TECHNICAL ARTICLE:

Introduction

In Japan, sawing is traditionally done at a steel distributor. A manufacturer rarely undertakes sawing but purchases cuts as needed from the steel distributor. For this reason, the Japanese steel distributor is broadly decentralised and specialised. In order to be able to satisfy the high requirements of the Japanese customers regarding ‘just-in-time-delivery’, steel distributors pick their location close to the customer to guarantee a short-term delivery.

Specialisation often means that round material is bought from other distributors, rather than flat material. The differentiation between steel distributors depends on the qualities of standards, such as structural steel, tool steel or corrosion-resistant qualities. According to this consistent delivery strategy, steel distributors in Japan are equipped with extensive sawing machinery. Here, streamlining efforts depend more and more on utilisation of sawing centres - a way to automate and save space, which in return brings additional advantages due to the high space costs. The following example shows the investment in a sawing centre and the consequential benefits to a steel distributor.

Overview of the Japanese Steel Distributor

The steel distributor Fujita Shoji Co Ltd, near Tokyo, is based in an industrial area where more than 200 steel distributors are situated. These distributors supply round and flat material of structural and tool steels to customers in the close vicinity. Since the beginning of the 60s, Kasto and Fujita have had a very close business relationship.

In 1975, the first bar storage system had been installed and is still in operation, while the first sawing centre was delivered to Fujita in 1982. With this modern machinery, Fujita is extremely well equipped for the extensive pre-manufacturing tasks. Therefore, more than 50 per cent of Fujita’s customers have their material cut on-site and demand a fast delivery. The delivery time of the cut pieces is usually one day, which means, when Fujita receives a saw order, it must be delivered the next day, usually to companies within a radius of 100km.

In order to also be able to meet the requirements of modern steel distributors, Fujita decided in 2000 to build a new warehouse in Sano-City, Kitakano, approximately 100km north-east of Tokyo. The transport links in north-south direction as well in east-west direction are very good. During the planning phase, the use of modern sawing centres was intended right from the start.

Centre with Operating Gantry Crane for Back-to-Back Storage

At the heart of the new production facility is a Kasto sawing centre (KASTOcentre), for shafts with individual bar storage as well as a cassette part to commission and to feed a mass production circular saw. The high space costs in Japan require optimum utilisation of space and, therefore, the steel structure was designed with variable height partitions. Additionally, the operating gantry crane was equipped with hinge forks for back-to-back storage of the material. This way, a large number of materials in different qualities and dimensions can be stored as well as made available and cut automatically. Also, large and heavy shafts can be cut without problems since the new sawing centre accepts material bars from 30 to 290mm diameter.

Sawing centre KASTOcenter Vario-Duo 2 with cantilever arm. In front, the bandsaw KASTOtec SC3 with disk rotator, deposit buffer and container carousel

The material bars are stored on cantilever arms and the entire in/out handling takes place via a fast operating gantry crane. Its loading traverse is equipped with hinge forks and can be used very flexibly and on both sides for handling and transport of up to 6.5 m or each time of 3.2 meter long bars (in front or back). Even larger asymmetric loads are not a problem for the operating gantry crane. With the hinge forks assembled in four groups, material up to a weight of 2.5 tons can be separated and safely transported.

The operating gantry crane removes the material bars according to orders and transports those to the quick change station of the fully-integrated SC-bandsaw KASTOtec SC 3. This quick-change station allows a bar change (chip to chip) in 100 seconds. This ensures that the saw does not have to wait for the following material, which is standard with conventional machines. Idle times are thus reduced to a minimum. Based on the experience with more than 100 systems delivered, it can be proven that a saw in the sawing centre with single and small series manufacturing can replace approximately 3 to 7 conventional saws as well as the appropriate operators.

Future-Oriented Sawing Technology

Due to the consistent further development of the sawing technology with the new KASTOtec series, increase in output doubles in high production operation with carbide blades and suited order spectrum, which in return clearly increases the profitability of highly technical sawing centres.

In order to be able to utilise these advantages, Kasto has paid attention to the following design and drive characteristics for the KASTOtec series:

• A very robust and vibration-optimised saw unit due to the highly damping material mineral cast
• A sturdy gear box
• High-saw drive power with an infinitely variable saw feed adjustment, which can be adjusted accurately and temperature-independently as well as permanently control
• A hydraulic side shift cylinder on both sides of the blade, which ensures a gentle handling of the sensitive carbide blades when the blade is retracting
• A tailored cutting data and operating software
• A cut in/out control for the saw feed
• A break-in program for new blades to optimally prepare the blade for later high performance

When developing the KASTOtec SC 3, a weak point with the cut-off removal was noticed and immediately eliminated. The goal was to streamline and automate the removal of disks and shafts with piece weights up to 200kg to prepare the cut pieces for shipment with less work involved. Moreover, the need for marked cut-offs increased and they needed to be removed with hardly any chips. Therefore, the KASTOtec SC3 at Fujita is equipped with a fully automatic sorting device where disks are cleaned, transported, rotated, stacked and palletised. The objective here was not to decrease the actual saw performance due to bottlenecks at the removal area and to save personnel in the saw surroundings on top of it.

