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Ask the right questions to secure the right G-code talent among an increasingly shrinking pool of talent.
G-code, also known as RS-274, is a programming language that directs Computer Numerical Control (CNC) machines to perform specific tasks. It was first developed in the late 1950s by the Electronic Industries Association for use in automated machine tools. This universal language instructs machines on tool usage, movement and speed, essentially controlling all aspects of the manufacturing process. Over time, G-code has been modified and enhanced by various machine manufacturers to fit specific needs. Today, it remains a crucial component in industries such as manufacturing and 3D printing.
The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.
G02 and G03 commands are used for circular interpolation. G02 moves the tool in a clockwise direction along a circular path, while G03 moves the tool in a counter-clockwise direction.
A simple square can be created using a series of G01 commands to move the tool in a straight line along each side of the square. The program would start with a G00 command to position the tool at the starting point, followed by four G01 commands to draw each side of the square.
G00 is used for rapid positioning of the tool, it moves the tool at maximum speed to the specified coordinates. G01 is used for linear interpolation, it moves the tool in a straight line between two points at a specified feed rate.
Some common G-code commands include G00 for rapid positioning, G01 for linear interpolation, G02 for circular interpolation (clockwise), G03 for circular interpolation (counter-clockwise), and G28 for return to home position.
G-code is a language that is used to instruct CNC machines on how to perform certain operations. It provides detailed, step-by-step instructions that guide the machine in creating the desired part or product.
Having relevant experience can be a strong indicator of the candidate's ability to perform well in the position.
The tech field is constantly evolving, so it's important for a candidate to be able to adapt and learn new technologies quickly.
Experience with CAD/CAM software is beneficial as it is often used in conjunction with G-code programming.
Good communication skills are necessary for explaining complex ideas to non-technical team members and stakeholders.
Problem-solving skills are crucial in programming as they will often need to troubleshoot and solve issues in their code.
This is important because G-code is the primary language for CNC programming and a strong understanding is necessary for the job.
The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.
Creating a circular hole would involve using a G81 drilling cycle command, followed by the X and Y coordinates for the center of the hole, and the Z coordinate for the depth of the hole.
G90 and G91 commands are used to set the positioning mode. G90 sets the mode to absolute positioning, while G91 sets it to incremental positioning.
Common errors include syntax errors, incorrect coordinates, and incorrect tool selection. Troubleshooting would involve carefully reviewing the G-code program, checking the syntax and coordinates, and ensuring the correct tool is selected.
A tool change can be performed using the M06 command followed by the T command with the number of the desired tool. For example, 'M06 T3' would change to tool number 3.
In absolute positioning, the coordinates given in the G-code commands are based on a fixed point on the machine, usually the machine's origin or zero point. In incremental positioning, the coordinates are relative to the current position of the tool.
At this point, a skilled G-code engineer should demonstrate proficiency in CNC programming, thorough understanding of G-code language, and problem-solving skills. Red flags would include inability to explain complex G-code concepts or lack of experience with relevant software or machinery.
G01 X10 Y10 F20G90G28 X0 Y0M02G92 X0 Y0 Z0G21The final few interview questions for a G-code candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.
Creating a 3D contour would involve using a series of G01, G02, and G03 commands to move the tool along the desired path. The program would need to include precise coordinates and feed rates to ensure the tool moves accurately along the 3D contour.
Some advanced G-code commands I have used include G41 and G42 for tool radius compensation, G81 for drilling cycle, and G98 and G99 for return level after canned cycles.
Spindle speed can be controlled using the S command followed by the desired speed in revolutions per minute. For example, 'S1200' would set the spindle speed to 1200 RPM.
G20 and G21 commands are used to set the units of measurement. G20 sets the units to inches, while G21 sets them to millimeters.
M-codes are used to control miscellaneous functions of the CNC machine, such as coolant control, spindle control, and tool changes.
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