Mechanical Technology Archive

Grant Ramsden, operations director at Weir Minerals Africa, talks about the company’s upgraded Heavy Bay Foundry (HBF) that serves the Coega Industrial Development Zone (IDZ).

Weir Minerals heavy bay foundry Coega PE Weir HBF recently started producing wear items for the very successful Trio® range of comminution equipment. These parts serve Weir Minerals Africa’s extensive customer base for Trio equipment in Africa and the Middle East.

In addition, the facility is well positioned to produce componentry for equipment used to service the Canadian oil sands industry, a strategic growth area for Weir.

Grant Ramsden, operations director at Weir Minerals Africa, tells Mechanical Technology that the intention is to grow Weir HBF’s order book significantly by competing for a larger share of the 1.0 to 17 t castings market. “This is a niche market and we believe we are now strategically geared to grow this business,” Ramsden says.

These milestones at Weir HBF are as a result of ongoing investments at the foundry that have brought the facility in line with recognised international best practice in castings. Upgrades to the facility commenced in 2013 shortly after Weir acquired the then Xmeco Foundry in a move that added significant value to its existing casting capability at that time.

Located close to the new deep-water port of Ngqura that serves the Coega Industrial Development Zone (IDZ), Weir HBF is well positioned to complement Weir’s strategy of being a best cost sourcing operation.

Both the IDZ and port have been identified by the South African government as critical support infrastructure for South Africa’s mining, oil and gas and energy industries, and are therefore set to be the beneficiary of ongoing substantial investments.

Ramsden says the acquisition also brought with it 60 years of experience and skills in producing a broad variety of castings in ferrous metals, as well as an extensive casting infrastructure and capacity housed at the five hectare site with some 16 000 m2 under roof.

The extent of Weir’s investment into the foundry is reflected by its exacting quality standards that have been firmly entrenched at the facility, which is underpinned by its ISO 9001, OSAS 18001 and ISO 14001 accreditations.

Like Weir’s other state-of-the-art foundry in Isando, standard operating procedures comprise about 150 repetitive processes aimed at eliminating inefficiencies, while significantly improving the quality of the end product.

“Repeatability ensures consistency and therefore optimum quality,” says Ramsden.

This quality philosophy has been adopted and implemented by the 106 employees throughout the operation including the foundry, heat-treatment and finishing component lines.

The heart of the operation is the pattern shop, and its current upgraded capability follows from a significant cash injection by Weir. Profiling of all castings and patterns is now undertaken using two seven axis, three dimensional scanning probes with accuracies of 1.0 µm (0.001 mm) that have replaced outdated templates. In addition, engineers have been equipped with state-of-the-art software that accurately simulates casting methods, enabling yields of up to 76% to be achieved during the operation, compared to 45% to 50% at some traditional foundries in the country.

Weir HBF is also capable of designing unique compound polystyrene patterns for once-off and short run castings, otherwise known as rapid prototyping. The solid model design is loaded into a new three-axis CNC milling machine for accurate cutting of polystyrene patterns.

Ramsden says that Weir HBF is considered a leader in the field, having drastically improved the foundry’s capability to service this important market.

“A furan sand mixture is compressed around the polystyrene patterns. The hot metal is poured into the polystyrene cavity, vapourising the polystyrene and forming the shape of the part. Where surface finish is imperative, the polystyrene pattern is removed from the sand once it has set and the casting is poured conventionally,” Ramsden explains.

The pattern shop has also been fully equipped and staffed to manufacture new patterns in wood and polystyrene, as well as to repair or modify wooden patterns of any size. The shop features the latest state-of-the-art beam saws and table saws used to accurately process marine plywood.

One of the major features of Weir HBF is its electric induction melting furnace range, consisting of six furnaces that provide an impressive melting and pouring capacity of up to 18 t at a single pour. Numerous heat treatment ovens allow precise heat treatment and stress relieving capabilities to suit the specific material option.

However, it is the large investment made into the new enclosed fettling booths, which are all equipped with dust extraction systems at the finishing line, that best demonstrate Weir’s commitment to health and safety at the operation.

Fettling operations are also set to receive cutting edge high frequency grinding technology that will improve ergonomics for workers. This new technology is based on an arm and spring system that bears the full weight of the tool, while reducing fettlers’ exposure to vibrations by up to 50%.

In order to remain a best-cost producer of castings, Weir endeavours to reduce process waste generated at all its foundries, and Weir HBF is aligned with these lean principles.

The recent commissioning of an advanced secondary sand plant at the foundry will significantly reduce manufacturing costs by enabling the recovery of furan sand. This plant uses magnetic separation technology to extract chromite sand added to furan sand during the moulding process. It also scrubs resins from the furan sand by attrition, allowing the foundry to realise significant savings in chemicals.

Ramsden says this recent investment will also improve the overall quality of castings by mitigating ‘sand burn-on’ caused by chromite sand build-up in the casting process.

The metallurgical laboratory has also received a major upgrade, which includes a new spectrometer that will be used to inspect the composition of furnace metal, and a sand particle analyser for assessing the quality of the sand used in moulding.

While investments have predominantly been geared at improving productivity and quality, the on-site canteen and clinic serve as a reminder that Weir has built its success on its employees. Weir HBF intends retaining its skilled artisans as it continues to raise its profile in the international foundry industry.

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