Process planning

Factors affecting process plan selection

The system suffered from large computational requirements which grew rapidly with the problem size.
The system required specification of a large number of heuristic generalization rules. However, the set of rules did not produce all the necessary generalizations needed for planning of complex part
When a new product is input to the system, no feasible output is guaranteed.
Therefore, some rules may still be needed to help guarantee that correct out are given.
We still can see the experimental approach has potential to automatically selected CAPP taking cutting conditions, material hardness, surface finished into considerations.

Study the overall shape of the part. Use this information to classify the part
Thoroughly study the drawing. Try to identify every manufacturing features and notes.
If raw stock is not given, determine the best raw material shape to use.
Identify datum surfaces. Use information on datum surfaces to determine the setups.
Select machines for each setup.
For each setup determine the rough sequence of operations necessary to create all the features.

Sequence the operations determined in the previous step.
Select tools for each operation. Try to use the same tool for several operations if it is possible. Keep in mind the trade off on tool change time and estimated machining time.
Select or design fixtures for each setup.
Evaluate the plan generate thus far and make necessary modifications.
Select cutting parameters for each operation.
Prepare the final process plan document.

Type of the feature being machined
Size of the feature
Technological attributes required of the feature (e.g. tolerance, surface finish)
Machining processes and their capabilities.

IF Diameter is 3-100 mm AND Tolerance is 0.08-0.4 mm AND Surface finish is 1.6-9.5 µm THEN Drilling is recommended
IF Diameter is 10-100 AND Tolerance is 0.013-0.08 mm AND Surface finish is 0.5-2.4 µm THEN Reaming is recommended
IF Diameter is 19-300 AND Tolerance is 0.025-0.13 mm AND Surface finish is 0.4-6.3 µm THEN Boring is recommended
IF Diameter is 25-300 AND Tolerance is 0.004-0.02 mm AND Surface finish is 0.1-1.6 µm THEN Grinding(Internal) is recommended
IF Diameter is 5-100 AND Tolerance is 0.03-0.087 mm AND Surface finish is 0. 4-9 µm THEN Turning/grooving is recommended
IF Diameter is 5-100 AND Tolerance is 0.012-0.035 mm AND Surface finish is 0.07-1.6 µm THEN Grinding (External) is recommended.

The proposed CAPP methodology takes in as input the attributes of the features and automatically generates all the feasible alternatives for machining the feature in order of preference after taking their relative costs into consideration.
Some advantageous features of the neural network based CAPP methodology as against the knowledge based approach are:

Its efficient knowledge acquisition capability owing to its ability to implicitly derive the rules from sample machining cases presented to the neural network
Its capability to generalize beyond the original machining cases to which it is exposed during the training and face intermediate situations with reasonably good accuracy with respect to those proposed during the training
High processing speed once the neural network is trained.