Vocabulary development: word building

Значение суффикса -er смотрите в разделе Section I, значение суффикса -ing – в разделе Section II.

Grammar study: Degrees of comparison of adjectives

Существует две степени сравнения прилагательных и наречий: сравнительная и превосходная. Образуются они четырьмя способами:

1. Суффиксальный – с помощью суффиксов -er, -est.

Sample from the text: Cutting tool must be made of material harder than the material which is to be cut. – Режущий инструмент должен быть изготовлен из материала более твердого, чем материал, который должен обрабатываться.

2. Аналитический – с помощью слов more и (the) most.

Sample: The most spread mechanical tools are cutters and milling cutters. –Самыми распространенными механическими инструментами являются резцы и фрезы.

3. Изменение основы слова –

good – better – the best

bad – worse –the worst

Sample: Improper choice of the tool will make processing the work worse. – Неправильный подбор инструмента сделает обработку детали хуже.

4. Синтаксический – с помощью союзов as … as – такой же, как…, not so… as – не такой, как …, the …, the – чем, тем.

Samples from the text: The more teeth a cutter has, the more rapidly it can remove material. – Чем больше зубьев у фрезы, тем быстрее она снимает материал.

Text

Read the text describing the types and functions of mechanical tools in production

Mechanical Tools Cutter

In the context of machining, a cutting tool (or cutter) is any tool that is used to remove metal from the workpiece by means of shear deformation. Archetypal examples are tool bits, drill bits, and milling cutters. Cutting tools must be made of a material harder than the material which is to be cut, and the tool must be able to withstand the heat generated in the metal-cutting process. Also, the tool must have a specific geometry, with clearance angles designed so that the cutting edge can contact the workpiece without the rest of the tool dragging on the workpiece surface. The angle of the cutting face is very important.

Non-grinding cutting tools often can be classified as linear or rotary. Linear cutting tools include tool bits (single-point cutting tools) and broaches. Rotary cutting tools include drill bits, countersinks and counterbores, taps and dies, milling cutters, and reamers. Other cutting tools, such as band saw blades and fly cutters, combine aspects of linear and rotary motion.

Cutting tools (non-grinding) are generally made of tool steels (today mostly of high speed steels (HSS), whether conventional HSS grades or cobalt HSS), carbides, ceramics, or industrial diamonds.

Milling Cutter

M illing cutters come in several shapes and many sizes. There is also a choice of coatings, as well as rake angle and number of cutting surfaces. The flutes (teeth) of the milling bit are deep helical grooves running up the cutter. The tooth cuts the material. Some cutter have more than one tooth. The more teeth a cutter has, the more rapidly it can remove material. The flutes of a milling cutter are almost always helical. If the flutes were straight, the whole tooth would impact the material at once, causing vibration and reducing accuracy and surface quality. The shank of a cutter is the cylindrical (non-fluted) part which is used to hold and locate it in the tool holder.

End mills are tools which have cutting teeth at one end, as well as on the sides. There are the following types of mills: slot, roughing, ball nose, slab, and others. Side-and-face cutter is designed with cutting teeth on its side as well as its circumference. Hobbing cutters are used in hobbing machines to generate gears.