Stainless steel forms a significant part of a beef abattoir, including the conveyors, fixed and elevated platforms, sterilisers, chutes, hand wash basins and, of late, water supply and wastewater piping. The stainless component may now expand even further in new abattoirs with the recent development of cast stainless steel skids and forged hooks for use on dressing conveyors.
Dressing conveyors in beef abattoirs traditionally use rollers rather than a skid system or, in some cases, extruded aluminium skids and hooks are used. Both of these systems have limited service lives due to the weight of the beasts. They also result in downtime when cleaning and, in the case of rollers, lubrication is required. Hygiene is critical throughout the trimming process, as the carcass' meat is exposed to the environment.
G & B Stainless (Crestmead, Old) and Meateng (Melbourne, Vic) recognised the need to develop a dressing conveyor system which would allow a rapid turnaround of hooks while assuring a high level of hygiene.
Using stainless steel would provide sufficient strength to hold heavy carcasses (weighing up to 1,000kg), while allowing the skids and hooks to simply pass through a washbox for sterilisation on their return to the starting point of the conveyor.
The project has evolved over six months from a prototype fabricated skid, which did not provide enough strength, to the existing cast skid and forged hook. The cast skid also incorporates a high density polyethylene insert, which is the only component to experience wear during service. This insert can be replaced at low cost when required.
The skids are cast by Austcast Stainless (Northgate, Old) using a vertical joint automoulding sand casting system. Grade AS2074 H5A (equivalent to AISI 304) stainless is used and full traceability exists for the castings, The stainless hooks are forged by John Ure (Wacol, Qld). Production costs are comparable with extruded aluminium skids, but the low rate of replacement makes the lifecycle costs very attractive.
Over 1,000 stainless steel skids and hooks have been in service at Stockyard (Grantham, Qld) for six months and, according to site engineer, Roger Tocknell, they have been performing excellently.
The new skids are not interchangeable with existing mild steel rollers, but G & B Stainless' Director, John Van Koeverden, said the company's next goal is to develop stainless rollers which can be used on existing conveyors.
This article featured in Australian Stainless Issue 11 - March 1998.