Weighing and Packaging Machines for Granules, Powders, and Bulk Products

Powders, granules, legumes, nuts, and dry mixes can vary in density. The same volume of product can weigh differently from batch to batch, from one bag of raw material to another, and even from the beginning of a shift to the end. Weighing and packaging machines address this issue by weighing the portion itself rather than measuring the volume going into the package. This allows the fill weight to be controlled even when the product’s density varies.

Weight consistency also matters when supplying customers and retail chains. The declared weight on the packaging needs to match the actual contents, and repeated underweight packages can result in customer complaints. Weighing each portion provides the factory with a documented weighing process and better control over fill weights.

Weighing vs. Volumetric Filling: What Is the Difference?

Volumetric filling measures the portion by a fixed volume and is an excellent solution for products with a stable density. Weighing filling, also called gravimetric filling, weighs the portion before it is released into the package. For products with varying densities, gravimetric filling allows for a higher level of accuracy and helps reduce two problems that fill deviation can create: underfilling that exposes the plant to weight complaints, and overfilling that increases raw material consumption over time.

The difference also becomes important when switching between products. A line that switches between different mixtures based on volume requires recalibration with each change, while a weighing system can switch to the required weight for the next product through the control system.

How Does a Weighing and Packaging Line Work?

A weighing system is typically integrated into a larger packaging line. A typical line for bulk products includes feeding the product into the weighing unit, weighing the batch, controlled release into the package, and final packaging in a bag, box, or tray. In the IMPAC catalog, this family is represented in several configurations:

• FLASH: A semi-automatic machine for weighing and filling dry materials in granular or bulk form, in which the filling is based on a vibrating channel that feeds the product to the weigher.
• Weighing and filling machine for powders and granules: A dedicated configuration for powdery and granular products that require precise dosing.
• VFFS systems for filling bulk products and packaging them in a bag: The machine forms the bag from a roll, fills it with the weighed portion, and closes it, with precise cutting according to the graphics printed on the roll.
• Filling and packaging of powders in bags in a fully automatic configuration, for continuous production lines.

The connection between the weighing unit and the packaging machine is an important part of the line design. The weighing rate must be synchronized with the rate of bag formation or box construction. If the two rates are not synchronized, one machine may have to wait for the other, reducing the effective line rate.

Which Products and Industries Use Weighing and Packaging Machines?

Seasonal industries, such as holiday nuts or agricultural produce at peak season, also need to consider line flexibility. A properly configured weighing system can switch between different products in a controlled manner, allowing the same line to serve several products throughout the year instead of being shut down between seasons. This can help make better use of the investment without purchasing a separate line for each product.

What Should You Consider When Choosing a Weighing System?

Three factors are particularly important when selecting the system. The first is the product behavior: a powdery product that tends to clump requires different handling than a heavy, free-flowing granule, and this affects the feed system. The second is the batch size and batch range: a line that packages both hundreds of grams and large batches requires a different design from a line for a single fixed batch. The third is the destination of the batch: a bag that is formed in place, a rigid container, or a sack. Each of these affects the packaging machine that follows the weigher.

The system should also be no more complicated than necessary. For a factory starting with medium output, a semi-automatic machine like FLASH provides weighing accuracy without requiring investment in a fully automatic line and allows for further growth.

What Should You Test Before Ordering a Weighing System?

Product testing is an important part of designing a weighing line because catalog specifications cannot show how every product will behave during feeding and filling. Testing with real samples examines how the product flows through the feed system: whether it flows freely, tends to bridge in the funnel, becomes airborne, or breaks in the passages. Each behavior can affect the required feed configuration, and it is better to identify these issues before the machine is designed.

The behavior of the batch when released into the package should also be tested. A fragile product like a snack requires a soft fall, while fine powder requires dust control so that the bag’s sealing area remains clean. A bag whose sealing area is contaminated with powder may close weakly, and this type of defect may only be discovered by the customer. A short test with real material can help identify these issues in advance and provide a reliable basis for defining the effective rate of the line.

How IMPAC Selects a Weighing System for the Product

IMPAC specializes in adapting the filling solution to the actual behavior of the product, and this is especially important in weighing applications. Before building the line, the product itself is examined: how it flows, how it behaves during feeding, and what happens to it when released into the package. Based on these factors, the feeding configuration, weighing unit, and subsequent packaging machine are determined, either from the catalog or through a dedicated adjustment. The experience gained since 1974 in designing industrial systems allows the feeding, weighing, and packaging stages to operate as one synchronized system.

Summary

For bulk products, weighing and packaging machines help control one of the factors that directly affects line profitability: the weight of each package. Accurate weighing filling helps reduce raw material waste caused by overfilling, helps protect the plant from weight complaints, and maintains a steady pace throughout a shift. 

Contact IMPAC with a sample of your product and the required portion data, and our engineering team will help define the weighing and packaging configuration for your line.

Frequently Asked Questions