Pharmaceutical Checkweigher | GMP Compliant Weight Inspection
Pharmaceutical manufacturing operates under GMP, which treats weight as a critical quality attribute rather than a commercial specification. A pharmaceutical checkweigher verifies every single tablet, capsule, sachet or blister against its declared fill weight, and records the result so the evidence exists for every batch released.
Why GMP requires 100% weight inspection
In pharmaceutical production, sampling cannot detect a systematic filling fault. If a filler runs slightly light for an extended period, a sampled check every hour will still pass, but the batch as a whole is underweight and must be rejected. Full inspection removes this failure mode. Because each reading is recorded against a timestamp and a product recipe, the production record becomes defensible evidence during an audit.
Typical pharmaceutical products
| Solid dosage forms | tablets, capsules, caplets, effervescent tablets |
|---|---|
| Blister and strip packs | blister packs, foil strips, pill sachets |
| Powders and granules | sachet powders, granules, lyophilised powder |
| Liquids and semi-solids | small bottles, vials, ointment tubes |
| Medical consumables | swabs, dressings, small device pouches |
GMP design requirements
Three design elements matter in a GMP environment. The frame and conveyor brackets must be food or pharmaceutical grade stainless steel with seamless welding and no crevices that cannot be cleaned. The control cabinet should be sealed and flush-mounted so it can be wiped down without residue traps. Where the line is washed down, an IP65 front panel and stainless steel cabinet are appropriate. Openings should be limited so that the machine cannot leak product or harbour organisms.
Data integrity and traceability
The most important feature of a pharmaceutical checkweigher is not the mechanics, it is the record. A compliant system stores up to 2000 product recipes, records pass, reject and total counts per batch, and exports individual weight records over USB or Ethernet. Those records can be written to your plant management system or MES, providing the per-unit evidence that a sampling-based system can never produce. Search by batch number, date or shift to retrieve the full history.
How to specify a pharmaceutical checkweigher
State the lightest and heaviest unit weight, the accuracy you need relative to the smallest dose, the throughput, the pack dimensions, and whether the machine will be washed down. For very light pharmaceutical products, specify the minimum scale division rather than only the accuracy, because a load cell that cannot resolve the dose will not give useful data. Confirm the data export format matches what your quality system expects.
Frequently asked questions
What accuracy is required for pharmaceutical products?
It depends on the dose size. A common specification is accuracy of ±0.5% of the target weight, but for very small doses you should require the minimum scale division to be at least one tenth of your smallest permitted weight variation.
Can the checkweigher meet GMP cleaning requirements?
Yes, provided the machine has a seamless stainless frame, a sealed cabinet and a quick-release conveyor. Specify the ingress protection level appropriate to your wash-down regime and confirm the surface finish during commissioning.
Is data export required for GMP?
For full traceability, yes. The standard expectation is that individual weight records are retrievable for every batch produced. USB and Ethernet export are both normally required, and the format should be agreed with your quality team before purchase.