On machines

Machine is a complex mechanism made of simple machines: a lever, a screw, a wedge, an inclined plane, a block. Future mechanical engineers should know all main and auxiliary parts of the machine, machine-tool or mechanism so as to be able to remove any failure or assemble new equipment. The principal parts of a machine are: a body, an engine, an axle, a shaft, a drive. The parts of a machine are joined with the connective elements: a bolt, a nut, a screw, a gear, a washer, a bearing, a rivet, a key, a pin. Mechanical students should have knowledge of assembling and disassembling a machine or mechanism. They should also have a good idea of types of fastenings, forms of threads; classes of gears, bearings, clutches, couplings and their failures.

To know various machines one has to study their design principles and application. The machines employed in food industry usually include feed mechanism, drive and working organs. Feed mechanism serves to feed the raw material into the machine, the drive mechanism actually drives the working organs which do the processing. All modern machines are driven by electric motors.

The machine is an artificial person, device that performs a mechanical movement or other actions for energy conversion, materials and information. Every modern machine has the following interrelated component mechanisms: engine (power source); transfer mechanism; working body (the executive mechanism); driving mechanism; regulatory mechanism moving the engine. Any mechanism contains links that may be in separate parts or units. Depending on the nature of the work flow machines may be divided into five classes:

Machines, engines, which convert any type of energy to mechanical work.

Machines converters, which convert mechanical work into some kind of energy, such as for electricity.

Transport vehicles.

Technological machines.

Monitoring control and electronic computers.

It’s impossible to mention here all the machines and apparatuses employed in various branches of food industry. Let's get acquainted with some of the machinery and apparatuses used for example, in breadmaking, meat and dairy industry, confectionery. They are:

I. the intermediary or overhead proofer in which the rounded dough balls are given a brief rest;

2. moulding and panning machine which shapes the dough pieces into loaf form, and automatically drops them into baking pans;
3.press feeding sheet of noodle dough directly to cutter;
4.kneader;

5.vertical hydraulic extrusion press;

6.battery of chocolate liquor mills;

7.hydraulic press for separating cocoa butter from chocolate liquor;

8.refrigerating installations in meat-packing plant;

9. pasteurising equipment in mill plant, etc.

Machines and equipment are becoming more efficient, reliable and econo­mical from day to day. A major advance in twentieth century manufacturing was the development of mass production techniques at the machine-building plants. Mass production refers to manufacturing processes in which an assembly line, usually a conveyor belt, moves the product to stations where each worker performs a limited number of operations until the product is assembled. In the automobile assembly plant such systems have reached a highly-developed form. A complex system of conveyer belts and chain drives moves car parts to workers who perform the thousands of necessary assembling tasks.

An important factor for the industrial engineer to consider is whether each manufacturing process can be automated in whole or in part. Automation is a word coined in the 1940s to describe pro­cesses by which machines do tasks previously performed by people. We know of the advance in the development of steam engines that produced automatic valves. We now use the term automation for specific techniques com­bined to operate automatically in a complete system. These tech­niques are possible because of electronic devices, most of which have come into use in the last thirty years. They include program, action, sensing or feedback, decision, and control elements as com­ponents of a complete system.

The program elements determine what the system does and the step-by-step manner in which it works to produce the desired result. A program is a step-by-step sequence that breaks a task into its individual parts. Some steps in an industrial automation pro­gram direct other parts of the system when and how to carry out their jobs.

The action elements are those which do the actual work. They may carry or convey materials to specific places at specific times or they may perform operations on the materials. The term mechani­cal handling device is also used for the action elements.

Perhaps the most important part of an automated system is sensing or feedback. Sensing devices automatically check all parts of the manufacturing process such as the degree of heat or the thickness of a sheet of steel or paper. This is called feedback because the instruments return or feed back this information to the central system control.

The decision element is used to compare what is going on in the system with what should be going on; it receives information from the sensing devices and makes decisions necessary to maintain the system correctly. If some action is necessary the decision ele­ment can give instructions or commands to the system.