Comparison of disc blade qualities available in the market

Published on 30 June, 2023

At the heart of every fruitful harvest lies well-prepared soil. Farmers know that soil preparation is a crucial step in ensuring the success of their crops. In this context, agricultural discs play a fundamental role in conditioning the soil for optimal plant growth. However, not all discs are created equal, and the quality of these tools can have a significant impact on agronomic performance. In this article, we dive into the world of agricultural discs, exploring the different features that distinguish options available in the market.

1. Agronomic functions and mechanical properties

Agricultural discs find their prime application on machinery like disc ploughs and disc harrows, where they undertake the pivotal task of cutting and incorporating crop residues into the soil. This preparatory step cultivates an optimal soil environment for crop growth, concurrently mitigating weed competition and enhancing seed germination conditions.

Within the realm of soil engagement, agricultural discs must encompass a spectrum of mechanical properties to ensure seamless execution of their agronomic functions:

Resilience against Wear : The discs must exhibit remarkable resistance against wear, persisting through extended usage without compromising performance.

Shock absorption and Breakage Resistance : Their structural composition should possess the ability to absorb shocks generated during operation and withstand breakage, ensuring longevity and sustained functionality.

Persistent Sharpness : Maintaining sharp edges even under duress is vital for efficient cutting and soil penetration, directly influencing the quality of soil preparation.

Precise Geometry : The geometrical integrity of the discs significantly affects their penetration depth and cutting efficiency, necessitating meticulous design for optimal performance.

These imperative mechanical properties are intricately linked to the quality of the manufacturing process. Only when these properties are thoughtfully engineered and meticulously integrated can agricultural discs not only accomplish their agronomic objectives but also contribute to enhancing agricultural efficiency and productivity.

2. Manufacturing process

The process of manufacturing agricultural discs follows a fundamental principle: shaping a steel component and applying heat treatment to attain the desired mechanical attributes in the final product.

Elevated Hardness for Optimal Wear Resistance : Achieving high hardness is essential to enhance wear resistance, enabling the disc to endure extended use without deteriorating. This property is pivotal in maintaining the disc’s cutting efficiency over time.

Considerable Flexural Strength to Dampen Shocks : The disc must exhibit substantial flexural strength to effectively absorb shocks that occur during operation. This capability safeguards against breakage and ensures longevity.

Precise Geometric Configuration for Functional Integration : The precise geometry of the disc is vital, as it not only affects its individual performance but also influences the performance of the entire machine. Accurate geometry guarantees proper functioning and compatibility with other machine components.

The expertise of disc manufacturers lies in striking a delicate balance between hardness and flexural strength. While a harder disc offers enhanced wear resistance, excessive hardness might compromise its ability to withstand impacts.

Key factors contributing to the production of high-quality discs or coulters encompass:

Choice of Steel Quality : Opting for high-quality steel with the appropriate metallurgical properties is paramount to ensure the desired mechanical characteristics in the final product.

Mastery of Heat Treatment : The meticulous application of heat treatment is a critical step. Proper heat treatment enhances the steel’s properties, optimizing hardness and flexural strength according to the intended use.

In essence, the crafting of superior agricultural discs demands a harmonious amalgamation of steel quality, precision heat treatment, and the mastery to strike the ideal balance between hardness and flexural capacity.

2.1.  Comparative Analysis of Steel Used by Disc Manufacturers.

The foundation of disc manufacturing lies in the quality of the base steel, as it forms the bedrock for meeting all necessary requirements. Three distinct types of steel are commonly employed.

65Mn Carbon Steel : This was the initial steel used for disc fabrication during the 1960s and 1970s. While still utilized for « low-cost » manufacturing in regions like India or China, it has become inadequate due to the evolving demands of mechanized agriculture and increased traction speeds. Its properties are no longer sufficient to address modern agricultural challenges.

30MnB5 boron steel : Introduced in the early 1990s, boron steel (30MnB5) marked a significant advancement. The addition of boron enhances the material’s mechanical attributes, including strength, hardness, and ductility. This innovation addressed many of the shortcomings observed with earlier carbon steel variants.

