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Commonly Used Screw Sizes in Manufacturing: Quick Reference Chart by Standard
Introduction
In manufacturing sites, screws are truly unsung heroes. While they may not be prominent, they are indispensable and crucial components for assembling machinery and products. Without screws, everything around us, such as cars, home appliances, and furniture, would fall apart.
The role of screws is not merely to fix parts. By selecting the appropriate screw and tightening it correctly, the safety and durability of the product can be ensured. Conversely, using an inappropriate screw or insufficient tightening can lead to product failure or accidents.
The basics of screw selection involve considering three elements: size, standard, and material.
- Size: Choose according to the thickness of the part to be attached and the size of the screw hole.
- Standard: Choose according to the place of use and parts, such as metric threads or inch threads.
- Material: Choose according to the operating environment and required strength, such as iron, stainless steel, or titanium.
It can be said that comprehensively judging these elements and selecting the optimal screw is the first step in quality control at manufacturing sites.
This article comprehensively provides necessary information about screws commonly used in manufacturing sites, focusing on a quick reference table by standard, including their types, applications, tightening torque, materials, and strength. We hope this deepens your knowledge of screws and helps you in your daily work.
1. Screw Sizes and Standards
Screw sizes and standards vary widely depending on the place of use and application. Here, we introduce representative screw standards commonly used in manufacturing sites in a quick reference table format.
Metric Threads (M threads)
Metric threads are screws measured in millimeters and are widely used in Japan and Europe. They are based on JIS B 0205 standard.
Quick Reference Table: Typical M-Thread Sizes
| Nominal Diameter (M) | Pitch (mm) | Typical Tool Size (mm) |
|---|---|---|
| M3 | 0.5 | 5.5 |
| M4 | 0.7 | 7.0 |
| M5 | 0.8 | 8.0 |
| M6 | 1.0 | 10.0 |
| M8 | 1.25 | 13.0 |
| M10 | 1.5 | 17.0 |
| M12 | 1.75 | 19.0 |
Inch Threads
Inch threads are screws measured in inches and are mainly used in the United States and the United Kingdom. Standards include Unified Thread (UNC/UNF) and Whitworth Thread (BSW).
Quick Reference Table: Typical Inch Thread Sizes
| Nominal Diameter (inch) | Pitch (threads/inch) |
|---|---|
| 1/4 | 20 (UNC) |
| 1/4 | 28 (UNF) |
| 3/8 | 16 (UNC) |
| 3/8 | 24 (UNF) |
| 1/2 | 13 (UNC) |
| 1/2 | 20 (UNF) |
Pipe Threads
Pipe threads are used to seal pipes and fluids. There are two types: tapered threads (R/PT) and parallel threads (G/PF).
Quick Reference Table: Typical Pipe Thread Sizes
| Nominal Diameter | Pitch (mm) |
|---|---|
| R1/8 | 0.907 |
| R1/4 | 1.337 |
| R3/8 | 1.337 |
| R1/2 | 1.814 |
Other Screw Standards
In addition to the above, there are various screw standards for different applications. Please refer to specialized documents as needed.
2. Screw Types and Applications
Screws come in various types depending on their shape and application. Here, we introduce common screw types and special-purpose screws frequently used in manufacturing sites.
Common Screw Types
| Screw Type | Application | Features |
|---|---|---|
| Wood Screw | Joining, fixing wood | Threaded shaft, pointed tip. Tightens by screwing into wood. |
| Tapping Screw | Forms threads while fastening into metal or resin | No pilot hole required. Enables efficient fastening. |
| Bolt | Used in combination with a nut | Allows strong fastening. Used for fixing machine parts, etc. |
| Machine Screw | Used for assembling machine parts and electronic devices | Small head, various shapes. |
Special Purpose Screws
| Screw Type | Application | Features |
|---|---|---|
| Drill Screw | Used for fastening metal sheets, etc. | Drill-shaped tip, no pilot hole required. |
| Coarse Thread Screw | Used for rough assembly of wood, fixing plasterboard, etc. | Coarse pitch, bites well into wood. |
| Others | Special screws for various applications | Please refer to specialized documents as needed. |
3. Screw Tightening Torque
Screw tightening torque is extremely important for preventing screws from loosening or breaking and ensuring product safety. By tightening with the appropriate torque, the screw’s original performance can be maximized.
Importance of Tightening Torque
- If the tightening torque is insufficient, the screw may loosen and the part may detach.
- If the tightening torque is excessive, the screw or part may be damaged.
Basic Formula for Torque Calculation
Tightening torque is calculated by the following formula:
Torque (T) = Torque Coefficient (K) × Screw Diameter (d) × Axial Force (F)
- Torque Coefficient (K): A value determined by the screw’s material and surface treatment.
- Screw Diameter (d): The nominal diameter of the screw.
- Axial Force (F): The force applied to tighten the screw.
Quick Reference Table: Recommended Torque Values for Typical Screw Sizes
| Screw Size | Recommended Torque Value (N・m) |
|---|---|
| M3 | 1.0～1.5 |
| M4 | 2.5～3.5 |
| M5 | 5.0～6.0 |
| M6 | 8.0～10.0 |
| M8 | 20.0～25.0 |
| M10 | 40.0～50.0 |
※The above are merely guidelines. Actual torque values vary depending on the screw’s material and condition, operating environment, etc.
Notes on Torque Management
- Use a torque wrench and tighten with the appropriate torque.
- Calibrate torque wrenches regularly to maintain accuracy.
- Select the appropriate torque value according to the screw’s material and condition, and the operating environment.
- After tightening, periodically check the torque to ensure there is no loosening.
4. Screw Materials and Strengths
The material and strength of screws must be selected appropriately according to the operating environment and load conditions.
Typical Screw Materials
| Material | Characteristics | Applications |
|---|---|---|
| Iron Screws | Common and inexpensive. High strength but prone to rust. | General machine products, building materials, etc. |
| Stainless Steel Screws | Excellent corrosion resistance. Rust-resistant, strong in high and low temperatures. | Products used outdoors, food machinery, medical equipment, etc. |
| Titanium Screws | Lightweight and high strength. Excellent corrosion and heat resistance. | Aerospace equipment, medical equipment, sports equipment, etc. |
Screw Strength Classes
Screw strength classes are defined by JIS standards. The strength class is indicated by numbers engraved on the screw head.
Strength Classes Based on JIS Standard
| Strength Class | Tensile Strength (N/mm²) | Yield Point or Proof Stress (N/mm²) |
|---|---|---|
| 4.8 | 400 | 320 |
| 8.8 | 800 | 640 |
| 10.9 | 1000 | 900 |
| 12.9 | 1200 | 1080 |
The higher the strength class, the greater the load it can withstand. When selecting screws, choose the appropriate strength class according to the usage conditions.
Summary
Screw selection in manufacturing sites is a crucial factor that affects product quality, safety, and durability. By selecting the appropriate screw and using it correctly, you can maximize product performance and minimize the risk of accidents and failures.
Finally
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