Treatment of springs - a challenging shot blasting application

rotary table satellite shot blast machine RDT 250
Three disk or wave springs are simultaneously loaded/unloaded, blasted on one side, flipped over and blasted on the other side in four separate chambers.
This compact processing cell for stress peening of chassis springs exposed to high loads is equipped with a hydraulic compression system.
The newly developed RRDK
The newly developed RRDK allows continuous shot peening of chassis springs in an 8-second cycle.

Shot blasting technologies for compression and release

Springs - probably no other industrial item is produced in such a wide variety. To prepare them for their respective use, these essential equipment components must be shot blasted for various technical reasons. Rösler offers different blast treatment options adapted to a multitude of spring sizes and geometries as well as the various treatment objectives.

There are many reasons requiring the shot blasting of springs like increasing their overall uptime, meeting stricter technical specifications with - at the same time - less weight, removing scale and other contaminants after heat treatment, or eliminating sharp edges. Rösler develops tailor-made solutions for a wide range of applications for batch as well as continuous feed shot blasting of springs. Essential for achieving optimum blasting results is always the selection of the right blast turbines. Whenever; high throughputs are required, very abrasive blast media must be utilized, or high Almen readings must be achieved in conjunction with shot peening tasks, Rösler Long Life turbines always represent an excellent technical solution

Batch processing - efficient material handling and repeatable results

For batch processing of springs Rösler tumblast batch systems (RMBC) are the preferred machine type. A leading manufacturer of engine valve springs and piston ring springs utilizes such tumblast systems for general blast cleaning and shot peening. The customer chose Rösler over other suppliers because of the individual adaption of its blast machines to the respective shot blast applications. For example, in order to achieve the best possible shot blast results the machines were equipped with special transport belts with integrated tumbling cams and mixing arms for increasing the tumbling/mixing intensity of the parts. Another RMBC for shot peening purposes offers sophisticated technical controls for managing the blast media flow and pellet size as well as the turbine speed (RPM). In this machine the movement of the belt is not monitored through the RPM of the drive motor but by a sensor mounted to the idler pulley shaft. This ensures that the actual movement of the belt is constantly monitored and controlled. Another equipment feature is the MAX-IMP system for automatic control and quick adjustment of the blast pattern. This guarantees the optimum location of the “hot spot”, which is essential for achieving the best possible shot peening results.
Rösler is the only equipment supplier who offers a second batch shot blast system, namely the highly versatile Multitumbler (RMT). At the center of the RMT system is a rotating drum with special wave like tumbling cams and a pyramid shaped bottom. Since the drum has no pinch points whatsoever, it allows the shot blasting of springs which, because of their size or shape, would be problematic for a conventional tumblast machine, for example, very small or disk shaped springs.

Custom engineered single piece processing

Special Rösler equipment designs ensure a maximum of process safety and cost efficiency for springs that cannot be processed in batches. An excellent example for continuous feed processing is the rotary table satellite shot blast machine RDT 250 4x3S that was purchased by a globally active automotive spring supplier for shot peening of disk and wave springs. This brand new RDT shot peening system handles three parts at a time in a 10 second cycle time and is equipped with four chambers: (1) Loading and unloading, (2) peening of the upper side, (3) automatic turning of the springs and (4) peening of the lower side. This clever concept reduces all non-productive handling times to the time required for indexing of the table, thus ensuring high productivity and high throughputs.
Another example for custom engineered continuous feed spring shot blasting is a system sold to a Turkish manufacturer of helical springs used in cars and trucks. In this swing chamber (RWK) machine chassis springs exposed to very high loads are stress peened. Towards this goal Rösler installed a hydraulic compression device that compresses the springs at forces specified by the customer. The stroke distance can be adapted to the different spring sizes. Like all systems for shot peening and stress peening this highly compact blast system is equipped with controls that manage the blast media flow and pellet size as well as the turbine speed (RPM).  

Fully integrated into the manufacturing flow

With the rotational continuous shot peening machine RRDK Rösler implemented a brand new spring peening concept at a German supplier of different chassis springs. This customer specializes on the development and production of suspension and chassis systems for cars and trucks. In addition, the company supplies sophisticated special springs for a wide range of industrial applications. The customer chose Rösler over other suppliers because of the maintenance friendly equipment design and the innovative part transport system: It consists of two rotating rollers whose distance can be adjusted to the various spring diameters. Between the rollers are pusher cams driven by a simple link chain. Link chains are less costly than the usually used bush chains and better suited for a shot blast environment. Blast media trapped between the joints can be easily removed by slackening of the chain.
The spring peening system is integrated into the manufacturing line and controlled by the main line computer. The springs are loaded into the peening system by a robot, placing a spring between the automatically spaced rollers every 8 seconds. The pair of rotating rollers causes the springs to constantly turn while passing through the blast zone. This guarantees a homogeneous, all-around and absolutely repeatable finish.