Why the drum screen grader is replacing roller graders as the preferred chestnut sizing solution — with accuracy improved from 75% to 90%+.
The Problem with Roller Graders for Chestnuts
In the past, when customers asked for a chestnut sorting machine, the industry default was the roller grader — the same machine used for cherry tomatoes and other round fruits.
But chestnuts are not round like cherry tomatoes. They have irregular, asymmetrical shapes — ranging from round to oval with varying degrees of flattening. They don't roll predictably between rollers. They shift, tilt, and wedge themselves into gaps that don't truly represent their size.
The result? Inconsistent sizing, misgraded nuts, and lost revenue.
Drum Screen Grader — Designed Specifically for Chestnuts
Fstsort now recommends a drum screen grader purpose-built for chestnuts. Unlike roller graders adapted from other fruits, this machine was engineered specifically for irregular agricultural products like chestnuts.
How it works:
Chestnuts enter a rotating drum. As the drum turns, they gently tumble over round holes of increasing sizes. The smallest chestnuts fall through the first set of holes, medium through the next, and the largest continue to the end. Each size exits through a separate outlet.
Why round holes make the difference:
· Roller graders measure chestnuts from one orientation — irregular shapes can slip through sideways
· Drum screen graders measure diameter from every angle as the nut tumbles — only chestnuts smaller than the hole size pass through
The result? Grading accuracy improved from 75% to 90%+ with customized drum hole sizes.
Key Advantages of the Drum Screen Grader
Feature | Benefit |
|---|---|
Round holes | Match the natural shape of chestnuts for accurate diameter separation |
Gentle tumbling | No cracking, no jamming — preserves nut integrity |
Consistent sizing | Precise diameter separation grade after grade |
High capacity | Up to 5–10 t/h |
Low maintenance | Simple design, easy to clean |
Adjustable grades | Change drum screens for different size ranges |
Flexible grade count | 3–6 grades, installed separately — not limited by container space |
Technical Specifications
All parameters are customizable to your specific requirements.
Parameter | Range |
|---|---|
Capacity | 3–10 t/h |
Number of grades | 3–6 |
Hole sizes | Customizable by diameter |
Material (food contact) | Stainless steel |
Voltage | 380V / 220V / 415V |
Common Grade Sizes for Chestnuts (Example)
Grade | Diameter Range | Typical Use |
|---|---|---|
Small | < 20 mm | Processing, peeling |
Medium | 20–25 mm | Retail, fresh market |
Large | 25–30 mm | Premium retail |
Extra Large | 30–35 mm | Specialty, export |
Jumbo | > 35 mm | High-end export |
We can customize according to any size.
Optional: Add a Washing Line
The drum screen grader can operate as a standalone sorter or be combined with a chestnut washing line for a complete solution.
The washing line includes: bubble washing tank, water sprinkles & brushes, air blowers, and a roller inspection table for manual sorting.
Updated: 2026 — New washing option now available based on Australian client feedback — a deeper tank option is now available to more effectively eliminate bad or empty nuts and impurities.
Not Sure Which Configuration Fits Your Chestnuts?
That's exactly what we're here for. Every operation is different — different volumes, different grade requirements, different budgets. If you want to know which sizes are suitable for your chestnuts, please visit our product page of chestnut washing, drying and grading line→