A small-scale fodder chopping machine was designed for dairy farmers who have a home business in rural areas for milk and meat production. The developed machine was fabricated in a local workshop and experiments were carried out on a farm in the Thakurgaon district, Bangladesh. The activities for the research work included setting an estimated budget to make the fodder chopping machine so that it remains within the purchase capabilities of the farmers. According to the budget, different parts were designed, such as an electric motor for the power source, a V-belt drive, a cutting wheel, a feed roller and cashing, a hopper and a supporting frame. After assembling the machine, performance tests on the cutting efficiency, machine productivity, energy requirements were carried out and some economic analysis on the fixed costs, variable costs and the break-even point were also performed. The whole method is described in the following step by step processes.
Description of the major components of the fodder chopping machine Supporting frame. The various parts of this machine are mounted on this frame. The complete frame is made up of mild steel angle. Cutter wheel and cutter blade. It is a circular wheel made from cast iron that holds the cutting blade. During operation, the cutter wheel rotates at a uniform speed and the attached blade cuts the fodder. Inlet hopper. This is made from a cast iron plate and this is where the raw fodder is kept prior to chopping. Feed roller. The feed roller is a device used to pull the fodder from the horizontal hopper and feed it to the cutting blades. The roller is driven by a helical gear mechanism that is connected to the belt drive. V-belt drive. The V-belt drive is used to transmit the power from the motor to the cutting wheel. The V-belt drive provides several advantages including that it requires no lubrication, it is highly efficient, it has a low noise generation level, has a long service life, is easy to install, and acts as a "safety fuse" refusing to transmit power during overload. Electric motor power source. An electric motor is used to convert electrical energy into mechanical energy. To construct this machine, a 1.49 kW motor was purchased from a local market.
Assembled fodder chopping machine The fabrication of the straw chopper machine was accomplished in a local workshop. A standard frame of (760 × 540 mm) was built by mild steel angle to rigidly support the whole assembly of the chopping machine. The diameter of the cutting wheel is 650 mm which is attached to a pulley (100 mm in diameter) of the motor through the V-belt. This machine was designed with two simple feed roller shafts whose diameters were 120 mm, while the inlet side was 215 mm and the outlet side was 165 mm.
Working procedure of the designed and developed machine The first step to start working this machine is connecting the machine to a single-phase power supply source. After switching on the power transmission through the V-belt, the motor will start, which will, in turn, rotate the cutter wheel. The raw fodder needs to put into the hopper; through the feed rollers, the machine will automatically start pushing the fodder into the cutting blade for chopping. The task of the operator is only to put the fodder into the hopper in the direction of the feed rollers. The lightweight particles of the chopped fodder are thrown outward towards the outlet by the centrifugal force of the cutting blade. So, it is advantageous to use a container to collect the chopped fodder.
Experimental set-up For this study, dried and stored Sharna rice straw, Napier grass, and seasonal maize leaves were used as the fodders to test the different performance parameters. The straw height was about 0.9–1.2 m, the Napier grass height was about 1.5–1.8 m and the maize leaves height was around 0.9–1.2 m. The straw was fully dry and lightweight, the grass and maize leaves were collected directly from the field. For the performance testing of each type of chopped fodder, 20 kg was used in each experiment.
Performance testing The machine performance tests were performed to evaluate the machine's capabilities while under operation. The major performance test parameters that were tested: (i) chopping efficiency; (ii) machine productivity; and (iii) energy requirement. The performance test was conducted based on the standard test of Chopper Machine of Organic Fertilizer Raw Material – Quality Requirement and Test Method as modified by Srivastava (1993). Testing was performed with 5 repetitions for each experiment with each kind of fodder.