Toshiba Machine has produced a total number of 9,500 sets of die casting machines since it manufactured the first one back in 1953. Since then to the present, its die casting machines have developed, responsive to the needs of each era. As for the die casting machines specifically, it is not too much to say that the technical development of injection performance has been directly regarded as the history of those machines. We explain hereinafter the technical needs and added injection characteristics for each era from the foundation up until today.
The first machine in 1953 was a 200 ton (1960kN) die-locking-force horizontal cold chamber die casting machine, which was delivered to Toshiba Corporation Nagoya Plant, being the most basic single-cylinder injection type and operated by oil pressure from an accumulator. At that time there were no manufacturers specialized in hydraulic equipment, and everything from hydraulic pump to valves had to be self-made in the company, taking a lot of labor; so we hear. After that machines up to 400 ton (3920kN) of die locking force were manufactured.
In the second half of 1950s, together with thin-walled die-castings such as camera (cases), washing machine motor rotors, etc; enlargement of them such as electric-fan stand arms, sewing machine arms, etc was promoted, requiring machines that can achieve higher injection speeds; and the ""CT series"" die casting machines were manufactured, which adopted the run-around hydraulic circuit. In addition to that, for the purpose of improving the internal qualities of die castings, a 250 ton (2450kN) die casting machine (""CTI series"") with an intensification injection cylinder was developed, which increased the final filling pressure. The effect of this intensification helped improve the qualities very much and the machine became a best-selling one right away after its sales release. The design concept of this injection characteristic has been succeeded up until today as a basis of the Toshiba Machine's die casting machine injection characteristic.
Standardization of the die casting machines started in 1961; as DC series die casting machines with the piston intensification injection cylinders, they were built in turn from 80 ton (784kN) to 800 ton (7840kN) in die locking force. Then, they were accepted by the industry as easy-to-operate machines having highly consistent performance of injection speed, injection pressure and intensification.
In 1966 DC*A series die casting machines were developed, aiming at the reductions of intensification-time lag and pressure buildup time, which were successfully achieved, and played an active part in improving die casting qualities and in producing large-sized die cast parts.
By 1971 core pullers were increasingly used on the dies as die cast parts became larger in size and more complex in configuration. Due to the effect of increased injection speed and/or pressure, a problem often arose that flashes gushed into clearances of cores. Especially for complex configuration castings with large-sized cores, such as automotive transmission cases etc, the generation of flashes hampers the automatic operations; the research started for the relation between flash occurrence and pressure spike (surge pressure), and reached an idea to control the injection according to a hypothetical increasing curve for the allowable limit of casting pressure, which is determined by each die casting; the DC*C series die casting machines were developed based on this idea. Theses machines were epoch making ones that had independent circuits for the injection speed and pressure-buildup-time, making it possible to select the injection condition best suited for each die cast part configuration; at the same time, the injection cylinder mounting was changed to a C-frame system, which increased the machine rigidity by a great margin. Furthermore for large-sized machines, the SELECTROL injection system, which enabled free selections of injection cylinder pressure and intensified one, was developed as well.
Since injection characteristic changes in the unit of one thousandth of a second, development of velocity/pressure sensors as well as that of computer control software was conducted and the basic technology was perfected on a 350 ton (3430kN) die-locking -force die casting machine. After that, ""SEMU"" (Shot End Master Unit) was developed, which limited its control elements to die closing/injection, and then was put on the market as a computer-equipped die casting machine, which was widely accepted in the industry.
Starting around 1993, more than 50% of large-sized die casting machines were shipped with computer control, making computer-controlled die casting machines spread at a speed higher than we had expected. Due to increasing control items and growing needs for controlling a die casting system as a whole, ""TOSCAST"" (TOSHIBA MACHINE DIE CASTING SYSTEM CONTROLLER) was developed, which can control each motion of the whole machine, various injection conditions, die closing, automation, quality control, production control, good parts control, maintenance management, trouble diagnosis, monitoring, etc, having newly adopted a 32-bit computer; today it is adopted on a wide range of die casting machines from 135 to 3500 ton of die locking force, and well accepted. At the present, 60 to 70% of the machines are being shipped as ""TOSCAST equipped machine"". From now on, as the products become more intricate and highly precise, the tooling system plan, casting condition and quality control must be put under tight control; we believe TOSCAST is the best system to resolve such technical issues. In the future, the computer usage will be further promoted; development of various technology is wanted, heading for elimination of working personnel in a whole plant. We at Toshiba Machine Co., Ltd. are determined to pursue everlasting research and development to fulfill the future needs, always aiming at the best die casting machine manufacturer in the world.