6 Kesalahan biasa dalam reka bentuk pemesinan CNC (Dan bagaimana membetulkannya)

If you’re a CAD designer working onPemesinan CNC bahagian, small design errors can lead to big problems: broken tools, wasted material, or parts that don’t fit. Berita baik? Most mistakes are easy to avoid once you know what to look for. Panduan ini memecah 6 most common CNC design blunders, dengan contoh sebenar, data, and step-by-step fixes to save you time, wang, dan kekecewaan.

1. Kesilapan 1: Designing Walls That Are Too Thin

Thin walls might seem like a way to save material—but they’re a disaster for CNC machining. Thin sections vibrate during cutting, break easily, or lose precision.

Mengapa masalah itu:

Low-stiffness materials (seperti aluminium) are especially risky. Contohnya, a 0.5 mm aluminum wall will twist or crack when a milling tool applies pressure. Even slightly thicker walls (0.6–0.7 mm) can warp, as the tool’s vibration bends the material.

Key Guidelines for Wall Thickness:

Contoh sebenar:

A designer created a 0.6 mm thick aluminum bracket for a drone. During milling, 9 keluar dari 10 brackets broke because the tool’s vibration bent the thin walls. When they increased the thickness to 0.9 mm, the success rate jumped to 98%—and the bracket still weighed less than 5 gram (no extra material waste).

Cara memperbaikinya:

• Follow the H:T (Height to Thickness) nisbah: Keep wall height no more than 5x its thickness (Mis., a 1 mm thick wall should be ≤5 mm tall).
• If thin walls are required (Mis., for a lightweight part), switch to sheet metal manufacturing instead of CNC machining—it’s cheaper and avoids vibration issues.

2. Kesilapan 2: Designing Features That Can’t Be Machined

CAD software lets you draw almost any shape—but CNC machines have physical limits. The most common mistake? Designingcurved holes (holes that bend or twist through the part).

Mengapa masalah itu:

CNC tools move in straight lines (along X/Y/Z axes) or fixed rotations (A/B/C axes). They can’t follow a curved path for holes—trying to do so will either break the tool or leave an uneven, unusable hole.

Contoh sebenar:

A medical device designer added a curved hole to a stainless steel sensor housing (to route wires). The CNC mill couldn’t cut the curve, so the team had to scrap 20 prototaip. They ended up redesigning the hole as two straight holes connected by a small channel—simple for the CNC to machine.

Cara memperbaikinya:

• Avoid curved holes entirely for CNC parts. Use straight holes, or split the path into multiple straight sections.
• If you must have a curved feature (Mis., for a custom pipe), gunakan Pemesinan pelepasan elektrik (EDM) sebaliknya. EDM uses electrical sparks to cut complex shapes—no straight tool paths required.

3. Kesilapan 3: Overusing Tolerances

Toleransi (the allowed variation in part size) are important for mating parts (Mis., a lid that fits a box). But adding tight tolerances to every surface wastes time and money.

Mengapa masalah itu:

• Toleransi yang ketat (Mis., ± 0.001 mm) require slower cutting speeds, special tools, and extra quality checks—all of which increase cost.
• Most CNC machines can’t even hit extremely tight tolerances. Contohnya, a basic 3-axis mill has a maximum accuracy of ±0.01 mm—any tolerance tighter than that is impossible.

Tolerance Guidelines by Machine Type:

Cara memperbaikinya:

• Only add tight tolerances to mating surfaces (Mis., the hole where a bolt fits). Leave non-critical surfaces (Mis., the outer edge of a bracket) with loose or no tolerances.
• Don’t assign numerical dimensions (like radius or diameter) to surfaces that don’t need precision. Contohnya, a decorative notch doesn’t need a tolerance—just a general size.

4. Kesilapan 4: Designing Unnecessary Aesthetic Features

It’s tempting to add complex shapes (Mis., 3D logos, tepi melengkung) to make parts look nice—but these features often require extra machining time and material removal.

Mengapa masalah itu:

• Aesthetic features like deep engravings or custom curves need 5-axis machining (more expensive than 3-axis) or multiple tool changes.
• Removing extra material for looks increases scrap—for example, a 1 kg aluminum block might become a 0.5 kg part with unnecessary cuts, wasting $10–$20 per part.

