YOUR DEEP DIVE GUIDE TO EVERYTHING ABOUT LIFTING MAGNETS

Have you ever come across magnets being used to hold up photos on a bulletin board or keep souvenirs stuck to your fridge? While these are common uses, did you know that magnets play a significant role in handling much heavier objects? Yes, lifting magnets are a game-changer when it comes to moving large and bulky metallic items!

Today, we’re diving deep into the world of lifting magnets, exploring their functionality, safety tips, and the myriad benefits they bring to various industries. Whether you’re a professional in construction, manufacturing, or simply someone curious about innovative tools, this article will provide insights into how these powerful devices work and why they might just be the solution you’ve been searching for in your next project.

At any point while reading, if you have questions or need clarifications, feel free to reach out to our LES team. They’re always ready to offer personalized guidance and discuss how we can tailor solutions to meet your specific needs. Now, let’s kick things off with a straightforward question...

WHAT EXACTLY ARE LIFTING MAGNETS?
This tool is exactly what its name suggests: a device designed to lift hefty loads effortlessly. Technically speaking, a lifting magnet—also known as a magnet lifter—is specialized equipment used primarily for lifting ferrous materials like steel and other metals.

It’s worth noting that stainless steel isn’t magnetic because of its unique molecular structure. To lift an object, a worker typically positions the lifting magnet above the item and activates it, creating an electromagnetic field that securely grips the metal. The magnet holds the object firmly until it reaches the intended destination, at which point it can be deactivated.

The lifting mechanism relies on a direct current (DC) supply to generate an electromagnetic field, ensuring a robust attraction between the magnet and the metal. However, if the power source is interrupted, the magnet releases the load, so it’s essential to ensure uninterrupted energy flow. In some cases, batteries are incorporated to prevent accidents caused by unexpected power failures.

One of the best aspects of lifting magnets is their adaptability. By adjusting the current, you can control the strength of the magnetic field, making them suitable for diverse industries and varying load sizes. Whether you’re dealing with lightweight scrap metal or massive steel beams, these magnets can be fine-tuned to handle the job.

Of course, there are alternative methods for lifting metals, such as using cranes or slings. But when it comes to magnetic materials, lifting magnets offer unparalleled precision and efficiency. Their ability to grip without causing damage makes them invaluable in scenarios where delicate handling is required.

In conclusion, lifting magnets aren’t just a niche tool; they’re a versatile asset in modern industrial operations. With proper training and adherence to safety protocols, these magnets can significantly enhance productivity while reducing risks. If you’re intrigued by their potential, don’t hesitate to explore further—you might discover that they’re the perfect fit for your next project!

Thanks for joining us on this exploration of lifting magnets. We hope you found this information enlightening and look forward to seeing how these remarkable devices could transform your work!

Polycarboxylate Superplasticizer

Some 20 years ago, a new type of Superplasticizer based on polycarboxylate polymers (PCE) was commercially introduced to the North American concrete construction industry. Just as the application of naphthalene-based admixtures starting in the 1970s enabled significant improvements in the numerous engineering properties of plastic and hardened concrete, polycarboxylates have further extended the performance of concrete mixtures.

For example, self-consolidated concrete and slump retention beyond two hours without significant set time extension have been made possible with PCEs. I was fortunate to be on the R&D/marketing team for a major chemical admixture company that launched the first group of polycarboxylate-based admixtures in the 1990s. Like all new technologies introduced into the building industry, there has been a long learning curve which underscores the highly diverse set of materials and applications with concrete construction. This article summarizes a few key performance attributes which have been learned from both commercial concrete applications and the research laboratory. Some of the benefits provided by polycarboxylate superplasticizers have been discussed and previously published in The Concrete Producer.

