レーザー切断 設計 Guide: 7 DFM Rules for 板金 Parts

重要ポイント

• 標準 レーザー切断 tolerance is ±0.1 mm for 板金 up to 6 mm thick — fiber lasers can hold ±0.05 mm を専門とし、ドイツ、米国、英国、欧州の産業用クライアントにサービスを提供しています。標準公差範囲は
• Minimum hole 直径 ≥ 材料 厚さ is the cardinal rule. Holes smaller than the sheet 厚さ burn rather than cut cleanly.
• Kerf width ranges from 0.1 to 0.3 mm and must be accounted for in press-fit 組立品. Most CAM software compensates automatically — do not draw kerf offsets into your DXF.
• Keep features at least 1× 材料 厚さ from edges and bends. Holes too close to bend lines will tear or distort during forming.
• Internal corner radii need ≥ 0.5 mm to prevent the laser from dwelling. Sharp corners are impossible — the beam has physical width.
• Thicker 材料 = wider 公差. A 10 mm steel plate cannot hold the same 精密 as a 1.5 mm sheet. 設計 for the process limits of your chosen 厚さ.

Introduction: What Makes a Laser-Ready 設計?

A レーザー切断 machine is fast, precise, and repeatable — but only if the part geometry respects the physics of the process. Unlike CNC milling, where a rotating tool removes 材料 progressively, a laser delivers a focused beam of energy that melts, burns, or vaporizes 材料 in a single pass. That difference creates a unique set of 設計-for-manufacturability (DFM) rules.

German and European procurement engineers sourcing from China often 送信 us DXF files that look perfect on screen but fail at the cutting head — holes too small, tabs too narrow, corners too sharp. This guide covers the seven non-negotiable rules for レーザー切断 DFM, with tolerance data sourced from ISO 9013 and real production feedback from our fiber laser floor in Dongguan.

Rule 1: Hole Sizing — The 1:1 Rule

The single most common DFM mistake in laser-cut parts: holes smaller than the 材料 厚さ. When the beam pierces a hole whose 直径 is less than the sheet 厚さ, the laser dwells too long in a confined space. Instead of a clean cut, you get a burned, tapered, out-of-round hole.

Best practice: hole 直径 ≥ 材料 厚さ (1:1 ratio). A 3 mm mild steel sheet needs holes at least 3 mm in 直径. Bare minimum: hole 直径 ≥ ½ 材料 厚さ — but expect quality degradation and consider a secondary drilling or punching operation for anything below the 1:1 threshold.

For 精密 組立品, also account for kerf: a drawn 10 mm hole will come out approximately 10.1–10.2 mm after cutting because the beam removes 材料 on both sides of the programmed path. This is normally within tolerance for clearance fits — but for press-fit or locating features, flag the hole as “critical” on your drawing so the CAM programmer applies kerf compensation.

最適な用途： clearance holes, bolt holes, lightening holes ≥ 材料 厚さ.
避けるべき場合： you need threaded holes or dowel-pin 精密 — use secondary 出荷前に問題を発見します。 after レーザー切断.

Rule 2: Kerf — The Invisible Cut Width

Kerf is the width of 材料 physically removed by the laser beam — typically 0.15 mm on thin sheet to 0.30 mm on thick plate. It varies with laser power, 材料 type, cutting speed, and assist gas. For 90% of parts, you can ignore it: modern CAM software reads your DXF at nominal dimensions and automatically offsets the toolpath by half the kerf width.

But kerf becomes critical in two scenarios:

1. Press-fit tab-and-slot 組立品. If you are 設計ing laser-cut parts that nest together without fasteners, you must account for kerf in the DXF. Rule of thumb: draw tabs 0.1 mm wider and slots 0.1 mm narrower than the target fit. This yields approximately 0.05 mm interference per side — enough for a firm press fit without deformation. Always prototype a test piece — exact kerf varies by machine and 材料 batch.
2. Multi-part nesting. When an inner part must drop into an outer cutout (e.g., an inlay or insert), add half the kerf to the inner piece and subtract half from the outer opening. Otherwise the gap will be too loose.

最適な用途： 標準 clearance-fit 組立品 where CAM auto-compensation is sufficient.
避けるべき場合： 設計ing press-fit joints without a prototype run — kerf varies and one test piece is cheaper than a scrapped batch.

Rule 3: Edge and Bend Clearances

Laser-cut features that are too close to edges or bend lines will cause problems downstream — during 曲げ加工, forming, or even just handling. The heat-affected zone (HAZ) around the cut edge can harden the 材料 locally, making it brittle near bends.

Follow these minimum distances for reliable 繰り返し注文の一貫性が保たれます。:

When a hole sits inside a bend zone, it will tear or ovalize during forming. If you must place a hole near a bend, add bend relief notches at the bend line ends to absorb the stress — these should be at least 0.5 × 材料 厚さ wide.

最適な用途： all bent parts — these clearances are geometry-driven, not machine-dependent.
避けるべき場合： 設計ing flat-only (no-bend) parts — edge clearances drop to 1× 材料 厚さ.

Rule 4: Corner Radii — No Sharp Inside Corners

A laser beam has physical width (the spot size) — typically 0.1–0.2 mm for a fiber laser. An inside corner drawn as a perfect 90° sharp corner in CAD is physically impossible to cut. The beam will dwell at the corner, burning a radius whether you want one or not.

