Adding a CNC lathe to your shop’s arsenal vastly increases the services you can offer. Turning operations from threading to boring, advanced finishes, and combined lathe and millwork provide new opportunities to cut different parts and attract new clients.
Unfortunately, as with any new tool, adding a new CNC lathe also opens the door for some common mistakes. To help you avoid them, here are some of the most common ones.
- Incorrect Programming
CNC machines require G-code programs to execute and cut the correct part. For better or worse, your new CNC lathe will execute the program exactly as you’ve written it. Write it correctly, and you shouldn’t have any problems. But if you program the incorrect instructions, your CNC lathe will still follow them.
Most modern CNC machines have various fault and abort failsafes to prevent them from damaging the machine. But if a program calls for an incorrect cut, you can easily ruin a part and possibly damage the machine. You can avoid incorrect programming in a number of ways. Improve your overall programming skills to gain a better understanding of CNC programming and reduce risks, or use conversational programming languages that do much of the actual programming for you.
You can also monitor your CNC operations more closely, to catch potential problems before they occur.
- Bad Feeds and Speeds
There’s a whole science behind feed rate and spindle speed. On a lathe, feed rate is the speed at which the tool moves along the workpiece. Spindle speed, of course, is how fast the workpiece is rotating. Cutting a part isn’t as simple as just turning the lathe on and letting it spin as fast as the motor will go. Most CNC lathes will have variable speeds, and you’ll need to know which ones work best for that workpiece.
Material types play a huge role here; you’ll need different feed rates for different metals. You may need to move slower on harder materials, but if you move too slowly you can overheat your part or destroy your cutting tool.
Avoid the mistake of bad feeds and speeds by knowing your machine’s capabilities and the properties of the material you’re trying to cut. You can also take advantage of some of the resources that are readily available on the Internet, like this feeds and speeds guide from CNC Cookbook.
- Improper Tools
Tools for lathework are far simpler than tools for milling machines, largely because of the design of the machine itself and the interaction between a rotating workpiece and fixed cutting tool. However, using the wrong tool can result in a number of problems, including rough edges, distortion, or even burn marks from overheated tools.
Be aware that poorly-fixed workpieces that are off-centered or loose can also cause chatter, vibrations between the workpiece and tool. Chatter can quickly warp or destroy tools and damage workpieces. Check your tailstock to make sure that both of your fixture points are tight and secure.
- Poor Tool Positioning
The default position of your lathe’s cutting tool is along the centerline of the workpiece. An experienced machinist might vary that position slightly from time to time, but you should take care to avoid the mistake of starting out too low or too high on your workpiece. A bad starting position can lead to broken tools, overheated parts, and poor cutting and finishing.
- Poor Maintenance
This is an easy mistake to make, especially with new CNC lathes. Don’t forget the importance of regular maintenance, including:
- Daily cleaning
- Removal of metal chips
- Regular inspection of fluid levels
- Routine, scheduled maintenance
Failing to follow a proper maintenance checklist is the best way to keep your new CNC lathe running, well, like new! Keep your machine clean, keep all fluids topped up, and give regular detailed inspections and maintenance. Better yet, follow a strict maintenance schedule to keep you and your machine on track.
Common mistakes happen to everyone, but a little bit of preparation can avoid most of them. Fortunately, most of the preparation you’ll need to avoid these mistakes is simple common sense. Take care of your equipment, know all the details of your machine and your materials, and educate yourself on the ins and outs of CNC programming.
With those precautions, you’ll be able to avoid these common CNC lathe mistakes and set yourself up for a successful career as a CNC lathe operator.
