Quality Enhancement of Foundry Products-A Case Study of Foundry Industry of Sri Lanka

The foundry industry in Sri Lanka dates back to as far as the second century BC and is still in its developing stage. The quality of foundry cast products manufactured in Sri Lanka is not up to a competent level with the international market. Highly labour intensive methods used, compared to other sectors of the metal working industry, and low productivity can be considered as significant reasons for the less competitiveness. Also, the technological development of this industry is stagnated and it should be improved to a great extent. This deficiency may be due to lack of knowledge in modern technology, unavailability of experts, scarcity of quality raw materials and inadequate new investments. All these factors are also highly influenced by the industrial policies implemented in Sri Lanka. Hence, it is essential to carry out a detailed study on the present situation in Sri Lankan foundries so that appropriate modifications can be implemented to the existing system. The study presented in this paper reveals the present situation of the foundry industry in Sri Lanka, including types of foundry products and the significant defects concerned with. The methodology adopted for this study includes a national survey carried out among the foundry industries in Sri Lanka. This is done by a structured questionnaire survey and interviews carried out with key people in the industry. The data collected from this survey has been analyzed with PC software according to the districts, types of foundries, items produced and the types of defects. In the latter part of this work, further studies will be carried out experimentally to enhance the total quality of the foundry products.


Introduction
The foundry industry is one of the most essential industries in the development of a particular economy as it is complementary to any metal-processing activity.The foundry industry is mainly divided into two categories as ferrous and non-ferrous castings.Cast iron comes under the ferrous castings and brass, bronze and aluminium are the major components of non-ferrous castings.The modern ferrous industry based on the cupola furnace was developed in Britain during the eighteenth century and imported to Sri Lanka in the latter part of the nineteenth century.A large percentage of foundries in Sri Lanka still use the obsolete and primitive technology and such foundries result in low productivity, wastage of material, low quality of products and unfavourable working conditions.The aim of this work is to investigate the present situation of foundries and identify the essential quality parameters of foundry products.

Analysis of the scale of the foundries in Sri Lanka
The scale of the foundries was decided according to the amount of raw materials used per month

Technology used in local foundries
A large proportion of castings, especially aluminium castings, are made using granite powder as the moulding sand (fig.5).
Unfortunately, the quality of the castings is not of the required level.This deficiency may be due to a lack of knowledge of the properties of moulding sand such as permeability, clay content, green compression strength and AFS (American Foundrymen's Society) sieve number, etc. and the testing methods of these

The quality of the castings
There is an urgent need to enhance the quality of foundry products as it is not up to a competent level with the international market.The quality of a product is closely related to the customer's requirements and quality parameters are dependent on the type of product.As an example, the most significant quality parameter of the castings in ornaments is the surface finish, but in automobile parts and in machinery parts strength & hardness are the significant quality parameters.
Casting defects such as blow holes, slag inclusions, sand inclusions, swell, erosion and cracks affect the surface finish of the castings.
Cracks are the major defects in all types of castings (fig 4).The quality of the casting basically depends on the casting process, gating system and the composition of the metal.
Normally, in local foundries, door & window fittings are produced by using the sand casting process, but in India the same products are produced by using the gravity die casting process, which produces a better surface finish relative to the local products.Today the production of brass castings is done by few foundries as the price of the pure Cu and Zn ingots is unbearable for the local foundrymen.
Therefore most of the foundries use brass scrap, which has a certain amount of other metals such as Al, Fe & Sn and results in a lower quality of product.In Sri Lanka, some customers pay attention towards the price rather than the quality of product and they are willing to buy products which are imported from India and China.

The local & international demand
Although mainly catering to the local market it   The recent changes in the economic scenario and progressive government policies can make a great impact on the Sri Lankan foundry industry.As a result of the government's reform policy and the classification of the foundry industry as a thrust industry it is obvious that both the government and the private sector of the country should involve themselves by directly implementing positive actions to upsurge the enthusiasm in local foundrymen to develop the foundry industry.

Conclusions
• Most of the casting defects that appear in local foundry products affect the surface finish.Therefore, surface finish was identified as the most significant quality parameter.

•
Most of the foundries, specially aluminium foundries, are scattered in the Colombo district.

•
The predominant type of foundry in Sri Lanka is the aluminium foundry.
• Most of the foundries produce ornaments and machinery parts.

Figure I :Figure 4 :
Figure 3 : Analysis of Foundry items

Figure 9 :
Figure 9 : Producing aluminium casting* using granite powder as a moulding sand.
has a high export potential.Local demand is extensively directed towards ornaments and machinery parts.However, the demand for kitchen equipment, door & window fittings are at a satisfactory level.At present this industry exports a few foundry products and it indirectly contributes to exports by supplying machinery components to industries such as tea and rubber [3J.Studies undertaken in Sri Lanka show that the efficiency and competitiveness of the local light engineering industry is in a satisfactory level relative to the international level.The country exports products such as precision tools, moulds and electrical enclosures and manufactures high quality water pumps and agricultural machinery for the local market.

Figure
Figure II : Designing a gating system for a brass ornament.

structured questionnaire survey sheet was prepared (Refer Appendix 1) including types of castings produced, types of items produced, total output capacity/year, source of raw materials, employment records, machinery & equipment and casting defects, etc.
•A

Table 1 :
Scale of the foundries

small scale a Small scale H Medium scale • Large scale Figure 6 : Analysis of the scale of brass foundries Aluminium foundries S Very small scale • Small scale • Medium scale Large scale 70% Figure 7 : Analysis of the scale of Aluminium foundries • Small scale • Medium scale 30% • Large scale Figure 8 : Analysis of the scale of cast iron foundries 4. Discussion
industry has existed from generation to generation in above mentioned regions and therefore the traditional technology and skilled foundrymen are bonded with these regions.scattered in the Colombo district.According to fig.2 most of the foundries in Sri Lanka are aluminium foundries and there are a very little number of bronze foundries.When analyzing the castings produced in Sri Lanka, ornaments and machinery parts form the majority, (fig 3).Some of the cast iron products are Brake shoes, Rubbing blocks, Rollers, Bearing blocks and different types of machinery parts.