At KT Tech, our mission is to help our customers succeed. This starts with transparency from the initial quote – we want our customers to understand the different factors that influence the costs associated with producing their parts, including features that may complicate manufacturing or increase prices.
Typically, when we receive 3D models and drawings in an RFQ, we quickly identify features that require discussion with the customer. We’ll inform the customers that alternative designs could be faster and less expensive to manufacture. Customers are usually open to our suggested changes but the back-and-forth process consumes valuable time.
That’s why we’re creating a series of DfM or “Design for Manufacturing” articles for our customers to reference. We’re focusing on common design choices that frequently require feedback and discussion. By highlighting these potential issues before they even submit the RFQ we aim to save our customers time - because for many customers, time is money.
The Challenges of Internal Corners
Machining tight corners can be extremely challenging without a sufficiently large corner radius. This difficulty arises because tight corners put significant stress on the machining tool, which must become longer as the corners get tighter.
To visualize this, think of a mechanical pencil – when you push out a long tip of graphite, that graphite can handle very little pressure before breaking. Similarly, long tools are at a higher risk of breaking, a factor considered in cost estimates for these parts.
Even if we find a way to machine the corner without breaking the tool, costs will still be higher due to the increased processing time, which escalates exponentially with tighter corners. Alternatively, 5-axis machining, a key services we offer at KT Tech, can sometimes manage these corners more effectively, but using this technology typically increases the overall quote.
In the image at the top of this blog, you can see an example of a problematic internal corner. The radius of that internal corner is so small that it’s practically a sharp corner. Not only that, it’s next to a much taller wall, making it very difficult – in this case, practically impossible – for a tool to reach that corner.
The Recommendation: Corner Radius Should Be Greater Than 10% of the Radius Depth
As a result of these factors, we typically tell our customers to make a corner radius greater than 10% of a radius depth.
In the image, the corners opposite the tight ones show what a better radius would look like. This corner is far more easily manufactured and will result in more cost-effective parts.
We recently encountered a part with a particularly tight corner. Finishing that corner alone actually took significantly longer than machining the rest of the part. As a general rule, if the exact tightness of a corner isn't crucial to your design, it's advisable to avoid such tight corners altogether. This approach simplifies manufacturing which helps to optimize production time and keep costs down.
Working with KT Tech on Design for Manufacturing
We’re fortunate to work with many companies in the early stages of product design, making them receptive to our DfM recommendations, such as using less tight corners. However, time is typically critical for these teams and even minor design changes can lead to several extra days of back-and-forth approval processes.
One effective strategy to avoid these delays is to include a callout in the design specifying a minimum radius for all internal corners. This proactive approach ensures that if any corners are sharper than intended, we can proceed without the need for extensive back-and-forth revisions and waiting for responses from all parties involved.
At KT Tech, we have extensive expertise in design for manufacturing and optimizing production costs for your parts. Request a quote today from our precision machine shop to learn how we can help you achieve cost-effective manufacturing solutions tailored to your needs.
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