A design engineer’s praxis in designing a product has undergone a great change in this decade. Earlier, designers were only responsible for functional requirements of the product but now they have a greater role to play in an organization – to design products which not only satisfy functional requirements but also manufacturability requirements by way of keeping product cost within the budgetary constraints and delivering innovative solutions to customers.
Functional requirements, especially for machining, translate into product design features like slots, pockets, holes, islands, grooves, profiles, etc. Design engineers have to select such features based on their prior experiences or guidelines / standards. However, when it comes to understanding downstream manufacturing capability, the knowledge is often in ‘tacit’ form. Designers have an uphill struggle in accessing this knowledge. Thus, at times the feature they add in their design is either not manufacturable or is difficult, and expensive or takes longer time to manufacture. In this case, designers may end up spending hours in design reviews with the manufacturing department or suppliers and would also have to spend considerable time in rework leading to poor design throughput. Hence, it is important that design engineers should have access to all the required downstream capability knowledge base.
Geometric’s DFMPro takes all this into consideration and capacitates design engineers to access this knowledge base, so that ‘informed decisions’ based on standards and downstream requirements can be taken. This saves a lot of effort and also ensures that design release timelines will be met and ECO/ECN instances will be reduced.
Machining guidelines for milling cutter radius:
For designing a milled component, it is important for a design engineer to understand what cutter sizes are available with internal manufacturing or with suppliers. This is important because if the required radius is not available with the machine shop, it would lead to additional investment in buying a new cutter or at times selecting a smaller cutter which would increase the production time drastically. This becomes more important for smaller pocket radius.
In the image depicted above, the design engineer created a pocket with side radius of 10 mm. General guideline for cutter selection is as below:
“Side Radius to Cutter Radius should be between 1.1 to 1.25.”
It means that a milling cutter with radius between 8.0 to 9.0 mm should be used for milling the side radius. DFMPro can check for appropriateness of side radii based on available cutters. By configuring cutter database within DFMPro, it will check whether such a cutter is available as per the mentioned range. If the milling cutter is available as per the range, then the analysis will pass and the radius would be acceptable. If not, the analysis will fail and DFMPro will suggest the next nearest milling cutter radius tool that needs to be considered based on this, the design engineer is suggested to modify the side radius value.
For example, if a cutter is not available with radius between 8.0 to 9.0 mm, then DFMPro will automatically find out the next nearest cutter radius e.g. 9.5 mm radius tool available in database. Using this nearest cutter radius, it will find the actual side radius value which needs to be provided on the pocket/slot feature. E.g. 10.45 mm to 11.875 mm side radius needs to be provided in this case. It is normally convenient for a design engineer to modify the side radius rather than using a non-standard milling cutter with additional cost.
This way DFMPro can help design engineers by way of providing better understanding of manufacturing requirements at the right time – that is, when the design is being created. It further promotes better collaboration of design with manufacturing and captures the right understanding of supplier capability to design parts the very first time. This drastically reduces the review time and avoids rework in design. For the downstream departments, it helps reduce manufacturing time and avoid issues like tool breakage due to wrong cutter selection.
Read some important machining guidelines here