Melting capacity allows Sarco to expand their casting product base

Company is internationally recognised for manufacturing of castings for the steel mill industry.

South African Roll Company (Sarco) has long been recognised as one of the leading international manufacturers of castings used in the steel and non-ferrous manufacturing industries. Producing castings weighing up to 65 tons requires the foundry to have large melting capacity and the machine shop to have custom-built CNC equipment. All the processes in between pouring of the metal and final machining have to match and accommodate the size and weight of the castings – no mean feat.

“Sarco has been manufacturing castings since 1947 and has been operating from its own dedicated foundry and machine shop since 1975, when the owners at the time the Dorbyl Group of Companies, commissioned a specialised facility. SARCO begun life in the Vanderbijlpark Vecor foundry. In 1974 the Dorbyl Group of Companies was established and Vecor became part of Dorbyl’s heavy engineering division,” explained SP van der Walt, Sales and Marketing Manager at SARCO.

South African Roll Company (Sarco) has long been recognised as one of the leading international manufacturers of rolls used in steel and non-ferrous manufacturing industries

Sarco have three furnaces with capacities of 22 tons each, one 5 ton, one 3 ton and one 12 ton unit giving the company a combined capacity of 20 000 tons in a year. The six coreless induction furnaces have a melt capacity of 86 tons

Sarco’s moulding sand system is based on the phenolic resin binder system. The company has recently invested in two new continuous sand mixers

“United Foundries, a well-known international Foundry, acquired the Dorbyl Roll Works from Dorbyl Limited in 1998. This resulted in the creation of the current name of Sarco. However, in November 2008, United Foundries sold Sarco to a shareholding group comprised of Nedbank Capital Private Equity, Medu Capital and Management and the company has since retained the name,” continued van der Walt.

Heavy engineering castings“In 2016 Sarco expanded their casting capabilities to service the local and international heavy engineering sector. A combination of sophisticated equipment, the latest technology, together with skills and experience acquired through over half a century in the business, positioned Sarco amongst the world’s leading roll manufacturers currently available to the steel industry.”

“The foundry has six coreless induction furnaces with a total capacity of 86 tons. In our case main frequency induction heating is a superior alternative to arc furnace heating, as induction heating provides a faster, more efficient heat. Additionally, a thermal analysis system is used to evaluate and optimise molten metal quality before tapping and casting.”

Sarco have 38 staff employed in the foundry and 10 are now dedicated to the general engineering castings side

Three mill rolls in a pit cooling off in the foundry

The general engineering side of the foundry preparing a slag pot mould

“Chemical composition and temperature are precisely controlled and adjusted by strict checks on the quality of raw materials and alloy additions, as well as the application of statistical process control methods. These controls, when combined with the induced stirring action in the liquid metal bath in this type of furnace, ensure the homogeneous melt essential for continued repetitiveness of the required metallurgical standards.”

“We have three furnaces with capacities of 22 tons each, one 5 ton, one 3 ton and one 12 ton unit giving us a combined capacity of 20 000 tons in a year, based on the capacity limits of equipment such as mould drying, casting pit space and heat treatment facilities.”

New sand reclamation plant and continuous sand mixers“Our moulding sand system is based on the phenolic resin binder system and we use local patternmakers to build our patterns.”

The slag pot mould

Mill rolls exiting one of the two bogie hearth heat treatment furnaces

Mill rolls are ultrasound tested before machining

“Towards the end of 2019 we installed a new sand reclamation plant and two continuous sand mixers. All the associated equipment such as hoppers and cooler classifiers are also new, including a new shakeout. This investment serves to improve the reclamation and reusability of the sand employed in the moulding process, thus reducing the impact on the environment whilst improving the quality of the product at substantially reduced production costs.”

“As you can imagine, with the size of the castings we are manufacturing we use plenty of sand so an investment in this technology was necessary.”

Dedicated heavy engineering castings floor“Initially when we introduced the concept of manufacturing heavy engineering castings into the foundry, all of these castings were done in the same pits and floor space as the mill rolls. Experience taught us that we had to separate the departments and now the general engineering castings department has its own pits, which have been upgraded, and floor space.”

A mill roll being set up for machining

The company can manufacture castings from 450 kilograms up to 85 tons

Sarco have a tailor-made WaldrichSiegen heavy-duty CNC lathe in the machine shop

“The area at our facility under roof is large so we have more than enough space. But who knows? In the future we could separate and hive off this section of the foundry into its own facility as we have enough adjacent land to make improvements and additions.”

