What Is a Combination Weigher? Complete Buyer's Guide

What Is a Combination Weigher — Quick Definition

A combination weigher (often called a multihead weigher) is an automated weighing machine that combines weights from several individual heads to reach a target package weight quickly and accurately. Unlike single-head or linear weighers, the combination weigher calculates optimum head combinations in milliseconds and releases selected buckets to deliver the final dose into the packer.

How a Combination Weigher Works

Vibratory Feeding and Distribution

Material is fed from a hopper onto vibratory feeders that evenly distribute product into multiple weighing buckets around the circular weighing head. Proper feeding ensures consistent bucket fill and stable weighing results.

Individual Bucket Weighing

Each bucket is mounted on a high-precision load cell. The machine continuously measures the weight of each bucket and sends the live data to the central controller.

Combination Calculation Engine

The core of the combination weigher is its software. It calculates all possible combinations of bucket weights to find the best match to the target weight with minimal overfill. The selected buckets dump their contents simultaneously into the chute for packaging.

Key Components of a Combination Weigher

Feeder and Distributor

Feeders control product flow and must be selected based on product shape, fragility and flow properties. For example, free-flowing snacks need different feeder settings than sticky, fragile products.

Weighing Heads and Buckets

Combination weighers come in different head counts (common configurations: 10, 14, 16, 20, 24, 32 heads). More heads generally mean higher speed and better accuracy for small-target weights.

Control System and HMI

Modern combination weighers use PLCs and touch-screen HMIs for recipe management, diagnostics, and connectivity (Ethernet, OPC-UA). Advanced models include statistical tools like target weight histograms and yield reports.

Why Choose a Combination Weigher — Main Advantages

High Throughput

Combination weighers are designed for high-speed packaging, typically handling dozens to hundreds of packs per minute depending on product and head count. They are ideal for snack foods, frozen vegetables, confectionery, and more.

Excellent Accuracy and Low Give-away

Because the combination algorithm finds near-optimal sums, these machines reduce overfill (give-away) while maintaining legal compliance — improving product yield and lowering material costs.

Flexibility Across Products

A well-specified combination weigher can handle a wide variety of products: granular, sliced, whole pieces, frozen, and many delicate items. Recipe storage makes changeovers fast.

Combination Weigher vs. Other Weighing Systems — Quick Comparison

Below is a practical comparison of combination weighers, linear weighers, and checkweighers to help you choose the right system for your line.

How to Choose the Right Combination Weigher

1. Know Your Product Characteristics

Consider size distribution, fragility, stickiness and bulk density. Fragile or coated items may need gentler feeders and special buckets; liquids or semi-liquids may require different dosing solutions.

2. Define Target Weight and Tolerance

Smaller target weights usually benefit from more heads because each head carries a smaller portion, enabling finer combinations. Specify the target weight range and acceptable tolerance to determine head count and bucket size.

3. Calculate Required Throughput

Estimate packs per minute and shifts per day. Match the weigher’s rated throughput (for your product) rather than the theoretical maximum. Ask vendors for real-world test data with your product.

4. Consider Sanitation and Material Contact Surfaces

For food and pharma, stainless steel (304/316), smooth welds, and easy-to-clean design are essential. Look for IP-rated motors and washdown-capable designs if you need frequent cleaning.

5. Control & Integration Needs

Ensure the weigher integrates with your existing packaging machines, PLCs, baggers and factory networks. Modern HMIs and remote diagnostics save downtime.

6. Footprint and Layout

Combination weighers occupy floor space and require infeed hoppers above them. Check layout for hopper filling, product handling, and maintenance access.

Installation, Commissioning, and After-sales — What to Expect

Professional Installation and Line Tuning

Optimal performance requires vendor-led commissioning: feeder tuning, recipe setup, and in-line testing. Plan 1–5 days of on-site support depending on complexity.

Training and Documentation

Choose suppliers who offer operator and maintenance training, spare parts lists, and clear manuals. Good training reduces downtime and improves yield.

