workholding is part of the operation plan
Preventing the workpiece from slipping is essential, but workholding serves other purposes too. The cutting tool must reach the surface, the machined area needs support, and the next operation must maintain the required datum relationship. These needs can conflict: a large gripping area may restrict tool access, while a long overhang can reduce rigidity.
Therefore, the workholding solution is not a detail to be added after the CAM program is finished. The raw version of the piece, the intermediate operation state and the finished version should be seen together.
Think of the second operation in the first drawing
Consider an example of a flanged, thin-walled hive. In the first operation, the screw female diameter and front face should be processed. When turned for the rear face, the finished surface should not be damaged, the part should not be deformed, and the reference must be re-established. This scenario shows why the workholding decision cannot only be made with the question "does it fit in the mirror?"
Design approval is required if a functional surface is to be replaced for temporary workholding purposes. The manufacturer's self-adding of a share or hole not in the drawing is not an accurate revision management.
When does the soft jaw make sense?
Soft jaws processed by part form may be an option in geometries where standard jaws are not suitable. However, it is not enough to be "part-specific" alone. Seating, contact surface, chips accumulation and clamping conditions are evaluated together.
NYC CNC's workholding series shows different solutions side by side. The useful lesson to be learned from here is that a single fixture is not suitable for everything. The choice should be based on the need for geometry, operation and production to be repeated.
Keep information in the repeated order
The fact that a fixture is on the shelf does not mean that the setting will be fully restored. The revision used, reference surfaces, cutting tool access and first piece control should be recorded in an understandable way. The photo helps; it is not technical instruction alone.
Combining operations on the same machine It can reduce some reattachments. Whether this is possible in your piece Our mill-turn capabilities We can talk over it.
Sources and further reading
- NYC CNC / Autodesk workingholding methods and John Saunders video series
- Questions about Saunders Machine Works Fixture plates
- TITANS of CNC Academy Design, programming and processing trainings
This article is an original narrative that deals with technical principles in resources through the process of parts and bids. Examples are for disclosure purposes; it does not mean partnership with resource organizations or their approval of FactorAB.