New focus on heavy engineering castings“With a team dedicated to the heavy engineering castings side, we have employed a dedicated sales and marketing, and technical team that has taken control of the production side.”

“Additionally, we have ramped up the skills of the staff in this department with an emphasis on those that are on the foundry floor. They have advanced methoding courses and others on foundry practices.”

“Our predictive metal analytics software is also used in the casting process. The software determines the liquid metal solidification morphology and quality.”

“Currently we are focusing on low alloy cast steel, high chrome iron, cast iron and SG iron but in the future, as demand grows, we will look at higher alloyed steels and other associated metals.”

“Using the equipment that is already in place for the mill castings, moulds are heated in gas-fired drying ovens, while efficient mould coating and chill spraying techniques ensure to clean casting surfaces at all times.”

Mill rolls in the machine shop waiting to be machined

A view of the heavy-bay machine shop

A smaller mill roll weighing in the region of 450 kilograms

“Some of the castings that we have manufactured in this division include slag pots, chocks, drop balls, mantle heads, leveller frames, wear liners, discharge heads and trunnions. But we are not limited to these. For any larger size castings for the mining, energy, transport, agriculture, construction, petrochemical and general engineering industries, we are more than capable of manufacturing.”

Heat treatment“We have a fully supportive heat treatment department that contains six large top hat type furnaces and two bogie hearth furnaces. All furnaces have interior stack bonded ceramic fibre block insulation and are heated by high velocity, gas-fired burners. Temperatures and cycle times are controlled by sophisticated instrumentation and programmable logic controllers. Thermocouples are attached to the castings and all cycles are pre-programmed into the PLC to ensure precise repeatability.”

“This service is also offered to the general engineering castings division clients.”

Quality assurance“Sarco is ISO 9001:2015, ISO 14001:2015 and OSHAS 18001:2007 accredited. The Quality Assurance department has strict procedures for planning, manufacturing, testing and document control. Equipment in the department includes a Bruker Q4 spectrometer, a portable XRF Bruker metal analyser, an Equotip, Struers Vickers and Rockwell hardness testers and other equipment associated with an internationally accepted laboratory.”

Manufacture of mill specific castings“Besides supplying ArcelorMittal, Columbus Stainless Steel and SA Metal locally, we also supply our castings to mills all over the world. Despite the size of these castings, it is still a very competitive market. Generally speaking, each of our castings are unique, and depending on what they are used for, they last for different amounts of hours of use. Some of these castings are bimetallic and consist of a wear resistant working layer (shell material) and a ductile iron (SG) core. The working layer (shell material) hardness ranges from 65ShC to 85ShC. Dimensions of these castings vary according to client-specific requirements.”

Machine shop (heavy and light bay)“Critical to the manufacture of mill roll castings is our machine shop. The machine shop has a wide variety of equipment, custom-built for roll manufacturing. The shop is divided into a heavy bay and a light bay. The heavy bay handles castings from 10 to 85 tons in cast mass with a bed diameter up to 1 650mm and total length up to 10 metres. The light bay is for castings from 450 kilograms up to 10 tons with a bed diameter up to 1 400mm and length of 5 500mm.”

In the smaller bay machine shop Sarco has two vertical boring mills to enable the machining of spin cast sleeves for universal mills

Damaged mill rolls are cleaned up before being taken for recycling

Sarco have a Bruker Q4 Tasman spectrometer for metal analysis

“Facilities include roughing lathes, CNC finishing lathes, single head milling machines, large and duplex neck milling machines, large and small finishing grinders, a rough/finish grinder, automatic ultrasonic scanning equipment and a Lismar roll inspection machine for surface defects detection.”

New Managing DirectorHaving previously spent six years with Sarco as a metallurgist, Harold Pretorius returned to the company 10 years ago. Pretorius held various positions at the company in these 10 years including Works Manager and Sales and Marketing Manager. Pretorius is currently appointed as the Managing Director of Sarco.

“Sarco is a strong company with a long history in the manufacture of mill castings. We have gained a highly regarded reputation worldwide and will continue to build on this,” said Pretorius.

“Our venture into manufacturing general engineering castings was at first tentative but as we have gained more experience and know-how, we are confident to pursue further business in this area. We have the latest technical equipment, processes and experienced staff to be able to manufacture any general engineering casting.”

“When manufacturing mill castings, we have to cast and machine them to the tightest specifications and material requirements. In such a context, the requirement for increased quantities will be produced in a process-consistent and cost-efficient manner.”

For further details contact Sarco on TEL: on 016 910 7000 or visit www.sarco.co.za