Fully integrated KASTOtec SC3 bandsaw with carbide tools, disk rotator, palletising unit,
container carousel as well as deposit buffer for long cut pieces

For a reliable process, the part is constantly cleaned during cutting with a cleaning device, which is integrated into the sorting device. The parts leave the saw almost completely free of chips. After the cut, the sorting device moves with the cut piece alongside a cam first horizontally out of the saw, crosses an area that can be opened into a container for removal of trim cuts and remnants or dropping of parts and swivels then by 90° to the top. Afterwards, the longitudinally moving out-feed roller conveyor - which can accept disks in push-out position as well as also transport shafts to the following out-feed buffer (can be occupied on both sides) - travels to the transfer position, where the disks are deposited flat.

Further disks can either be stacked onto the previous ones or they can be placed next to them. If the required number of saw cuts on the roller conveyor is reached the roller conveyor moves the cuts to the transfer location. With this new technology, the saw cuts can be stacked space-saving next to each other, on top of each other or back-to-back until the deposit area (pallet base area minus frame) is full or the order is finished. Depending on the job on hand, the parts are either stacked as high as possible or the cut pieces are deposited evenly onto the deposit area.

A pallet lift brings a Euro pallet, which is usually covered with carton, under the pusher where pieces are made available. To balance the inevitable tolerances, the pallet is supported elastically. The pusher is pulled out from under the material and the cut pieces are slipped onto the Euro pallet. Then, the Euro pallet is lowered with the material. Long shaft-shaped cut-offs or individual pieces can either be pushed onto a table on the back-side of this pallet station or subsequently moved left or right onto a deposit buffer.

Container Carousel for 10 Euro Pallets

For an optimum long order processing cycle without any personnel, it is absolutely necessary to have a large number of Euro pallets ready. Therefore, in longitudinal direction of the saw, Euro pallets are transported with a revolving container carousel that has 10 locations.

The revolving container carts can be loaded and unloaded with forklifts, eliminating stackers. To change pallets, they are moved automatically and NC-controlled to the transfer position, the pallet lift moves under the Euro pallet with two fork arms and lifts and lowers the pallet.

Storing Stations: Cantilever Arm and Cassette for Feeding

On the right hand side - next to the fully integrated bandsaw KASTOtec SC3 (for single order cuts as well as small series cutting) - is the storage area of the KASTOcenter VarioDuo 2 with two separately movable storing carts. One cart is equipped with a step-like cantilever frame in order to have individual bars in correct position ready for the sawing centre. After positioning the bars, the appropriate material data and its length is entered into an operating terminal. The cart is moved into the system, and subsequently the operating gantry crane moves the material to the desired workstation - as long as there are no prioritised move-out or transfer moves waiting.

KASTOtec sorting unit of the KASTOtec SC3 when stacking cut pieces

Next to the storing cart for individual bars is another storing cart, where cassettes can be loaded and unloaded. These self-supporting bar stock cassettes are stored in a specially designed area of the steel structure on columns with cantilever arms. Contrary to individual bar storage for the supply of the fully automatic band saw KASTOtec SC 3, the cassettes are used to store larger quantities of bar stock bundles or material bars that are not intended to be automatically handled.

Also small dimensions can be stored inside the cassettes. Therefore, the sawing centre at Fujita is divided into halves: one half is a ‘sawing centre’, with orderly storage and individual bar access, and the other half is a high volume cassette storage system with the following functions:

• Buffer stock to feed the fully automatic sawing centre;
• Material storage to commission entire bars;
• Material storage to fully automatically feed the mass production circular saw KASTOspeed C 14.

This alone shows the variety and difference of the individual tasks that have to be performed in a steel distribution facility like Fujita Shoji. To handle the large quantities, Fujita installed a lateral material conveyor in the loading area. Bundles, arriving via truck, are loaded onto this conveyor, buffered and, if necessary opened and then either loaded into cassettes or moved into the sawing centre. The entire system is designed to automate all tasks - receiving, order cutting, commissioning or high production sawing - as much as possible. Therefore, they also invested in the commissioning area of this sawing centre, where the material is removed from the cassettes according to order, bundled and then prepared for shipment.

