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23. August 2018

Rösler: In-line blast cleaning for a wide range of castings

Rösler: In-line blast cleaning for a wide range of castings

Highly adaptable continuous feed spinner hanger machine for foundry applications


When a Russian manufacturer of mining equipment set up a new foundry, the company chose a continuous feed spinner hanger shot blast machine RHBD22/27-F from Rösler to finish their castings. Besides the heavy-duty foundry design ensuring high cost efficiency and uptimes, the customer was impressed by the operational adaptability of the blast cleaning system. It allows in-line core sand removal and blast cleaning of castings made from different metal types. 

For more than 90 years the Tomsk Vakhrushev Electromechanical Plant, JSC (TEMZ) has manufactured mining equipment and machinery for other industries.  Their product portfolio includes fans, jackhammers, pneumatic and hydraulic tools, as well as electrical drill presses and saws. The company produces the required equipment components as steel, grey iron and aluminum castings at its location in Siberia. A major customer demand for the new TEMZ foundry operation was that the new shot blast machine must be able to cope with the wide variety of different castings. Other requirements were a high cost efficiency and high equipment uptime.

Evgeny Laza, chief technologist at TEMZ, explains: “Very important for us was also that a supplier had at least 15 years experience in building shot blast equipment, maintains a service organization with spare parts warehouse in the Russian Federation, has a proven track record with this type of equipment and is an innovator in the field of shot blasting”. Moreover, the new blast system had to be integrated into the manufacturing flow in an existing building, which because of the tight space conditions posed a significant challenge to the Rösler engineers.

Well designed, robust equipment concept for foundry operations
One reason why Rösler was able to secure this order against numerous competitors was that the continuous feed spinner hanger shot blast machine RHBD 22/27-F was specially designed for foundry operations with heavy duty wear protection. For example, the blast chamber is completely fabricated from manganese steel. In addition, the “hot spot” area contains a wear lining that consists of replaceable cast and case hardened wear plates. All other sections inside of the blast chamber are equipped with easily exchangeable manganese steel plates. The customer was also impressed by the flexibility of Rösler to adapt the blast machine to the specific space requirements at TEMZ. Evgeny Laza explains: „When it came to the development of solutions and the handling of all technical details, Rösler reacted a lot faster than the other equipment suppliers. Everything Rösler did was focused on our specific requirements”. Another positive factor was certainly that since 2012 the company has already been operating three shot blast machines from Rösler. 

Fully automatic in-line blast cleaning adapted to a variety of different work pieces  
The continuous blast machine is equipped with an integrated transport system that allows the handling of single work pieces or work piece batches, weighing up to seven metric tons. Work piece loading can take place at both ends of the blast machine. After shakeout the castings are transferred to the transport device of the shot blast machine with carriages supplied by the customer. There they are placed in a special lifting device and lifted up. Once the parts are in place the operator enters the part specific blast program into the PLC and drives the work piece trolley into the blast chamber. 

The blast chamber is equipped with four Gamma 400 G turbines with a drive power of 22 kW each, arranged in-line. During the blast process the castings are continuously rotating. The high performance turbines, designed and built by Rösler are equipped with throwing blades in a “Y” shape design.  Compared to conventional turbines they generate an up to 20% higher blast performance while simultaneously maintaining lower energy consumption. In addition, the throwing blades can be switched around allowing the use of both their sides. A blade exchange takes place with a quick-change system without having to remove the turbine. This results in uptimes, which are at least twice as long compared to conventional turbines. 

Automatically adjustable shell valves allow for adaption of the blast media flow, up to a maximum of 290 kg/min (640 lbs./min) to the castings being blasted. The rotational speed of the turbines and the spinner/hanger trolley can also be adjusted to the respective blast cleaning task by frequency inverters. Before travelling to the unload station the cleaned parts pass through a cleaning station, where residual sand can be removed with a manual compressed air system. All these process parameters are stored in the individual blast programs and ensure the perfect adaption to the various shot blast tasks. For example, aluminum castings require a lower blast intensity than steel castings. The system control allows access to 30 specific programs for different castings, as well as the blast cleaning after heat treatment. A special program for de-coring (core sand removal) allows the turbines to be switched on sequentially, allowing the removal of the sand in layers, which prevents the media recycling system to be overloaded. 

Media recycling with a cleaning efficiency
The media recycling system was also designed to keep the wear rate at a minimum. The sand/media mix is first passes over a vibratory screening unit where coarse particles and sand lumps are discharged. Then the mix passes through a magnetic separator. A finely tuned guide system evenly distributes the media/sand mix over the entire width of the drum to generate an extremely thin curtain of sand and media. This, combined with the high attractive force of the electromagnets in the drum, generates a separation efficiency of up to 99.7%. 

The replenishment of blast media  is a fully automatic process. A sensor in the media hopper monitors the media level. As soon as the level falls below a defined value, media is added in small quantities. This ensures a homogeneous operating mix and guarantees consistent, repeatable blasting results.   

Because of the aluminum castings, the dust collecting system for the blast machine consists of an explosion protected wet dust collector with automatic sludge discharge. 

Easy maintenance and quick service 
TEMZ also demanded a maintenance-friendly equipment design guaranteeing a high uptime. A large maintenance platform allows easy access to all components requiring regular service. Remote electronic access by Rösler service engineers to the system controls permits quick trouble shooting in case of a malfunction and support for programming or changing of programs.

Evgeny Laza concludes: „Rösler not only handled all tasks quickly and professionally but also provided optimal support to our people. This resulted in trouble-free operation of the shot blast machines in our company for more than 5 years”.

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