UGNX Academy

Tag: Secondary Roughing

  • Siemens NX Secondary Roughing Programming Masterclass: Master Wang Teaches High-Efficiency Corner Cl

    📝 Key Takeaways:

    NX Secondary Roughing: Master Wang’s Practical Techniques

    Opening: Lingering Issues from the Last Program

    Hello everyone, I’m Master Wang. In our last session, we finished programming the roughing operations for the first side. However, in some areas, the program ran slowly, and the computer lagged a bit. In the workshop, time is money, and a slow program means lost production! So today, we need to address these lingering issues, especially those “unmachined” areas, which are regions that weren’t fully cleaned up.

    Checking and Addressing Residual Stock

    Alright, let’s go back one step and quickly check which areas weren’t fully milled. Listen up: don’t just focus on the large flat surfaces. The real problem spots, where the tool is likely to engage heavily and cause issues, are often the small corners and grooves. I’ve noticed several areas that were “skipped” or “missed,” leaving behind a bit of residual stock. Some areas, especially on the side walls, still look like they have “remnants.”

    • Problem Areas: Found several spots, particularly edges and corners, where small amounts of stock remained after the previous program, looking “unmachined.”

    • Solution Approach: A “Corner Cleanup” operation is needed to remove this residual stock, preparing the part for subsequent finishing passes.

    First Corner Cleanup: Addressing Residuals on the First Side

    For this residual stock, we can simply copy an existing program and make a few parameter adjustments. This is the most efficient method and minimizes errors.

    Program Duplication and Parameter Adjustment

    I’ll directly copy one of our previous programs. Remember, after copying, the first thing you must do is check several key parameters:

    • Connections: Change the connection type from default to “Move” to prevent unnecessary tool lifts and air cuts.

    • Stock: For a corner cleanup operation, set the stock directly to 0. Our goal is to remove all the excess material.

    Tool Entry/Exit Strategy: Avoiding Collision Risks

    As soon as the program ran, I immediately spotted an issue: the tool entry/exit was problematic, preventing the tool from safely entering and retracting. This is one of the most common mistakes made by beginner programmers!

    • Original Problem: The tool entry/exit path was unreasonable, prone to scratching the workpiece or making air cuts.

    • Solution:

      • Change the tool entry/exit method to “Same as Open Area”, allowing the tool to enter and retract in obstacle-free regions.

      • Select “Arc Engage” for the tool entry method, with a radius of 1 millimeter. Arc engagement effectively prevents the tool from plunging directly into the material, reduces impact, protects the tool, and results in a better surface finish.

    Tool Selection and Boundary Handling

    For this corner cleanup, we’ll choose a 10mm flat end mill (Ø10mm). Its size is suitable, allowing it to reach into narrower areas while maintaining sufficient rigidity. A Ø6mm tool might be too weak.

    Next, I noticed that a certain spot might not have been thoroughly cleaned due to the toolpath, which is “not ideal.” However, it’s not a major issue. For the roughing stage, as long as it doesn’t affect subsequent finishing, occasional minor imperfections can be temporarily “overlooked.” We need to learn to prioritize and not get bogged down over-focusing on minute details during roughing; that’s not a good practice.

    Second Side Machining: Efficiency and Strategy

    With the first side done, we need to quickly flip the part and machine the other side. Remember, in the workshop, flipping the part and fixturing are among the biggest time costs, so programs must be correct the first time, minimizing rework.

    Coordinate System Transformation and Program Reuse

    The quickest method is to transform the coordinate system, then copy the existing program and make minor modifications. Most parameters are universal.

    • Blank Geometry Selection: The key is to select the blank geometry as this “B-side” after flipping. We previously machined the A-side; now we’re machining the B-side, and this absolutely cannot be mistaken.

    • Cutting Layers: For roughing, let the software automatically identify the cutting layers; it will find the last layer to mill.

    • Stock Setting: To be safe, we can leave a small amount of stock after corner cleanup, for example, 0.05 millimeters. This provides a margin for error in case of deformation or undetectable residual material during finishing. Never aim to machine to zero stock in one go; that risk is too high.

    “Surface Blocking” Technique: Handling Complex Regions

    While observing the machining of the second side, I found that some internal regions might experience redundant machining or be difficult to clean effectively. In such cases, we need to employ the “surface blocking” technique.

    • Purpose: To prevent the tool from entering areas that should not be machined, or to simplify toolpaths in complex regions.

    • Operation:

      • Select an “Offset Plane” to isolate the areas that need to be “blocked.”

      • Use the “Trim” function to cut away excess geometry, essentially defining a clear machining boundary for the tool.

    • Master Wang’s Tip: This trick is particularly useful when dealing with castings, forgings, or parts with complex internal structures. It effectively prevents “air cuts” and “heavy cuts.”

