November 19, 2018
CoGri Australia upgraded an existing warehouse floor to meet the super-flat DM1 flatness specification requirement for the installation of a 18m high very narrow aisle (VNA) racking with a top beam of 16m, for one of Australia’s largest carton manufacturers.
The facility, which is located just a street away from CoGri’s Sydney office, is an old manufacturing plant. The warehouse used to house an automated storage retrieval system (ASRS) but was decommissioned many years ago. The ceiling height is 22m and was going unutilised. Growth in the business meant expansion was needed, so the decision was made to convert the area to a VNA storage and one of the highest in Australia. Super high VNA is not uncommon in Europe, where the top beam now reaches to around 18m, but in Australia, even 16m top beam racking is quite rare.
A flat floor for VNA use is always important, but when you start going to 16m high and beyond it takes the importance of flatness to a whole new level. As the static lean table below demonstrates, a floor out of flatness transversely by just 6mm, produces as static lean of 80mm when the truck is 16m high, however, when the truck is moving, the static lean can be multiplied by three due to the dynamic movement of the truck and allowing for the general mast tolerances, meaning the fork truck can sway left to right by as much as 240mm. The rack-to-rack dimension is 2195mm, but pallet-to-pallet reduces the aisle width to just 1870mm. With the fork truck in the aisle, the distance between the fork truck and the racking is significantly reduced to around 140mm either side of the truck.
The table below shows the static lean ‘S’ of a fork lift truck assuming the mast is rigid. Due to the engineering tolerances in the mast and the dynamic force when the truck is moving this could increase the static lean by up to 3 times the figure shown.
A Profileograph survey was carried out well in advance of the decision to install the VNA racking and showed some transverse errors exceeding 12mm. A 12mm difference in transverse would have produced a static lean of 160mm and allowing for dynamic movement of up to 480mm would be present, which would have certainly caused a collision with the pallets and/or racking, as well as a high risk of the fork truck coming off the wire guidance. Apart from the obvious operational safety concerns, it would be terrifying for the operator if the floor flatness was not rectified.
The importance of floor flatness cannot be underestimated at any lift height, and especially when the fork trucks are guided by wire, so it is always advisable to get the floor tested well before VNA is to be installed.
Rectification/upgrading of the floor to meet the tight tolerance required to operate safely at 16m high was achieved using CoGri’s patented LaserGrinder®. All five aisles were ground, approximately 360 linear metres, full aisle width, in just under two weeks. The floor now has a maximum transverse of less than 2mm, well within the DM1 specification for the safe operation at 16m.
Once the floor was finished and the racking installed, CoGri Australia installed the wire guidance which will be used by the Jungheinrich trucks to guide the fork trucks safely down the aisle.
Prior to upgrading the floor flatness and the installation of the wire guidance, CoGri also carried out joint, spall and crack repairs to the floor, as part of the upgrade package. All-in-all, it was a challenging but rewarding project and one that produced significant productivity gains for our client by utilising otherwise unusable real estate.
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