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Surface finishing options for diecasters

Rosler GmbH is progressive with leading edge technologies when it comes to diecast component surface preparation and/or finishing. The company’s philosophy is through customer-lead research and development and “finding a better way” of processing by design and justification. 

There are a number of ways diecasting manufacturers can choose to go when looking to deburr and finish large numbers of components. Here, Rosler considers the options of vibratory versus blast.

The metal casting sector employs a number of various technologies to manufacture millions of component parts, in a cost-effective manner. Raw castings frequently require a surface preparation or finishing process such as deburring and edge breaking. Another important finishing process is the general cleaning and aesthetic finishing of the cast components and the removal of any remaining mould release agent.

The finishes demanded range from component aesthetics, keying the surface for adhesion before applying paint, coating or glue, to achieving a fine ‘pre-plate’ finish.
New alloys, re-defined casting methods and additive manufacturing spurn new process applications.  All metals, including light alloys, super alloys, non-ferrous metals, to grey iron, steel and stainless steel castings are most likely to require and undergo a surface preparation and/or finishing process.

Many smaller aluminium, magnesium and zinc diecastings are finished in continuous vibratory systems. This is a wet process and depending on the subsequent operation may require a rinse and/or drying process. The removal of flash and the removal of sharp edges can be achieved within a processing time from as little as five minutes.

The majority of residual burrs caused by complex split mould tools can be removed, provided they could be reached by the grinding media.

Continuous vibratory systems from Rosler are available as linear or circular - long radius systems and each system can be demonstrated in the company’s test process facilities. These surface preparations and finishing systems can easily be linked with the help of Rösler’s in-house specialist IT design team. This enables the equipment to be interfaced with the customer’s actual diecasting process and clipping cell, allowing a fully automatic and highly cost-effective finishing process.


Recycling of the process liquid cuts costs

Besides deburring and edge breaking the process offers a washing and cleaning effect. Rosler GmbH manufactures recycling systems to allow the re-use of the water/compound mix. This reduces the water and compound consumption to a minimum and, with the addition of a wastewater centrifuge, the compound and water can be used over and over again before final discharge.

This saves the user considerable cost for water and compound. Last but not least, it helps to keep the environment clean and assists in the achievement of a ‘consent to discharge’ by the local authority.


Additional applications

Other applications are the smoothing and polishing of parts such as bathroom, kitchen and plumbing fittings, or handles for doors and windows made from alloys of aluminium, copper, zinc, gunmetal and stainless steel.

Frequently, in such cases the mass finishing process is preceded by an auto clipping machine or belt grinding operation to remove any heavy split line, metal sprue or runner.

The ultimate subsequent finishing process can achieve close to mirror image polished surfaces with values of less than Ra 0.02µm. 

This control and repeatable finesse is achieved by the interaction of the various manufacturing sections of the Rosler Group. The group’s varied disciplines work together to achieve innovative, superior process methodologies and the in-house desire for continuous improvement, new development and manufacture of chip media and compounds. This results in complete new process initiatives, many of which are customer lead.                                                                           

Depending on geometry, size and surface condition of the cast component, a selection of surface preparation and finishing process methods such as a circular or tub vibrator, a high energy centrifugal disk system, a ‘drag’ plunge or ‘surf’ finishing process can be considered and employed.

According to the component or part size and machine process type, hundreds or even thousands of parts can be processed simultaneously. Automation reduces idle times for parts loading and unloading to an absolute minimum or even eliminates it!

An example of special equipment is the centreless vibrator, which allows the deburring and surface finishing of round components with a diameter of up to 2,000mm.


Alternative, surface preparation processes and finishing technologies to consider

Deburring and the removal of sharp edges, with relatively short processing times represents only a small part of the overall range of Rosler GmbH surface preparation and finishing technologies.

The company also manufactures ‘dry’ processes, such as a fine abrasive blast, delivered by either a Gamma Y long life turbine or by compressed air. This method should also be considered, however it should be noted that a dry blast process cannot achieve a polished finish.

The advantage of a dry blast system is that it provides a very economic commercial process. The components remain dry, do not readily surface oxidise and have no surface watermarks.

Smaller to medium sized components may be cascaded whilst medium to larger components can be placed in linear fashion or even hung.

Small batch barrels, small continuous linear through barrels to larger sized machine capacities remain the commercial favourites. Whilst more sensitive components may be processed on a wire mesh continuous blast machine with process speeds of 500mm to above 6,000mm/minute.

Of special interest, diecastings of mainly flatwork and with a thin profile can be processed with the right process application.

These three dry process methods and handling of the component parts account for more than 50 per cent of the volume of all diecastings. These diecastings are commercially processed to standards within the automotive, plumbing, valve, electronics, nuclear, toy, white goods and other manufacturing industries.


How to surface prepare and/or finish large components?

The company’s surface preparation and/or finishing is not limited to the processing of smaller and medium sized component parts. It can also be utilised, for example, for the surface finishing of engine casings for aircraft turbines and structural airframe parts with a length of more than 6,000mm.

Even today many parts are still manually deburred after a machining process. This requires highly skilled and dedicated personnel to prevent damage of higher valued components.

Rosler surface preparation and finishing technologies can offer 100 per cent repeatability.

Additional or alternative solutions can be tailor-made for every conceivable application.

Today, automation of any process equipment is now an economic factor, including process control, handling, quality, inspection, repeatability and reliability in integrated turnkey solutions. Stand-alone single machines still have their place!


Special surface finishing solutions

Special surface preparation and finishing technologies offer solutions for any modern foundry operation and assistance can be found by developing such solutions at Rosler test centres.

For more information contact Sandra Banks and quote ‘diecasting’, Tel: +44 (0) 151 482 0444, email: [email protected]