    Secondary Roughing: Larger Tools for Enhanced Efficiency

    With the initial roughing and corner cleanup complete, we now move to true “secondary roughing.” The strategy here is to use larger tools to quickly remove the bulk of the remaining stock.

    Tool Selection and Cutting Parameters

    Since this is secondary roughing, we need to “upsize” the tool to boost cutting efficiency.

    • Tool: Go straight for a 20mm flat end mill (Ø20mm), or choose a 16mm or 18mm one depending on the specific situation. A larger tool allows for a greater volume of material removal per pass and fewer toolpaths.

    • Cutting Layers: With a larger tool, the previous fine “cutting layers” are no longer relevant; the software will determine them automatically.

    • Stock: For secondary roughing, leaving 0.3 to 0.5 millimeters of stock is appropriate, providing ample allowance for finishing passes.

    • Stepover: Based on the tool diameter and material, we’ll set it to 0.35 millimeters here. This needs to be adjusted according to actual conditions and machine rigidity.

    • Tool Entry/Exit Distance: Set this to 1 millimeter to ensure safe tool entry and retraction.

    Machining Simulation and Performance Evaluation

    After generating the program, you must carefully review the machining simulation. No matter how perfect the simulation, it’s never as real as watching the cutting sparks at the machine! But simulation can help us identify most problems beforehand.

    • Expected Outcome: Most areas should be cleaned up effectively by the Ø20mm tool.

    • Limitations: However, a Ø20mm tool certainly cannot reach all small corners and deep cavities. These areas must be left for subsequent finishing passes or smaller tools. During the roughing stage, don’t expect perfection everywhere; that’s unrealistic and uneconomical.

    Summary: Pitfall Avoidance Guide

    Alright, that concludes today’s lesson on secondary roughing programming. Master Wang has compiled a few practical tips to avoid common pitfalls—these aren’t things you’ll learn from textbooks:

    1. Computer Performance is a Bottleneck for Efficiency: NX program calculation, especially for complex surfaces or multi-axis simultaneous machining, is very resource-intensive. If your computer lags, it’s better to pause, optimize settings, or upgrade hardware, rather than pushing through. That’s a waste of time.

    2. Roughing Prioritizes Efficiency, Finishing Prioritizes Precision: For roughing, be bold with large tools, fast feed rates, and aggressive material removal. Don’t chase 0.01mm precision during the roughing stage; that’s counterproductive. However, always leave sufficient stock to provide adequate allowance for finishing passes.

    3. Tool Entry/Exit is the First Line of Safety: Improperly set tool entry and exit methods can, at best, affect surface quality, and at worst, lead to tool breakage or machine collisions. Always select appropriate arc or open-area entry/retraction based on workpiece geometry and tool characteristics.

    4. Pitfalls After Program Duplication: Copying programs saves time and effort, but the most common mistake is forgetting to modify critical parameters like geometry, blank, stock, and machining direction. Always double-check these after every copy. Just like today, I almost copied the geometry from the A-side to the B-side and forgot to change the machining face—that would have been a “wasted effort.”

    5. “Surface Blocking” is a Lifesaver for Complex Parts: For parts with deep cavities, complex internal structures, or regions that shouldn’t be machined, effectively utilize “surface blocking” or “area restriction” functions. This significantly optimizes toolpaths, preventing air cuts or damage to the workpiece.

    6. Multi-axis Programming is a Challenge: In the future, we’ll cover 4-axis and 5-axis simultaneous machining. These involve even greater computation and are more prone to programming errors, requiring more patience and experience. Be prepared, so you don’t get “stuck” when NX calculates the program.

    Alright, that’s it for today. Go practice more, commit these tips to memory, and we’ll pick up next time!

    [/CONTENT]

    👤 About the Author:
    The author is a veteran CNC machining professional with 15 years of industry experience, specializing in UG NX programming. This article is an original work representing personal practical insights.

    ⚠️ Copyright Notice: Unauthorized reproduction or distribution without prior communication is strictly prohibited.

  • Siemens NX Secondary Dynamic Milling In-depth Analysis: Stock Inheritance Mechanism, Toolpath Optimi

    📝 Key Takeaways: Master Wang guides you through practical Siemens NX Secondary Dynamic Milling, unveiling the “stock inheritance” mechanism. Gain in-depth understanding of how 3D machining impacts toolpaths, and learn to adjust operation sequences to avoid common “red alarm” errors. Master the trick of setting Minimum Stock Removal to optimize cutting efficiency. This guide emphasizes when to use Workpiece vs. “A” mode, eliminating confusion, ensuring precise and efficient machining, and reducing costs!

