Cutting conditions

Relative motion is required between the tool and work to perform a machining operation. The primary motion is accomplished at a certain cutting speed. In addition, the tool must be moved laterally across the work. This is a much slower motion, called the feed. The remaining dimension of the cut is the penetration of the cutting tool below the original work surface, called the depth of cut. Collectively, speed, feed, and depth of cut are called the cutting conditions. They form the three dimensions of the machining process, and for certain operations, their product can be used to obtain the material removal rate for the process:

2. Выполните аннотационный перевод текста

3. Выполните следующие задания:

а) Выпишите из текста предложения, при переводе которых вы использовали приемы:

- замена простого предложения сложным,

- замена сложного предложения простым,

- членение или объединение предложений,

- изменение типа синтаксической свзяи.

Укажите рядом с выписанным предложением прием перевода и перевод.

б). Найдите в тексте и выпишите 2 простых предложения. Переведите.

в) Найдите в тексте и выпишите 2 сложных предложения. Переведите.

Вариант 5

1. Переведите текст письменно. Stages in metal cutting

Machining operations usually divide into two categories, distinguished by purpose and cutting conditions:

• Roughing cuts, and

• Finishing cuts

Roughing cuts are used to remove large amount of material from the starting workpart as rapidly as possible, i.e. with a large Material Removal Rate (MRR), in order to produce a shape close to the desired form, but leaving some material on the piece for a subsequent finishing operation. Finishing cuts are used to complete the part and achieve the final dimension, tolerances, and surface finish. In production machining jobs, one or more roughing cuts are usually performed on the work, followed by one or two finishing cuts. Roughing operations are done at high feeds and depths – feeds of 0.4-1.25 mm/rev (0.015-0.050 in/rev) and depths of 2.5-20 mm (0.100-0.750 in) are typical, but actual values depend on the workpiece materials. Finishing operations are carried out at low feeds and depths - feeds of 0.0125-0.04 mm/rev (0.0005-0.0015 in/rev) and depths of 0.75-2.0 mm (0.030-0.075 in) are typical. Cutting speeds are lower in roughing than in finishing.

A cutting fluid is often applied to the machining operation to cool and lubricate the cutting tool. Determining whether a cutting fluid should be used, and, if so, choosing the proper cutting fluid, is usually included within the scope of cutting condition.

Today other forms of metal cutting are becoming increasingly popular. An example of this is water jet cutting. Water jet cutting involves pressurized water in excess of 620 MPa (90 000 psi) and is able to cut metal and have a finished product. This process is called cold cutting, and it increases efficiency as opposed to laser and plasma cutting.

Relationship of subtractive and additive techniques

With the recent proliferation of additive manufacturing technologies, conventional machining has been retronymously classified, in thought and language, as a subtractive manufacturing method. In narrow contexts, additive and subtractive methods may compete with each other. In the broad context of entire industries, their relationship iscomplementary.