Special products

Special products in our foundry are scorifiers from following steel grades:

• ČSN 422944 - Recommended for melting crucibles and crucibles for salt baths to be used in carburizing or sulphur medium. Operating temperature 1200°C.
• ČSN 422952 - Is suitable for melting crucibles and crucibles for salt baths. Operating temperature 1150°C.
• ČSN 422955 - Recommended for pouring and batched crucibles for fused basalt. Operating temperature 1200°C
• ČSN 422913 - Recommended for melting crucibles and crucibles for salt baths operating in carburizing or sulphur atmosphere. Operating temperature 1000°C.

The crucibles are delivered annealed.

Resistance of the crucibles

The crucibles are resistant to nitrides, less resistant to chlorides, sulphides and cyanides. The usual metal baths, except for lead baths, melt the iron. This feature is not desirable e.g. for baths of aluminium and its alloys because it may effect the purity of the molten metal. The crucibles made from chromium-nickel steels have proved successful for molten copper and its alloys. In the lead bath, only litharge on the bath surface may cause corrosion. Therefore, we recommend to apply a plain iron sheet as a protective band on such places. The crucibles made from plain steels are prone to scale formation. If the scales fall on electrical heating coils, they can disturb operation or destroy the coils. Therefore, it is recommended to apply the alloy steel crucibles for heating purposes. The chromiumnickel steel crucibles are very sensitive to gases bearing sulfur compounds, reduction gases and carburizing substances. The sensitivity of the crucible increases with an increase in nickel content and temperature. The chromium steel crucibles are best resistant to the effect of all these influences.

Service Life of the crucibles

It depends substantially on the operation conditions and on proper handling during operation. The crucibles made from plain steels have the shortest service life. However in some cases they may be very economical.

The service life of the crucible may be considerably lower in the following cases:

• local overheating - When heating by gas, it is necessary that the flames be directed tangentially towards the crucible wall. In addition to this, heating with excess air, which may form oxidizing flames, should be avoided. Local overheating can be avoided by periodically turning the crucible. When heated from below, a protection shield should be installed under the crucible so that overheating does not occur.
• periodical short-term application - When the crucible is heated and cooled very often, it may become very scaled and this may impact its ser- vice life, especially in case of plain steel crucibles. The crucible should be continuously held at a temperature that enables the salt to remain liquid.
• quick heating - Too rapid heating is not enough to molten content of the crucible was able to absorb the transferred heat evenly and it may happen that the crucible overheats and breaks. At the same time, scales form quickly on the interior. It is recommended, therefore, that the crucible should be emptied after finishing the work and when using it again, the crushed salt should be melted gradually.
• deposits in the crucible - The deposits act as insulation which causes accumulation of heat at the bottom and, hence, strong scaling. Thus the salt bath is exposed to the danger of decomposition. Therefore, the crucible must be thoroughly cleaned from time to time.
• too low cyanide content in cyanide bath - This has an especially damaging impact on crucibles made from plain steels. During hardening and tempering, the bath should contain more than 5% cyanide and more than 3% cyanide when tempering. The lower salt concentration may cause corrosion, and the iron trioxide or iron monoxide (sponge iron) is separated and set on the bottom of the crucible thus lowering its service life.

Round crucibles

Casting Pattern-No.	Volume I	Weight kg	H	Diameter d1	V	Diameter d	Diameter D	r	r1	s	R	R1	T	E	Flange
21964	2,5	19	250	140	270	170	260	15	30	15	70	85	5	150	A
21736	6	42	300	190	325	230	350	20	40	20	95	115	5	165	A
21718	14	75	450	230	475	270	410	25	45	20	115	153	5	290	A
40125	14	64	280	300	300	340	435			20	142	162			B
21886	17	75	350	300	375	340	500	30	50	20	150	170	5	150	A
ETE-1730	18	120	500	225	535	275	500	40	65	25	*	*	*	*	A
B-81787	18	72	490	245	510	285	400			20	115	135			B
41427	19	127	620	220	650	280	460	30	60	30	210	240			A
T-285	21	40	335	260	350	290	400			15	120	135			B
21740	32	105	550	300	580	340	500	30	50	20	150	170	10	350	A
21667	35	155	500	350	535	400	570	30	55	25	175	200	10	270	A
22585	38	150	580	290	615	340	510	30	55	25	145	170	10	380	A
KM-001	48	160	520	405	475	450	590			22	174	220	6		B
ETE-1731	55	220	500	400	535	460	680	40	70	30	*	*	*	*	A
323	55	140	530	380	550	420	585			20	*	*	*	*	B
22903	66	240	800	350	835	400	570	30	55	25	175	200	10	570	A
1-1781	75	195	720	440	750	475	600			20	170	190			B
21668	75	225	500	520	535	570	740	30	55	25	260	285	10	185	A
20391	90	175	630	535	660	575	700			20	230	250			B
ETE-1729	95	320	550	510	590	570	790	40	70	30	*	*	*	*	A
ND-1260	140	290	475	700	540	900			30	350	380				B
ETE-1732	140	435	800	510	840	570	790	40	70	30	*	*	*	*	A
22469	140	355	800	520	835	570	740	30	55	25	260	285	10	485	A
ND-1259	240	560	660	780	730	850	1000			35	380	415			B

*) lenticular bottom

Oval crucibles

Casting Pattern-No.	Volume I	Weight kg	D x Da	d x da	d1 x d1a	r	r1	r2	s	E	H	V	G	C	B	F
ETE-1512	89	320	770 x 570	610 x 410	550 x 350	25	55	80	30	535	600	640	200	258	80	25
22774	105	220	800 x 600	610 x 410	560 x 360	35	60	70	25	535	600	625	200	250	90	30
ZS-196	150	420	920 x 720	760 x 560	700 x 500	25	55	80	30	535	600	640	200	200	80	25
22622	195	290	970 x 760	770 x 560	730 x 520	40	60	90	20	560	620	640	210	320	75	20