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Industrial robots are computer-controlled, freely programmable machines that can be fitted with various grippers, tools and other attachments. On production lines, they can also carry out complex work operations without human intervention. They are programmed by manual guidance once, after which they repeat the sequence automatically. Robots are available that can handle useful weights of over 2 t, for example the FANUC M-2000iA/2300 with a payload of 2,300 kg^[2] or the KUKA KR 1000 titan, whose foundry variant carries 1,000 kg^[1], and can therefore also be used in foundries.

References

1. KUKA AG: KR 1000 titan, technical data by variant. Product page, accessed 27 August 2026.
2. FANUC Europe Corporation: M-2000iA/2300, 2.3t Heavy Payload Robot. Product page, accessed 27 August 2026.

An inductor is the heating assembly for channel furnaces and casting units. A channel inductor is constructed in a very similar way to a transformer, and comprises a closed iron core/yoke on which are mounted 1 or 2 coils. The channel is arranged as a secondary winding at 90° through the yoke opening. An inductor has a relatively high area output in the channel, in relation to the cross-section and the inner jacket surface of the channel. An 800 kW inductor has a coupling surface of approx. 2.1 m2. The inductor coil for example – at 660 V/50 Hz – has 34 windings with an effective current of approx. 1212 A and this 41,208 ampere windings. The channel consequently has a current level of 41,208 A, since the number of windings is 1. This corresponds to a current density of 1.84 A/mm2. The area outputs are: approx. 890 kW/m2 for the inductor and approx. 380 kW/m2 for a comparable crucible furnace with 3 t capacity and 800 kW output.

Induction is based on magnetism in conjunction with electrical voltages and currents. The following rules apply, as used in the design and construction of motors and for transformers: when an electrical conductor is placed in an alternating magnetic field, an electrical voltage is induced in the conductor. When a current flows through the conductor, a thrust is imparted to the conductor, which acts at an angle of 90° to the direction of the current. This property is used in the construction of motors.

In the generator, a voltage is generated in the rotor or stator winding of a conductor.
In the transformer, a core holds 2 separate coils, each with a different number of windings. The voltage is transformed to a higher or lower level, depending on the number of windings, i.e. the transmission ratio. Because the actual output remains the same, the current changes in the inverse proportion.

e.g.
Primary: 10 kV 200 windings 50 A 500 kVA Secondary: 1 kV 20 windings 500 A 500 kVA

The crucible induction furnace is based on the induction principle of transformers, which is explained below by means of an example.

A medium-frequency furnace with a 5 t capacity has an output of 3,000kW at 3,000 Volt, 11 windings and a crucible wall thickness of 140 mm. An effective current of 1,000 A flows in the coil.
If the melt or scrap charge is now applied as a secondary winding, this gives a theoretical voltage in the crucible of 273 Volt and a total current as a product in the melt of approx. 11,000 A. This high current acts as an eddy current, which heats and melts the charge.

A connection between the coil and bath (lining leak) can also be identified with an earth short or imbalance monitoring device. In this way, a warning signal can be generated if the melt penetrates into the vicinity of the coil.
There is also the danger that a winding short caused by this metal will damage the conductor to such an extent that cooling water escapes.

It is essential at all times to avoid water getting into the melt. The voltage must therefore be switched off automatically if the bath gets dangerously close to the coil. This danger can also be significantly reduced by the appropriate design of the coil. The furnace itself also includes the additional electrical devices shown in Figure 114 for a medium-frequency furnace; the only difference in a mains frequency furnace is the absence of the frequency converters.

Hydraulic systems are complete systems for the hydraulic operation of machinery, consisting of a pump assembly, hydraulic working cylinders or hydraulic motors, pipe systems and control devices. The energy is transmitted by a hydraulic fluid, such as oil or emulsion, which is supplied by the pump assembly at pressures of up to 200 kp/cm2.

Hood extraction systems were installed above furnaces in the same way as forge hearth extraction systems. Very high air transport capacities are required due to the large separating distance from the furnace platform. In order to increase the air speed at the end of the hood, flow nozzles were installed in the funnel. Since these hoods have to be swung to the side for charging and casting, a complicated swivelling system is also necessary. In order to reduce the high separating distance during melting, raising and lowering systems can also be fitted. One could say that this system can be optimised, but for the same result, the costs are significantly higher than with other extraction systems.

Heat losses occur in all vessels containing melts at high temperatures. In the case of channel holding furnaces, the losses are determined by the melt contact surface, the bath surface and the inductor idle losses. For a 120 kW inductor the inductor losses amount to approx. 25 kW and for a 2,000 kW inductor approx. 100 kW. With optimum vessel design, the melt diameter also corresponds to the height of the melting bath, thus achieving the lowest possible contact/bath surface with the largest possible capacity. Holding furnaces can act like a “thermos flask” depending on the heat insulation and the lining. With a 13-t crucible furnace, the following losses must be expected: 120 kW thermal wall loss, 20 kW bottom loss, 35 kW surface loss with closed cover, totalling 175 kW idling losses.

Hard casting is the term for an iron-carbon alloy with a low graphitising factor, so that the material solidifies white.

Graphite clay crucibles must be prepared for optimum earthing at the crucible bottom. Earthing in the casting spout is only effective after the 1st casting. In order to earth the crucible, a spiral with at least 5 windings of 3 mm wire is installed in the furnace bottom. This spiral is then covered with fine-grain graphite powder to a level such that the graphite clay crucible reaches its installation height after a few rotations. The back-fill compound is then filled in and compacted. Finally, the upper edge of the back-fill compound is sealed off with a patch, so that the back-fill compound cannot trickle out when the crucible is tipped. Prior to the 1st charging with scrap or molten material, the crucible should be heated up inductively at an output of approx. 40 kW/250 kg of crucible weight. The crucible should have a light red colour approx.100mm below the crucible edge. Fine material (preferably chips) should now be placed in the bottom and normal scrap filled in on top. The 1st charge can now be melted.

Gas burners are operated as normal burners with air, or as high-performance burners using oxygen. Depending on the size of the crucible, holding, storage or channel furnace, outputs of from 100 to 500 kW are used, and more rarely 750 kW. The application temperatures to the ceramics range from 800 °C to 1,200 °C. The flame temperatures are considerably higher, and can reach levels of up to approx. 2,400 °C.

Furnace transformers, except in the case of medium-frequency systems, are designed as step transformers. As a rule, 10- or 12-step secondary windings are used for mains frequency systems. The switching takes place in the no-load condition on the secondary side. The top 5 or 6 steps are designed for nominal output, while at the lower steps, the output falls by the square of the reducing voltage. The lowest step is set so that the relevant furnace can still be kept hot at 60% of its capacity, without the temperature rising significantly. In the case of a 12.5-t furnace, the output used by the furnace should be about 140 kW. If the maximum voltage is 2,000 V for 2,600 kW, the lowest voltage step must operate at 465 Volt.