A custom bolt drawing must give the supplier enough information to quote, manufacture, inspect, and pack the part correctly. A simple sketch with “M20 bolt” is not enough for production.
In real sourcing, many custom bolt problems come from missing details. The bolt shape may be clear, but the thread length, tolerance, material, grade, coating, or inspection requirement is not. That creates quotation delays, wrong samples, or failed assembly after delivery.
For drawing-based orders, buyers should treat the drawing as the main technical contract.
Basic Information Every Custom Bolt Drawing Needs
A custom bolt drawing should clearly define the geometry, material, strength, surface finish, and acceptance criteria.
| Zeichnungselement | Was ist anzugeben? | Warum es wichtig ist |
|---|---|---|
| Produktname | Custom bolt, anchor bolt, shoulder bolt, U-bolt, etc. | Defines the part type |
| Standardreferenz | DIN, ISO, ASTM, ANSI, or “made to drawing” | Helps compare with standard fasteners |
| Durchmesser | Nominal and actual critical diameter | Controls fit and strength |
| Gesamtlänge | Gesamtlänge der Schraube | Affects assembly depth |
| Gewindesteigung | Metrisch, UNC, UNF oder Spezialgewinde | Verhindert ein Verrutschen der Muttern |
| Gewindelänge | Vollgewinde oder Teilgewinde | Steuert das Engagement |
| Kopfstil | Hex, square, round, socket, special head | Affects tooling and clearance |
| Material | Carbon steel, alloy steel, stainless steel, etc. | Steuert Festigkeit und Korrosionsbeständigkeit |
| Klasse / Klasse | 8.8, 10.9, 12.9, B7, A2-70 usw. | Definiert die mechanische Leistung |
| Oberflächenbeschaffenheit | verzinkt, HDG, schwarz oxidiert, Dacromet, glatt | Kontrolliert Korrosion und Gewindepassung |
Käufer können vorhandene vergleichen Standardbefestigungen before deciding whether a custom bolt is required.
Critical Dimensions to Mark
Thread and Shank Details
Thread information must be complete. Do not write only “M16” if the thread pitch is important.
Beinhaltet:
- Hauptdurchmesser
- Gewindesteigung
- Gewindelänge
- Schaftlänge
- Chamfer or thread start
- Gewindetoleranz bei Bedarf
- Passender Mutterbedarf
Head and Special Features
For non-standard heads, mark all working dimensions. This includes head height, across flats, socket depth, hole diameter, radius, groove, slot, bend angle, or welded feature.
If the part is not available as a catalog item, kundenspezifische, nicht standardmäßige Verbindungselemente should be quoted with a complete drawing or approved sample.
Material, Grade and Finish Requirements
Material and strength should not be assumed from appearance.
| Anforderung | Beispiel |
|---|---|
| Material | 40Cr, SCM440, 304, 316, carbon steel |
| Festigkeitsklasse | Class 8.8, 10.9, 12.9, ASTM A193 B7 |
| Wärmebehandlung | Quenched and tempered, if required |
| Oberflächenbeschaffenheit | Zinc plated, hot-dip galvanized, Dacromet |
| Test documents | MTC, hardness test, tensile test, inspection report |
Für Anwendungen mit hoher Auslastung siehe hochfeste Verbindungselemente and define mechanical testing before production.
Common Drawing Mistakes
Vermeiden Sie diese Probleme:
- Missing thread pitch.
- No tolerance on critical dimensions.
- Material listed but no strength grade.
- Coating not clearly defined.
- No matching nut or washer information.
- Drawing does not match the physical sample.
- Revision number missing.
- No inspection or certificate requirement.
Für korrosionsempfindliche Anwendungen vergleichen Sie Beschichtete Verbindungselemente bevor Sie das Ziel bestätigen.
Abschließende RFQ-Checkliste
Before sending a custom bolt drawing, confirm:
- Drawing version and unit system
- Size, thread, head, and special features
- Material, grade, heat treatment, and coating
- Quantity and tolerance
- Anwendungsumgebung
- Erforderliche Zertifikate und Prüfberichte
- Packaging and labeling needs
A good custom bolt drawing reduces guessing. It helps the supplier quote faster, produce more accurately, and inspect the final parts against clear requirements.