Loctite 638 vs. 680: High Strength Compare
Loctite 638 Overview
Features of Loctite 638
Loctite 638 is a high-performance retaining compound designed for bonding cylindrical fitting parts with narrow bond gaps. Key features of Loctite 638 include:
- High Temperature Performance: Exceptional performance in high-temperature conditions.
- Good Oil Tolerance: Tolerates minor surface contaminants, making it suitable for various industrial applications.
- Quick Fixture Time: Requires only four minutes to set, providing fast and reliable bonding (Henkel Adhesives).
- Gap Fill Capability: Can fill gaps ranging from 0.15 mm to 0.25 mm.
- Corrosion Resistance: Offers excellent protection against rust and corrosion, ensuring long-lasting connections.
- Versatility with Metals: Works on both active and passive metals, making it a versatile choice for a variety of applications.
Applications of Loctite 638
Loctite 638 is used in several industrial settings, particularly where high strength and reliability are required. Common applications include:
| Application | Description |
|---|---|
| Shafts | Bonds shafts to prevent loosening and leakage due to shock and vibration. |
| Gears | Ideal for gear assemblies requiring durable and secure fittings. |
| Pulleys | Effective in bonding pulleys to avoid slippage and ensure operational efficiency. |
| Cylindrical Parts | Suitable for a range of cylindrical components, especially those with narrow bond gaps approaching 0.25 mm. |
In slip fit assemblies, Loctite 638 should be applied to only one of the parts and then assembled with a twisting or turning motion to ensure optimal bonding (Loctite FAQs).
Overall, Loctite 638’s combination of temperature resistance, quick setting time, and robust bonding capabilities make it an ideal adhesive for high-load environments and precision applications. For a comparison with other adhesives, check out our articles on loctite 565 vs. 567 and loctite 609 vs. 680.
Performance of Loctite 638
Understanding the performance characteristics of Loctite 638 is essential for selecting the right adhesive for your applications. When comparing Loctite 638 vs. 680, it’s crucial to consider their temperature range, fixture time, and tolerance to contaminants.
Temperature Range
Loctite 638 is designed to operate effectively within an extensive temperature range, making it suitable for a variety of high-performance applications. It can endure temperatures ranging from -55°C to 180°C (-65°F to 355°F) (Henkel Adhesives). This versatility allows it to perform well in both low and high-temperature environments, providing reliable bonding in different conditions.
| Property | Unit | Value |
|---|---|---|
| Operating Temperature | °C | -55 to 180 |
| Operating Temperature | °F | -65 to 355 |
Fixture Time
Fixture time refers to the period required for the adhesive to achieve initial handling strength, defined as 0.1 N/mm². Loctite 638 offers a quick fixture time of just five minutes for handling strength to be achieved, enabling efficient assembly processes. This rapid curing property makes it ideal for precision applications requiring swift turnaround times.
| Property | Unit | Value |
|---|---|---|
| Fixture Time | minutes | 5 |
Tolerance to Contaminants
Another standout feature of Loctite 638 is its excellent tolerance to minor surface contaminants such as industrial oils. This characteristic is vital for applications involving cylindrical parts like shafts, gears, and pulleys. Loctite 638 can fill gaps up to 0.25 mm (0.010 inches) effectively, ensuring solid and reliable bonding even in less-than-ideal conditions. By tolerating minor surface impurities, Loctite 638 provides robust performance without necessitating perfect surface preparation.
| Property | Unit | Value |
|---|---|---|
| Gap Fill | mm | 0.25 |
| Gap Fill | inches | 0.010 |
For more insights on different adhesives and their applications, you can explore comparative articles such as liquid nails vs. e6000, flex paste vs. flex seal, and contact cement vs wood glue. The versatility and robust performance characteristics of Loctite 638 make it a suitable choice for various assembly needs, providing reliable bonding in diverse environmental conditions.
