Wpi Manufacturing Engineering Labs

WPI Manufacturing Engineering Labs possess a myriad of CNC machines (from 3 axis to 5 axis), however during our instance at the MFE seminar we used the CNC MiniMills. These machines require two main components to machining any piece/part, Tooling and G-Code (SPRIT was the software used to generate the G-Code). We had learned the tools depend on material’s mechanical and physical properties and precision and desired finishing for the final product. However, the classification of this tools is twofold, Milling Tools and Turning Tools; the first one characterizes types of CNC Milling Machine and latter CNC Lathe Machine.  

During our seminars, tools were organized by material and type (size and form), we only could experiment with the Milling Machines ones due to time matters; Lathe Machine was not studied in our seminars, but process of selecting tools is quite similar. ASTM and ISO standards chart for selecting a desired tool are necessaries and provided in groups, such as: Steal (P0-P1), Stainless Steel (M1-M3), Cast Iron (K1-K3), Non-Ferrous Materia (N1-N7), High-Temp Alloys (S1-S4), Gardened Materials(H1-H4).  Each classification defines the content of elements on each material, e.g., 30% Carbon Alloy Steel, information was gathered from WPI Manufacturing Labs.

After the material is selected, we must define our tool Type, Dimension and Material for Application purpose. For dimension, there thousands of options depend of the item’s design but most common (in WPI MFE lab) are 1/4", 1/8”, 3/8”,1/2", and others. In contrast, WPI MFE Labs only have few Mill Tooling available, Endmill for Non-ferrous, Endmill General Purpose, Ball Endmill, 3/8” Drill Mills, Taps, and Facemill 3”.  Note:  Lathes, Plasma Cutters, Electric Discharge Machines, Water Jet Cutter, are other types of CNC machine we have not covered in our seminar.

Finally, CNC Machine uses two type of code M-codes and G-codes, the main differences is that one does not command axis motion in a 3-dimensional axis control and the later allow command the specific movement. In practice, G-code is more feasible and reliable for the purpose. In our seminars, we did not touch in deep the G-coding, instead, we used a software (SPRIT) to generate the G-code from a CAD model. This saved us a lot of time, because programming by hand this code would deplete most our time, but we still needed to understand the basics of the code to proof-read in case of mistake. For example, letter “T” changes the tools to another one and “M05” stops the spindles and the “M30” Program End, those a some of the G-code we must read prior deployment our code into the machine. Crashes are other issues that can be avoided by proof-reading the code.    

Machine safety and equipment

CNC machines safety can be divided in twofold, one, safety of the users at the time machine is running; second, the safety of the machine (keep machine in good conditions) avoiding wears and others damages from users’ mistakes. Both Operator and Machine safety is mandatory an following a set of rules imposed by the officers from MFE Labs are required. This rules and recommendations to follow while working in with these machines are listed below:

• Clothing, for examples long-sleeves can get stuck in the milling machining, so is required to be careful when the machine is full-operated.
• Machine should be operated only by trained users, we cannot use the machine alone and our design must be checked by one of the expert priors running it on the machine.
• Tools must be sharp, sett correctly, and free of crack.
• If time is an opportune, tool must be testes.
• Only use tools within machine limits and other parameters.
• Never use tools with damaged tips or cracked.
• Always keep sure that you are mentally focused, and your finger slightly touching the stop and start buttons; in case of emergency.
• Only one people can operate the machine, i.e., one people cannot be in the machine’s computer and the other working inside the machine.

Similar rules are applied for equipment management, however, since the machines are different some extra rules and precautions must be taken: