In this article, we will explain in detail the various types of screws used in manufacturing sites and the key points for selecting them. Choose the optimal screws according to the application and material to improve work efficiency and safety.

1. Basic Structure and Role of Screws

1-1 Basic Structure of Screws (Head, Shaft, Thread)

Screws are simple yet crucial parts used to securely fasten multiple components. A screw consists of three main elements: the head, shaft, and thread.

• Head: This is the part that is turned with a screwdriver or wrench. There are various shapes such as Phillips (+), slotted (-), hexagon, and star. Additionally, there are countersunk and round head shapes, which are selected depending on the application.
• Shaft: The shaft connects the head and the thread, and its length and strength affect the screw’s overall performance. The thickness and length of the shaft determine the holding force and load-bearing capacity.
• Thread: The thread is a spiral groove engraved along the outer circumference of the shaft. When turned, it bites into the target material, providing holding power. The pitch (spacing) of the thread varies depending on the application. A coarse pitch is suitable for quick tightening, while a fine pitch offers greater holding power.

1-2 Function and Role of Screws

The most basic role of screws is to connect and securely fix multiple components. This function allows the firm connection of parts in all kinds of products, from buildings and machinery to electronics, ensuring stable performance over a long period. Screws, with their simplicity and high reusability, offer unique advantages over methods such as welding or riveting.

Stability of Fastening

The primary role of screws is to stably fasten parts or structures. As the threads bite into the material, they generate strong holding power, able to withstand external pressure and vibrations. Especially with screws, once fastened, objects can be kept safe for a long time. This makes screws indispensable in industries like construction, automotive, and aviation.

Ease of Disassembly and Reassembly

Unlike other fastening methods (such as welding or adhesives), screws can be easily removed with tools, making the disassembly and maintenance of machinery or products simple. If upgrades or parts replacements are needed, components fastened with screws can be easily removed, allowing for smooth repairs and modifications. This characteristic also contributes to cost savings in manufacturing.

Loosening Prevention Techniques

In environments with vibrations or operating machinery, screw loosening can be a problem. Therefore, various loosening prevention techniques have been developed. For example, combining screws with washers or nylon nuts can prevent them from loosening naturally. Furthermore, some screws themselves are designed with anti-loosening structures, often used in high-vibration environments.

Strength Against Pressure and Vibration

Screws are designed to withstand environments where pressure and vibrations occur. For example, in construction machinery, automobiles, and aircraft, intense vibrations and shocks are present, but using properly designed screws ensures reliable fastening of parts. Moreover, to maintain durability even under special conditions, screw materials and surface treatments are carefully chosen. This allows screws to function effectively even in harsh environments.

Adjustable Clamping Force

Another important role of screws is the ability to adjust clamping force. Using a torque wrench allows screws to be tightened with the appropriate force, preventing both overtightening and loosening. In this way, the clamping strength can be freely adjusted as needed, enhancing mechanical safety and performance. In fields requiring high precision, such as precision equipment and aviation, torque management is a crucial factor.

Special Applications of Screws

Screws may also serve special purposes beyond standard fastening. For instance, waterproof screws, heat-resistant screws, and tamper-proof screws for security purposes are designed for specific applications. This versatility makes screws highly effective across various industries and uses.

1-3 Screw Materials and Strength

The material of screws is an essential factor that greatly influences their use environment and application. Screws are made from various materials, each with its own unique properties. Choosing the right material is directly linked to the longevity, safety, and efficient operation of screws.

Iron Screws

Iron screws are the most common and are often used in applications requiring high strength. Iron itself has high strength and excellent load-bearing capacity. It is cost-effective and widely used in many manufacturing industries.

However, iron screws have a drawback: they are prone to rust. Therefore, they cannot be used as-is in outdoor or high-humidity environments. In such cases, iron screws with zinc plating or chromate treatments are used to improve corrosion resistance. Additionally, applying coatings to the screw surface can protect against corrosion and wear, extending the screw’s lifespan.

Stainless Steel Screws

Stainless steel screws offer excellent corrosion resistance and are less likely to rust. They are often used in outdoor or humid environments and in environments where chemicals are used. Stainless steel is an alloy containing chromium and nickel, making it resistant to rust and suitable for places where maintenance is difficult or long-term performance stability is required.

However, stainless steel screws are slightly more expensive and somewhat weaker than iron screws. Therefore, in cases where ultra-high strength is required, other materials may be selected. Still, stainless steel screws are the best choice in environments where corrosion resistance and aesthetics are important.