Contoh sebenar:

A consumer electronics brand added a 3D engraved logo to the back of an aluminum phone case. The logo required 2 extra tool changes and 15 minutes of machining time per case. When they switched toElectropolishing (a post-processing step that smooths the surface) and a simple printed logo, they cut production time by 25% dan disimpan $5 setiap kes.

Cara memperbaikinya:

• Tanya: “Is this feature necessary for function?" Jika tidak, skip it.
• Use post-processing for aesthetics: Electropolishing (smooths surfaces), Anodizing (adds color), or laser engraving (Cepat, cheap logos) are better than machining complex shapes.

5. Kesilapan 5: Designing Too Deep Cavities

Cavities (hollowed-out sections) are useful for lightweight parts—but CNC tools have a limited cutting length. Too-deep cavities cause tool failure or poor quality.

Mengapa masalah itu:

• Milling tools work best when cavities are 2–3x the tool’s diameter. Contohnya, a 15 mm tool can safely cut cavities up to 35 mm dalam (2.3x its diameter).
• Deeper cavities lead to:
  1. Tool deflection: The tool bends under pressure, leaving uneven walls.
  2. Chip buildup: Debris gets stuck in the cavity, scratching the part.
  3. Tool breakage: The tool protrudes too far from its holder and snaps.

Contoh sebenar:

A designer created a 50 mm deep cavity in a plastic part using a 15 mm tool (3.3x the tool’s diameter). The tool deflected, making the cavity walls 2 mm thicker on one side—rendering the part useless. They fixed it by reducing the cavity depth to 35 mm and adding a small ledge (no loss in functionality).

Cara memperbaikinya:

• Follow the tool diameter rule: Keep cavity depth ≤3x the tool’s diameter.
• Untuk rongga yang lebih dalam:
  • Use a longer tool holder (to reach the bottom without bending).
  • Cut in small increments (1–2 mm at a time) to reduce tool stress.
  • Use high-pressure coolant to flush out chips.

6. Kesilapan 6: Designing No Radius for Internal Corners

CNC milling tools are cylindrical—they can’t cut sharp internal corners. Designing sharp edges forces the machine to use smaller tools (lebih perlahan, lebih mahal) or leaves uneven corners.

Mengapa masalah itu:

• A sharp internal corner requires a tool with a tiny diameter (Mis., 1 mm) to fit into the corner. Small tools cut slowly and break easily.
• Even if you design a sharp corner, the CNC will automatically leave a small radius (equal to the tool’s radius)—so your part won’t match the CAD design.

Internal Corner Radius Guidelines:

Cara memperbaikinya:

• Tambah a corner radius to all internal corners in your CAD design. Make the radius slightly larger than the tool’s radius (Mis., a 6 mm tool needs a 3.5 mm corner radius).
• If you need a sharp edge (Mis., for a part that fits into a rectangular slot), design an Bawah (takuk kecil) sebaliknya. Undercuts let the tool reach the corner without leaving a radius.

7. Yigu Technology’s Perspective on CNC Design Mistakes

Di Yigu Technology, we’ve seen every one of these mistakes delay projects or waste money. The biggest takeaway? Design for manufacturability first. Before finalizing a CAD model, Tanya: Can a CNC machine actually cut this? Is this tolerance necessary? Small tweaks—like adding a corner radius or simplifying a curved hole—save time and avoid rework. We often work with designers early on to review plans, catching issues before they become costly problems. By aligning design with CNC capabilities, you’ll get parts that work right the first time.

8. Soalan Lazim: Common CNC Design Questions

Q1: What’s the thinnest wall I can safely design for CNC aluminum parts?

Stick to a minimum of 0.8 mm for aluminum (6061). Thinner walls (0.6 mm or less) will vibrate and break during machining. If you need something thinner, use sheet metal instead.

S2: Can I use EDM for all impossible-to-machine features?

EDM works for complex shapes like curved holes or sharp internal corners, but it’s slower and more expensive than CNC. Use EDM only when CNC is impossible—for most parts, simplifying the design (Mis., straight holes) lebih baik.

Q3: Do I need to add tolerances to every surface of my CNC part?

Tidak! Only add tight tolerances to mating surfaces (Mis., holes for bolts). Non-critical surfaces (Mis., the top of a bracket) can have loose tolerances or no tolerances at all—this cuts machining time and cost.