Demag cranes for two paper-roll stores in Thailand
Via its joint venture MHE-Demag, Terex Material Handling has been awarded a contract by Siam Kraft Industry Co. Ltd. for the delivery of five fully automated Demag process cranes. The cranes will be used in two paper-roll shipping stores in the Ratchaburi province. Siam Kraft Industry Co. Ltd. manufactures Kraft carton, corrugated paper, Kraft sack papers and Kraft papers as the base material for core papers in the towns of Ban Pong and Wang-Sala, which are located some 80 km west of Bangkok.
An automated paper-roll shipping store that is equipped with three cranes accommodates the entire output of the newly installed PM16 paper machine; a further store provides space for the production output of the PM1 and PM3 paper machines. In both roll stores, Demag process cranes equipped with mechanical roll grippers provide for fast and, above all gentle storage of the paper rolls. The crane installations can lift up to four rolls at the same time, thus achieving handling rates of 120 rolls per hour in the roll store for the PM16 and 80 rolls in the roll store for the PM1 and PM3 paper machines. The scope of delivery also includes the installation of a Demag Warehouse Management System (WMS) at both locations for management of the stores and control of the crane systems. Both stores are planned to enter service at the beginning of 2015. These installations are the result of Terex Material Handling’s international project engineering and manufacturing network. Close co-operation between MHE-Demag in Thailand, which is responsible for providing customers with help and advice, and the engineering departments at Terex Material Handling in Germany, result in paper-roll stores that are precisely tailored to meet the customer’s specific needs. This also applies to manufacturing: besides the process crane components and the mechanical paper-roll grippers, the warehouse management system is supplied by Terex Material Handling. The steelwork for the crane girders and crane runways is manufactured locally by MHE-Demag. The crane systems are assembled and installed and the value of the installation is maintained by the service network provided by MHE-Demag.
Demag technology as key part of growth strategy
“The investment in two new paper-roll shipping stores is a key element of our growth strategy”, explains Chartchai Leukulwatanachai, Managing Director of Siam Kraft Industry: “For these projects, we rely on a company with regional expertise in the form of MHE-Demag and an international technology network. We also decided in favour of Demag process crane engineering thanks to a large number of first-class references.”
Lutz Dowy, Vice President Global Product Management & Process Cranes at Terex Material Handling, adds: “The equipment installed at the two paper-roll shipping stores marks the first fully automated Demag crane systems in Thailand. The installations play a major role in boosting the storage capacity and handling volume at the locations operated by Siam Kraft Induistry.”
Two shipping stores for three paper machines
Siam Kraft Industry Co., Ltd. is a subsidiary of SCG Paper. With a production capacity of 1.7 million tons per year at twelve production facilities in the three countries Thailand, the Philippines and Vietnam, SCG Paper is one of the largest manufacturers of paper in the ASEAN region. The newly installed PM16 paper machine has an annual production capacity of 320,000 t of recycled corrugated base papers weighing between 105 and 150 g/m². To ensure that the production output is carefully stored and retrieved just in time, Siam Kraft Industry is investing in a new paper-roll shipping store for which MHE-Demag is supplying three process cranes. A new shipping store for the PM1 and PM3 paper machines featuring two identical Demag process cranes will subsequently be built in the town of Ban Pong.
Maximum performance and availability in 24/7 operation
When the new PM16 paper machine achieves its full production capacity at the Ratchaburi Mill, up to 1,050 t of paper will have to be placed in the paper-roll store every day. The rolls, which are configured to meet individual customer specifications, measure between 620 and 2,520 mm in width and weigh between 400 and 2,400 kg.
The store for the PM16 covers a total area of more than 3,300 m² and can accommodate some 10,500 t of paper when filled to a capacity of 80 per cent. The store is filled around the clock in 24/7 operation, while product is retrieved in two shifts. During periods in which no loading operations are performed, the cranes optimise the store with reference to subsequent retrieval operations. The shipping store is divided up into two areas in which the rolls of paper can be placed in stacks up to a height of 13.5 m, depending on their relevant diameter. Three identical ZKKW double-girder overhead travelling cranes, which have a load capacity of 2.8 t and a span of 35.5 m, operate on a crane runway that measures 90 m in length. The cranes handle unwrapped rolls that have a maximum diameter of 3,600 mm and weigh up to 2,880 kg.
Siam Kraft Industry placed emphasis on a high level of dynamics when planning the store: up to 120 rolls can be handled per hour. Besides a consistent storage concept, the high handling speeds specified by the paper manufacturer require high performance to be delivered by the crane systems. The variable-speed long and cross-travel drives reach speeds of up to 120 and 100 m/min, respectively; lifting speeds of up 57 m/min are achieved, depending on the load. Besides the high operating speeds, the crane control system employs dynamically overlapping travel motions to ensure that the three cranes, which operate on one runway, achieve the required high handling rates.
Safe and reliable handling: fours rolls of paper in one lift
The high handling rates are also achieved by the use of mechanical roll grippers. For paper rolls measuring up to 900 mm wide, the mechanical gripper can lift up to four rolls at the same time. To do this, the process crane is precisely positioned above the centre of the roll by the warehouse management computer. Six arms engage the rolls with a constant contact pressure. Additionally integrated safety circuits – such as the redundantly designed sensors installed in the gripper – provide for safe and reliable handling in the automated storage processes.
Thanks to the compact design of the mechanical roll gripper, the rolls of paper can be placed in a tight storage pattern. This enables the best possible utilisation of the available space to be achieved with minimum gaps of only 150 mm in the store layout. This generation of mechanical grippers has already proven to be a success in automated paper-roll stores in Europe and China for many years.
Identical store concept for PM1 and PM3
The same store concept was also adopted for a common roll store for the PM1 and PM3 paper machine. The rolls in this store, which are configured to meet individual customer specifications, measure between 620 and 2,520 mm in width and weigh between 360 and 3,300 kg. The store covers a total area of more than 2,800 m² and can accommodate some 8,650 t of paper when filled to a capacity of 80 per cent. The rolls are stored around the clock according to the production output of the paper machines; there is a window of opportunity of 12 to 20 hours per day for retrieval.
Two identical ZKKW double-girder overhead travelling cranes, which have a load capacity of 3.3 t and a span of 35.5 m, operate on a crane runway that measures 76 m in length. These cranes are also equipped with mechanical grippers to pick up wrapped and unwrapped rolls of paper and store them in stacks up to a height of 13.5 m. The two cranes handle up to 80 rolls per hour.