Effect of grain moisture content
The shelling of maize grain is extremely difficult to undertake at moisture contents above 25 per cent, and may not be carried out efficiently at moisture contents between 17 and 25 per cent. Shelling maize at these high moisture contents results in high mechanical grain damage, reduced grain stripping efficiency and high power consumption. In general, efficient shelling is best undertaken after the grain has been suitably dried to a moisture content of 13 to 14 per cent. On the other hand, the use of combine harvesters, for the shelling of maize in the field before it is sufficiently dried, can result in high damage rates of the grain of up to 20 per cent .

Shelling damage
Appropriately dried maize may still be damaged during shelling by corn sheller https://www.shellermachine.com/. Such damage will be of little consequence if the maize is to be further processed shortly after shelling (e.g. it may be milled or cooked). On the other hand, shelled maize which must be stored over a long period will deteriorate as a result of attacks by secondary pests or fungal invasion which spread through the damaged surface of the grain. This deterioration will happen even if the grain is sufficiently dry and properly stored.

The extent of shelling damage depends on the shelling technique, the skill of the operator, and the type of maize being shelled. In general, manual shelling methods - with exception of those involving scrapping and beating - and efficient small shellers result in much less grain damage than do large, powered shellers. However, many farmers or mill operators do not use these small shellers efficiently and do produce a high fraction of damaged grain for the following reason. A number of rotary hand shellers are equipped with an adjustable spring which allows an increase in the pressure on the cob in order to improve the shelling action. Since most farmers cannot tolerate the loss of unstripped grain nor the extra effort required to recover it by hand, they tend to adjust the spring to a high pressure setting in order to ensure a complete stripping of the cob. Such a high pressure results in extensive damage of the grain surface, and in the loss of grain if the latter is to be stored over a long period of time.

Factors affecting the choice of shelling technique
Depending on the scale of production, one or more shellers may produce the required output of shelled maize. The most appropriate shelling technique will thus be the one which minimises production costs per unit of output for a given loss rate of damaged grain, quality of output (e.g. extent to which the shelled grain is free from sand, stones, dead pests, etc.) and the quality of raw materials (e.g. moisture content, size and quality of the cobs, the relative softness of the grain endosperm).

When comparing two alternative shelling techniques, multi crop thresher machine https://www.shellermachine.com/multi-crop-thresher-machine is a good choice for corn farmer.The working lifetime of the various components of the sheller machine should be relatively high since no wearing or rubbing parts are employed.