    Foreword: Master Wang on Dynamic Milling

    Alright lads, today we’re talking about “Secondary Dynamic Milling” in Siemens NX, also known as “Secondary Roughing.” At its core, this is the same beast as the regular Dynamic Milling we’ve discussed before. Both use a 3D approach to clear out corners and residual material. Don’t let the complex name fool you; once you grasp the principle, it’s straightforward to operate. If you’ve mastered regular Dynamic Milling, Secondary Dynamic Milling will come naturally.

    The “Stock Inheritance” Mechanism in Siemens NX

    Listen up, this section is critically important. Textbooks might not cover it in such detail; this is all hard-won experience from real-world pitfalls.

    Problem Revealed: Has the Stock “Been Machined”?

    Have you ever encountered this situation: it’s clearly a secondary roughing operation, but when you look at the Workpiece, it appears as if it’s already been machined, with all the edges nearly gone? This isn’t the software glitching out; it’s the fault of “inheritance”! Just as Master Wang demonstrated in the audio, if you select a A-1 Dynamic Milling operation, the Workpiece looks like it’s already finished – that’s not right.

    This is because Siemens NX, by default, will treat the machining result of the previous operation as the “stock” for your current operation. If that “previous operation” you’re referencing has already machined the part completely, then your secondary roughing operation will naturally have nothing left to do.

    Root Cause: Inheritance Relationships Between Operations (Workpiece)

    The Workpiece we select under “Geometry” isn’t a static entity; it has “memory.” Especially when you select “Use 3D,” it will faithfully read the residual stock after the previous referenced operation. This “Use 3D” option tells the software that you want to perform precise 3D residual stock calculations, not just a simple 2D contour determination.

    If your Dynamic Milling operation is placed after the roughing operation, it will inherit the stock remaining after the roughing pass. If the roughing hasn’t been defined correctly, or is defined incorrectly, or even hasn’t been machined yet, then this Dynamic Milling operation might have nothing to machine or might machine the wrong areas. As mentioned in the audio, if the preceding operation also used 3D, then the subsequent operation inherits its machining result, layer upon layer, just like Russian nesting dolls.

    Pay attention, this is important: If your operation uses Workpiece and has “Use 3D” checked, then its calculation is based on the final machining state of all preceding operations that also used Workpiece and “Use 3D.”

    Solution: Operation Sequencing and “A” Mode

    When the stock seems incorrect and the operation turns red (error), your first reaction should be to check your operation sequence! Arrange operations with clear inheritance relationships, such as roughing and secondary roughing, according to the actual machining sequence. Just as Master Wang demonstrated in the audio, move the roughing and dynamic milling operations to the front so they machine the original stock first. This way, subsequent operations will correctly inherit their machined state, the operations won’t turn “red,” and a simple “generate” will pass them.

    Master Wang’s Pro Tip: For beginners, if you’re unclear about the “Workpiece” inheritance relationship, **just avoid using Workpiece altogether; directly select “A.”** Selecting “A” means you’re telling the software that this operation is targeting the entire geometric model of your part. As for the stock, we manually define the machining area or control it via toolpath. This can prevent many unnecessary issues and “red alarms.” Since you’re not using 3D for stock calculation, it won’t inherit the machining state of preceding operations; it will only recognize your currently defined machining region. This is a “lazy” yet effective method to avoid detours!

    Practical Parameter Settings for Secondary Dynamic Milling

    Theory’s done; now let’s get practical and see how to adjust the parameters. These are the optimal configurations I’ve refined over many years; just use them as is.

    Tool Selection and Stepdown: The Power of Templates

    For tool selection, it depends on the actual situation, for example, using a D4 end mill. I, Master Wang, typically use templates, so many parameters are ready to go with a click. For instance, the Stepdown (Depth of Cut), we usually set it to around 0.5mm (approx. 0.02 inch), depending on the material and tool conditions. Other connection parameters and the like usually don’t need changing if you’re using a template.

    Why use templates? Efficiency! Who has time to set everything from scratch every time? Consolidate common parameters, and you save effort, time, and reduce errors. This is a crucial step for improving your efficiency in the future and the cornerstone of standardized production.

    Key Parameter: Minimum Stock Removal

    This parameter, “Minimum Stock Removal,” listen very carefully, is the key to Dynamic Milling efficiency!

    Its purpose is to tell the software not to machine an area if the remaining stock is less than this value. In the audio, Master Wang suggests setting it to 0.5mm (approx. 0.02 inch). Why?

    • Consider this: if you set it too small, for example, 0.01mm (approx. 0.0004 inch), the software will relentlessly calculate and try to remove material in areas with almost no stock. This will generate an excessive number of toolpaths, leading to calculation times that will make you question your life choices.

    • Furthermore, the actual machining effect won’t improve much, and efficiency might even decrease due to too many air cuts.

    • Therefore, setting it to 0.5mm (approx. 0.02 inch) ensures most residual material is removed while avoiding unnecessary calculations and cutting. This is based on experience and represents a balance between cost and efficiency. You can’t justify tying up the machine and tool for such a tiny, negligible amount of stock, can you?