Comparing Loctite 638 and 680
Choosing the right retaining compound can be essential for ensuring the durability and strength of mechanical assemblies. This section compares Loctite 638 and Loctite 680, focusing on strength, viscosity differences, and ideal applications.
Strength and Viscosity Differences
Understanding the differences in strength and viscosity between Loctite 638 and 680 can help in selecting the appropriate product for your needs.
| Property | Loctite 638 | Loctite 680 |
|---|---|---|
| Fixture Time | 5 minutes | 10 minutes |
| Gap Fill | Up to 0.010 inches (0.25 mm) | Up to 0.015 inches (0.38 mm) |
| Temperature Range | -65°F to 450°F (-55°C to 232°C) | -65°F to 300°F (-55°C to 150°C) |
| Tolerance to Contaminants | High | High |
Loctite 638 demonstrates superior high-temperature performance and is suitable for applications requiring narrow bond gaps up to 0.010 inches (Loctite 638). Its fixture time of approximately 5 minutes ensures rapid handling strength, making it ideal for precision applications.
In contrast, Loctite 680 offers the ability to fill larger gaps up to 0.015 inches. This makes it more versatile for various conditions. Its primary strength lies in its primerless, anaerobic cure feature, which ensures reliable bonding even in slightly contaminated environments.
Ideal Applications for Each
The choice between Loctite 638 and 680 depends on the specific application requirements, including gap size, load stress, and environmental conditions.
Loctite 638:
- Ideal for precision applications where narrow bond gaps are present.
- Suitable for shafts, gears, and pulleys.
- High-temperature performance makes it appropriate for systems exposed to varied thermal conditions.
- Quick fixture time of 5 minutes ensures faster handling and assembly.
Loctite 680:
- Suitable for applications requiring a larger gap fill.
- Versatile for use under room temperature curing.
- Performs well in slightly contaminated environments.
- Best for situations where primerless, anaerobic cure is beneficial.
For detailed information about Loctite 638 vs. 680 and their benefits, you can explore specific application requirements. Understanding the unique strengths of each product ensures optimal performance and durability in your mechanical assemblies. By comparing factors such as temperature range, gap fill, and fit tolerance, users can make informed decisions for the best outcomes.
Also, consider exploring other comparisons such as loctite 603 vs. 609 and loctite 620 vs. 680 to further understand their specific applications and strengths.
Choosing Between Loctite 638 and 680
Choosing the right Loctite product for your project involves understanding the specific factors that differentiate Loctite 638 and 680. Both have unique properties that make them suitable for various applications. Here’s a detailed comparison to help you decide.
Factors to Consider
When selecting between Loctite 638 and 680, several factors should be taken into account:
-
Gap Size:
Loctite 638 is ideal for precision applications with narrow bond gaps up to 0.010 inches. Loctite 680 accommodates larger gaps up to 0.015 inches, making it more versatile (Stickyn). -
Fixture Time:
Loctite 638 offers quick fixture times of about 5 minutes. Loctite 680 cures at room temperature but may take longer to fixture depending on the conditions (Stickyn). -
Load Stress:
Consider the load stress the application will face. Loctite products are designed to ensure optimal performance and durability in mechanical assemblies. -
Environmental Conditions:
Evaluate the environmental conditions where the bond will be used. Each product has unique benefits that perform well in diverse environments.
Specific Application Requirements
Depending on the specific needs of your project, one product may be more suitable than the other.
| Attribute | Loctite 638 | Loctite 680 |
|---|---|---|
| Precision | High (up to 0.010 inches) | Moderate (up to 0.015 inches) |
| Fixture Time | Quick (5 minutes) | Slower, room temperature cure |
| Load Bearing | High | High |
| Versatility | Less versatile, specific fits | More versatile, larger gap sizes |
| Environmental Tolerance | Broad | Broad |
Figures courtesy (Stickyn)
Use Cases
-
Loctite 638:
-
Ideal for precise, high-strength bonding in narrow gaps.
-
Suitable for applications requiring rapid fixture times.
