The casting of high-alloy steel demands the use of advanced technologies, modern production methods and a knowledge of the latest alloys for corrosion, abrasion and heat resistance.

Throughout its history, Steloy Castings has remained abreast of technology advances in order to enhance its focus on customer service, says Leon Jonker, director materials and quality.

Steloy Castings recently supplemented its Computer Numerical Control (CNC) pattern-making capability with a large-scale CNC router, which has opened up a new world of casting possibilities for customers.

The multi-functional five-axis machine with its 3 x 4 metre bed can, in addition to machining large-size pattern equipment, also machine complex one-off moulds without patterns. This will streamline production and also bring cost benefits for customers, says Jonker.

"Designed as a method to rapidly produce prototypes or single castings, CNC machining of moulds is not new, but it is new to South Africa," he says.

For some years now, Steloy Castings has utilised a three-axis CNC centre for the machining of smaller-size computerised solid models, making use of the latest SolidWorks and Cimatron software to produce patterns to the highest standards.

To help ensure the integrity of the end product, all three Steloy plants also have access to centralised solidification analyses and modelling (Magmasoft) software, which is used to cross check conceptual pattern design and casting methods.

Swiss spectrometry
Steloy Castings recently acquired a Swiss optical emission spectrometer that is considered the most advanced in the South African foundry industry. With the acquisition of this, its fifth, spectrometer, the group also extended its range of certified calibration standards in order to support the certification of products.

"The Thermo Electron ARL 3460 spectrometer enables analysis of an unequalled variety of alloys across a wide spectral range, ensuring accuracy and product integrity," says Jonker.

Equipment such as these, combined with stringent quality control measures, ensures adherence to the highest standards and specifications. Mechanical testing, spectrographic analysis, radiographic inspection, liquid penetrant testing, magnetic particle inspection and pressure testing are all applied either in-house or by approved and certified subcontractors.

Quality management
In 1991, Steloy was the first independent sand foundry in South Africa to be awarded the ISO 9002 listing for quality management, and today all three divisions are SABS ISO 9001:2008 listed.

In 2006, the group was the first South African foundry operation to be awarded European Pressure Equipment Directive (PED) accreditation, which today applies to all three plants. This is of particular benefit to local valve manufacturers exporting to the European common market where all vessels with service pressures that exceed 0,5 bar are required to be PED compliant, says Jonker.

"PED accreditation confirms our ability to cast to international quality standards, and is also indicative of our quest to provide the highest levels of customer support. While an advantage in securing international pressure equipment component contracts for Steloy, PED accreditation was obtained with the express purpose of assisting local valve and pump manufacturers producing pressurised systems for the European market."

Material matters
With many of Steloy's castings destined for operation-critical applications, the group remains at the cutting edge of material grades as these are developed, says Jonker.

In the late 1980s, Steloy was the first South African foundry to regularly cast duplex alloys, and today it often casts valve components in super duplex alloys and petrochemical components in advanced heat resistant high alloys, to standards including ASTM, API, BS, DIN and EN.

"The Steloy product range is constantly evolving to accommodate new alloys and other developments. Our material data sheets are used by customer engineers worldwide in their design calculations," Jonker says.

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