|Chiping - Course: Technique for Manual Working of Materials. Methodical Guide for Instructors|
Based on the variants mentioned in section 3, the exercises can be designed as a single subject-oriented instruction or in several stages.
Based on the "Instruction examples for practical vocational training - Chipping" the trainees can carry out 5 exercises with an increasing degree of difficulty.
These "Instruction examples ..." also comprise a list of materials (initial material, hand tools, measuring and testing tools, accessories) as well as a sequence of operations associated with the exercise. Also contained is an illustrative working drawing. Thus, the trainees avail of all the necessary information in order to begin their exercise-related work.
If the course of the exercise reveals that the quality of the workpieces does not meet the requirements, the trainees must carry out comprehensive preliminary exercises.
In this case they should use any waste parts. After having practised the skill sufficiently, the envisaged workpiece can be manufactured.
The following hint for organising the work should be taken into account:
The trainee has to carry out all the necessary work by himself - from cutting the initial material up to the completion of the workpiece.
This is the only way to guarantee a just evaluation of the achievements.
If the proposed instruction examples cannot be used for the exercises, it will be possible to select other workpieces. In this case the instructor has to make sure that the trainees can practise all the working techniques mentioned earlier.
4.1. Instruction examples
What follows is a brief description of the individual instruction examples in order to give a survey of those workpieces on which the knowledge previously acquired can be practised.
Instruction example 10.1.
Training workpieces for cutting-off chiselling
The technique of cutting-off chiselling will be practised at various cross-sections of steel.
Instruction example 10.2.
Case for safety goggles
Cutting-off and shearing chiselling practises are employed to form a metal sheet in such a way that it can be bent to form a case. This case for safety goggles must be properly dimensioned. It can be fixed close to the drilling or grinding machines.
Instruction example 10.3.
Dog vice for sheet metal
The trainee has to produce a bore line on angle steel and to chisel off sections and cut-outs. This workpiece can be used for clamping metal sheets in a workshop vice..
Instruction example 10.4.
The trainees practise the chipping chiselling of surfaces and grooves on cast iron. They employ cape and grooving chisels.
After its completion this workpiece can be used as an accessory for drilling machines.
Instruction example 10.5.
Several flat steel components serve to practise cutting-off and chipping chiselling by producing break-throughs and by working on surfaces. After its completion this device can be used as an accessory for marking-out operations.
4.2. Criteria for practical training
It is recommended to determine some crucial points of evaluation and supervision. The following criteria can serve as a guideline:
- Is the chisel position precisely perpendicular?
- Does the trainee drill the corner points in thin metal sheets and continue by chiselling on a hardened support?
- Does the trainee notch thicker sections from all sides in order to break them?
- Does the trainee prepare long dividing lines by producing a guide notch?
- Does the trainee prepare curved contours, which are to be chiselled off, by providing a bore line?
- Is the chisel position properly inclined?
- Does the trainee chisel off thin layers at narrow surfaces with the chisel in an angular position?
- Does the trainee chisel off thicker layers in several stages?