CNC Router Parts-based metal printers SOP: Difference between revisions

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Introduction

Provide a background on the method - link to wikipedia or elsewhere.

Safety

Safety checks must be carried out before any action when entering 329. Safety training is critical for continued lab usage and is a requirement of the department before access to the lab can be granted by the lab overseer.

Safety courses required

Baseline of knowledge needs to be guaranteed before anyone can be trusted with lab usage.

1. 329 safety training - hazards
2. MSE departmental safety training
3. Gas cylinder safety training
4. Welding safety training

Collection of personal protective equipment

PPE is to keep YOU safe so that you can keep doing what you want to do.

1. Safety glasses – always required
2. Welding helmet – required only if canvas cover not used
3. Green jacket – required only if canvas cover not used
4. Steel toes are highly suggested
5. Natural fiber clothing is suggested

SDS and other

Knowing what chemicals are in the lab and how they interact with each other is critical when accidents happen.

1. Appropriate SDS sheets should be viewed online.
2. Note the hazards listed on the door to the lab. If you introduce any new equipment or materials you must clear them with the responsible person listed on the lab door. If the responsible person is out of date, contact the departmental administrators to get it updated.

Equipment or Bill of Materials

Calibration & Tolerances

Operation & Procedure

[Digital prep] Software prep

The following digital preparation should be completed before you enter the lab space.

Plan development

Decide on the end goals of the test/project to make sure this process works towards those goals.

1. Check stock for desired wire alloy and substrate alloy compositions ideal for the part.
2. Consider the material properties and dimensional requirements for the desired part.
3. If working on a developmental alloy, identify comparable systems and investigate their welding characteristics. This will allow early weld parameter tuning and help predict potential issues.

G-Code generation

G-code is the direction list the printer uses to understand what you want it to do.

1. G-code should be generated via the open sourced software Cura for complex designs (https://ultimaker.com/software/ultimaker-cura). Cura has many parameters, the most important ones are, travel speed, line width, layer height, and extrusion.
2. Alternatively, if a simple geometry is needed G-code can be generated via notepad with simple G-code G0 X0 Y0 Z0, F, E, and G4 commands.
3. After G-code is prepped it can be uploaded to Franklin, the firmware running the printer through a simple browse and select method .
4. Example G-codes are shown below, commands can be looked up online for specific functions and added as necessary. The M42 P6 S255 or S0 lines toggle a specific relay tied to the activation circuit of the welder, so it necessary in any multi-layer print.

• TBA Figure 1: Example G-code for printing a single line 100mm in length, annotated for descriptions
• TBA Figure 2: Example G-code for printing a two layer 40 x 40 mm block with a line width of 2mm

[Lab operation] Printing process and operation

Consistency in operation is paramount for reliable results.

Substrate / nozzle Prep

1. For printing aluminum, the substrate material suggested is a 6061 aluminum alloy (T6 or annealed is being investigated) between 2.4 and 3.2 mm in thickness (Z) and 150 x 150 mm (X-Y). Locate a substrate.
2. As received, it has a built-up oxide layer and cutting fluid remnants which must be removed to allow effective electrical and thermal contact. To do this a circular belt sander is used on both sides of the substrate until a shinny surface is obtained.
3. Place the substrate on the copper chill plate and stack the window frame on top of the substrate so it aligns with at least 3 holes drilled into the copper plate.
4. Insert the grounding cable onto the same plane as the substrate so it makes physical contact.
5. Hand screw in three points of contact securing the window frame to the substrate.

CNC Printer start-up and prep

1. Turn on the printer by activating the power strip on the print table. This supplies power to the printer, as well as the sensor circuit, and laptop to run the printer.
2. The laptop running the printer uses Linux and the username/password is reprap/reprap.
3. After logging into the laptop, transfer the G-code for printing if necessary via a USB key and open the internet browser window. It has been modified to have the printer access terminal as the homepage as seen in figure 3.

• TBA Figure 3: Nominal Franklin interface.

1. The browse button is used to upload G-code for Franklin to consider. Only have one file uploaded at once as Franklin is temperamental with multiple files.
2. The current position of the nozzle is set as the 0,0,0 X-Y-Z position upon powering the printer.
3. Use the position X-Y boxes to actively move the nozzle and position it at the desired starting location in the X-Y plane.
4. Once the nozzle is in position transfer the X-Y values to the Target boxes and this will apply an additive modifier to the G-code values causing the print to start from that location.
5. Ensure that there is no excess wire coming from the nozzle, then slowly lower the Z target position box until the nozzle is touching the substrate (lightly – piece of paper is a good tool here). Then increase the Target Z value by the determined stand off distance.

• Change the “wire” box value to 0.01, increase the Target Z value by 10, toggle the welder circuit trigger to the off position and click the “run selected job” button to do a dry test run. Reset values if successful and satisfactory.

Metal additive process operation

1. The printer, G-code should be prepared and a dry run completed. Do not start the printer without a successful dry run as this will potentially damage the system (e.g. running the gun or print assembly into the work table)
2. Input the appropriate multiplier value for “wire” to reach the desired extrusion rate .
3. Set the wire stick out length to be about 2-3mm by extruding wire in franklin. This is important so that the wire does not jam in the tip during arc ignition.
4. Press the abort and home buttons in order to reset the wire extruded values and prepare the Franklin Firmware for testing.
5. Turn the gas cylinder to the desired gas flow rate.
6. Turn on the chiller if desired.
7. Power on the welder and verify the power setting is appropriate.
8. Toggle the welder circuit trigger to on.
9. Turn on the fume hood air flow
10. Press the run selected job button to begin the test.
11. Change the Target X-Y values to modify the start position of successive tests on the same substrate if desired.

Shutdown

References