Our Philosophy and Processes

Philosophy

SG Castings, being an integral part of WB White Foundry and sister company of Architectural Street Furnishings, has many longstanding links with British Industry. Keeping as many skills as possible in house and keeping those skills hands on is important to us, and combining processes that are many hundreds of years old with technological advances means we are in a position to take forward a very wide range of casting projects.

Our staff teams are experienced, multi-skilled and multi-disciplined, our management teams and even board of directors are time served in the foundry industry giving us a great base of knowledge and learning which allows us to have a flexible and customer led approach to manufacturing.

Dedicated to British Industry, pouring ductile cast iron in Nelson, Lancashire.

Processes

Pattern Making

SG Castings has its own pattern shop based at sister company WB White Foundry. Pattern making is a highly skilled occupation that requires not only a high level of competence of hand manufacturing patterns in timber, fibreglass and resins, but also in-depth knowledge of the moulding and casting processes. Patterns are literally built up to be a replica of the product to be manufactured, but as the molten metal will contract when cooling the patterns have to manufactured to take this into consideration, this means manufacturing a contraction allowance into the pattern.

Pattern makers also need to understand how the product will physically mould so runner systems (the path the molten iron will take inside a closed mould) have to be considered and tapers have to be designed into the pattern to allow correct moulding to take place. So that when the pattern is removed from the mould then the mould will stay in place and not be torn apart or damaged.

Our dedicated pattern shop, employing three pattern makers, is of great benefit to all of our customers:

Customers have a direct link with the pattern process, meaning that development and manufacturing costs are kept to a minimum, and that we can be responsive to any changes, developments or product modifications our customers require. Given that castings are often manufactured to extreme levels of accuracy, both dimensionally and with regards material specification, this direct link to the pattern making process is a key part of our casting service.

With our own pattern shop, core shop and moulding facilities SG Castings keep all processes in house.

Moulding

Moulding is the process of turning the pattern into a receptacle that will allow the iron to be poured. SG Castings and WB White Foundry use sand moulds (in both furan and green sand). There are a number of ways to mould a pattern ready for casting. In most cases a pattern or moulding box is used - this allows the sand to be rammed over the pattern yet contained in a box. This is done in two halves - the result, once the pattern is removed, is complimentary moulds - that when placed together leave a void in the shape of the casting.

Moulders are responsible for making sure moulds are a true replicate of the pattern, and that not only do they fit together perfectly but also that the iron will run freely into them once poured. This means a suitable in-gate and runner system has to be moulded as well as breather holes to avoid back pressure and to assist in the iron running into all areas of the moulded void.

Core Making

Cores are negative moulds that replicate the shape of the interior voids of the finished product. In the case of many engineering parts - motor components, thermostats etc, these cores are complex and the process of building them into the mould a critical job. Not only must they be accurately sited into the moulds, they must also be studded so they don't literally float to the top of the molten iron inside the mould.

Finishing and Inspection

SG Castings have facilities for shot blasting, fettling and linishing, with access to wider facilities at WB White Foundry.

Once a poured casting is cooled it is knocked out of the mould. The bare casting may have a moulding sand residue as well as flashing where the two mould halves join. There will also be an in-gate and runner system attached to the casting. These elements need cleaning off and removing. Flashing and the runner system will need cutting or grinding off, whilst sand residue is removed by high impact shot blasting. This process also leaves the casting with a consistent overall finish, perfect for any finishing or machining processes that may be required.

Tapping ductile cast iron from the furnace, ready for pouring into sand moulds.

Metallurgy

SG Castings have two dedicated metallurgists, one at SG castings and one based at WB White Foundry, as well as a fully equipped on site laboratory consisting of a metallography microscope to analyse the microstructure of iron and a spectrometer to measure the chemical composition of iron.

Metallurgy is in basic terms, the science of metals. Metallurgy is important to the casting processes as it allows the constant monitoring of material specification and gives us expertise to fall back on when looking at material characteristics - both for finished products and how varying grades of iron will behave in the moulding process.

Having our own in house metallurgists also allows a greater level of quality control and inspection. Constant core testing ensures we maintain material grade and quality 100% of the time, and where necessary testing for hardness and porosity can go hand in hand with traditional quality control procedures to give a comprehensive overview of metal and casting standards.

Metallurgy also improves both our new product development and existing development / after sales services. During new product development the metallurgist input is valuable in ensuring appropriate grades are specified, and during existing product development metallurgist input gives important and often critical feedback of existing processes, allowing products to move forward in a more efficient manner.