Alloy Steel Screws

Alloy steel screws are made by adding chromium, nickel, molybdenum, and other metallic elements to iron, resulting in extremely high strength and durability. This type of screw is used in locations where high loads are applied, or mechanical strength is crucial. They are widely used in demanding environments such as automobiles, heavy machinery, and construction equipment, where strength is vital.

Alloy steel screws can be further strengthened through heat treatment and have high resistance to impacts and pressure. This improves reliability in manufacturing environments, ensuring safety.

Aluminum Screws

Aluminum is a very lightweight material and is widely used in industries where weight reduction is critical, such as aerospace and automotive industries. Aluminum screws also have excellent corrosion resistance, providing stable performance over long periods.

However, aluminum is weaker compared to iron or alloy steel, making it unsuitable for locations where high loads are applied. Nonetheless, its lightweight and corrosion-resistant properties make it a very effective choice in scenarios where weight is a limiting factor.

Titanium Screws

Titanium is a material that is both lightweight and strong. It also has excellent corrosion resistance, allowing it to be used in very harsh environments. Titanium screws are often used in specialized fields, such as aircraft, medical equipment, and chemical plants, where both lightweight and high strength are needed.

The greatest advantage of titanium is its superior specific strength (high strength relative to its weight), but its main drawback is the high cost. Therefore, titanium screws are not suited for general applications and are mainly used in advanced technical fields.

Surface Treatment and Coating

In addition to the material, surface treatment and coating are important factors for screws. For example, zinc-plated screws have a zinc layer formed on the surface, making them less likely to rust. Chromate treatments and phosphate coatings are also widely used to enhance corrosion and wear resistance.

For specialized applications, screws may undergo treatments such as fluorine coating, nickel plating, or black oxide treatment. These treatments not only reduce friction but also improve the long-term stability of the screws’ performance.

2. Main Types and Uses of Screws

2-1 Machine Screws (Widely Used from Precision Equipment to Everyday Items)

Machine screws are small screws used in a wide range of applications, from everyday household items to precision and electronic equipment. They are the most common type, available in various materials and sizes. Typical applications include fastening internal parts of home appliances, computers, and cameras. Machine screws come in Phillips, slotted, and hexagonal heads, and can be installed or removed with screwdrivers or wrenches.

When selecting machine screws for manufacturing sites, material and coating selection is crucial. For example, stainless steel, resistant to rust, or high-strength alloy steel is recommended. Additionally, choosing the right size ensures effective prevention of loosening and sufficient strength between parts.

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2-2 Tapping Screws (For Fastening to Wood or Metal Sheets)

Tapping screws are widely used for fastening wood or thin metal sheets without the need for pre-drilled holes. They are commonly used in furniture assembly and fixing metal panels on construction sites.

Tapping screws are mainly made of steel, and some are coated with corrosion-resistant treatments to adapt to outdoor environments. Since drilling is unnecessary, they are handy for tasks requiring rapid assembly or efficient work, especially when combined with power tools in manufacturing.

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2-3 Self-Drilling Screws (Improves Work Efficiency by Eliminating Pre-Drilling)

Self-drilling screws have a drill-shaped tip, allowing them to be screwed directly into metal sheets or hard materials without the need for pre-drilled holes. This eliminates the separate step of drilling, significantly improving work efficiency. They are widely used in construction and manufacturing sites for quick fastening of metal sheets and steel materials.

These screws demonstrate strong fastening power, especially in thick materials. Stainless steel self-drilling screws are also available for use in highly corrosive environments. The advantage for workers is that one screw can handle both drilling and fastening in one step.

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3. Features and Applications of Special Screws

3-1 Tamper-Resistant Screws (Ideal for Security Measures)

Tamper-resistant screws are designed to be removed only with specialized tools and are used in public facilities, vending machines, ATMs, and other devices. These screws prevent theft and unauthorized manipulation, making them widely used in locations where security is a priority.

Tamper-resistant screw designs include types with one-way slotted heads or unique shapes like stars or triangles, making them impossible to remove with regular drivers or tools. Additionally, stainless steel is often used, providing durability against external environments for long-term use.

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3-2 Micro Screws (Used in Precision Devices and Small Electronics)

Micro screws are extremely small screws used in the assembly of precision equipment and small electronic devices. They are designed to precisely fix tiny parts in products like smartphones, cameras, and medical devices, where high precision is required.

Since these screws are very small in diameter, special precision drivers are needed instead of regular tools. Materials with high corrosion resistance and wear resistance are often selected, such as stainless steel and titanium. In manufacturing, handling these screws requires advanced skills and caution, making dedicated workspaces and tools essential.

