Pin Mill — one machine, three mills
The THOR-PM Series Universal Pin Mill — high-speed, impact-based grinding for fine to medium-fine powders. Engineered for the food, pharmaceutical, chemical and battery industries, it delivers premium milling at a realistic price point — optimising CAPEX so plants of every scale can access top-tier engineering.
- Output
- Fine – micro-fine
- Capacity
- 10 kg/h – 10 t/h
- Motor power
- 3.7 – 250 kW
- Model range
- 6 sizes · Ø160–1000
Three configurations
One base machine
Two intermeshing pin discs — one stationary stator, one ultra-high-speed rotor — fling feed outward through concentric pin rings at over 120 m/s. Swap a screen, spacer ring or grinding liner on the same chassis to run screened, screenless or liner-equipped.
- Tip speed
- 120m/s
- Rotor Ø
- 160–1000mm
- Rotor speed
- ≤18krpm
- Capacity
- ≤10t/h
What is a Pin Mill?
A pin mill is an industrial dynamic-impact grinding machine engineered to achieve fine to micro-fine particle-size distributions. THOR by CI offers the series in two core configurations: Screened and Screenless.
The Screened Pin Mill surrounds the milling chamber with a high-precision sieve to enforce a strict mechanical cut-off size. The Screenless Pin Mill relies entirely on centrifugal aerodynamics to sweep fine particles out — bypassing physical meshes and completely circumventing screen-plugging (blinding). This flexibility lets one platform process dry, crystalline, brittle, oily and soft materials into fine powders.
Where Pin Mill sits on the particle-size scale
How it works
Feed enters at the centre and is flung outward through intermeshing rings of hardened pins — each ring at a larger diameter, so impact energy climbs all the way to the discharge.
Centrifugal feeding
Raw material enters through a central axial inlet and is directed onto the inner concentric ring of pins.
Multi-stage pin impact
Two intermeshing disc plates carry rows of hardened pins; centrifugal force flings feed outward through the rows.
High-velocity collisions
Travelling centre-to-rim, particles hit the pins at over 120 m/s — repeated impact and shear breaking them along crystalline planes.
Classified discharge
Sizing is governed at the periphery — a sieve screen (top-cut), an air-swept spacer ring, or a ribbed grinding liner.
Three mills in one base machine
The peripheral insert is fully interchangeable — change the cut, change the mode, on the exact same chassis.
Screened — Strict mechanical top-cut
An interchangeable sieve screen at the discharge boundary lets only sub-aperture particles pass — tight control over maximum particle size.
Screenless — Air-swept, no blinding
A smooth-bore spacer ring replaces the screen; the rotating disc's air current sweeps fines to a peripheral chute — eliminating any chance of screen blockage.
Liner-equipped — Impact + friction attrition
A segmented, high-durability ribbed grinding liner (breaker ring) slides in — projecting particles against heavy ridges to combine pin impact with aggressive shear.
Main components
Seven core assemblies — engineered around one universal, quick-change chassis.
Standardized housing chassis
Heavy-duty casing with universal internal tracks — screens, spacer rings or liners mount on the same base machine.
Rotor pin disc
Dynamically balanced steel disc with concentric rows of high-strength cylindrical impact pins.
Stator pin disc
Matching stationary disc on the chamber door; its pin rings intermesh precisely between the rotor pins.
Sieve screen insert
High-durability perforated or woven-wire mesh cylinder clamped around the milling zone to enforce strict output limits.
Ribbed grinding liner
Segmented high-chrome or tungsten-carbide breaker-ring inserts that mount in place of the screen for shear-impact grinding.
Drive spindle & bearings
High-precision spindle on oil-mist-lubricated heavy-duty bearings, rated for speeds up to 18,000 rpm.
Hygienic housing door
Single-hinged, quick-opening door exposing rotor, stator and insert zone for fast changeover and deep cleaning.
Advantages & limitations
What the THOR-PM does exceptionally — and where pin-mill physics sets a ceiling.
Advantages
Standardized 3-in-1 platform
Swap screened, screenless and liner modes on one base machine — slashing CAPEX and spare-parts inventory.
Hygienic clean-in-place design
316L stainless, mirror-polished surfaces and seamless welds — a true micro-pulveriser for food and pharma.
Narrow particle-size distribution
Precise intermeshing pin geometry yields a tight PSD — consistent product, minimal over-grinding.
Operational versatility
Runs standalone for intermediate fine grinding, or couples downstream with dedicated classification.
Modular classifier compatibility
For separation down to 10 µm, couple the discharge to a THOR-AC Air Classifier that returns coarse to the mill centre.
Limitations to plan for
Vulnerability to abrasive wear
Quartz, silica or sand (Mohs >3.5) wears the pins fast — risking contamination and frequent pin replacement.
Screen blinding in screened mode
Cohesive, fatty or hygroscopic feeds can bind the sieve — switch to screenless or an air-classification loop.
Friction heat accumulation
High rotor speeds heat the chamber and can melt fats, chocolate or sugar unless water-cooling or LN₂ dosing is fitted.
High idle power draw
Spinning the disc to 18,000 rpm demands substantial power to overcome drag and inertia, even when empty.
Milling, mixing & bulk handling
The THOR-PM Series drops into automated, continuous process lines.
Controlled gravity feeders
Variable-speed rotary valves or electromagnetic vibratory feeders meter the central inlet to prevent over-feeding.
Dust-free pneumatic receivers
Fine powder discharges straight into a vacuum conveyor or positive-pressure transport line — no ambient contamination.
Dynamic air-classifier loops
Couple to a THOR-AC Air Classifier in a closed pneumatic circuit to tune the product top-cut D97 in real time.
Specifications
Six frame sizes from bench-scale to heavy industrial. Final sizing is confirmed after pilot trials with your actual feed material.
| Model | Rotor diameter | Motor power | Rotor speed | Capacity |
|---|---|---|---|---|
| TH-PM-160 | Ø160 mm | 3.7 – 7.5 kW | 6000 – 18000 rpm | 10 – 50 kg/h |
| TH-PM-250 | Ø250 mm | 11 – 18.5 kW | 4000 – 12000 rpm | 100 – 800 kg/h |
| TH-PM-400 | Ø400 mm | 30 – 45 kW | 2500 – 7500 rpm | 800 – 1800 kg/h |
| TH-PM-630 | Ø630 mm | 55 – 90 kW | 1600 – 4800 rpm | 2000 – 4000 kg/h |
| TH-PM-800 | Ø800 mm | 100 – 160 kW | 1200 – 3600 rpm | 4000 – 7000 kg/h |
| TH-PM-1000 | Ø1000 mm | 160 – 250 kW | 1000 – 2800 rpm | 7000 – 10000 kg/h |
Specifications are typical and subject to change. Final sizing confirmed after pilot trials with your feed material.
Other platforms
The rest of the THOR family Compare or pair — air classifying is often integrated with a mill