5 questions about single-shaft shredders

1. What are the differences between single- and dual-shaft shredders?

The main difference is straightforward: single-shaft shredders have one rotor and dual-shaft shredders have two. Single-shaft shredders typically operate at variable speeds, offering flexibility depending on the material and processing requirements, while dual-shaft shredders run at a consistent slower speed with higher torque.

The shredding process also is distinct. Single-shaft shredders use a hydraulic ram to push material against the rotor, which cuts it using sharp blades and a stationary counter knife. Dual-shaft shredders rely on two rotors that work together, “biting and pulling” material into the cutting zone to tear it apart.

Another difference is output particle size. Single-shaft shredders have sizing screens for precise, uniform particle sizes ideal for applications that need consistency. Dual-shaft shredders are better when uniformity isn’t as important.

2. What industries typically use single-shaft shredders and how are they used?

Size reduction often is the first step in recycling processes, so single-shaft shredders are used in industries such as plastics, wood, paper and waste management.

In the plastics industry, shredders process production scrap, which can be reintroduced into manufacturing or sold on the market. The wood industry uses shredders to break down material for use in products like animal bedding or for further downstream processing. Similarly, the waste-to-energy sector uses single-shaft shredders in turning material into refuse-derived fuel that powers furnaces, incinerators and more.

3. What materials can a single-shaft shredder process and what materials are a struggle?

Single-shaft shredders are versatile, processing diverse materials, including rigid and soft plastics, film, fiber, wood, composite materials, paper and municipal or industrial waste. However, they’re not ideal for handling metals.

While small amounts of tramp metal present little problem, material streams containing large amounts can damage the machine. Most models include safeguards to manage small metal contaminants and ensure clean output. If you’re unsure about your material, arrange a test run or seek guidance from an equipment expert.

4. How do I determine the right size and configuration of a shredder for my application?

Start with your material—its composition, type, form and input size all affect shredder performance. Different materials, or the same materials at different input sizes, process differently.

Throughput requirements and input size are important and closely linked. A shredder may achieve the desired throughput with a larger-sized output material using a smaller machine, but producing smaller particles at the same rate may require a bigger shredder.

Consider what happens to the material after shredding. Will it go through additional processing? If so, downstream equipment needs may impact your shredder’s configuration.

5. What factors should I consider when purchasing a single-shaft shredder?

Focus on quality, both in construction and performance. A feature-packed shredder won’t help if it’s always breaking down. Choose a reputable vendor with strong after-sales support.

Safety is key. Features like overload protection, amp-load detection and emergency stops ensure safe operations. Maintenance-friendly designs, such as easy-access doors and quick access to wear parts, can save time and reduce downtime.

Finally, think about your specific needs:

• Do you need tramp metal protection?
• Is your material abrasive, requiring a hard-faced rotor?
• Does your process generate heat that would require a cooling system?

If you’re unsure, consulting with an expert can help you make the best choice for your application.