Calibrating a Multihead Weigher: Simple Steps to Improve Accuracy

Introduction: Why Calibrating a Multihead Weigher Matters

Understanding the business need for precise weighing

Accurate weighing directly impacts product quality, yield, and regulatory compliance. Manufacturers using multihead weighers need predictable performance to reduce giveaway, prevent underfills, and meet customer specifications. Calibrating a multihead weigher is a practical, repeatable process that ensures consistent accuracy and reduces downtime — especially important for high-speed applications where even small errors multiply across thousands of packs.

Preparation: Get Ready Before You Calibrate

Gather tools, choose representative product, and warm up the machine

Before you start calibration, collect calibrated test weights or certified reference samples, cleaning supplies, and any vendor-specific diagnostic tools. Use a product sample representative of your production run (size, shape, moisture, flowability). Run the weigher for a 10–30 minute warm-up to stabilize electronics, pneumatic systems, and feeding behavior. This preparation reduces variance and speeds up the calibration cycle.

Leveling and Mechanical Checks: The Foundation for Accuracy

Ensure stable mechanical conditions and clean weighing heads

Begin by checking the machine is level, firmly anchored, and free of vibration sources that can skew readings. Inspect feed chutes, hoppers, and weighing buckets; remove product residue and dust. Replace damaged or sticky parts. Mechanical stability is essential — even well-tuned electronics cannot compensate for a tilted frame or inconsistent product flow.

Zero and Tare: Establish a Clean Baseline

Reset the scale to eliminate offset errors

Perform a zeroing routine on the entire system to clear offsets in electronics and load cells. If the multihead weigher supports per-head tare adjustments, confirm tare values are correct and reset if needed. Zeroing should be done with no product in the system and after mechanical checks to avoid introducing bias.

Static Calibration: Verify Load Cell Response

Use certified test weights to check each head

Static calibration verifies the linear response of each weighing head. Follow the manufacturer’s procedure to place known weights on each head or a calibration fixture, and record the displayed values. If discrepancies exceed acceptable limits, adjust the head gain or calibration factor. Static checks are often faster and highlight faulty load cells or signal issues early.

Dynamic Calibration: Simulate Actual Production

Run product through the machine and compare to target weights

Dynamic calibration evaluates performance under real operating conditions. Feed product at normal speed and run multiple cycles. Compare the weigher’s outputs to manual or lab-verified weights. Pay attention to distribution, hopper filling, and vibration during this test. Adjust software parameters — such as combination algorithm, compensation factors, and head delays — to correct systematic bias.

Head Balancing and Individual Head Tuning

Balance heads to reduce variability and improve combination accuracy

Head balancing ensures each weighing head contributes consistently to combinations. If one head consistently over- or under-weights, tune its sensitivity, check the mechanical condition of its bucket and suspension, and adjust feed rates. Balanced heads increase the pool of viable weight combinations and lower the average giveaway required to meet targets.

Feed System and Product Handling: Optimize Flow

Adjust vibratory feeders, gate speeds, and chute geometry

Uneven or pulsating product feed causes inconsistent fills and calibration drift. Tune feeder amplitude, frequency, and gate timing to ensure smooth, even feed into hopper pockets. For sticky, friable, or irregular products, consider flow aids or redesigned dosing chutes. Proper product handling reduces rejections and stabilizes weighing performance.

Software Settings: Fine-Tune Algorithms and Compensation

Use the weigher’s software to refine combinations and tolerances

Modern multihead weighers include algorithms that select head combinations to achieve target weights with minimal giveaway. Adjust parameters like maximum heads per combination, combination priority, and acceptable variance windows. Enable temperature or humidity compensation if supported. Back up configuration profiles so you can restore validated settings quickly.

Verification Runs and Statistical Validation

Confirm calibration with repeated test lots and statistical checks

After adjustments, execute verification runs: minimum 30–100 packs depending on production volume. Record measured weights and calculate mean, standard deviation, and percent out-of-tolerance. Confirm results meet customer specifications and internal quality targets. Statistical validation builds confidence and documents that the weigher performs reliably under production conditions.

