Even if your machine cycle times are shorter than average, there’s no reason not to strive for efficiency. Whether you parse through your code manually or use a G-code optimizer, improving your computer numerical control (CNC) programs is among the fastest, most cost-effective ways to realize efficiency gains.
G-code, or geometric code, is a programming language that guides CNC machine movements, such as commands that define motion, position, and function (and other values) using alpha-numeric codes. For example, G00 means rapid movement, G01 means linear feed move, and G02/G03 means clockwise/counterclockwise feed move.
Flexibility is another feature of G-code, making it useful for programming specific machining requirements.
But G-code programming requires training and time, meaning it can challenge programmers and operators, and it can be a hurdle for improving machine-shop productivity.
Are your cycle times too long?
Because the length of a job is determined by geometric complexity, material type, and project scope, your typical surface feet-per-minute metric can range anywhere from a few feet to a few hundred feet. That said, even if your cycle times are consistently above average, you likely still have room to improve.
This field sees a steady stream of new CNC machines, procedures, and software. Operations with enough resources to adopt the latest tools gain a competitive advantage. They enjoy the benefits of reduced cycle times, including improved product quality and increased profitability.
If your facility relies on legacy production technologies, reducing cycle times via G-code optimization is essential.
Don’t make these G-code mistakes
The most straightforward way to optimize G-code for more efficient machining is to avoid programming mistakes. Syntax errors are among the most common. These can cause unplanned downtime and inaccurate cuts. For example, replacing “0” with “O” will keep the program from properly loading during operation.
In the worst-case scenario, you can send bits of metal flying or damage your equipment. You could inadvertently force your spindle to drill into the table using G1 for extrusion movements instead of G0 for non-extrusion. Alternatively, accidentally having negative curvature for a non-curved cutting area could ruin your part.
If your geometry is off, you may end up with overlaps, gaps, or duplicates. Even if it does not cause surface-finish problems, you are still left with unoptimized instructions. Every moment spent cutting air or retracing toolpaths is unnecessary downtime. With strategic improvements, you could save a great amount of time.
Has your scale ever been incorrect? Missing a single character could result in your machine registering 35 millimeters instead of 0.35 millimeters — an undesirable difference, to say the least. While issues like these are relatively easy to catch, you save more time eliminating them during programming than fixing them during setup or operation.
G-Code optimization techniques
Leverage these optimization techniques to shorten your cycle times. Whether you use a G-code optimizer or strip block numbers, you should see noticeable improvements.
1. Automate programming. Like many machining operations, your employer likely has strict cycle times. If you, like most workers, find this stressful and distracting, you are more likely to be error-prone — especially when completing precision-based work or monitoring parallel processes.
Automation is ideal for efficiency optimization in these cases. It can reduce your production time per piece without sacrificing precision. Its resource savings are particularly noticeable in projects with complex geometries.
2. Use smoothing functions. Using smoothing functions to soften jagged geometry reduces the curvature and sharpness of segments, minimizing deceleration and jerkiness at junction points. Moreover, it reduces toolpath length, increasing your machine’s speed and shrinking cycle times.
3. Use a G-code optimizer. Post-processing tools like a G-code optimizer help you identify areas of opportunity. You can reduce cycle times by up to 70% with optimization software alone — even on toolpaths previously optimized by computer-aided manufacturing.
4. Reduce your program’s size. While lacking CNC memory is not a problem with many modern machines, your operation still may be using legacy models. You can reduce your program's size by using drip feeding — sending your program over a few instructions at a time.
Simplifying your G-code involves making your program concise and clear. Start by stripping unessential comments and block numbers. If operations are similar, you can use subroutines and loops to avoid redundancy-related bloat.
5. Test and verify G-code. Test and verify your program before running it on your CNC machine. You can perform test cuts, use the built-in emulator, or leverage third-party simulation software. This way, you can quickly resolve bugs, errors, and inconsistencies in your code.
Apply Lean manufacturing principles
Lean manufacturing principles involve identifying value, and creating flow and ideal processes. Incorporate them into your programming process by detecting and eliminating waste. Fixing code redundancy, air cuts and unnecessary add-ons are good starting points. How many features in your custom CNC software do you use regularly?
With lean principles, conciseness is critical. Tweaking programs for each job may result in efficiency gains during operation, but it will needlessly lengthen programming times. Unless you consistently make custom parts, practice reuse. Canned cycles and recycled G-code will serve you well, helping you reduce length and complexity.
Be mindful of eliminating defects ahead of time — not fixing them after the fact. Optimize your numerical control files by applying lean manufacturing principles. Adjust speeds and feeds, ensuring you balance cycle time and product quality. Work on making your toolpaths more optimal, as well.
Above all, you should continuously strive for perfection. However, an eye for inconsistencies and areas of opportunity is shaped over years of experience. To streamline the process, consider a G-code optimizer or post-processing visualization tool. This way, you can quickly fix unoptimized code while gaining practical knowledge.
The point of optimizing CNC programs
Unless your employer can afford the latest in CNC programming or machining technology, optimizing your numerical control files for efficiency is one of the only ways to remain competitive in this market.
Emily Newton is the Editor-in-Chief of Revolutionized, an online magazine exploring the latest industrial innovations.
