Trials were necessary to design system.

About six trials were taken for different weight of chopper and stroke displacement. During each trial no external force was applied. The chopper was just lifted manually and released to fall down due its self-weight and gravity. Therefore for while calculating force only acceleration due to gravity was taken into account.

Trial 1

            First trial was taken with designed chopper. The weight of chopper was recorded which was 2.44 kg. Then 1 kg waste was taken in a bucket. The stroke displacement was kept 30 cm. Total no. of strokes were counted. No. of strokes were 243 for required particle size of waste.

Trial 2

            In second trial some weight in the form of soil into the hollow chopper was added, the total weight of chopper was 4.650 kg. This trial was taken for 1 kg waste. The stroke displacement was kept same as that for 1St trial 30 cm. Counted no. of strokes were 163.

Trial 3

            Third trial was taken for the same weight of chopper 4.650 kg and 1 kg waste. The stroke displacement was kept 20 cm. There were 220 strokes were required to cut the waste.

Trial 4

            In fourth trial some weight was again added into chopper. The total weight was 5.864 kg. The amount of waste was 1 kg. Stroke displacement was kept 30 cm. There were 130 strokes were required to chop the whole waste.

Trial 5

            After discussing about the results from previous trials it was decided to keep the weight of chopper 5 kg. As per the system requirement the total amount of waste to be chopped is 5 kg at a time.

            Hence for this trial waste was taken 5 kg. The weight of chopper was 5 kg. But in this trial the waste did not get chopped due to the size of vessel taken. It was observed that the waste was only compacting in the bucket.

            So it was decided to take another trial by increasing the size of vessel.

Trial 6

Before chopping

            Due to the problems in previous trial the vessel size was increased. A vessel (drum) of 30 cm radius was taken. The layer thickness of waste in the drum was 7 cm. For this amount of waste 360 strokes were required.

While chopping

          This trial was successful and it was concluded that about 15 cm layer thickness of waste can be chopped.

Chopped waste


The force was calculated by following formula,

                        F = m x a


F = force, N

m = mass, kg

a = acceleration, m/s2

            The details about calculations of force and trials is given in table below,

Trial no. Weight of chopper, kg ( m ) Weight of waste, kg Accln due to gravity, m/s2 ( a ) Force, N ( F ) Length of stroke, cm No. of strokes
1. 2.44 1 9.8 23.912 30 243
2. 4.650 1 9.8 45.57 30 163
3. 4.650 1 9.8 45.57 20 220
4. 5.864 1 9.8 57.4672 30 130
5. 5 5 9.8 49 30
6. 5 5 9.8 49 30 360

Conclusions –

From all the trials it was concluded that the system was designed for 50 N. The capacity of system was 5 kg. Weight of chopper was 5 kg. The thickness of layer of waste should be about 15 cm.