Corrosion is a longtime enemy of most mechanical fastening systems, but some highly corrosive environments exacerbate the problem and require the use of very specific materials and products.
One such product is Challenge Europe’s A4/ASTM 316 stainless fasteners. With the addition of molybdenum, A4 (ASTM 316) stainless steel has significantly better corrosion resistance than the more popular A2 (ASTM 304) steel, but is slightly more expensive. Although A4 stainless steel is often referred to as marine grade, Challenge Europe has noticed a growing demand for this economical grade to meet the needs of the non-marine industry, where equipment is required to withstand more severe conditions of use.
The non-magnetic properties of A4 also make it particularly suitable for use in the instrumentation and medical industries. That’s why Challenge also offers a range of A4 stainless steel prefabricated nuts, bolts, screws and washers to meet production and service/maintenance requirements.
The durability of the A4 grade fastener makes it a favorite of British industry. Now, combined with service packages such as Kanban, Line Supply or Vendor Managed Inventory (VMI), Challenge Europe can provide design and manufacturing engineers with the fasteners they want at the price they want and work with procurement to ensure a seamless process. assemblies.
Fastening to thin-walled materials is fraught with many difficulties. Add to that extreme temperatures and conditions, and you’ve got serious bonding problems. It is because of these problems that Bollhoff has achieved a rather unusual application in highly corrosive environments.
For winter sports equipment designers, finding the right way to attach straps to skis can sometimes be a “straight from slope to slope” challenge. However, in a recent series of evaluations to determine preferred binding options, a leading snowboard manufacturer decided to use Bollhoff Rivnut rivet nuts to meet design goals.
Attaching to or notoriously difficult thin-walled materials is where a high-strength solution is required, which is why Bollhoff has developed Rivnut, a range of products specifically designed for thin-walled products. Provides a secure and reliable installation where threading is simply not possible. . In fact, Rivnut works great with thin-walled metal and plastic (and combinations) and is available in a variety of sizes and finishes to suit most projects.
There aren’t many applications for mechanical bindings that solve a number of snowboard fit issues. Not only must these panels withstand multi-directional shock loads, sufficient compression and vibration for their entire service life, but they must also withstand (for many years) extreme cold and humidity in service.
Thus, in addition to the necessary structural requirements placed on bindings, corrosion remains a constant threat in these harsh environments: addressing this problem is another reason why snowboard manufacturers choose Bollhoff Rivnut. Tests have shown that the rivnut is the only fastener of its kind that provides both the design strength and the required long-term corrosion resistance.
While stainless steel is clearly the preferred choice for many applications that require absolute corrosion resistance, standard Rivnut fasteners can also be specified as other steels with a variety of coatings that help prevent electrolytic and galvanic corrosion, as evidenced by the saline test results. Fog Bollhoff Complete.
The nut is available in standard aluminium, steel or stainless steel, with a choice of standard stainless steel or zinc and zinc nickel plating to provide the long term corrosion resistance required for specific applications.
Another benefit for fabricators requiring high strength fasteners in thin wall materials is that a rivet nut can be listed as either a nut or a stud. Not only does this provide a useful opportunity for the design engineer, but it can also bring additional benefits to the shop floor, depending on the skills of the workforce and the equipment currently in use.
Of course, the ocean is an extremely aggressive environment. Over the years, engineers have discovered many ways to join materials, from the use of glue to methods such as welding. Despite these developments, mechanical fastening remains the preferred choice in the maritime sector.
Stainless steel has been the traditional material used for metal fasteners as it provides superior corrosion resistance and strength at a reasonable cost, but it is not the only material suitable for the needs of the marine industry.
Ben Stafford, materials science expert at material comparison site Matmatch, says: “When components are selected and designed, they must be able to withstand harsh marine conditions, meaning that mechanical properties are also critical. Corrosion-resistant materials such as composites, for example, are very attractive in terms of power, but their use is limited due to strict maritime regulations.”
Currently, such regulations strictly control the choice of materials that can be considered for marine applications. However, there are many suitable materials, such as brass, that engineers can turn to when choosing the right fastener.
However, metals such as brass and stainless steel are not the only materials suitable for the manufacture and production of marine fasteners. Statistics show that with the transition of ship hull materials to lightweight materials, the demand for lightweight high performance fasteners such as polymeric materials will increase.
Unlike many metals, polymers do not corrode in salt water. But while metals can corrode underwater, some polymers can struggle above sea level. This is because some polymers degrade when exposed to UV radiation.
However, plastics such as polyvinylidene fluoride (PVDF) are UV resistant, which means they do not degrade in the sun and become brittle over time, which reduces the strength of fasteners.
Post time: Jul-31-2023
