|Cutting by Milling - Course: Techniques for machining of material. Trainees' handbook of lessons (Institut für Berufliche Entwicklung, 17 p.)|
For the preparation of this technique you need to do the following:
- mental planning of the sequence of operations like
· the selection of the milling machine to be applied (horizontal or vertical milling machine)
· the selection of the metal slitting saw blade to be used (coarse-tooth or fine-tooth; diameter and width)
· the selection of the clamping means
· selection of the measuring and testing means
· the technological process (sequence of operations) of cutting by milling
- arrangement of the necessary tools, measuring and testing means as well as the auxiliaries paying attention to the basic principles of their proper storage and safe position.
- checking the functioning and the functional safety of the milling machine, the tools and the auxiliaries to be applied. Reject worn out tools immediately!
The lubrication of the milling machine and the oil-level check should be carried out according to the lubrication schedule.
Clamping of the workpieces for milling
For cutting by milling mainly such clamping means are applied which are used when milling on horizontal and vertical milling machines, e.g.:
- machine vice
- direct clamping on the machine table, and on the
- rotary table
- special clamping means.
The clamping of the workpieces can be carried out depending on their geometrical forms and their dimensions in a single-piece or multi-piece clamping (package clamping). When applying machine vices, clamping jaws are often used for cutting by milling.
Figure 10 - Separating jaws
1 - machine vice
2 - separating jaws
3 - workpiece
4 - stop
For an exact adjustment of the clamping means the localization should be carried out according to the accuracy requirements by means of tongues, stop bars, stops and other auxiliaries, including dial gauge/bevelled edge square.
Clamping means (clamp iron, lock screws) should be fixed on those parts where the cutting by milling is not impaired (space for the milling tool and the clamping means).
In order to constantly reach the required space and length dimensions, suitable stops (stop jacks, stop bars) are to be fixed for a clear localization of the workpieces.
When using workpiece clamping means you should pay attention that no changes on the workpiece supporting and bearing surfaces are carried out. Before the fixture's clamping on the machine table or on the rotatory table the ground spaces of the fixture should be cleaned by all means.
When clamping the workpieces you should pay attention to burr-freeness and cleanliness of the bearing and working faces in any case. Uncleanliness and burrs lead to a positional deviation while clamping. The results are quality flaws and damages (flaws) on the surface of the workpiece.
Handling sharp-edged workpieces and tools you should wear safety gloves to avoid cuts on your hands. The deburring of the workpieces should be carried out only with proper files.
Clamping of the tools for cutting by milling
For the fastening and the setting-up of the clamping means (long and short cutter arbors) only proper clamping tools (spanner and cross spanner) should be used. Irrespective of the clamping means to be applied the labour safety requirements should be taken into account:
For deburring the workpieces before clamping or before measuring and testing only proper files should be used! Sharp-edged workpieces and milling tools should be moved with safety gloves or a suitable rag to avoid cuts on your hands!
Selection and application of the measuring and testing means
For measuring and testing the workpieces (dimensional and positional deviations) you should use:
- a vernier caliper
- a steel square/bevelled edge square
- a depth gauge
- a universal bevel protractor (for workpieces with bevelled surfaces)
Before measuring and testing the workpieces should always be deburred and cleaned.
Only functioning measuring and testing means should be applied. Damaged measuring and testing means should not be used and immediately be sent on for repair or be removed.
The durability of the measuring and testing means does depend on a proper positioning and storing at the workplace and on a careful handling. Damaged measuring and testing means should not be used. They should be sent on for checking and repair or be removed. Which clamping auxiliaries should be used with cutting by milling if the clamping of the workpieces is carried out in machine vices?
What should you always consider when clamping, or measuring and