This article was originally published a couple of years ago. I republished it to call attention to the extensive updates to our Design for Manufacturing page which has nearly double the number of DFM recommendations from 19 to 33.
Many of our readers own or work in CNC manufacturing businesses of all sizes and many would like to start such a business manufacturing a product, perhaps something similar to this neat Kickstarter project for the latest precision machined Aluminum Sentinel Cache.
One thing all manufacturing has in common is the desire to keep the manufacturing cost as low as possible by being as efficient as possible. The best possible place to attack efficiency is in the design process before a single chip is made. That’s certainly the cheapest place to do it.
As part of our CNC Manufacturing Cookbook, we’ve written an article on Design for Manufacturing (abbreviated DFM). In it, you’ll find 33 different areas that can be changed during the design process to reduce the cost of manufacturing. Here’s one of the 33 to give you a taste:
|Depth of Cut vs Radius of Corners||You can’t cut a tight corner radius with a tool whose diameter is more than twice the corner radius. At the same time, the stiffness of a tool changes with the third power of length and the fourth power of diameter. Making the tool twice as long makes it 1/8 as rigid. Making the tool twice the diameter makes it 16x more rigid. Therefore, avoid designing parts with tight radius corners that are very deep.
A good guideline is keep the ratio to 3:1 depth vs diameter (2x corner radius). So, a pocket with a 1/4″ corner radius should be no more than 1 1/2″ deep or you’ll greatly increase the manufacturing costs.
Here’s another tip: choose a corner radius just slightly larger than the endmill radius that will be used to make the corner. This reduces the loads on the endmill due to lower tool engagement angles in the corner and will reduce your manufacturing costs as a result either by allowing the endmill to be fed faster or by causing it to last longer.
We’ve laid the 33 DFM tips out in Cookbook-style to make it easy to refer to as you consider each type of feature in your part design.
It’s also important to note that even Job Shops who are not creating their own products can benefit from DFM. In our article on Secrets of the Top Machine Shops, we revealed that top job shops get ahead by providing their customers with DFM advice to help the customers lower the cost to manufacture parts. It makes sense: what customer wouldn’t want to learn how to make their parts more cheaply?
Given the value of DFM, it should come as no surprise that we have tools to help you with it.
Our G-Wizard Calculator includes both a Rigidity Calculator to help you understand the trade-offs between tool length and diameter and our proprietary Cut Optimizer that lets you calculate the optimum depth of cut to minimize deflection and chatter. It will even directly provide DFM tips via the CADCAM Wizards applet:
DFM Tips like this one for pocket depth are built right into G-Wizard…
If you haven’t tried it, go ahead, we offer a free 30-day trial.
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