設計 rule: specify inside corner radii of at least 0.5 mm. This prevents the laser from dwelling and produces a clean, predictable corner. For structural parts subject to fatigue loading, larger radii (≥ 材料 厚さ) also reduce stress concentration — a free 機械的 benefit.

For tight-fit 組立品 where a square corner is functionally required (e.g., a rectangular tab fitting into a pocket), add “mouse ear” corner reliefs — small drilled holes at the inside corner positions. These are added as a secondary drilling step after レーザー切断 and give a true 90° corner for assembly.

Rule 5: 材料 厚さ Drives 公差

Every レーザー切断 tolerance chart in this guide comes with a 厚さ caveat — and for good reason. As 材料 gets thicker, the laser beam must deliver more energy, the kerf widens, heat input increases, and the cut edge develops taper (wider at the top than the bottom).

用途 On your drawing, reference ISO 2768-mK for 一般公差 and ISO 9013 for thermal cut-specific 公差. ISO 9013 is purpose-built for laser, plasma, and oxy-fuel cutting — it correlates tolerance classes directly with 材料 厚さ, so you don’t need to guess how tight you can go on a 12 mm plate.

最適な用途： specifying 公差 that the process can actually hold — use ISO 9013 as your reference 標準.
避けるべき場合： you need ±0.02 mm across a 15 mm plate — that job belongs on a CNC mill, not a laser.

Rule 6: Notches and Tabs — Keep Them Sturdy

Notches and tabs are the workhorses of 板金 設計 — they locate parts during 溶接, create interlocking joints, and reduce hardware count. But they are also the features most likely to fail during handling if 設計ed too thin.

• Notch width: ≥ 1.5 × 材料 厚さ. A 2 mm sheet needs notches at least 3 mm wide.
• Notch length: up to 5 × 材料 厚さ. Longer is fine — the width constraint is the critical one.
• Tab width: ≥ 材料 厚さ or 1 mm (whichever is greater). Thin tabs bend during handling and throw off weld alignment.
• Notch corner radius: ≥ 0.5 × 材料 厚さ. Sharp notch corners are stress risers and crack initiation points.

When 設計ing interlocking tab-and-slot 組立品, remember the kerf rule from above: the tab will come out slightly undersized and the slot slightly oversized if you draw both at nominal. A 0.1 mm offset in your DXF (wider tab, narrower slot) is the difference between a snug assembly and a rattling one.

Rule 7: File Format — DXF, STEP, and What to 送信

The DXF file format (Drawing Exchange Format) is the universal language of 2D レーザー切断. Your DXF should contain only the cut プロファイル in 1:1 scale, with all geometry on a single layer. Do not include title blocks, dimensions, bend lines, or assembly annotations in the cut layer — these will be interpreted as cut paths and scrap your part.

If your part has bends after レーザー切断, 送信 two files: a flat-pattern DXF for the laser programmer and a STEP or dimensioned PDF showing the formed geometry with bend angles, radii, and critical 公差. The STEP file tells the brake press operator what the finished part should look like; the DXF tells the laser what to cut.

File checklist for a complete RFQ package:

• ✅ Flat-pattern DXF (1:1, single layer, no dimensions, no title block)
• ✅ STEP or 3D model of finished part (for quoting and forming reference)
• ✅ Dimensioned PDF showing formed view with critical 公差 called out
• ✅ 材料 specification: grade (e.g., S235JR, 1.4301, EN AW-5754), 厚さ, surface finish
• ✅ Quantity and any special packaging or marking requirements

Putting It All Together: A DFM Checklist for レーザー切断

Before you 送信 your next DXF to a レーザー切断 service, run through this seven-point checklist. Five minutes of DFM review saves days of rework and scrapped 材料.

1. Hole check: Every hole 直径 ≥ 材料 厚さ? Flagged any holes that need secondary drilling?
2. Kerf check: For press-fit 組立品, tab and slot dimensions include kerf offset? Prototype tested?
3. Clearance check: All holes, slots, and notches meet minimum distance to edges and bend lines per the table in Rule 3?
4. Corner check: Inside radii ≥ 0.5 mm? Sharp corners replaced with mouse-ear reliefs where functionally required?
5. Tolerance check: Specified 公差 appropriate for 材料 厚さ? ISO 9013 or ISO 2768-mK referenced on drawing?
6. Notch/tab check: Notch width ≥ 1.5× 厚さ? Tab width ≥ 1 mm or 材料 厚さ?
7. File check: DXF = 1:1 flat pattern, single clean layer, no dimensions in cut path? STEP and dimensioned PDF included?

実際の事例： A German industrial equipment manufacturer sent us a 5 mm S235JR bracket DXF with 2 mm holes — less than half the 材料 厚さ. The laser burned through but the holes were 0.4 mm out of round and tapered 0.15 mm from entry to exit. We caught it at first-article 検査, re-drilled the holes on a CNC mill, and the customer now uses our DFM checklist before every release. One pre-production review saved a 500-piece batch from scrap.

まとめ

レーザー切断 DFM is not a long list of arbitrary constraints — it is the physics of a focused beam meeting metal, expressed as 設計 rules. Respect the 1:1 hole-to-厚さ ratio, keep features clear of bend zones, specify achievable 公差 for your 材料 厚さ, and 送信 clean DXF files with a STEP reference. These seven rules cover the vast majority of レーザー切断 quality issues we see on incoming drawings. For parts that push any of these limits — ultra-thin sheets, press-fit 組立品, or thick plates near the process ceiling — a 5-minute engineering review before production is always cheaper than a rejected batch.