Author: T. Vadamalaiappan, Sundram Fasteners retired QA manager

Everyone on our planet has begun to feel the effects of pollution, greenhouse effect and global warming. The climate crisis has become a reality.

When we think of extinction, we think of popular animal species such as tigers and rhinos. But we don’t know that many plants, insects, and small animals (such as frogs) are facing rapid mass extinction due to habitat loss and fires. Our food cycle and life cycle are closely related to each species.

The fastener industry is already working hard to protect nature, such as complying with ELV (End-of-Life Vehicle), RoHS (Restriction of Hazardous Substances) and REACH (Registration, Evaluation, Authorization and Restriction of Chemicals) and other directives before the specified time. Fastener manufacturer The transition from hexavalent passivation to trivalent passivation also reduces pollution. Fastener factories all over the world are also equipped with modern electroplating and zero-discharge sewage treatment plants.

Now any industry needs to save energy and raw materials. The global annual output is 27 million tons, and there is still a good space for saving fastener products. After the Covid-19 pandemic caused the worst economic recession in history, the urgent need for optimization and protection is unprecedented. The overall review and pragmatic methods in terms of configuration, form, shape, size specifications and surface treatment can further expand the protection scope of fastener products.

Bolts and screws are forged in the multi-station forging press using the following two processes and versions:

Trimmed version of the head: the hexagonal plane and flange are created by the final trimming operation. This will cause it to look like a pruned flower. The top surface of the head is flat.

Formed or indented head version: In this method, the hexagon and flange are gradually formed in multiple stages and are fully formed by flowing the material into the mold to obtain the final shape. In this version, no pruning is involved. This version may require a groove diameter or dent diameter deliberately created with a punch on the top surface of the head-so it is called the indented head version. Such grooves or dents improve the formation of the head, but never affect the final performance. All specified size requirements will be met, such as the width of the hexagonal span (s), the minimum span of the angle (e), the height of the head (k) and the height of the wrench (kw).

However, the current ISO group external hexagonal drive fasteners, such as hexagonal head bolts (ISO 4014, ISO 4015, ISO 4016 and ISO 8765); hexagonal head screws (ISO 4017, ISO 4018 and ISO 8676) to version two (formed head Or concave head) There is no specific requirement. These standards do not specify the optional groove diameter required for the shaped or recessed head version in the head shape. Therefore, a large number of such bolts and screws continue to be manufactured in trimmed versions, wasting a lot of resources.

The following amendments to these ISO standards will help:

Including optional groove or indentation diameter (d1) on the top surface of the tool head with a depth of approximately 1.0 to 2.0: the groove or indentation diameter helps material flow and fill corners, flats, flanges, and obtain a perfect seat Noodles, as well as good grain flow and head health.

Make the gasket surface diameter (dw) and depth (c) optional: In the version that is trimmed by the process, small burrs may protrude from the corners due to high-speed shearing. Therefore, a raised step similar to the diameter of the washer surface (dw) and the depth (c) of the washer surface is provided to contain burrs below the diameter of the washer surface, thereby providing a flat and smooth seating surface. However, in the formed or indented version, no trimming or cutting operations are involved. Therefore, it can produce a perfect seating surface with a good contact area. Therefore, no raised steps, such as the diameter of the gasket surface, are required in the molded version on the seat side.

Another advantage of the shaped or sawtooth hexagonal version is that it has better grain flow and less residual stress, which gives it better head stability compared to the trimmed version.

The next protection range of fastener products is size specifications. ISO has developed a complete set of standards for the specifications of external hex drive fasteners. It includes the following-hexagonal bolts (ISO 4014, ISO 4015, ISO 4016 and ISO 8765) and hexagonal head screws (ISO 4017, ISO 4018 and ISO 8676). ISO has also studied the flat width and height of the hexagon of the fastener head. About 25 years ago, some changes were made to the head size in the above-mentioned standard. This enables lighter and more efficient equipment and structures without compromising performance.