NIAUX 200 Special Grade Boron Steel : Distinguishing itself from the rest, Forges de Niaux employs a distinctive category of boron steel for its patented quality, NIAUX 200. Notably, NIAUX 200 boasts a higher carbon content compared to conventional boron steel, resulting in a remarkable hardness of up to 60 HRC for both discs and coulters. This elevated hardness translates to exceptional wear resistance and prolonged performance.

2.2 Heat-Treatment Technics

While the quality of steel forms a critical foundation, the mastery of heat treatment stands as an equally indispensable factor. The primary objective of heat treatment is to enhance critical attributes such as strength, hardness, ductility, and toughness, consequently elevating the overall performance of the manufactured discs. The heat treatment process can be executed through two distinct approaches:

Quenching by Oil or Polymer : This method involves a single quenching process using oil or polymer. While cost-effective, it doesn’t necessitate a subsequent tempering operation. However, it’s important to note that this approach, while budget-friendly, may not yield an optimal grain structure for the steel. As a result, the mechanical properties might not reach their full potential.

Quenching by Water Followed by Tempering Operation : This more comprehensive technique commences with water quenching followed by a tempering operation. Through this process, the steel grain structure is optimized, offering superior mechanical characteristics to the final product. Although this solution is comparatively costlier, it ensures the attainment of the best possible mechanical attributes in the finished disc. The careful balance achieved through water quenching and tempering guarantees enhanced durability, wear resistance, and overall effectiveness of the discs.

3. Comparative Analysis of Different Qualities of Discs Available on the Market

Based on varying steel qualities utilized and the applied heat treatments by manufacturers, the qualities of discs present in the market can be categorized into three main families : low-cost production, mid-range Production and premium production.

3.1.   Low-Cost Production

These types of productions are often concentrated in regions like China, India, or local markets where smaller quantities of discs are produced. The primary objective is to minimize production costs. Manufacturers typically prioritize the utilization of 65Mn carbon steel, coupled with a simple oil quenching process. However, the use of this high-carbon steel renders the disc susceptible to breakage if excessive hardness is applied.

3.2  Mid-range Production

Originally produced in Europe and North America since the 1990s and 2000s, “Mid-Range” productions have also emerged in South America and Turkey. The shift from carbon steel to boron steel has allowed for increased hardness of discs, up to a maximum of 50 HRC, while mitigating the risk of breakage. Manufacturers using this steel have the option of choosing between a simple polymer quenching or water quenching combined with tempering to achieve a superior steel structure. However, similar to “Low-Cost” productions, “Mid-Range” discs maintain uniform hardness across the disc’s surface. As a result, pushing hardness beyond 50 HRC is unfeasible, as excessive hardness at the disc’s center would inevitably lead to systematic breakage.

3.3  Premium Production

Currently, a sole manufacturer offers a disc quality surpassing all others. The NIAUX 200 quality produced by the French manufacturer FORGES DE NIAUX boasts a unique design patent. The Niaux 200 manufacturing process involves applying a hardness variation across the disc. The disc’s center retains a hardness below 50 HRC for optimal flexural capacity without the risk of breakage, while the specific section in direct contact with the soil reaches hardness levels up to 60 HRC. This approach guarantees Niaux 200 discs the best wear resistance on the market, optimal fracture resistance, and a self-sharpening edge ability due to the high hardness value of the bevel.

In the intricate landscape of modern agriculture, the significance of agricultural discs extends far beyond their physical form. These unassuming tools hold the power to transform the soil into a nurturing environment for crops to thrive. As we’ve journeyed through this exploration of agricultural discs, one truth shines clear: the choices made in disc quality directly influence agricultural outcomes.

From the foundational selection of steel quality to the precision of heat treatment techniques, each facet contributes to the unique identity of a disc. The “Low-Cost” options, born of cost-conscious considerations, may serve as entry points but often come at the expense of longevity and performance. Meanwhile, the “Mid-Range” discs strike a balance, marrying advancements in steel and treatment for a more dependable outcome. However, the pinnacle of quality, as exemplified by the “Premium” production like NIAUX 200, is a testament to innovation, a harmonious interplay of hardness and resilience, engineered to yield the utmost in performance and longevity.