ハードロック工業 List of Products and Services

Content Overview 【Loosening of Screws】 Principles/Types/Evaluation/Testing/Countermeasures 【Design and Tightening of Screw Fasteners】 Mechanics/Design of Screw Fasteners/Screw Tightening Methods/Screw Tightening Tools 【About Screws】 Standards/Types and Usage/Materials/Surface Treatment/Strength of Screw Components 【Screw Troubles】 Troubles during Screw Tightening/Troubles after Screw Tightening/Others (Troubles) ↓↓For more details, click here↓↓

• Work tools

Fatigue fracture is a failure phenomenon that occurs suddenly and without warning under conditions where a constant load is applied repeatedly, and it can also occur with variable loads. On our technical information site "Screw Fastening Technology Navigation," which contributes to solving issues related to screw fastening, we provide detailed information about metal damage known as "fatigue fracture." Please take a look through the related links. [Contents] ■ What is fatigue fracture? - Evaluation of fatigue characteristics - Factors that change fatigue characteristics - Fatigue mechanisms ■ Characteristic fracture surfaces of fatigue fracture - Beach marks - Striation patterns ■ Concepts of fatigue strength safety design *For more details, please feel free to contact us.

• Work tools

The main forms of corrosion include "uniform corrosion, pitting corrosion, and galvanic corrosion." Other types of corrosion include "crevice corrosion," which occurs due to the formation of an oxygen concentration cell in very small gaps on the order of microns; "grain boundary corrosion," where crystal grain boundaries are preferentially corroded; "erosion corrosion," which involves corrosion accompanied by the action of fluid wear; and "high-temperature oxidation," which occurs when exposed to high-temperature air or steam. On our technical information site "Screw Fastening Technology Navi," which contributes to solving issues related to screw fastening, we introduce the three main forms of corrosion (uniform corrosion, pitting corrosion, and galvanic corrosion). Please take a look through the related links. [Contents] ■ Main forms of corrosion - Uniform corrosion - Pitting corrosion - Galvanic corrosion ■ Special corrosion cracking - Stress corrosion cracking - Hydrogen embrittlement cracking *For more details, please feel free to contact us.

• Work tools

The technical information site "Screw Fastening Technology Navi," which contributes to solving challenges in screw fastening that our company operates, introduces steel materials. As the basics of steel materials, it includes topics such as "the difference between ferrous and non-ferrous," "what carbon steel is," and "manufacturing methods," presented with diagrams and tables. Please take a look through the related links. 【Content Overview】 ■ Basics of Steel Materials 　・Difference between Ferrous and Non-Ferrous 　・What is Carbon Steel 　・Manufacturing Methods ■ About Heat Treatment 　・Basic Heat Treatment 　・Microstructural Changes Due to Heat Treatment ■ Major Steel Materials *For more details, please feel free to contact us.

• Work tools

"Mechanical properties" refers to the collective term for the mechanical characteristics possessed by metallic materials, with tensile strength, elongation, reduction of area, hardness, and impact value being representative examples. Our technical information site, "Screw Fastening Technology Navi," which contributes to solving issues related to screw fastening, provides detailed information on typical mechanical properties using diagrams and tables. Please take a look through the related links. [Contents] ■ What are mechanical properties? - Tensile testing and stress-strain diagrams - Reduction of area, hardness, impact value - Relationship between tensile strength and hardness ■ Typical mechanical properties - Steel materials - Non-ferrous metals *For more details, please feel free to contact us.

• Work tools

There are a variety of tools available for tightening or loosening screws. Generally, tightening tools such as "spanners" and "megawrenches," as well as "monkey wrenches" and "pipe wrenches," are used. On our technical information site "Screw Fastening Technology Navi," which contributes to solving screw fastening challenges, we introduce some slightly special tightening tools. For more details, please refer to the related links. [Contents Listed] ■ Torque Wrench ■ Impact Wrench ■ Power Wrench ■ Hook Spanner *For more information, please feel free to contact us.

• Work tools

When tightening bolts and nuts, the points to be aware of regarding the relationship between the tightening torque and axial force in the threaded connection can be broadly divided into the following two points: (1) When the tightening torque is too high relative to the strength of the bolt and nut. (2) When the tightening torque is too low relative to the strength of the bolt and nut. Our technical information site, "Screw Fastening Technology Navigation," which contributes to solving issues related to screw fastening, confirms the stresses generated inside the bolt during tightening and provides detailed information on the damage to screws when the tightening torque is too high. Please take a look through the related links. *For more details, feel free to contact us.

• Work tools

In the tightening of screws, when torque is applied to the nut while the bolt is under axial force, the relationship between the bolt axial force and the torque applied to the nut is derived as an application of the "principle of the inclined plane." On our technical information site "Screw Fastening Technology Navi," which contributes to solving issues related to screw fastening, we provide detailed explanations of the principle of the inclined plane in the case of square screws, using diagrams and other materials. Please take a look from the related links. *For more details, feel free to contact us.

