Why the Cutting Architecture Matters
Search for a scrap shredder machine and you will find three architectures dominating the market: single-shaft, twin-shaft, and hammer mill. They look similar from the outside — a hopper, a drive, a discharge conveyor — but they cut metal in fundamentally different ways, and choosing the wrong one is the most expensive mistake a recycling plant can make. This guide explains how each type works, what it handles best, and where it fits in a scrap processing line.
Single-Shaft Shredders: Precision Sizing with a Pusher Ram
A single-shaft shredder cuts against a fixed counter-knife comb using one rotor fitted with bolt-on knives. Material is pressed onto the rotor by a hydraulic feed ram, and an interchangeable screen under the rotor determines the final particle size.
Best for: aluminum, copper, and brass scrap where output size must be tightly controlled for downstream briquetting, melting, or sale.
The TG-SingleShaft 200 is a typical example: a 55 kW drive, hydraulic feed ram, interchangeable screen for precise particle size control, bolt-on tool-steel knives, and PLC-controlled auto reverse that clears jams without opening the machine. If your plant processes sorted non-ferrous fractions and sells on size specification, this architecture gives you the most control per kilowatt.
Twin-Shaft Shredders: The Mixed-Scrap Workhorse
Twin-shaft shredders use two counter-rotating shafts carrying cutting discs that grip, shear, and tear material between them. There is no screen in the basic configuration — output size is governed by disc width and shaft design — and the slow, high-torque shearing action handles contamination and variable feedstock far better than high-speed designs.
Best for: mixed ferrous scrap, auto bodies, white goods, light iron, aluminum castings, and mixed turnings — in short, unsorted yard material.
The TG-2200 Twin-Shaft Metal Shredder illustrates the top of this class: a 2000 HP (1492 kW) drive rated at 80 tons per hour on mixed scrap, shafts rotating at 12–22 RPM, and bolt-on alloy cutting discs that can be replaced individually in the field. The slow-speed shearing action also produces noticeably less noise and dust than a hammer mill — a practical advantage for yards near residential areas in Vietnamese and Indonesian cities. For lighter duty, the TG-LightMetal 80 applies the same twin-shaft principle to sheet steel, aluminum, copper, brass, and cable on a 2x15 kW drive.
Hammer Mills: Fracturing Dense Metal at Speed
A hammer mill — in metal recycling usually called a heavy-duty metal crusher — swings high-inertia hammers on a fast rotor, fracturing material by impact rather than shearing it. This is the right tool when the metal is too dense or too thick for shearing: cast iron, steel billets, thick-walled sections.
Best for: dense cast iron and steel that must be reduced to consistent charge material for foundries and smelters.
The TG-Hammer 800 Heavy-Duty Metal Crusher uses manganese hammers to fracture dense feed into consistent charge material for downstream melting. The trade-offs are higher noise, more dust, and faster hammer wear on abrasive material — which is exactly why many plants run a hammer crusher as a first stage and a shredder downstream, rather than forcing one machine to do both jobs.
Side-by-Side Comparison
- Cutting action: single-shaft shears against a comb; twin-shaft shears between two rotors; hammer mill fractures by impact.
- Output control: single-shaft (screen) is most precise; four-shaft designs with screen baskets (such as the TG-FourShaft 400, screens 20–60 mm) come close; twin-shaft and hammer mill output depends on tooling.
- Feedstock tolerance: twin-shaft handles the dirtiest, most variable feed; single-shaft prefers pre-sorted material; hammer mills want dense metal.
- Noise and dust: slow twin-shaft is lowest; hammer mill is highest.
- Wear parts: bolt-on knives and discs (single- and twin-shaft) are field-replaceable; hammers are heavier consumables.
How to Choose for Your Plant
Ask three questions. First, is your feed sorted or mixed? Mixed yard scrap points to twin-shaft; sorted non-ferrous points to single-shaft. Second, does your buyer specify output size? If yes, prioritize screened designs. Third, is your material dense enough to resist shearing? If yes, add a hammer crusher stage. Many Southeast Asian recyclers end up with a two-stage layout — for example an integrated system like the TG-ScrapLine 150, which coordinates infeed conveyor, shredding, magnetic separation, and baling into one continuous flow.
All Tiangong machines are CE-marked, configurable for 50 Hz and 60 Hz power, and ship with a spare-parts kit and 12-month warranty. Tell us your material mix and target tonnage, and our engineers will recommend the architecture — and the configuration — that fits.