A review of advanced conveying and stacking systems in the tannery15 November 2007
Probably the most significant advancement in the leather industry in recent times is the automation of materials handling. Such innovation has been led by the need to reduce time and costs by streamlining production. It is driven by the need to meet ever-changing health and safety requirements. The purpose of any tannery is to turn hides or skins into saleable leather and in any tannery that is going to survive in today’s market place, this has to be achieved as quickly as possible and with the least amount of investment. Production must run smoothly to allow this to happen. Therefore, anything that enables the tanner to speed up the movement of leather through the tannery in a smooth, efficient manner without investing in manpower has to be good; automated conveying and stacking is essential in the modern tannery. There is no doubt that tannery work can involve a lot of bending and lifting of heavy, wet and slippery hides; bad backs and beamhouses go together! The automation of the movement and lifting of materials around the tannery has most certainly made some of the less pleasant jobs in the tannery easier and much safer. In addition, replacing forklift trucks with conveyors not only reduces costs but also reduces the risks of accidents. But whilst we might think that the tanning industry has not fully embraced the world of automation with quite the same enthusiasm as some other sectors, such as the car manufacturing industry, there are some good reasons for this. The tannery environment is often corrosive and hides and skins are notoriously variable which makes automation challenging to say the least. However, at this spring’s Tanning Tech, which took place alongside Lineapelle and Simac in Bologna, automated conveying and stacking systems for every stage of the leather making process featured strongly. For the beamhouse, Persico offered a complete continuous feed fleshing system with an integral and synchronised pneumatic handling system that lifts hides to the fleshing machine where they are automatically released. The hides do not need turning in the flesher; in a single movement they exit through the back of the machine where they can be conveyed directly onto the splitting machine. Anyone who has tried lifting a large limed hide will know only too well how difficult it is to get sufficient grip to actually lift it. Consequently, the grips on automated lifting devices need careful design such as those produced by Italprogetti Engineering. These stainless steel grips have a sprung fork arrangement to ensure that hides do not slip. Feltre’s Tornado conveyor system is supplied in various forms; Tornado Flesh that feeds hides to all types of fleshing machines, Tornado Blue that feeds wet-blue presses and Tornado Set that feeds samming and setting machines. This system has more clamps in the chain circuit than normal so provides a more continuous supply of hides to the machine whilst allowing the speed of movement to be slowed down, thus increasing productivity and improving safety. Linta have produced one of the first wet-blue splitting machines that requires no manual handling at all. The hides come from the through-feed samming machine to the splitter via a conveyor. The hides are automatically fed into the splitting machine, reducing the need for operators and overcoming safety issues. Aerial chain conveyors have been used for the transportation and drying of tanned leather for some time now. Thema specialise in such overhead systems and offer conveyors to which the leather can be attached by suspending over rods, metal hooks or grips. The system can be automated to allow the leather to be loaded on and off the conveyor. Tanmac gave details of several machines to aid the handling and stacking of wet-tanned leather. Their ROB4 stacker for use after splitting will stack grains and splits on different pallets with grain side up or down. The speed of the extracting conveyor is automatically regulated to avoid creasing. The ROB9 selection line can be incorporated with area, weight or thickness measurement devices. Officine Meccaniche MM have specialised in the automation of tanneries since 1969 and provide stacking and conveyor systems for all stages of processing: from drum loading conveyors that have built in devices for weighing hides to final leather packaging. Their new stacker/grouper machine permits leather to be stacked onto a horse or pallet in any way that you choose; grain up, grain down or alternating and aligns them on which ever edge of the pallet you choose. It will automatically group the leather, bundle it and even attach the measurement slip to the last one in the bundle if desired. For a new and innovative method of transportation of hides around the tannery, Feltre have a fully automated system of tiltable platforms that move piles of hides from one machine to another via train-like rails in the tannery floor. Each platform is powered by rechargeable batteries and is radio controlled via a programmable control panel for ease of use so there are no problems with cables around the tannery. The system, known as Transfer, can deal with hides from all stages of processing and can be designed to utilise areas of the tannery that would otherwise be considered ‘dead space’. The system was eloquently demonstrated at Tanning Tech with a working model and video presentation. When integrated with their electronically controlled automated grading table, viewer and stacking machines it proves that automation in the tannery is a reality, not myth. As previously mentioned, one of the difficulties in automating the tannery is the hostile environment. Conveying and stacking systems must be well engineered, constructed from materials that will withstand whatever the tannery cares to throw at it and be easy to maintain and repair. Gemata’s Comstack stacking machine features an easy to use control panel for programming that also has a ‘help’ function which enables the operator to quickly locate and rectify faults with a self-diagnosis system. Equitan, who have recently achieved ISO 9001 status, make a wide range of thermo-welded conveyor belts from highly resistant synthetic materials able to withstand the tannery environment. For the beamhouse, their drum loading conveyors and bins are constructed from stainless steel for reliability and longevity. Whilst Tanning Tech is a shadow of its former self, this has not discouraged the innovation of new technologies that have the potential to increase productivity in the tannery without increasing manpower or risks. Like it or not, the old ‘craft’ image of the tanning industry is rapidly changing.