two hands in white gloves holding dark, grainy rubber material.

Grinding of rubber

Two different solutions for one material

Whether tire rubber or technical rubber from production: customers of diverse application areas benefit from Hosokawa Alpine’s solutions for cryogenic and ambient rubber grinding for maximum fineness. This task places special demands on machines and systems. For example, it is important to coat the grinding tools, as they otherwise wear out more quickly due to the fillers in the rubber which can lead to machine downtimes. Here, Hosokawa Alpine has developed special solutions for both ambient and cryogenic grinding.

Another challenge to the process is that finely ground rubber is very flexible and yields during screening. This complicates the screening process and requires special solutions, especially when classifying finenesses < 180 µm. The Stratoplex ASP II air classifier provides a remedy: the classic air classifier from Hosokawa Alpine can separate very fine fractions (e.g. 75 µm, 125 µm, 180 µm ...) from the ground material. For coarser fractions, a centrifugal screen is installed in the ambient system.

Energy efficient grinding
Solutions for cryogenic and ambient rubber grinding
Grinding and classifying from a single source

Ambient grinding

New technologies for the grinding of rubber

The feed material is ground by means of pressure and shear stress. We can now deliver the highest-quality machines for your plant and product safety in the ambient grinding of rubber. We have combined our know-how to offer you customised process technologies for optimum solutions.

Features and benefits of ambient grinding:

End fineness easily achievable by using an in-line screening machine
No oversized product due to closed-loop process
Fine powder with very good flowability and a high surface quality

Ambient grinding solutions with Hosokawa Alpine's Rubber Powder Mill (RP)

The Hosokawa Alpine Rubber Powder Mill (RP) works continuously in grinding and classifying. It can handle all vulcanised rubber types with more than 45 Shore. Due to grinding technology, a very low energy consumption without cooling (process temperature 60–85 °C) is possible. The grinding tools have slowly rotating discs and are silent in operation. The grinding and classifying process is performed in a closed loop without oversize particles. The classifying step uses a specially designed screen in which the sieve mesh is quickly interchangeable for different applications/requirements.

Active rubber powder from 100–1000 μm with very large surface energy
Reduced material costs
Great mixing ability of the active rubber powder
Time-reduced vulcanization
Mixing up to 80 % in the production of TPE

Typical particle sizes after the ambient process (using a 630-μm screen)

< 100 μm	12 %
< 160 μm	24 %
< 250 μm	40 %
< 315 μm	52 %
< 400 μm	67 %
< 500 μm	82 %
< 630 μm	98 %

Technical specifications

	RP 500	RP 600
Throughput capacity (kg/h)	up to 300	up to 400
Process temperature	60–85 °C	60–85 °C

Cryogenic grinding

Find your optimum solution for the grinding of rubber

The feed material is cooled down to the "glass transition temperature" by liquid nitrogen. With the specially designed Hosokawa Alpine Contraplex CW II pin mill – in combination with our Stratoplex ASPII classifier – we guarantee innovative technology from one single source for highest quality in grinding of rubber.

Features and benefits of cryogenic grinding:

Fractions below 125 μm at high yield and very low “oversize” content
Fine powder with very good flowability
Separation of different fractions with Alpine Stratoplex ASP II classifier
Fine powder in cubic form with a smooth surface

Cryogenic grinding of rubber with Contraplex CW II and Stratoplex ASP II

The Hosokawa Alpine Contraplex CW II pin mill is a pin mill with two driven pin discs. In counter-rotating mode, much higher relative speeds are possible. The highest relative speed develops at the outermost pin rows and can be up to 250 m/s. The fineness can be adjusted by altering the speed of the pin discs.

High relative speeds for grinding to a high fineness

Depending on the application and market, finer fractions (e. g. < 180 μm, < 125 μm) are sometimes required. Due to the fact that it is not possible to grind rubber granules any finer in an economical way, it becomes necessary to separate a finer product (fraction) from the cryogenic process downstream. For such applications, the Alpine Stratoplex ASP II turned out to be the ideal machine with regard to yield, efficiency and investment costs.

Standard air classifier for high throughputs in the fine to medium-fine separation range of d₉₅ = 75 to 180 μm
High fines yield at high precision of cut and high loading
Low energy consumption

Technical specifications

	CW II 250	CW II 400	CW II 630	CW II 800	ASP II 315	ASP II 400
Throughput capacity (kg/h)	200	500	900	1400	800	1500
Process temperature	at glass transition point	at glass transition point	at glass transition point	at glass transition point	ambient	ambient