have been removed in the previous processes. Fatliquoring automotive leather has to be done to a very high standard in order to avoid the release of vapors that can fog a car’s win- dows. The dyeing process gives the base color to the substance of the leather. These processes are also done in drums, but of a smaller size than in the previous steps. The drums can be made of tropical hardwood, stainless steel or polypropylene, and here also the more modern Cang- ilones design is available. Further processes follow, such as “setting out” the wet leather to remove water from the hides often using machines with spiral blades and felt
The Superpress from Bergi is a popular choice for embossing leather destined for automotive interiors.
sleeves or conveyors, and special drying processes such as toggling or vacuum drying. After this stage the leather is called “crust leather”. Crust leather is further processed with the use of stainless steel (dry) milling drums that soften the leather by redistributing the fat in the voids between fi bers under controlled tempera- ture and humidity for a number of hours. In the auto industry these machines typically are from Erretre (Arzignano, Italy). After this, the leather is either rollcoated and/or sprayed with a base coat and fi nish coat to give it the fi nal surface coloring. At this point the leather is dried. Then to again soften the leather a vibration staker is used. This consists of a through-feed machine with interacting fl at vibrating plates with male protrusions and female gaps.
Embossing
Subsequently the leather may be milled again prior to a surface embossing procedure done on a through-feed roller em- bossing machine, typically a Superpress from Bergi (Arzignano, Italy). The embossing is done with special rolls engraved with the leather’s fi nal design. Then the leather is usually milled again. Following this the leather goes to a cutting plant to be cut
to different shapes which are then sewn together to make automotive seating. Automotive and furniture upholstery leather require machines with working widths up to 3400 mm to process full hides. Traditionally, shoe and other types of leather are
processed as sides (half hides from whole hides that have been cut down the backbone). As in metalcutting, evolution has seen the advent of more process controls and the use of computers, touch-screen pan- els, PLCs, recipes for machine operation and automation for dosing, loading and unload- ing and operating the drums. Today chemicals such as lime and chrome are recycled and advanced effl uent water treat- ment plants including biologi- cal processes are used. Also, through-feed machines linked together with conveyors be- tween different processes and automatic hide stackers and pallets are utilized.
Although early in the last century many tannery machines
came from fi rst the US and later several European coun- tries, nowadays most modern machines are designed and produced in Italy.
The types of leather can be full grain where the grain (outside surface of the leather) is conserved; corrected grain, where the outer grain surface is partially buffed off in through feed machines with a cylinder covered in abrasive paper; or the lower-cost fi nished and embossed splits (the lower por- tion of the hide when split). Corrected grain and sometimes stucco is used to improve the quality of leather with superfi - cial defects such as scratches and tick marks.
Where do the Hides Come From? Leather used for North American vehicles is mainly produced
or fi nished from US, Brazilian or Agentine hides, with a large concentration of fi nishing operations taking place in Mexico. Approximately a dozen leather manufacturers account for 90% of the world’s automotive leather production, many of these companies with plants on different continents.
In 1984 Peter J. Helfer and his wife formed Campex LLC. Initially involved in tannery equipment sales in Latin America and the import of crust leather to the US, since 1991 Campex has represented European drum, machinery and equipment manufacturers mainly for the leather tanning and fi nishing industry.
25 — Motorized Vehicle Manufacturing 2015
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