CNC machining is capable of incredible precision manufacturing at affordable costs, but as with any process, there are ways to get those costs down further—through prudent decision-making and a better understanding of the tools and techniques involved. The following design guide will provide you with some practical tips for controlling costs when you’re designing projects meant for CNC machining.
Keep Those Corners Rounded
CNC machines are capable of creating 90-degree corners, but the process adds a significant amount to machining time. This is because the machine has to stop, then be rotated, and then continue along its path. That extra time can start to eat into your budget, so a more sensible design option would be to include rounded corners. This way, the machine can continuously run and won’t have to take needless breaks that will extend your production time.
Go Light On The Deep Pockets
Like trying to do right angles, attempts at deep-pocketed parts take more time than is ideal. This sort of design, with all of that extra material being removed, often requires special tools to achieve. It’s more prudent, generally, to limit pocket depth to save time and money.
Watch Your Tolerances
In the simplest terms, machine tolerance (also known as dimensional accuracy) is the amount of variance allowed in the dimensions of whatever part you’re manufacturing. The greater the difference between those upper and lower limits, the “looser” the tolerances are said to be. Smaller differences, meanwhile, are known as “tight” tolerances.
Now, designs with tighter tolerances are almost always going to be more expensive because they’re a bit trickier to achieve on certain surfaces (thanks to the limitations of some machines) and they often require more thorough inspection to make sure they’re produced correctly.
There’s also the deburring cost to consider, as attempts to achieve those tight tolerances often result in burred edges (those raised parts on the sides that can form after machine tooling) on manufactured parts. As you may have suspected, the deburring process can be rather costly, thus, an “easy” way to reduce some of your costs is to loosen some of your tolerances.
Consider Thick Walls Instead Of Thin Ones
Thin walls on components are typically fragile, which means that they’re going to take more time to produce correctly, and as we’ve already demonstrated more than once, time is money. In lieu of those time-consuming, thin walls, try using thicker walls in your part design. This is, of course, assuming weight isn’t too great a concern in your design (thicker walls will weigh more). If it is, you may have to consider other cost-saving measures instead.
Make Use Of Standard Drill Sizes
Somehow it all comes back to time: by incorporating standard drill sizes into your plans, you can cut down on the amount of time that you’re spending in production, since those are typically ready to go. If you’re using custom sizes, on the other hand, prepare for manufacturing to take longer and cost more as the manufacturer will probably need to break out their end mill tool to get the job done.