How to Get an Accurate 板金加工 Quote: RFQ Checklist & 価格設定 Guide

重要ポイント

• 送信 both STEP and a dimensioned flat pattern — 板金 shops need the formed 3D to understand the part and the flat to nest for レーザー切断. Without the flat, they are reverse-engineering your bend table.
• Call out material by gauge and grade, not just “steel” — 1.5 mm cold-rolled steel (DC01) quotes differently than 1.5 mm 304ステンレス, and the difference is not just the metal price — stainless runs slower on the laser and wears tooling faster.
• Specify bend radius and K-factor if you know them — otherwise the shop uses its own press brake tables, and flanges may land short or long relative to your CAD model.
• Quantity determines process — below roughly 1,000 pieces, レーザー切断 + CNC 曲げ加工 is almost always cheaper than スタンピング. Above 5,000, スタンピング tooling amortizes and unit cost drops sharply.
• 溶接 is where tolerance stacks break — a welded assembly with three formed components has a different tolerance envelope than each individual piece, and your RFQ should acknowledge it.
• 仕上げ spec must include thickness, not just color — “powder coat black” is a start; “powder coat RAL 9005, 60–80 µm” is what a fabricator can actually quote against.

板金 quoting has more variables than 出荷前に問題を発見します。 — the same bracket can be laser-cut from cold-rolled steel for $3.50 or stamped from 5052 aluminum for $11.20, and both are “板金ブラケット.” The difference is in the details that most RFQs leave out: the bend radius, the K-factor assumption, the flat pattern, the weld callouts, the finish thickness.

This guide gives you a sheet-metal-specific RFQ checklist that covers the seven pieces of information every fabricator needs to return a quote you can actually compare against the next one. It builds on the design rules in our 板金 design guide — if you have not read that yet, start there for bend radius and hole-spacing rules, then come back here to package your RFQ.

Why 板金 Quotes Vary — Often by 2–3×

The core formula is the same as any fabricated part: Cost = 材料 + (Machine Time × Rate) + 仕上げing + Assembly. But 板金 adds two complications that machined parts do not have:

• Flat pattern development. A shop receives your formed 3D model and must unfold it into a flat blank. The flat size depends on the K-factor — and every shop calibrates K-factor against its own press brakes. Two shops using different K-factors will nest different blank sizes, use different amounts of sheet, and quote different material costs. If you provide the flat pattern, you remove this variable entirely.
• 工程 switching at volume. At 50 pieces, レーザー切断 + CNC 曲げ加工 is the obvious choice. At 5,000 pieces, a progressive スタンピング die — with an upfront cost of $8,000–$25,000 — may cut the per-part cost by 60–80%. Neither shop is wrong; they are quoting different manufacturing strategies. Your RFQ should tell them which strategy to assume.

The 7-Element 板金 RFQ Checklist

1. 3D CAD Model + Flat Pattern (If You Have It)

送信 the formed 3D model as STEP — this is what the fabricator uses to understand the finished part. If you have developed the flat pattern in your CAD package (SolidWorks, Inventor, Fusion 360 板金 environment), 送信 it as a separate DXF or as a flat configuration in the STEP file. Include the K-factor you used. If you do not have a flat pattern, the fabricator will unfold the part using their own bend tables — this is normal, but tell them which K-factor you designed to so they can match it. For a deeper dive into why flat patterns matter, see our bend radius and K-factor guide.

2. 材料: Gauge, Grade & Coating

“鋼” is not a material callout. Write: “1.5 mm cold-rolled steel, DC01/SPCC, uncoated” or “2.0 mm 5052-H32 aluminum sheet.” If the part will be galvanized after fabrication, specify whether it should be hot-dip (thicker zinc, slightly rough surface) or electro-galvanized (thin, smooth, paint-ready). 材料 choice also drives the K-factor and minimum bend radius — our 板金 material selection guide covers the trade-offs for each grade.

3. Bend Radius & Grain Direction

If your CAD model was built with a specific inside bend radius (e.g., 2 mm for a 1.5 mm sheet), call it out on the drawing. If you do not specify, the shop defaults to a radius equal to the 板厚 — which is usually safe but may not match your fit-up. Also note grain direction: 曲げ加工 perpendicular to the rolling grain reduces cracking risk on aluminum and stainless parts. If your drawing しません show grain direction, the fabricator defaults to perpendicular — but confirming it in the RFQ removes an assumption.

最適な用途: Specifying one consistent inside bend radius for the entire part — one tool setup, lower cost.
Avoid: Mixing radii on a single part without a reason — each radius change adds a tooling setup charge.

