|Fibre Concrete (FCR) / Micro Concrete (MCR) Roofing Equipment (GTZ, 1991, 20 p.)|
FCR and MCR being relatively new technologies, the number of equipment suppliers are still very few. In the early stages of development, the equipment used was locally made by research institutes and appropriate technology groups, which mainly experimented with the production of large sheets. No equipment was commercially available.
ITW of Cradley Heath, U.K., who were the first to develop small roofing components and a method to produce them by vibration, were also the first to supply equipment on a commercial basis. The earliest equipment was the portable 'Mini Plant' (1983), which was followed two years later by an 'Industrial' version of the same production process, and a series of other modified and improved equipment later on.
While this equipment was principally available all over the world, the relatively high capital and transport costs, prohibitive currency exchange rates and import restrictions in many developing countries led to the local production of equipment. Thus there are several types of FCR/MCR equipment on the market and it may be difficult for a newcomer to this technology to decide which one should be bought. The following points will help the potential buyer to make a good choice.
Design of Screeding Machine
· The design of a screeding machine is the result of several stages of development:
- Development and design of prototype
- Testing and modification of prototype
- Field testing of 5 to 10 prototypes for at least 1 year
- Modifications resulting from field tests
- Finalization of design, production manual, accessories, etc.
These steps can only be followed if appropriate workshop facilities, qualified engineering capacity, qualified production and quality control capacity and sufficient funds are available. Depending on the extent to which these requirements are met, there are great differences in the quality of machines available.
· If an FCR or MCR tile production plant is to operate successfully in a developing country, the equipment must be capable of withstanding rough use. If possible, machines that have been in use under such conditions for a reasonably long time (say 3 to 4 months) should be inspected to check, for example, whether the screeding surface and/or the hinged frame is warped or damaged, handles or switches are broken off, and so on.
· Special consideration should be given to the working conditions for the production team, especially with regard to operation procedures and handling of products, that is, avoidance of dangerous or exceptionally hard manual work and activities that have to be done in a bent position.
· A balance must be found between the desired output rate, quality standard and level of sophistication. Complicated mechanical devices often necessitate special training and experience for maintenance and repairs. Spare parts can be expensive and if imported. may be difficult and take long to procure.
· The choice of screeding machine will also depend on the tile size required, which is basically a choice between the pantile (or Roman tile, depending on the mould) of 50 to 60 cm length, 25 to 29 cm width and 6 mm thickness (requiring 8 to 12 tiles to cover 1 m²), and the larger semi-sheet, which is 60 x 60 cm and 8 mm thick (requiring 4 elements to cover 1 m²).
· The type of energy required to operate the vibration mechanism is one of the most important selection criteria. Hand or foot operated machines can be used anywhere, and are the only viable option in remote areas, where power supplies are unreliable or not available. If electric machines with car batteries are used in such areas, it may be possible to recharge the batteries with a photovoltaic solar energy system, but such devices have so far not proved successful.
· The vibration mechanism normally consists of rapidly rotating eccentric weights. With two shafts rotating in opposite directions, the horizontal component of vibrations can be neutralized, so that the screeding surface is subjected to a simple harmonic motion in the vertical direction only.
· A less common vibration method is with flat metal springs, which hit the underside of the screeding plate at a rate of about 2000 times per minute, by turning a rattle wheel. With this method it is more difficult to achieve uniform vibration frequency, but the machine is very cheap to construct and easy to repair, but on the other hand very noisy.
Design of Setting Moulds
· Since a very large number of moulds are needed, they represent the highest single cost factor. The industrially produced PVC moulds are the best in all respects, but by far the most expensive. Considerable costs can be saved if the moulds are produced locally.
· The most successful locally made moulds are concrete moulds (as described above). However, great care is needed in production and handling. The usual practice for initial curing is to put the moulds with the fresh tiles in special wooden racks, which have to be covered with plastic sheets to retain the moisture in the tiles. If this is not done properly, parts of the tiles may dry out earlier, causing cracks. Therefore, self stacking concrete moulds should be preferred.
· With good equipment, good tiles can be produced, but if the ingredients are of poor quality or prepared incorrectly, good equipment is not likely to produce good tiles. Therefore, quality control must begin with the selection and preparation of the ingredients.
· Broken tiles, leaking roofs and other serious problems associated with FCR in the early stages of development have shown the extreme importance of strict quality control during all phases of tile production, roof construction and installation of tiles. A tile testing kit, as described under Testing Equipment, is essential in every FCR and MCR production plant.
· But, above all, the main prerequisite for good quality products is a thorough professional training of the production team and supervisory staff, and efficient management.
· Equipment suppliers are basically of two types:
- private, commercial producers
- non-government organizations (NGOs) based in developing countries.
The advantages of private producers
+ their dependency on good sales, and hence the need to produce good equipment, as failures or bad service would seriously harm their reputation and ultimately stop business;
+ their experience in international trade and good administrative backing, making them reliable business partners.
However, the need to support a qualified technical and
administrative staff with modern equipment, to maintain a consistently high
standard and respond to changing needs, makes their products expensive.
Importing these into a developing country not only increases the costs
considerably (high exchange rates, transport costs, insurances, duty, etc), but
also can be extremely difficult (due to import formalities and restrictions,
long delivery time, problems due to breakage in transit, etc).
The advantages of NCOs are:
+ their high motivation and closeness to the target group,enabling them to adapt their methods end products to local requirements, and provide assistance and advice whenever needed;
+ their low overhead and production costs, and if their equipment is sold locally, the addidonal additional on foreign exchange, transport costs, duty, the trouble with import formalities and delivery time, and the like.
However, these groups do not always have the required funds,
technical staff and workshop facilities to carry through all the tests and
modifications that the maturing of a new product needs. Unfortunately, this
problem is sometimes underestimated.
· Personal visits to the manufacturer and/or sites at which their machines are in use should be undertaken as far as possible. The value of reference lists is to be able to meet or correspond with users, to learn about their experiences. If such lists do not contain addresses, these should be specifically asked for.
Professional Training Courses
· Of special importance are training courses offered by all good equipment suppliers. As far as possible, these courses should be conducted at a place where the whole production team can participate.
· There should be no preconditions for participation in the courses, other than knowledge of the language used. The method and content must be understandable for people without special skills or formal school education, and the course should cover all phases of tile production, roof construction and laying of the tiles, as well as administration and marketing.
Purchase of Machine
· The "FOB" price (free on board) includes packaging,transportation and insurance costs of the machine within the retailer's country. This price can be artificially inflated in order to compensate for the reduction offered on the factory price.
· As regards sales or rental conditions, one must be suspicious of contracts providing for price indexing based on the number of tiles produced or for payment of royalties for patent use, which is often not justified. A patent is not necessarily a proof of guaranteed quality and constructors frequently apply for patents for processes that are already of the public domain.
· It is advisable to include a penalty clause in the contract, to safeguard against late delivery,
· In the case of an after sales service contract, the waiting period for repairs and maintenance must be clearly indicated. A detailed handbook should be provided, including specifications of all spare parts and a maintenance plan, indicating operations necessary and expected maintenance frequency.