Chill Mould Casting

Laboratory Work № 5

Objective: Get acquainted with the chill mould construction, its features and with the chill mould casting technology; evaluate quality of the foundry made by the chill mould casting comparing to the ones made by the sand mould casting, evaluate the metal recovery; determine chill moulds’ temperature influence on quality of the foundry.

Equipment and Materials:

1. crucible furnace - 2

2. melting crucible - 1

3. chromel-alumel thermocouple - 1

4. thermometer (millivoltmeter) - 1

5. zinc alloy ЦАМ 10-5 - 3 kg

6. chill moulds - 3

Necessary Theoretical Knowledge

The essence of chill mould casting lies in making a foundry by casting the metal into a chill (chill mould).

Fig. 5.1 Foundry’s shape (a) and chill mould’s shape (b) for foundry casting: 1 – chill’s halves; 2 – the rod; 3 – risers; 4 – pouring basin; 5 – riser pipe; 6 – choke; 7 – pins for chill’s cooling rate increase.

Features of chill mould casting comparing to sand mould casting are:

- possibility of nonexpendable mould’s use (up to a few thousands times);

- high cleanness and precision of the foundry;

- fine-grained and dense structure, which provides high level of mechanical properties of the foundry;

- decrease of the critical features for mechanical treatment or its exclusion in further treatment technology;

- high labour productivity and comparatively low cost price of the foundry.

Characteristic feature of the chill mould casting technology is high cooling rate, almost total absence of gas permeability and mould flexibility.

Therefore in order to decrease foundry cooling rate, the moulds are coated inside with the fireproof suspension or paint and are heated up to 200 – 450°C.

The disadvantages of the chill mould casting are high chill mould production cost, difficulties at making complex shaped castings and possibility of cast iron foundry chilling.

Work Execution Order

1. Heat the furnace up to 550 – 600°C.

2. Melt the alloy.

3. Heat two chill moulds to 150 and 300°C and paint them with the fireproof paint.

4. Pour the molten alloy into the chill moulds, which have the temperatures of 20, 150 and 300°C.

5. Take the foundry off the chill moulds after it is cooled.

6. Examine visually the quality of the foundry surface, set the presence of external defects.

7. Compare the smoothness of the surface with the surface of the sand mould foundry.

8. Determine the influence of mould’s temperature on the foundry quality and the fullness moulds’ filling.

Content of the Report

Describe the essence of the chill mould casting, its peculiarities, advantages and disadvantages. Characterize the quality of the made foundry: value of the dimensional features and the surface smoothness, metal recovery.

Describe the chill mould’s temperature influence on the structure of the foundry.

Control Questions

1. What is the essence of the chill mould casting?

2. What is the peculiarity of the foundry production into chill mould?

3. how is the preparation of the chill mould for metal pouring held?

4. when is the chill mould casting efficient?

5. how does the chill mould’s temperature influence on the foundry quality?

6. what are the advantages and disadvantages of chill mould casting?

Дата добавления: 2015-11-14