-
Loctite 680:
-
Best for applications with larger gaps and a need for flexibility in machining tolerances.
-
Suitable for high-strength bonding in versatile conditions.
Choosing between Loctite 638 and 680 also depends on specific application requirements. For more comprehensive comparisons, you can read about related adhesives such as loctite 620 vs. 680 and loctite 609 vs. 680.
Benefits of Loctite Retaining Compounds
Reliability and Strength
LOCTITE retaining compounds are renowned for their reliability and strength. By filling the entire gap between parts, these compounds provide 100% contact, unlike interference fits that only offer 20%-40% actual metal-to-metal contact. This comprehensive contact ensures a stronger, more secure fit for cylindrical parts.
Additionally, LOCTITE retaining compounds are effective in filling gaps left by pins, keyway assemblies, splines, and set screws, providing a dependable and cost-effective method to secure cylindrical parts. This feature is particularly beneficial in reducing the need for extensive machining and rework.
The strength of LOCTITE retaining compounds stems from their ability to create a durable thermoset plastic bond between parts. This bond enhances the reliability of assemblies, minimizes fretting corrosion, and eliminates the need for expensive machining processes (Henkel Adhesives).
Corrosion Resistance
Corrosion resistance is a significant advantage of LOCTITE retaining compounds. Specifically, Loctite 638 is designed to create a durable barrier on both active and passive metals, significantly reducing the likelihood of rust and corrosion over time (Stickyn). This barrier ensures long-lasting, robust connections that maintain their integrity even in challenging environments.
For more information on different types of adhesives and their comparisons, check out our articles on construction adhesive vs. epoxy and liquid nails vs. e6000.
| Feature | Loctite 638 | Loctite 680 |
|---|---|---|
| Contact Level | 100% gap filling | 100% gap filling |
| Corrosion Resistance | High, suitable for various metals | High, similar properties |
| Application Benefits | Cost-effective, reduces machining | Cost-effective, diminishes rework |
For usage tips and optimal fit guidelines, explore our section on usage tips for Loctite 638 and individual comparison articles like loctite 609 vs. 680.
Usage Tips for Loctite 638
When working with high-strength retaining compounds like Loctite 638, following the optimal fit guidelines and proper assembly techniques can ensure the best results. This section outlines key recommendations for using Loctite 638 effectively.
Optimal Fit Guidelines
To achieve optimal performance with Loctite 638, it is important to consider the fit of the parts being assembled. For thicker products with high viscosity like Loctite 638, the ideal fit ranges between 0.05 mm to 0.1 mm. This ensures that the adhesive can penetrate into the gaps and provide a secure hold.
For slip fit assemblies, apply Loctite 638 to only one of the parts and align the parts before fastening them together with a twisting or turning motion. This method guarantees that the adhesive is evenly distributed, enhancing the bond strength and sealing capabilities.
| Product | Ideal Fit (mm) |
|---|---|
| Loctite 638 | 0.05 – 0.1 |
Assembly Techniques
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Surface Preparation: Clean the surfaces to be bonded to remove any contaminants such as grease, oil, or dirt. A clean surface is crucial for the adhesive to bond effectively.
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Apply Adhesive: Dispense Loctite 638 onto one of the mating surfaces. For slip fit assemblies, ensure the adhesive is applied uniformly.
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Join Parts: Align the parts and fit them together, using a twisting or turning motion to distribute the adhesive evenly. This motion helps to achieve maximum coverage and ensures a strong bond.
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Curing Time: Allow the adhesive to cure for the recommended fixture time before subjecting the assembly to any load or stress. Loctite 638 typically achieves handling strength within a few minutes but may require several hours for full cure, depending on the materials and temperature.
For more detailed information on maintaining the reliability and strength of your bonds, visit our section on benefits of Loctite retaining compounds.
Applying these guidelines and techniques will help you get the most out of Loctite 638. For additional information on adhesive comparisons, such as loctite 609 vs. 680 or loctite 620 vs. 680, please check our other related articles.