• Work tools

When fixing the joined components, the types of fastening screws include bolts and nuts. Axial force refers to the force that pulls the bolt in the axial direction when the bolt is tightened, causing the bolt tightening area to stretch slightly. The reactive force that attempts to return to its original state during this process is the axial force. If the axial force is not within the appropriate range, it can lead to loosening or cause the joined components to break, making daily management of proper tightening torque and axial force crucial. Now, to determine the necessary tightening torque for managing the appropriate axial force, it can be calculated using a simple formula. We provide detailed information on this in our technical information site "Screw Fastening Technology Navi," which contributes to solving screw fastening challenges, so please check it out through the related link. *For more details, please feel free to contact us.

• Work tools

In the fastening of mechanical structures (screw joints), screws are important components. They can be removed when necessary. The ability to repair mechanical structures and reuse them is a key feature. According to the screw fastening general rules (JIS B 1083:2008), screw fastening is a method or state of joining two or more items by fitting the threaded part of a bolt with the nut or the internally threaded part formed on the item, and tightening the screw. A screw joint is defined as the entire structure that has a screw fastening part or a part of a structure that includes a screw fastening part. Our technical information site "Screw Fastening Technology Navigation," which contributes to solving screw fastening challenges, provides detailed information about "the structure of screws." Please take a look through the related links. *For more details, please feel free to contact us.

• Work tools

The technical information site "Screw Fastening Technology Navigation," which contributes to solving issues related to screw fastening that our company operates, introduces the "design of screw fastening bodies." It explains the design methods for a bolt fastening body that connects two hollow cylinders with a single bolt and nut. We provide detailed explanations with diagrams and formulas on how to design the bolt to meet specific conditions and the design policies for each condition. Please take a look at the related links. [Contents] ■ How should the bolts of screw fastening bodies be designed? ■ What is the internal force coefficient Φ? *For more details, please feel free to contact us.

• Work tools

The Junker axial perpendicular vibration test is a test for the loosening of screws caused by repeated loads in the axial perpendicular direction. The principle of the Junker test is illustrated in the left diagram. By applying repeated forces perpendicular to the axis of the screw, it generates a loosening torque, allowing for continuous measurement of changes in axial force. In actual usage scenarios of screws and bolts, vibrations occur regularly and are a primary cause of loosening. The Junker test machine artificially generates vibrations in the axial perpendicular direction, which are prone to cause a decrease in axial force, for observation and verification. *For more details, please refer to the PDF document or feel free to contact us.*

• Work tools

The NAS test refers to the accelerated vibration test described in the U.S. aerospace standards: NAS (NATIONAL AEROSPACE STANDARD) 3350/3354, which is commonly known as the NAS test. Since the test is based on requirements for the aircraft industry, it emphasizes the effects of acceleration (deceleration) environments and high-temperature conditions. At Hard Rock Industries, the "impact vibration test in accordance with NAS3350/3354" is referred to as the NAS test. Additionally, the U.S. aerospace standards specify that the materials for applicable bolts and nuts are primarily heat-resistant alloys, and the lubricants used are also specified, along with various other criteria. To properly conduct the NAS test, it is necessary to adhere to all of these standards; however, for products intended for the Japanese market, tests that conform to the NAS test are generally conducted. *For more details, please refer to the PDF document or feel free to contact us.*

• Work tools

When physically defining the loosening of bolts and nuts, it can be defined as "the decrease in fastening force (bolt axial force)." So, what factors contribute to this decrease in fastening force? They can be broadly divided into two categories: "loosening due to non-rotation of the threaded part" and "loosening due to rotation of the threaded part." When considering methods to prevent loosening, it is necessary to examine these two factors. In the products of Hard Lock Industries, development focuses on how to prevent loosening caused by the rotation of the threads, resulting in overwhelmingly superior anti-loosening characteristics. [External force factors for loosening due to thread rotation] 1. Axial direction of the bolt 2. Direction perpendicular to the bolt axis 3. Direction around the bolt axis *For more details, please refer to the PDF materials or feel free to contact us.

• Work tools

To perform safe screw fastening, sufficient initial tightening force F is required, and for that, it is necessary to tighten with an appropriate tightening torque T. The characteristics of the fastening methods for screw fasteners can be broadly divided into two categories: elastic region tightening and plastic region tightening. Therefore, when tightening bolts, it is important to select the strength classification (yield stress) and friction coefficient that correspond to the target bolt axial force. Thus, to perform appropriate screw tightening, it can be said that it is essential to have a good understanding of the friction coefficient, which significantly affects the tightening torque and initial tightening force. 【Fastening Methods for Screw Fasteners】 ■ Elastic Region Tightening: Tightening within the range where the bolt does not yield ■ Plastic Region Tightening: Tightening within the range where the bolt yields and reaches the ultimate tightening axial force *For more details, please refer to the PDF document or feel free to contact us.

