Online Checkweigher

In-Motion Weight Inspection & Automatic Rejection

In-motion weight capture, automatic pass/fail judgement and rejection

Also known as an in-motion or dynamic checkweigher, this machine captures the weight of each product while it is continuously conveyed and judges it against the target weight and tolerance limits set for the current recipe. It is used to find underweight, overweight, underfilled or incomplete products.

The value of an online checkweigher is not simply producing a number. It turns the weight result into an executable production decision: conforming products continue, abnormal products trigger an alarm or are rejected automatically, and the data is recorded.

Four core actions

1. Dynamic weighing – products pass the weighing section continuously and the system captures each weight.
2. Weight judgement – compares the reading against the recipe limits to classify pass, overweight or underweight.
3. Reject handling – alarm, pusher, swing arm or air blow, configured to the product.
4. Data recording – stores weight, output and rejection results, with optional host system connection.

Workflow

1. Product infeed – stable spacing into the weighing section.
2. Dynamic weighing – capture the current product weight.
3. Weight judgement – compare with recipe upper and lower limits.
4. Result execution – pass, alarm or automatic rejection.
5. Data recording – save weight and inspection results.

Typical applications

• Underweight detection – identifies products below the set range, revealing underfill or missing material.
• Overweight detection – finds products above target, helping control filling or packing.
• Missing-part judgement – uses weight difference to indicate whether a component is missing inside the pack.
• Process quality control – treats weight as a quality indicator to observe process drift.
• Line integration – forms a continuous flow with packing machines, print-and-apply labellers, inspection, sorting and conveying.
• Production data recording – stores weight, count and rejection results as required.

Why accuracy cannot be reduced to a single number

Online weighing is a dynamic measurement. Products keep moving on the conveyor, so real weighing performance depends not only on the load cell but also on the product and site conditions.

A more useful question than “what is the accuracy?” is: what weighing result can my product actually achieve at my target speed?

• Product weight and range – the range must match the actual product weight band.
• Product size and centre of gravity – length, base and centre of gravity affect stabilisation time.
• Conveyor speed – higher throughput leaves less time for stable sampling.
• Product spacing – insufficient spacing reduces available settling time.

We recommend confirming performance through sample testing or technical evaluation with real products, target throughput and site conditions, rather than treating a single laboratory parameter as the on-site result.

FAQ

What is the difference between a checkweigher and a weigh-price labeller?

A checkweigher focuses on weight judgement and rejection. A weigh-price labeller additionally generates and applies a label carrying the measured weight and other variable data.

Can it detect missing parts inside a sealed pack?

In many cases yes, by using the weight difference between a complete and an incomplete product. Feasibility depends on how large the difference is relative to the product weight variation.

What rejection methods are available?

Alarm, pusher, swing arm and air blow, selected according to product weight, shape and fragility.

Can weight data be exported?

Yes. Weight, output and rejection results can be recorded and connected to a host system, database or MES depending on the project.

How is the right model selected?

Based on product weight range, size, target throughput and line layout. Sample testing is the most reliable way to confirm performance.

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