4. 溶接: 工程, Seam 長さ & Critical Joints

If your part is a welded assembly, specify: 溶接 process (TIG for stainless/aluminum/cosmetic welds; MIG for production steel), which seams are structural vs. cosmetic, and whether you need continuous welds or stitch welds. A drawing that says “weld corners” gets a different quote than one that says “TIG weld all four seams, continuous, grind flush.” For assembly-level parts, note that 公差 stack across weldments — a ±0.5 mm flatness on a single bracket is achievable; on a welded box with four sides, it requires a fixture and a post-weld straightening step. See our 溶接 methods guide for process selection.

5. Surface 仕上げ: Standard, 厚さ & Color

The four most common 板金 finishes, and how to specify them:

• 粉体塗装: “RAL 9005 jet black, 60–80 µm, indoor use” or “RAL 7035 light grey, 80–120 µm, outdoor UV-stable.”
• 亜鉛めっき: “Zinc plate, clear/blue 不動態化処理, 5–8 µm” — note that zinc provides conductivity for grounding but roughly 100 hours of salt-spray resistance vs. ~500 for powder coat.
• 陽極酸化 (aluminum parts): “Type II, Class 2, black, 10–15 µm per MIL-A-8625.”
• Galvanized (pre-coated stock): Specify “DX51D+Z 亜鉛メッキ鋼 sheet” — note that laser-cut edges and weld zones lose their zinc and need touch-up or post-galvanizing.

6. Quantity & Manufacturing Method

This is the decision that swings unit price the most. Always quote at 2–3 quantity tiers — for example, 20 / 200 / 2,000 pieces — because the manufacturing method changes with volume:

最適な用途: Quoting 20 / 100 / 500 (or your real tiers) to see where the unit price inflects.
Avoid: Asking for “best price” at 10 pieces and 10,000 pieces in the same RFQ — different shops, different equipment, different answer.

7. 検査 & Documentation

If you need a 5. 最終検査と文書化, FAIR per AS9102, 材料証明書 traceable to the mill, or weld quality documentation (dye penetrant / X-ray), call it out. These documents require time and calibrated equipment; a shop that charges for them is not overcharging — they are doing the work. Our 品質管理 in metal fabrication guide covers what each report means and when to ask for it.

板金 RFQ Template: Copy, Paste & 送信

1. 设计 status: [production-ready / prototype — minor changes possible]
2. Files attached: STEP file + PDF drawing [+ DXF flat pattern if available]
3. 材料: [gauge + grade + temper + stock finish, e.g. 1.5 mm CRS DC01, uncoated]
4. Bend radius: [inside radius used in CAD, or “use 1× 板厚”]
5. Quantity tiers: [e.g. 20 / 100 / 500 pieces]
6. 溶接: [none / TIG cosmetic / MIG structural / spot — specify seams or “per drawing”]
7. 重要寸法： [standard + color + thickness, e.g. powder coat RAL 9005, 60–80 µm]
8. 検査: [dimensional report / FAIR / material cert — or “standard 溶接手順仕様書（WPS）”]
9. Question for the fabricator: “What is driving cost on this part, and would スタンピング make sense at any of these quantities?”

レッドフラグs When Comparing 板金 Quotes

• A quote returned in under an hour with no questions about bend radius or flat pattern. 板金 has too many variables for a no-questions quote. Either the shop assumed everything — or they did not think about your part at all.
• No mention of grain direction, K-factor, or bend deduction. These are not optional details — they determine whether your flanges land on dimension. A shop that しません ask about them is not building to your model.
• “We don’t need the flat pattern.” A capable shop can unfold your part, but they should at least tell you which K-factor they used. A shop that waves this off is rolling dice on your 公差.
• One quote is 50% below the cluster. Check whether they quoted the right material, whether they included finishing, and whether they assumed レーザー切断 when you may need スタンピング at volume. The cheapest quote is often the one that read the drawing least carefully.

Real-world example: A European equipment builder sent an enclosure drawing for quoting. Five shops returned prices from €18 to €47 per unit at 200 pieces. The spread traced to two assumptions: three shops assumed laser-cut + bent corners with minimal 溶接; two assumed welded seams with post-weld 研削 for a cosmetic finish. The drawing showed a folded-corner design — but the bend relief detail was missing, so two shops read it as a butt joint. One missing callout on a 0.5 mm bend relief created a €29/unit spread across a 200-piece order — €5,800 on a single line item.

送信 a Complete 板金 RFQ, 見積もりを依頼 You Can Compare

板金 quoting is more art than science when the RFQ is incomplete. Fill in the seven blanks above — CAD, material, bend radius, 溶接, finish, quantity, and 検査 — and every fabricator is solving the same problem from the same inputs. The quotes will still differ, but they will differ on equipment, labor rate, and capacity — things you can evaluate — not on guesses about what you meant.

If you are preparing a 板金 RFQ and want a DFM review before it goes out, BravoFabs checks bend radii, hole-to-edge clearance, weld accessibility, and material utilization on every quote — free, before any metal is cut.