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3-3 High-Tech Screws (Tap Tight Screws with Excellent Vibration Resistance)

Tap-tight screws have excellent resistance to vibrations and shocks and are designed to prevent natural loosening of the screws. They are particularly suitable for use in environments where frequent vibrations or impacts occur, such as vehicles, aircraft, and industrial machinery.

Unlike regular screws, tap-tight screws feature a unique thread shape that ensures they bite securely into the target material, preventing loosening. Moreover, no additional lock washers or adhesives are needed, improving work efficiency and reducing costs. These screws are also easy to remove, making maintenance more efficient.

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4. Key Points for Selecting Screws

4-1 Choosing the Right Material Based on Application

One of the most important factors in screw selection is choosing the right material. Screws must be selected based on the environment in which they will be used and the required functions. For example, screws used outdoors require corrosion resistance, so stainless steel or zinc-plated steel screws are recommended. Stainless steel screws resist rust and maintain durability over long periods, making them ideal for use in humid or rainy locations.

On the other hand, in situations requiring high strength, alloy steel screws are suitable. Alloy steel has high strength and is used to fasten heavy machinery and high-pressure components. When selecting screws for manufacturing, it is important to choose materials appropriate for the application to ensure long-term durability and reliability.

Additionally, in situations where weight reduction is necessary, aluminum or titanium screws may be used. In industries like aerospace and automotive, lightweight and high-strength materials are preferred, improving the overall performance of the product.

4-2 Selecting the Right Size and Shape

The size and shape of screws must be carefully chosen to match the size of the materials and parts being fastened. If the size is inappropriate, the fastening will be insufficient, leading to loosening or damage to the parts. For example, if the screw is too short, it won’t securely fasten the parts, and they may loosen during operation. Conversely, screws that are too long may penetrate the target object, causing damage to machinery or products.

Additionally, the shape of the screw must be suited to the environment and application. For example, hex bolts are ideal for applications requiring high clamping strength because they can be tightened with significant torque. On the other hand, countersunk screws are valued in applications where aesthetics or safety are important because they do not protrude above the surface.

4-3 Matching Screws with Tools to Improve Work Efficiency

Maximizing work efficiency requires selecting screws that are compatible with the tools being used. Choosing the right tools for the type and shape of the screws improves work speed and reduces the chances of screw breakage or errors. For instance, hex or Torx screws require dedicated hex wrenches or Torx wrenches. These tools enable efficient torque application, ensuring proper tightening.

Furthermore, when using power tools or automatic fastening machines, it’s essential to prepare bits or attachments that match the size and shape of the screws. Choosing the right tools reduces work time, prevents mistakes, and enhances overall productivity.

5. Troubleshooting and Maintenance of Screws

5-1 Loosening Prevention Measures

Screw loosening is a frequent issue in environments where vibrations or external forces are applied. This is particularly a challenge in places like factory machinery or automobiles, where vibrations are constant. Implementing loosening prevention measures is crucial to addressing this issue.

Typical solutions include using spring washers or nylon nuts. Spring washers apply spring-like force between screws, preventing loosening due to vibrations. Nylon nuts, which feature nylon rings inside, bite securely into the threads, reducing loosening.

Additionally, chemical methods like applying thread-locking agents to the screw joints can also be effective. These agents harden when applied to the joints, preventing loosening due to vibrations or impacts. Implementing these measures can prevent screw-related troubles in manufacturing environments.

5-2 Proper Torque Management

Proper torque management is essential for securely tightening screws. Overtightening screws can lead to breakage or damage to components, while insufficient torque can result in loosening or detachment. The basic rule of torque management is to use a torque wrench and tighten screws to the torque values specified by the manufacturer.

Torque wrenches come in various types, including click-type and digital, allowing for precise torque management. In applications like precision equipment or safety-critical areas, strict torque control is required. Regular calibration of torque wrenches is also important to maintain accurate torque management.

5-3 Dealing with Rust and Deterioration

Screws can rust or deteriorate depending on the environment in which they are used. Particularly in locations with moisture or outdoors, rust can weaken the screws, potentially causing parts to break. To prevent rust, material selection and surface treatment of the screws are crucial.

Stainless steel and zinc-plated screws have excellent corrosion resistance, making them ideal for outdoor or high-humidity environments. Regular maintenance, such as checking the condition of the screws and applying anti-rust sprays or grease, can further extend the life of the screws and prevent potential issues.

Conclusion

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