• Work tools

In addition to the perpendicular direction of the bolt axis, axial repeated loads can also cause loosening. In the case of axial repeated loads, if the bolt and nut are properly tightened and sufficient initial axial force is applied, it can be understood that even with a large repeated load of 80% of the bolt yield axial force Fy, common hex nuts are unlikely to experience rotational loosening. On the other hand, if the initial axial force significantly decreases due to some factor, hex nuts and hex nuts with spring washers will completely experience rotational loosening at 50% of the bolt yield axial force Fy, and even double nuts will see the initial axial force drop to about half. From the above results, it can be understood that in the case of hard lock nuts, even when the initial axial force is low or decreases due to some factor, they are less likely to experience rotational loosening. *For more details, please refer to the PDF document or feel free to contact us.

• Work tools

The loosening of screws can be broadly classified into two types. One is "rotational loosening," which occurs when the male and female threads rotate relative to each other in the direction of loosening, and the other is "non-rotational loosening," which occurs even when they are not rotating relative to each other. Additionally, screws are used in many aspects of our daily lives. However, when screws loosen when we do not want them to, it can not only disrupt our daily lives but also lead to major accidents. It is important that screws do not loosen when we do not want them to, and that they do loosen when we want them to. Therefore, research on screw loosening and methods to prevent it is considered urgent. [Classification of Loosening] ■ Rotational Loosening ■ Non-Rotational Loosening *For more details, please refer to the PDF materials or feel free to contact us.

• Work tools

The damage to screws and bolts can be broadly categorized into three types: "damage," "failure," and "fracture." Damage refers to the separation of a part of the material or the occurrence of permanent deformation, and it does not necessarily indicate a hindrance to use. Failure refers to the separation of a part or the whole of the material or the occurrence of significantly large permanent deformation that renders it unusable, while fracture refers to the separation of the material due to failure. In other words, damage or fracture of a bolt occurs on the surface of the bolt, particularly from the bottom of the thread valleys where stress concentration is high. For more detailed explanations, please refer to the related link page. 【Forms of Bolt Damage】 ■ Damage: Separation of a part of the material or occurrence of permanent deformation ■ Failure: Separation of a part or the whole of the material or occurrence of significantly large permanent deformation that renders it unusable ■ Fracture: Separation of the material due to failure *For more details, please refer to the PDF materials or feel free to contact us.

• Work tools

The cause of loosening screws lies in the play (clearance) of the threads between the bolt and the nut, and if this can be completely eliminated, it would achieve the ideal anti-loosening effect. Our anti-loosening effect utilizes the "wedge," which has been used in wooden construction for a long time. We have conducted extensive research and developed a product that applies the principle of this "wedge" to the nut. That groundbreaking product is the 'HLN Hard Lock Nut.' 【Features of the HLN Hard Lock Nut】 ■ Anti-loosening effect recognized worldwide ■ Torque and axial force management possible ■ Reusable ■ Easy and good workability ■ Contributes to significant cost reduction *For more details, please refer to the PDF materials or feel free to contact us.

• Work tools

The loosening of screws is related to a decrease in fastening force (bolt axial force), and the causes can be broadly divided into two categories: "non-rotational loosening of screws" and "rotational loosening of screws." When the bolt axial force is low or decreases, the number of cycles until bolt failure decreases, leading to a very dangerous situation. In combination with measures against non-rotational loosening, our 'HLN Hard Lock Nut' exhibits a powerful anti-loosening effect based on the principle of wedging. Therefore, you can use it with confidence without worrying about a decrease in fastening force. [Causes of Screw Loosening] ■ Non-rotational loosening of screws - Initial settling - Indentation loosening - Loosening due to micro-movement wear, excessive tightening, and other external forces - Loosening due to thermal causes ■ Rotational loosening of screws *For more details, please refer to the PDF document or feel free to contact us.

• Work tools

The "HLS [Hard Lock Set Screw] (R)" is a locking part developed from the application of the wedge principle, similar to HLN and HLB, which support safety in industrial society for mold fastening. Like the hard lock nut, it maintains a stable anti-loosening effect under all conditions, and being made entirely of metal, it has minimal wear points and sustains a high anti-loosening effect. It meets the needs of various fields, from industrial machinery to mold fixation. 【Features】 ■ Extremely high anti-loosening effect, semi-permanent ■ Reusable ■ Easy and good workability ■ Provides economic benefits *For more details, please download the PDF or feel free to contact us.

• Interior and exterior construction accessories

It has a strong anti-loosening effect that is not found in other lock nuts, along with excellent workability and ease of attachment and detachment.

• Fastening hardware

The Hard Lock® nut, born in Japan and growing worldwide, possesses a strong anti-loosening effect, excellent workability, and ease of attachment and detachment that other lock nuts do not have. Could the principle of a wedge be applied to anti-loosening? This theme was tackled, and after repeated trial and error, the Hard Lock nut was completed.

• Interior and exterior construction accessories