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Bespoke Engineering for a Far From Typical Production Process

Grainger & Worrall has long been established as one of the UK’s leading suppliers of specialist aluminium castings serving the prestige and high performance engine markets. At the end of 2011 Omega Foundry Machinery was approached by the company to provide the latest technology solutions to meet the ever changing production requirements of their Bridgnorth foundry. 

Grainger & Worrall’s remit was for two high productivity moulding lines that focused on latest technology, minimum operator input and compact footprint. The technology incorporated must focus on minimising sand and chemical consumption, minimal mixed sand wastage, provide real time production data – including the amount of raw materials consumed, number of each mould component produced and the facility to store all accumulated data. The moulding lines would then have to feed a pouring and cooling system which would ultimately lead to mechanical and thermal reclamation. 
The type of moulding incorporated at the Bridgnorth foundry is far from ‘typical’ and therefore required a certain amount of bespoke engineering involving close co-operation between customer and supplier. This was a perfect opportunity for Omega to utilise its latest mould handling technology together with the latest generation of the IRIS pattern recognition and data logging system.

Two carousel moulding lines suitable for the phenolic urethane process were installed, each carousel having eight stations to enable fast cycle times that match with the customer’s production requirement (fig.1). Each carousel has a Spartan 310P mixer, which is Omega’s latest generation of continuous mixer, and each mixer is equipped with temperature sensitive part-3 addition which will control the part-3 according to the sand temperature – essential for any mechanised moulding line, air injection on all chemical inlets, full set of tungsten carbide tipped blades and ‘Smart’ sand gates – high speed linear actuators that can give any required sand output at the turn of a switch. The ‘Smart’ gate system removes the need for multiple pneumatic cylinders and means that the mixer operator can easily select a low output from the mixer when producing small mould sections or increase to maximum sand output when filling the largest moulds. Each time the sand output is changed the two resins and part-3 are also adjusted automatically.

The heart of the system
The heart of the system is the latest version of Omega’s IRIS system, where every pattern has a small RFI tag embedded inside with a unique identification number. Once the pattern is placed on the compaction table the IRIS antenna (fig.2) will identify the pattern by reading the tag number, this number will then relate to a specific recipe that is stored on the industrial PC inside the main control panel. The mixer then starts and delivers the precise amount of sand, chemicals, compaction frequency as well as duration of compaction. The production of each mould is then monitored by the PC and networked to the production office. The production supervisor can then interrogate the mixer from his office PC to see what is being produced in real time as well as how many of each mould have been made, the quantity of raw material that has been consumed and even what each individual mould cost to produce. This information can be stored on a hard drive and retrieved at a later date. The system also enables the production supervisor to set the number of each mould to be produced so, if the operator forgets how many moulds he has made, the system will warn him when he reaches his production target. The main screen can also display a job card for each pattern and each job card can show important information relative to that pattern including a picture of where chills, loose pieces or sleeves should be placed.

Continuing the journey
Once the mould has cured it enters the hydraulic rollover draw machine for fully automatic, perfectly parallel mould stripping, the stripped mould is then powered out of the rollover on to the waiting coring and closing line. The empty pattern is returned to the carousel for further production.
Once the mould has been closed, it is then fed to the pouring line where the moulds are cast and then placed on to one of the available cooling lines. Once the mould has cooled sufficiently it is moved to the Gamma 12LL reclamation plant where a hydraulic wipe-off will push the mould from the casting pallet on to the shake-out deck (fig.3). The casting is retrieved by jib crane and placed in a bin for transferring to the finishing area, the reclaimed sand is then pneumatically conveyed to the thermal reclamation plant for processing. 

A very ‘green’ process
100% of the sand used on the carousel lines is thermally reclaimed with only a very small percentage of new sand addition to make up for natural losses. The Richards/Omega thermal reclamation plant incorporates the patented ‘Dead Bed’ system which enables Omega to give a three-year guarantee for the furnace lining and gas burners. The plant also has the benefit of an integral heat exchanger that enables heat energy to be recovered from the hot sand as it leaves the furnace and fed back to the furnace as hot air, this together with the three layers of thermal insulation inside the furnace, enables the thermal reclamation plant to run at the lowest levels of gas consumption.
By utilising Omega’s latest technology, Grainger & Worrall continue to meet their customer’s growing needs as well as keep their overhead costs to a minimum. Additional benefits are: maintaining a consistency of quality, ability to hold production data records for future interrogation, staying within environmental legislation and maintaining their position as a world leader in the production of specialised, high integrity aluminium castings. 
Another example of Omega’s continuing development program aimed to meet the needs of the ever changing foundry industry.

Republished by kind permission of Grainger and Worrall
Contact: Chris Wilding, Omega Foundry Machinery Ltd, Morley Way, Peterborough PE2 7BW. UK. Tel: +44 (0) 1733 232231, email: chris@ofml.net web: www.ofml.net