The Polycarboxylate Family

The term “polycarboxylate” actually applies to a very large family of polymers, which chemists can design to impart a special performance to concrete mixtures. Subsequent to the introduction of so-called general purpose PCE superplasticizers, new PCE products have been developed especially designed to provide high early strength and different levels of slump retention, as well as provide different capabilities to manage air contents in concrete. One such class of polycarboxylates has little impact on initial slump, but because of a time-release function built into the PCE polymer, concrete slump increases generally in a predictive manner as a function of mixing time (see Figure 1). Thus, such a product can be added at various dosages to an already admixed concrete to dial in slump retention as a function of job conditions (haul time, temperature, delay before discharge, etc). Very often, a superplasticizer will be formulated with a blend of two or more PCEs to achieve a combined performance of both early strength and long slump life. Researchers will continue to actively manipulate PCE polymer structure to meet the ever changing material and construction requirements.

  • Air entrainment: Essentially all polycarboxylate-based admixtures are formulated with a defoamer to control unwanted air entrainment inherent with the PCE polymer. For both air-entrained and non-air entrained concrete applications, air contents can usually be effectively managed with selection of the PCE-based superplasticizer product most compatible with job materials. Varying carbon content in fly ash can make consistent air contents challenging as the hydrophobic nature of defoamers leads to adsorption by fly ash carbon. In general, compared to polynaphthalene sulfonate polymer (PNS) based superplasticizers, PCE-based products can make air-entraining admixtures (AEA) more efficient, meaning a lower AEA can be required to achieve the same air content.
  • Impact of clays: Unlike PNS superplasticizers, the PCE polymer will be readily and irreversibly adsorbed by certain clay fines that could be present in various aggregate sources. Figure 2 illustrates the impact that a clay- bearing sand, having a methylene blue value of 1.30, can have on the dosages of PNS verse PCE-based superplasticizers to achieve compatible slump. Normally, with clay-free or low-clay sands, PCEs are dosed about one-third that of PNS-based superplasticizers for comparable slump. However, when clays are present in certain sands, up to a 50% higher dosage of PCE versus PNS can be expected. Therefore, if the dosage of a PCE superplasticizer were to unexpectedly increase, checking for clay fines in the aggregate supply should be prioritized.
  • Flexible dosing: Again, unlike PNS-based superplasticizers, which invariably should be added in a delayed addition mode (that is, after the cement and water have begun to mix), PCEs are relatively insensitive to the time of addition, allowing for greater flexibility in the concrete batching process.
  • Incompatibility with PNS superplasticizers: Use of PCEs and PNS-based products in the same concrete mixture results in rapid loss of workability. Thus, the two technologies, PNS and PCE, should not be used in the same concrete mixture.
  • Strength Synergy with calcium-based set accelerators: When PCE-based superplasticizers are used with set accelerators and corrosion inhibitors comprised of calcium salts, unexpected strength gains have been observed compared to a similar concrete mix admixed with a PNS-based product. This synergy in strength gain with PCEs was first observed in a mix containing a calcium nitrite-based corrosion inhibitor. The data summarized in Table 1 was reported by a concrete producer who had been using a combination of a lignosulfonate-based ASTM C494 type A water reducer and a Type G PNS/Lignin-based superplasticizer to manufacture prestress piles.

This remarkable strength difference, obtained by merely changing the superplasticizer type from a PNS to a polycarboxylate, was verified from a scientific study, and can be useful in reducing cement contents while still meeting strength specifications. Interestingly, the strength difference does not seem to be associated with increased heat of hydration, but rather is related to a denser microstructure produced by the combination of a calcium-based accelerating or corrosion-inhibiting admixture and polycarboxylate-based admixture.

The PCE superplasticizer replaced both the PNS/lignin and Type A water-reducing products at about one-third the dosage rate. Also, note the 50% drop in AEA dosage rate with the PCE admixed concrete to obtain the same air content.

To summarize, though the concrete industry has learned much about harnessing the versatility and understanding the limitations of PCE-based superplasticizers, chemists, working with concrete technologists, will continue to modify the polymer structure to achieve new capabilities for the production, placement and service life of concrete mixtures.

by-Ara

PCE based plasticizer

Shanghai Hongyun New Construction Materials Co., Ltd , https://www.hongyunpce.com