In order to guarantee the highest possible material turnover, the commissioning takes place at a rotating station with two roller conveyors located inside the shelf system as well as in the outer area with two roller conveyors and a cross-transfer unit. This well-equipped station allows the operating gantry crane to deliver a new cassette in the shortest possible cycle-time and then receive a restored cassette. A continuous material flow cycle is reached when material is placed onto the in-feed roller conveyor, moved out of the shelf system, moved across onto the commissioning location, commissioned and again moved back to the shelf system. While material is removed from one cassette, the next cassette in line is already in position. Altogether, the maximum 4 buffer locations are available in the area of the commissioning station.

Mechanised commissioning station for round and square shafts for push-button controlled commissioning

The commissioning of round and square material bars was automated with a lift device. The separation station consists of two separately liftable (inclined towards each other) material ejectors, which push the material out of the cassettes with the push of a button. The material is moved onto a buffer, while the width of the buffer is adjustable to the material width that is being removed from the cassette. With a second separation unit with loading disks, the desired number of bars is taken out of the cassette, gathered onto a chain conveyor, banded and finally moved to the shipping area. This allows fast and reliable commissioning with only a few employees and to commission everything directly with the inventory control computer.

Mass Production with Reloading from the Sawing Centre

The third task of the KASTOcenter is the fully automatic supply of a mass production circular saw type KASTOspeed C14. With its work range of 140mm, pieces up to a length of 300mm can be cut fully automatically and without personnel. For this purpose, the location of the longitudinally moving outfeed station enables the loading magazine of the fast mass production circular saw to be supplied directly.

Out-feed side of the mass production circular saw KASTOspeed C14,
located in front of the cassette part of the sawing centre

The mass production saw KASTOspeed C14 is ideally suited for the repeated accurate cutting of forging and stamping blanks, blanks for turning, shafts and other ready to use cut pieces of steel. The KASTOspeed C14 works with throw-away carbide saw blades in thin-cut technology. Feed and cutting speeds, which are to individual sawing requirements, ensure shortest cycle times for high cutting performance and therefore maximum productivity. Due to the integrated, fast material feed carts and the fast switching, hydraulically dampened, lifting swivel-out measuring stop, the material is transported and positioned accurately with consistency. In practical operation, this leads to minimum handling and feed times resulting in a high output ratio of precise cut-offs.

Inventory Storage Management and Order Management

To automatically control the different but very complex sequences, highly intelligent, high-end software is needed. It is used in the inventory control computer KASTOlvr based on an up-to-date, industry-standard hardware. Characteristic of this inventory control computer is a graphical user surface in standard ‘Kasto look and feel’, an SQL-capable data bank, and an easy operator guidance with extensive diagnosis and statistical possibilities. Orders can be transferred via an interface to higher-ranking systems and acknowledged after they are finished.

In case of problems or operating errors, the Kasto-phone service is available. With this support, the system in Japan can be analysed, modified and also operated - directly by a service engineer in Achern. For storage inventory, the KASTOlvr has background data in form of material master data and storage location management. The material master data stores dimensions, qualities, technology data, storage strategy, and heat numbers.

The inventory management data store source locations, target locations as well as individual bar lengths. A saw order can be easily determined by cut length, number of pieces, material and order number leading to a simple order generation. The consistency of this equipment, with ergonomic operator guidance, ensures the use in workshops. In order to ease the handling of the entire system for the Japanese operators, the screen menu contains Japanese characters. Also, the software contains heat management.

Conclusion

Fujita Shoji Co Ltd recognised the signs of change early on and followed the trend of smaller batch sizes and short-term customer deliveries by investing early on in highly economic saws and sawing centres. The obvious competitive advantage is short-term, more flexible and reliable delivery to customers with reduction in cost, personnel and floor space at the same time.

Moreover, production peaks can easily be processed in shifts with no operators. A substantial part of the streamlining of this newly installed sawing centre at Fujita is the also installed band saw KASTOtec SC3 offering high efficiency when cutting according to order. This, on the one hand, is due to the very high cutting performances by utilising carbide technology and, on the other hand, to the task-adapted sorting technology with disk rotating, stacking and palletising so that former manual tasks, like removing cut-offs after the cut, are done fully automatically.

Equipped for the future with modern control and handling technology, the sawing centre installed at Fujita is the rational and economic answer for today’s high flexibility requirements combined with on-time delivery. With this technology, Fujita is well equipped for the increasing competition for added value and just-in-time delivery in steel distribution and the future industry.