Maintenance and Spare Parts

Schedule routine checks for load cells, drives, vibratory motors, and bucket surfaces. Keep critical spares such as belts, sensors, and feeder parts in stock. Preventive maintenance extends equipment life and keeps accuracy stable.

Return on Investment (ROI) for a Combination Weigher

How ROI Is Typically Calculated

ROI considers reduced give-away, increased throughput, labor savings and downtime. A simple annual savings estimate can be: Savings = (Give-away reduction per pack x packs/year) + labor & waste savings - annual maintenance.

Example

If a line packages 5 million packs/year and a new combination weigher reduces average give-away by 0.5g per pack (product cost $10/kg), annual material savings = 5,000,000 x 0.0005 kg x $10 = $25,000. Add labor and throughput gains to estimate payback.

Why Kenwei for Combination Weighers

Company Overview and Strengths

Kenwei is a powerful manufacturer of multi-head weighers. We are committed to the development and manufacturing of metal detectors, multi-head weighers, linear weighers, and check weighers. Our machines are characterized by high speed and high precision. We also provide our customers with one-stop automated weighing and packaging solutions to meet customers’ customization requirements. Located in Fusha High-tech Industrial Park, Zhongshan City, Guangdong Province, Kenwei supplies integrated systems, design, manufacturing, installation, technical training and quick after-sales service.

Product and Service Highlights

Kenwei offers a range of combination weighters with 10–32 head configurations, stainless steel construction, user-friendly HMIs and options for high-speed packaging lines. The company emphasizes customization, rapid commissioning, and global support to ensure ROI for food, frozen, snack and industrial applications. Visit https://www.kenweigroup.com/ for product details.

Common Pitfalls When Buying a Combination Weigher

Avoid Overrated Speed Claims

Vendors sometimes quote speeds with ideal products. Insist on test runs with your actual product and packaging to confirm achievable throughput and accuracy.

Neglecting Total Cost of Ownership (TCO)

Consider spare parts, service contracts, installation and changeover time. A lower initial price may mean higher long-term costs if maintenance or support is weak.

Ignoring Integration Complexity

Ensure the vendor provides integration support for your bagger, metal detector and conveyor systems. Poor integration causes line stoppages and reduced throughput.

Practical Checklist Before Purchase

Essential Buyer Questions

Ask these before signing: What head counts are optimal for my target weight? Can you test my product in your demo lab? What sanitation standards does the machine meet? What is the warranty and lead time for spare parts? Do you provide on-site commissioning and training?

FAQ — Frequently Asked Questions

What products can a combination weigher handle?

Combination weighers can handle a wide range: snack foods (chips, nuts), frozen vegetables, confectionery, pet food, salads, bakery items, and many non-food items like screws or small components. Very sticky or slurry-like products may need special solutions.

How many heads do I need?

Head count depends on target weight and throughput. Higher head counts give finer weight increments and higher speed for small target weights. Common choices: 10–16 heads for medium-sized portions; 20–32 heads for high-throughput, small-weight packs.

How accurate are combination weighers?

Accuracy typically ranges from ±0.2g to ±2g depending on product and machine configuration. Real-world accuracy depends on product variation, feeding consistency, and regular calibration.

Can I integrate a combination weigher with my existing line?

Yes. Reputable suppliers provide electrical and mechanical interfaces, as well as communication protocols for SCADA or factory networks. Confirm compatibility during purchase.

What maintenance is required?

Regular cleaning, load-cell checks, feeder tuning, and replacement of wear parts. The vendor should supply a maintenance schedule and recommended spare parts list.

How do I test a machine before buying?

Request a factory acceptance test (FAT) or demo with your product. Real product testing is the most reliable way to verify speed and accuracy claims.

Where can I get more information or a demo?

Contact established manufacturers like Kenwei for product brochures, demo videos, and lab tests with your product. Visit https://www.kenweigroup.com/ to inquire about solutions and demos.