Vol. 2
November Issue
Year 2001


in Vol. 2 - November Issue - Year 2001
High Energy Centrifugal Disk Finishing Machines An Advanced Finishing Technology

Trowal High Energy Single Batch Machine TT 90-SM

Trowal High Energy Double Batch Machine Tandem TT 280A/2c

 In the Spotlight

USF Walther Trowal GmbH & CO. KG is a pioneer in surface finishing located in Haan, Germany, with worldwide facilities and representations. It manufactures finishing machines, abrasive media & compounds as well as water treatment plants for finishing effluents.

High energy centrifugal disk processing is a finishing technology for all types of metal parts which helps to reduce cost and saves processing time.

The finishing process takes place in so-called centrifugal disk machines utilizing a cylindrical bowl and a rotating bottom. The abrasive media and parts mass is accelerated by the rotating bottom (spinner) and pushed against the stationary bowl creating high pressure of media to parts. The mass of media and parts is forming a constant high pressure roll during the entire cycle time.

Centrifugal Disk Machines mainly for small and medium sized Parts

The metal removal rate of centrifugal disk finishing machines is up to 10 times higher in comparison to conventional vibratory finishing machines. This finishing technology significantly reduces cycle times and produces a high consistency of quality in the finished parts.
Centrifugal disk finishing is mainly recommended for small to medium size components requiring strong radiusing, blending of parting lines on die castings or investment castings or general surface finish improvements on cast, forged or machined surfaces. Centrifugal disk machines are designed and manufactured with wear resistant materials such as high quality polyurethane. The areas in the stationary bowl and on the rotary spinner are the most strained parts of the machine requiring utmost care of design and process control.
Precision machining of the spinner and spinner drive, selection of the most suitable geometry of bowl and spinner and the use of highly wear-resistant materials are imperative for long lifetime.

Spinner and Gap Adjustments after each Process Cycle

The interface (gap) between the rotating spinner and the stationary bowl is the most critical area for the  finishing process and machine uptime. Parts or media lodgment in the gap area must be prevented at all cost to avoid severe damage of bowl and spinner.
How can this be achieved? Modern centrifugal disk systems utilize spinner and gap adjustments after each process cycle. After discharge of the media/parts mass from the bowl the gap area must be opened and backflushed to remove debris such as metal swarf and small worn media particles.
Then the spinner must be precisely readjusted to the pre-determined gap size prior to loading the next batch. Also, precautions have to be built into advanced high energy finishing machines to monitor potential jamming of particles in the gap and immediately turn off the machine if such a problem occurs. USF Walther Trowal centrifugal disk finishing machines of the Turbotron range provide all these features in an automatic and PLC-controlled mode. Manual adjustment of the gap and cleaning of the gap area after each cycle is very labor intensive and relies on the reliability of the operator which may be risky.
Trowal Turbotron machines are available in single batch models in modular design with or without attached screening machines and fully automatic double batch systems with intermediate hopper, linked screening machine and hydraulic loader.

Second Batch of Media on Stand-by Position

The automatic double batch systems with bowl sizes ranging from 60 - 520 l (2 - 18 cuft) provide utmost efficiency and productivity by reducing idle machine times like loading, discharge and readjustment of the gap to a minimum. A second batch of media is on stand-by position in the hydraulic loader and can be placed into the work bowl with new parts immediately after discharge of the finished batch onto the intermediate hopper. The finished batch will be separated from the media while the second batch is already being processed in the work bowl.
A linked screening system provides a gentle separation of parts from media and a classification of undersized media and returns the media to the stand-by position in the hydraulic loader.

Select your new centrifugal disk-finishing machine as productive and reliable as possible with:
- automatic rinsing of the gap area and gap readjustment significantly increasing the lifetime of the most sensitive and expensive parts of the machine
- automatic sensing of jammed debris in the gap area like media splinters, metal swarf, thin and small components
- advanced spinner and bowl geometry design made of hot poured  polyurethane of highest quality offering high wear resistance in an extremely abrasive environment.
-full parts and media discharge from work bowl to prevent parts mixing with the next batch
- double-batch processing system with low idle times between batches 
- tandem systems with 2 processing bowls and 1 screening machine for higher productivity and less floor space requirements

USF Walther Trowal offers a complete solution for machines, abrasive media and compound as well as effluent treatment and recycling plants.

Author: Rolf-J. Picard
For Information: 
Walther Trowal GmbH&Co.KG
Rheinische Str. 35 - 37
42781 Haan, Germany
Tel: +49-2129-571-0
Fax:  +49-2129-571-225
E-Mail: info@walther-trowal.de