The head height of bolts and screws has also been revised from the 0.8 diameter standard to the 0.65 diameter standard. For nuts of flat width (S), the same changes have been implemented. Almost worldwide standard and special fastener industries have accepted the change in flat width (S). However, there are still certain areas in the world that are operating in accordance with the old standards. The purpose of general standards is interchangeability and material protection. Through universal and rapid adaptation, this became very successful.

However, other specifications further reduce the hexagonal flat width of hexagonal and hexagonal flange bolts and screws by 1 mm to 2 mm. This helps to make lighter and more efficient equipment. In the case where the flat width of the hexagonal screws and bolts is reduced, the applied torque changes little, but the clamping load can still be achieved.

The size changes and further ranges made by ISO are shown in the following table:

It can be seen that there is room for further improvement by reducing the width of the hexagon across the plane. This will translate into material savings of millions of tons.

The last area that can improve the protection of fasteners is the traditional galvanized fasteners, which can be replaced with zinc-aluminum sheet coatings-such as Geomet®, Magni, Dörken-whenever possible-to provide very good resistance. Corrosive. The process of using dipping and spinning is also relatively simple and does not involve pickling. This means that these surface treatments do not need to be baked in an oven at 200°C to 230°C for 4 to 8 hours—to avoid hydrogen embrittlement—similar to electroplated fasteners. This saves a lot of energy. Zinc-aluminum flake coating is a clean and green process, which greatly reduces sewage treatment, pollution, disposal and discharge. Requirements for electroplating standards (such as ISO 4042-"Fastener plating system") should refer to alternative coatings, such as ISO 10683-"Fastener non-electrolytic application of zinc flake coating system" as a safer alternative to the environment. This will provide users and designers with options and clarity in the early stages of new product or process development.

The savings brought about by the above changes will result in the savings of millions of tons of materials and gigawatts of energy. The ISO standard can be modified immediately to produce a shaped or indented version of the head as an optional version. In the second stage, the change of the hexagon across the plane can be increased by 1mm to 2mm. The option of choosing environmentally friendly zinc sheet non-electrolytic surface treatment instead of zinc electroplating can also be implemented immediately. Fastener users should check their current parts, as well as new developments in environmentally friendly surface treatments.

The fastener industry and the user world must agree to these easy-to-implement changes. All these changes are not new and have been implemented by some users in the industry without any problems. It should be noted that most special fasteners also specify the standard size across the plane width, and their influence is very large.

For the fastener industry, this is an opportunity to help slow the rapid development of global warming and avoid the existential threat of our planet. As climate scientists have warned, with the current carbon dioxide emissions of 36.8 gigatons in 8 years, we only have a 65% chance of keeping the global average temperature within +1.5°C. Otherwise, the temperature rise will reach an uncontrollable and irreversible degree, leading to mass extinction.

The contribution of the fastener industry in the industrial revolution is amazing. It is time for it to quickly review and implement these simple protection measures and leave a habitable planet for the next generation. I call on industry experts, users, and standards organizations—ISO, ASME, ASTM, SAE, DIN, JIS, and GOST—to consider, review, and implement these changes.

Let us continue to improve our quality, environment and occupational health and safety, strive to achieve tolerance, zero defects and zero losses, and protect our diversity for our future. This can be achieved through clean, green, visual, sustainable, and smooth manufacturing and a supply chain that achieves the highest quality at the lowest cost.

Dedication: This document is given to Mr. N. Balakrishnan, President and mentor of Sundram. As an executive, he took Sundram Fasteners Ltd to new heights. As an outstanding fastener technology expert, designer and kind person, he died unexpectedly due to Covid-19 on June 20. He likes and encourages my writing.

Will joined Fastener + Fixing Magazine in 2007. In the past 14 years, he has experienced all aspects of the fastener industry-interviewing key figures in the industry, visiting leading companies and exhibitions around the world.

Will manages the content strategy of all platforms and is the guardian of the magazine's prestigious high editorial standards.

No account? Sign up

Signing up for fasterandfixing.com enables you to manage your account details.