsu
Problem background: The error of 50kg bagged quartz sand reaches ±1.2%
(exceeding the tolerance by 300%)
Implementation steps:
1. Mechanical calibration: Adjust the sensor levelness (originally tilted by
1.8°)
2. Electrical optimization: Set up three-stage filtering (originally no
filtering enabled)
3. Material compensation: Add antistatic agent + reset drop height
result:
- Accuracy improved to ±0.4% (in accordance with GB/T 13507-2022)
- Reduced monthly claim losses by RMB 230,000
- Passed ISO 9001 packaging certification
conclusion
The weighing accuracy of quartz sand packaging is the lifeblood of cost
control and brand reputation. Mastering the three-dimensional adjustment method
of "mechanical calibration + electrical calibration + material compensation",
combined with the daily 5-minute inspection system, can stably achieve the
international advanced level of ±0.5%. It is recommended that enterprises
configure online automatic weight checkers (real-time monitoring for each
package) to build a complete packaging quality defense system.
Get customized services for the "Quartz Sand Packaging Accuracy Improvement
Plan" now, with a professional team of engineers providing on-site calibration
within 72 hours!