Filling Weight Variation: Compare Accuracy and Product Giveaway

A filling machine can hit the target on one container and still produce an expensive production run. To compare equipment properly, look at the average net fill, variation between packs, underfilled packs and extra product given away. Measure these under the same conditions instead of relying on one demonstration reading.

This guide explains a practical comparison method for procurement. It complements our accepted output and operator workload test, which covers the full operating cycle rather than dosing alone.

Define what the pack declares

Start with the quantity shown on the retail package: mass, volume or another declared measure. Net mass is the gross filled mass minus the container and closure mass included in the weighing step. A volumetric machine setting and a scale reading are different measurements, so state which result determines acceptance.

If the pack declares volume but the trial uses weighing, agree how density and temperature are handled. Do not silently treat one gram as one millilitre for every liquid. Product characteristics and the applicable sales-market requirements determine how the final pack should be checked.

Check the measurement system first

Use a scale suitable for the pack and the tolerance you want to evaluate. Its displayed resolution, condition and verification matter, as do a stable surface, drafts and vibration. An unstable reading can look like filler variation even when the dispensed portion is unchanged.

Decide whether each empty container will be weighed or a representative tare will be used. Individual tare readings make container variation visible. If an average tare is used, quantify how much the empty containers vary and consider whether that approach can support the intended comparison.

Separate startup from steady production

At startup, operators may prime the product path, remove air or adjust the recipe. Record these packs and adjustments rather than quietly discarding them from the whole-shift result. Then identify a steady production sample in which the settings remain unchanged.

Repeat the check after product replenishment and after a planned pause. For a multihead filler, label the filling head as well as the sample sequence. A combined average can hide one head running high and another running low. Keep the observations traceable to the conditions that produced them.

Use a simple comparison sheet

For every sampled pack, record the time or sequence number, filling head where applicable, gross mass, tare and calculated net mass. Add the target quantity and the agreed acceptance limits. Note spills, missing containers and manual corrections separately rather than treating them as ordinary good packs.

• The mean shows the average net content across the sample.
• The lowest and highest readings show the observed range, not the full possible production range.
• The spread between readings helps compare repeatability under the tested conditions.
• The number outside the agreed limits shows which packs need attention.
• The number of acceptable packs per hour connects quality to useful output.

Agree the sample size and timing before the test. A handful of favorable readings should not become a guarantee for an entire shift, and changing the sampling method between suppliers makes the results harder to compare.

Calculate extra product without hiding short fills

For a simple purchasing illustration, imagine an average measured net fill of 503 grams against a 500 gram target. The average excess is 3 grams per pack. Across 2,000 packs, that would represent 6 kilograms of additional product. These are illustrative numbers, not the performance of a MUJIU model or a recommended production setting.

The average alone is not enough. Some containers could still fall below the required limit while others are filled heavily. Reducing the setting to save product before understanding the variation may increase rejects. Compare excess product alongside the distribution of net weights and the applicable packaged-quantity requirements.

Investigate variation before changing the target

Possible contributors include inconsistent product supply, air in the product path, changes in temperature, unstable container positioning, nozzle drips and different adjustment between heads. For powders, flow and bulk-density changes may also affect the dose. Work through the observed conditions systematically instead of compensating for every problem by adding more product.

Change one setting at a time and repeat the same measurement procedure. Record the effect on output, cleanliness and rejected packs as well as the weight result. A slower cycle may improve one measure but change the line capacity you need; a faster cutoff may reduce dripping while altering the final portion.

Put the agreed method into the purchase specification

State the product, container, target quantity, operating conditions, measurement procedure and acceptance limits together. Ask the supplier to record actual results against that method during the equipment trial. Keep commercial claims about accuracy separate from the details of how accuracy was measured.

Use the machine acceptance checklist to connect the weight test with operation, changeover and handover checks. Send MUJIU your filling project details, including the declared pack quantity and required accepted output, to discuss an appropriate comparison and equipment configuration.