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Informacje o firmie How to Select the Right Carriage Bolts

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How to Select the Right Carriage Bolts

2026-01-14
Selecting the appropriate carriage bolts requires a comprehensive consideration of application scenarios, base materials, environmental conditions, and regional standards. A well-matched selection ensures fastening reliability, service life, and cost-effectiveness. Below is a detailed, step-by-step guide to choosing carriage bolts:

1. Determine the Application Scenario and Base Material


The core design of carriage bolts (round head + square neck) makes them ideal for soft or semi-rigid materials. Clarify the following key factors first:

  • For wooden structures (decks, pergolas, log cabins, garden furniture): Prioritize bolts with a square neck size that matches the pre-drilled square holes of the wood. The square neck should fit tightly into the wood to prevent rotation during nut tightening, avoiding damage to the wood fiber.
  • For light steel or metal components (roof trusses, guardrails, machinery brackets): Choose bolts with high dimensional precision to ensure the square neck can be embedded into the pre-punched slots of metal plates, ensuring stable load-bearing without slipping.
  • For outdoor or public facilities (park benches, playground equipment): Focus on corrosion-resistant performance and safety— the smooth round head prevents accidental scratches, making it suitable for high-traffic areas.

2. Choose the Right Material and Surface Treatment


Material selection is directly linked to the service life of carriage bolts, especially in corrosive environments.

  • Carbon steel
    • Application scope: Dry indoor environments or mild outdoor environments with low humidity.
    • Surface treatment options:
      • Electro-galvanizing: Basic corrosion resistance, cost-effective, suitable for short-term indoor use.
      • Hot-dip galvanizing: Thick zinc coating provides excellent anti-rust performance, ideal for outdoor construction, agricultural machinery, and municipal infrastructure.

    • Performance grades: Common grades include 4.8 and 8.8. Grade 8.8 is recommended for heavy-load applications.

  • Stainless steel
    • A2 stainless steel (equivalent to 304): Good corrosion resistance, suitable for humid indoor environments, coastal areas with low salt content, and food processing equipment.
    • A4 stainless steel (equivalent to 316): Added molybdenum element enhances resistance to pitting and seawater corrosion, ideal for marine engineering, coastal construction, and chemical equipment.
    • Performance grades: A2-50, A2-70, A4-50, A4-70. The numerical suffix represents tensile strength; higher numbers indicate stronger load-bearing capacity.


3. Match Regional Standards and Thread Specifications


Carriage bolts comply with different international standards based on target markets, which directly affect thread size, head dimensions, and compatibility.

  • Global/export markets: Select bolts manufactured to ISO 8677:2016 (metric threads M5–M20). This standard is widely recognized and compatible with most international projects.
  • North American market: Follow ANSI/ASME B18.5 standards, which specify inch threads (1/4"–1"). Pay attention to the rounded head contour and square neck size required by this standard to match local assembly tools and workpieces.
  • European market: Choose bolts that meet DIN 603 standards (metric threads M5–M24). This standard has strict requirements for dimensional tolerance and surface smoothness, suitable for high-precision machinery and construction projects.
  • Chinese domestic market: Comply with GB/T 12-1985 standards, which are aligned with ISO specifications and ensure seamless integration into domestic supply chains.

4. Confirm Additional Key Parameters


  • Shank length: Measure the total thickness of the fastened workpieces and add an allowance (usually 1–2 cm) to ensure the nut can be fully tightened and locked.
  • Head size: Ensure the round head diameter is compatible with the installation space—avoid oversized heads that cannot fit into narrow gaps or affect the appearance of finished products.
  • Non-standard customization: For special scenarios (e.g., ultra-long shanks, customized square neck sizes), communicate with manufacturers to confirm mold availability and production lead times.
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Szczegóły wiadomości
Do domu > Aktualności >

Informacje o firmie-How to Select the Right Carriage Bolts

How to Select the Right Carriage Bolts

2026-01-14
Selecting the appropriate carriage bolts requires a comprehensive consideration of application scenarios, base materials, environmental conditions, and regional standards. A well-matched selection ensures fastening reliability, service life, and cost-effectiveness. Below is a detailed, step-by-step guide to choosing carriage bolts:

1. Determine the Application Scenario and Base Material


The core design of carriage bolts (round head + square neck) makes them ideal for soft or semi-rigid materials. Clarify the following key factors first:

  • For wooden structures (decks, pergolas, log cabins, garden furniture): Prioritize bolts with a square neck size that matches the pre-drilled square holes of the wood. The square neck should fit tightly into the wood to prevent rotation during nut tightening, avoiding damage to the wood fiber.
  • For light steel or metal components (roof trusses, guardrails, machinery brackets): Choose bolts with high dimensional precision to ensure the square neck can be embedded into the pre-punched slots of metal plates, ensuring stable load-bearing without slipping.
  • For outdoor or public facilities (park benches, playground equipment): Focus on corrosion-resistant performance and safety— the smooth round head prevents accidental scratches, making it suitable for high-traffic areas.

2. Choose the Right Material and Surface Treatment


Material selection is directly linked to the service life of carriage bolts, especially in corrosive environments.

  • Carbon steel
    • Application scope: Dry indoor environments or mild outdoor environments with low humidity.
    • Surface treatment options:
      • Electro-galvanizing: Basic corrosion resistance, cost-effective, suitable for short-term indoor use.
      • Hot-dip galvanizing: Thick zinc coating provides excellent anti-rust performance, ideal for outdoor construction, agricultural machinery, and municipal infrastructure.

    • Performance grades: Common grades include 4.8 and 8.8. Grade 8.8 is recommended for heavy-load applications.

  • Stainless steel
    • A2 stainless steel (equivalent to 304): Good corrosion resistance, suitable for humid indoor environments, coastal areas with low salt content, and food processing equipment.
    • A4 stainless steel (equivalent to 316): Added molybdenum element enhances resistance to pitting and seawater corrosion, ideal for marine engineering, coastal construction, and chemical equipment.
    • Performance grades: A2-50, A2-70, A4-50, A4-70. The numerical suffix represents tensile strength; higher numbers indicate stronger load-bearing capacity.


3. Match Regional Standards and Thread Specifications


Carriage bolts comply with different international standards based on target markets, which directly affect thread size, head dimensions, and compatibility.

  • Global/export markets: Select bolts manufactured to ISO 8677:2016 (metric threads M5–M20). This standard is widely recognized and compatible with most international projects.
  • North American market: Follow ANSI/ASME B18.5 standards, which specify inch threads (1/4"–1"). Pay attention to the rounded head contour and square neck size required by this standard to match local assembly tools and workpieces.
  • European market: Choose bolts that meet DIN 603 standards (metric threads M5–M24). This standard has strict requirements for dimensional tolerance and surface smoothness, suitable for high-precision machinery and construction projects.
  • Chinese domestic market: Comply with GB/T 12-1985 standards, which are aligned with ISO specifications and ensure seamless integration into domestic supply chains.

4. Confirm Additional Key Parameters


  • Shank length: Measure the total thickness of the fastened workpieces and add an allowance (usually 1–2 cm) to ensure the nut can be fully tightened and locked.
  • Head size: Ensure the round head diameter is compatible with the installation space—avoid oversized heads that cannot fit into narrow gaps or affect the appearance of finished products.
  • Non-standard customization: For special scenarios (e.g., ultra-long shanks, customized square neck sizes), communicate with manufacturers to confirm mold availability and production lead times.