This material contains 5 selected instruction examples which serve the purpose of applying and consolidating the knowledge of the techniques of centring, drilling, counterboring and countersinking, reaming and tapping on the drilling machine.
The information given about the necessary materials, tools, measuring and testing means and auxiliaries serves as a basis for preparing and carrying out the sequence of operations. In instruction example 2 the steel is characterized by the value of the tensile strength in the unit “Megapascal (MPa)”.
The previous knowledge necessary is mentioned as a recommendation. It should be repeated before starting work. The specified sequence of operations reflects the order of steps leading to the manufacture of the corresponding workpiece. In order to reach good quality, it is necessary to follow this order of steps.
Premachining of the workpieces (turning, milling) is in most cases a prerequisite for the sequence of operations of the above-mentioned techniques.
The whole sequence of operations implies the correct choice of cutting values. Hints on this can be taken from the “Trainees’ handbook of lessons”.
Each instruction example is provided with a working drawing from which the required shapes and dimensions of the workpiece can be taken. It is also possible to choose other pieces for exercise with smaller or larger dimensions. The admissible deviations of dimensions without tolerance indication can be taken from the following table.
Nominal size |
Admissible deviation in mm |
0.5 - 6 |
± 0.1 |
6 - 30 |
± 0.2 |
30 - 120 |
± 0.3 |
120 - 315 |
± 0.5 |
The allowable surface roughness Rz is given in µm (0.001 mm).