Documentation and Calibration Records

Keep traceable logs for compliance and continuous improvement

Document calibration steps, parameter changes, verification data, and any replacement parts or repairs. Maintain calibration certificates for test weights and instruments. A clear calibration history supports audits, helps diagnose recurring issues, and improves MTTR (mean time to repair) by providing a troubleshooting trail.

Routine Maintenance and Calibration Schedule

Establish daily, weekly, and monthly checks

Create a practical schedule: daily operational checks (visual inspection, zero check), weekly performance spot-checks (sample packing and verification), and monthly or quarterly full calibration including static and dynamic procedures. Higher-volume or critical product lines may require more frequent validation. Regular maintenance extends component life and keeps accuracy within tolerance.

Troubleshooting Common Calibration Problems

Identify and fix frequent causes of drift and inaccuracy

Common issues include contaminated load cells, loose electronics connectors, worn bucket pivots, uneven product distribution, and environmental influences (temperature, draft). If accuracy degrades quickly after calibration, suspect mechanical wear or environmental instability. Use the machine’s diagnostic tools and consult the manufacturer when faults persist.

Environmental Factors: Control What You Can

Minimize temperature, humidity, and vibration effects

Weighing performance can be sensitive to ambient conditions. Keep the weighing area temperature-stable, protect electronics from drafts, and isolate the machine from heavy machinery that induces floor vibrations. If operating in extreme environments, consider insulation, enclosures, or temperature compensation features in the control software.

When to Contact Kenwei for Calibration Support

Expert assistance for complex products, high-speed lines, and system upgrades

Kenwei is a global manufacturer of multihead weighers with deep experience in high-speed, high-precision systems. If calibration challenges persist after in-house troubleshooting — or if you need on-site commissioning, training, or tailored combination algorithms — Kenwei provides one-stop automated weighing and packaging solutions, installation, technical training, and after-sales support from Guangdong Kenwei’s experienced team.

Business Benefits of Good Calibration Practices

Reduced giveaway, fewer rejects, and improved throughput

Well-calibrated multihead weighers reduce product giveaway and underfills, improving profit margins and brand trust. They also minimize rejects and rework, improving line uptime and throughput. Investing in calibration and preventive maintenance delivers measurable savings and supports regulatory compliance for weight declarations and packaging laws.

Conclusion: Make Calibration a Repeatable, Documented Process

Standardize the steps and commit to continuous improvement

Calibration is not a one-time fix — it’s an operational discipline. Standardize procedures, train operators, and keep clear records. Perform pre-shift checks, scheduled full calibrations, and statistical verification after product or environmental changes. With these steps, you’ll improve weighing accuracy, reduce waste, and get the most value from your Kenwei multihead weigher or any other system.

FAQ — Common Questions About Calibrating a Multihead Weigher

How often should I calibrate a multihead weigher?
Daily operational zero checks are recommended; perform weekly spot-checks and a full static + dynamic calibration monthly or after any significant product change, maintenance, or detected drift. High-speed or high-value lines may require more frequent validation.

Do I need certified test weights for calibration?
Using NIST-traceable or nationally certified weights for static calibration is best practice. For dynamic validation, use representative product samples weighed on a calibrated laboratory scale to confirm production performance.

What tolerance should I aim for?
Tolerance depends on product, pack size, and customer requirements. Typical industry expectations range from a few tenths of a percent of pack weight for high-value items to larger tolerances for coarse, bulk products. Align targets with contract specifications and regulatory requirements.

Can software alone fix accuracy problems?
Software tuning helps, but persistent inaccuracy often stems from mechanical issues, product handling, or environmental factors. Combine mechanical maintenance, feed optimization, and software adjustments for reliable results.

What if one weighing head is inconsistent?
Check for mechanical damage, worn pivots, contamination, and electrical connector issues. Run static tests on that head to isolate the problem. If the load cell is faulty, replace or recalibrate it per manufacturer guidance.

Does Kenwei offer calibration services or training?
Yes. Kenwei provides installation, commissioning, technical training, and after-sales support. For complex products or high-speed lines, Kenwei’s engineers can assist with on-site calibration, algorithm tuning, and preventive maintenance planning.

How do I document calibration for audits?
Maintain a calibration log with dates, personnel, procedures used, test weight certificates, verification data (sample sizes and statistics), and any corrective actions taken. This traceable record demonstrates control and compliance.