|CERES No. 091 - January - February 1983 (FAO Ceres, 1983, 50 p.)|
Significant efforts have been devoted to introducing new or improved agricultural implements to the small farmer to increase his productivity and financial return. These implements include more efficient hand tools, animal-drawn and motorized equipment and a range of devices for crop processing. Success in the widespread application of such devices has, however, been limited. The problems of introducing and disseminating small-scale agricultural technologies are complex. Obstacles include the understandable conservatism of the small farmer, lack of credit facilities, limitations of extension services and, in some cases, the inappropriateness of the technology. One factor that has received relatively little attention is the need to ensure that a technology can be produced locally to a quality sufficient to ensure satisfactory performance, and at a price that is both attractive to the users and allows the local manufacturer to make a profit.
The concept of designing equipment to suit indigenous manufacturing capacity in terms of the production processes and skills used and the materials available is increasingly well understood, though the problems of developing effective technologies within these constraints should not be underestimated. However, as the case study in this article will illustrate, there is a complementary need for attention to the detailed design of components and assemblies and the application of production engineering and planning procedures. Attention to these matters can greatly affect the quality and cost of an item of agricultural equipment, the management skills involved in its manufacture, and hence its chances of successful introduction.
In 1981 I spent two months in India advising a small engineering company on the manufacture of an animal drawn tool-carrier, the Nikart. The Nikart was designed by the Overseas Division of the National Institute of Agricultural Engineering (NIAE) in England. It is a wheeled tool-carrier drawn by a pair of oxen. The design philosophy behind the Nikart was that it should provide a one-man ride-on implement, have fair versatility without incorporating costly features not needed by most users and be capable of manufacture at reasonable cost.
The Nikart was developed in collaboration with the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT), based near Hyderabad, India. Prototype Nikarts built by NIAE were tested by ICRISAT? and the design was modified to improve operating performance and suit locally available components.
By mid-1980 the Nikart was ready for small-scale manufacture in India, and a small engineering company in Hyderabad that was enthusiastic about producing the machine was identified. The company, Mekins Agro Industrial Enterprises, was well managed but had limited technical resources. The first Nikarts produced were of poor dimensional quality. At this stage I was asked to assist Mekins in improving their manufacturing procedures.
The primary objective of my involvement was to design and construct a set of jigs and fixtures for the manufacture of the Nikart. During my seven-week stay in Hyderabad, five welding jigs, three drilling jigs and a series of marking-out templates were built. We applied conventional engineering principles in designing the jigs, but were careful to ensure that:
- they were simple to use, and that components could only be located in the jigs in the correct position;
- they were of sufficient accuracy to allow good quality Nikarts to be produced off them;
- they accommodated the dimensional variations of locally available steel sections, while locating the critical points on the Nikart accurately;
- they were simple to make.
Except for the grinding of the drilling jig bushes, all the jigs were made in the Mekins factory. This was felt to be important in transferring skills in the design and use of jigs. It also minimized the investment cost of the tooling.
The use of these jigs reduced the time that was needed to mark and cut the components and to fabricate the various subassemblies. A much greater degree of precision was also achieved, making fitting at the final assembly stage easier. These jigs minimized the manufacturing time and the number of reject components, thus also reducing the cost of producing the Nikart. They ensured that the products were of a satisfactory level of quality and consistency. Consistency is important in facilitating the supply of spare parts once the machines have been sold. If the spare parts are produced on the same jigs as the original machine, there should be no fitting problems.
To complement the introduction of jigs, we defined simple planning procedures for the production of batches of Nikarts. This involved defining the manufacturing operations for each of the individual components and the various stages of assembly. Based on this, the sequencing of operations on the different items of manufacturing equipment was specified so that work began on those components with the longest lead time and that machine set-up time was minimized.
To some extent these two criteria were in conflict, but the net result was that both labour and equipment were used more efficiently, and the time taken to manufacture a batch of Nikarts was minimized.
The engineers involved in the design and development of the Nikart put considerable effort into evolving a technology suitable for local manufacture, particularly in terms of materials, components and production processes used. Nevertheless in the course of designing the jigs a series of modifications to the Nikart were identified to simplify manufacture. These were all detail design changes that had no effect on the performance of the Nikart and that were largely imperceptible to the casual observer. However, taken in total, they had a significant influence on the ease and cost of manufacture. For example, several components were specified as being made from 40 x 12 mm steel strip. According to the steel suppliers catalogues, this was a standard, available section, but in practice it was very difficult to obtain. By analyzing the dimensions of all components and making minor changes where appropriate, it was possible to utilize those material sections that were easiest to process and to minimize the range of different material sections required to produce the Nikart. The latter helped to reduce the management problems of purchasing and stock control and the working capital tied up in raw materials.
Similarly, another feature of the original Nikart design, the adjustable height wheel mounting, required a high-quality channel section of specified tolerance that, although manufactured in India, is allocated on a quota basis, and it is very difficult for a small manufacturer to guarantee regular supplies. Mekins was therefore forced to use a lower quality specification. This necessitated a series of detail design changes to allow the wheel leg assembly to be produced to a satisfactory standard with the lower quality material that was easily available.
Two other example of design modifications that simplified manufacture are of interest: by making a simple design change, it was possible to make the foot-rest in one piece instead of two; by altering the configuration of the joint between three components, it was possible to allow a wider tolerance on the dimensions of the parts and to simplify the design of one of the welding jigs.
In the last year Mekins has produced and sold more than 70 tool carriers, including some for export. The Nikarts have proved to be of good quality, have performed satisfactorily and are very competitive in cost with other products available in India. To follow up this initial success the marketing company with whom Mekins collaborates is about to embark on a major sales drive in one Indian state.
Although this case study is concerned with one agricultural technology in one location, it illustrates certain principles that can assist the introduction of low-cost agricultural equipment generally. The most important of these is that the design of a piece of equipment cannot be separated from the processes by which it is to be manufactured if the device is to be both technically successful and commercially viable. The overall design should be conditioned by the materials, components and manufacturing processes and skills that will be available locally. However, detailed attention to the design of components and subassemblies is equally important. This attention to detail cannot turn a bad technology into a good one. But if it is based on an understanding of the capabilities of, and constraints upon, small-scale industry, it can significantly affect the cost and quality of products whose basic design is sound. Besides good design, attention to production engineering procedures is needed in order to exploit the benefits obtainable from the use of jigs and fixtures and from the application of simple planning techniques. The detailed design of a piece of equipment will likely have to be adapted to suit different circumstances in different countries, even if the basic principles of the design remain the same.
Certain specific lessons can be drawn from the tool-carrier example:
· The fact that a particular material specification is available in a country does not necessarily mean that it is easily obtainable by the small-scale industrial sector.
· Even if the same manufacturing processes are used, a prototype made in a well-equipped development workshop staffed by skilled technicians, is produced under very different conditions from those applying in a small scale industry. The design of the device should take account of the level of skills and the condition of the manufacturing equipment likely to be found in the small-scale sector.
· Careful, detailed design can have an important effect in reducing production management and organizational problems and in assisting the smooth running of small-scale manufacture.