    Toolpath Generation and Simulation: Efficiency and Observation

    Don’t just watch the software run; you need to understand what’s happening behind the scenes.

    Time-Consuming Nature of 3D Calculation

    3D machining in Siemens NX, especially dynamic milling that requires precise residual stock calculation (particularly when you have “Use 3D” checked), will take a comparatively longer time to calculate, and this is normal. That’s because the software has to analyze the entire 3D model, calculate the stock at every point, and then plan the toolpaths – this is far more complex than simple 2D operations.

    So, when calculations are slow, stay calm, grab a cup of tea, and don’t click around aimlessly. Patiently wait; a high-quality toolpath is worth it.

    Observing Cutting Sparks: Beyond Software Simulation

    Software simulation might look great, but it’s still just a simulation! When you’re on the machine later, keep your eyes on the cutting sparks and your ears on the cutting sound. If the sparks are too yellow or the sound is too dull, you might be experiencing excessive Depth of Cut; immediately reduce the feed rate. If the sparks are too bright or the sound is too crisp, it could indicate tool wear or parameters set too low. You need to combine all these observations to truly prevent tool wear and ensure machining quality.

    This is “real skill” that you won’t learn from textbooks; you have to gradually accumulate it yourself. Most of my fifteen years of experience, Master Wang, came from “seeing” and “listening” on the shop floor.

    Master Wang’s Secret: The “Golden Rules” of Siemens NX Programming

    Next are Master Wang’s “plain-talk” summaries for Siemens NX programming, simplifying those complex topics from before. These are your “golden rules” for future work.

    When to Use `Workpiece` and `Use 3D`

    Listen closely, the core principle is: If your operation needs to precisely calculate the residual stock based on the machining results of a preceding operation (e.g., secondary roughing after roughing, or secondary dynamic milling after cavity milling), then:

    • You must set “Geometry” to Workpiece and check “Use 3D” in your Roughing operations and all Dynamic Milling operations requiring this precise residual stock calculation.

    • Furthermore, their sequence in the operation navigator must be strictly correct, adhering to the actual machining process. Otherwise, you’ll get a flurry of “red alarms,” and you won’t know how to proceed.

    • The purpose of this setting is to enable the software to accurately “know” how much material remains to be cut. From roughing to semi-finishing, this progressive calculation of residual material is crucial for ensuring final accuracy and efficiency.

    Strategy for Non-3D Toolpaths: Revert to “A” Mode

    Aside from the 3D Dynamic Milling operations mentioned above that require precise residual stock calculation, for **all other operations, such as face milling, floor/wall milling, contour milling, etc.**, you should consistently set “Geometry” to “A.” Then, manually specify the part (the geometry to be machined) and manually specify the cutting region (the area for the toolpath to clear).

    The advantage of doing this is that operations no longer influence each other’s “stock” status. If you change the order of one operation, the others won’t turn red due to inheritance issues. This greatly simplifies your learning and troubleshooting, making programming much more controllable. For these non-3D machining modes, they don’t need to know precisely how much stock was removed in the previous step; they only need to know which face or region to machine.

    In the initial learning phase, this method will help you avoid many detours and the awkward situation of “everything turning red” with one change. Once you have enough experience and a thorough understanding of Siemens NX’s inheritance mechanism and 3D calculations, then it won’t be too late to experiment with more complex Workpiece management.

    Summary: Pitfall Avoidance Guide

    • Operation Sequence is Key: For operations involving “stock inheritance” (especially Workpiece operations with Use 3D enabled), ensure they are arranged according to the actual machining sequence, like an assembly line, step by step, without skipping.

    • Don’t Panic at “Red Alarms”: If an operation turns red, chances are it’s an inheritance issue. Check references and sequence, or if an operation that depends on prior machining has been moved too early.

    • Flexible Use of “A” Mode: For most standard machining operations, using “A” mode and manually defining the machining area can effectively avoid the complications of stock inheritance. This is the most reliable method for beginners.

    • Minimum Stock Removal Must Be Reasonable: Randomly setting it to 0.01mm (approx. 0.0004 inch) is a waste of resources! Set it to 0.5mm (approx. 0.02 inch) or even larger, based on actual needs, to balance efficiency and quality, and reduce calculation time.

    • Experience is the Best Teacher: Software is just a tool. Theory must be combined with practical operation. Observe more, think more, to truly become an expert. Don’t just stare at the screen; pay attention to the machine and analyze problems!

    👤 About the Author:
    The author is a veteran CNC machining professional with 15 years of industry experience, specializing in UG NX programming. This article is an original work representing personal practical insights.

    ⚠️ Copyright Notice: Unauthorized reproduction or distribution without prior communication is strictly prohibited.