The Quality Of Steel Concrete Block Moulds For Block Machine Affects Output
December 15, 2020 – When investing in a concrete block machine, many buyers focus primarily on the main equipment while overlooking a critical component: the mould. Yet the quality of steel used in concrete block moulds directly determines output, production efficiency, and long-term profitability. A high-quality mould with correct design, precision assembly, and superior materials can produce tens of thousands of bricks before requiring replacement, while an inferior mould may fail after only a few hundred cycles.
This article explores how steel quality affects mould performance, what specifications to look for when purchasing concrete block moulds, and how UNIK Machinery's mould manufacturing standards help customers achieve higher output and lower production costs.
The Direct Link Between Mould Quality and Output
The relationship between mould quality and block machine output is straightforward yet often underestimated. A set of concrete block moulds with correct design and assembly, manufactured from high-grade steel, can press more than 10,000 bricks without replacement. Advanced international standards can achieve 60,000 to 70,000 cycles. In contrast, inferior moulds made from low-quality steel may produce only a few hundred or even dozens of products before they are scrapped.
Each time a mould fails, the entire production line must stop. Changing moulds is time-consuming and labor-intensive. During replacement, the brick machine cannot produce, directly reducing daily output and profitability. Beyond lifespan, the design and assembly of block machine moulds also impact output-whether the mould can be changed directly on the brick machine, whether automatic demoulding is supported, and whether automatic core pulling is available (when producing hollow products) all affect overall production efficiency. UNIK's new-generation brick machine moulds have transitioned from plywood hammer forming and manual core-pulling to press-formed and automatic core-pulling designs, increasing output by up to six times.
Why Steel Quality Matters in Mould Production
Steel is the foundation of any high-performance concrete block mould. During production, moulds endure intense vibration (3800-4500 r/min), hydraulic pressure up to 25 MPa, and continuous abrasion from sand, aggregates, and cement. Inferior steel leads to premature wear, dimensional inaccuracy, cracking, and deformation-all of which translate directly into lost production time and higher operating costs.
China's steel materials used for forming concrete product moulds exceed 10,000 tons annually. The cost per ton of steel moulds varies with the types of bricks produced and can sometimes exceed 6,000 yuan per ton. The cost of the mould occupies a considerable proportion of the entire block product cost. Therefore, to further reduce production costs and maximize output, high-quality, long-life, and correctly designed moulds should be widely adopted.
Premium Steel Grades for Concrete Block Moulds
Not all steel is equal when it comes to concrete block mould manufacturing. Professional mould manufacturers select specific steel grades optimized for the demanding conditions of block production:
Cr12MoV – A high-carbon, high-chromium die steel offering excellent wear resistance, hardenability, and dimensional stability. Ideal for high-volume production of hollow blocks, solid bricks, and paving stones. Achieves surface hardness of HRC60-63 after proper heat treatment.
9CrSi – A low-alloy tool steel with good hardenability and toughness. Particularly suitable for interlocking block moulds that require precise edge retention and resistance to chipping. Surface hardness reaches HRC59-62 with carburizing heat treatment.
42CrMo – A chromium-molybdenum alloy steel known for its high strength, toughness, and fatigue resistance. UNIK uses 42CrMo forged blocks for wear sleeves and structural components requiring exceptional durability under cyclic loading.
Mn18 (Manganese Alloy) – A work-hardening steel that becomes naturally more abrasion-resistant under vibration and impact. UNIK applies Mn18 for cavity shells in high-wear applications, where the steel's surface hardness increases progressively during production.
20CrMnTi – A carburizing steel suitable for mould components requiring a hard, wear-resistant surface combined with a tough, shock-absorbing core. Often used for presser feet and core-pulling mechanisms.
Premium moulds use low-carbon alloy steel with carburizing capability. UNIK's steel moulds are manufactured from vacuum-degassed alloy tool steels such as Cr12MoV and 9CrSi, materials specifically chosen for their optimal balance of hardness, wear resistance, and toughness. These premium steels undergo rigorous multi-directional forging processes that break down coarse internal grain structures, creating uniform, fine-grained material flows that serve as the foundation for exceptional durability.
Heat Treatment: The Key to Maximum Mould Life
Selecting the right steel grade is only half the equation. Proper heat treatment transforms raw steel into a high-performance mould component. Heat treatment creates a hard, wear-resistant surface while maintaining a tough, vibration-absorbing core-exactly what concrete block production demands. UNIK's heat treatment protocols for concrete block moulds include:
Carburizing – A case-hardening process that diffuses carbon into the steel surface, creating a hard outer layer (HRC59-62) while preserving core toughness (HRC35-40). Carburized layer thickness reaches 1.3-1.5mm, providing material for multiple re-sharpening cycles.
Vacuum Quenching – UNIK uses vacuum quenching at 980°C followed by tempering at 580°C, achieving uniform hardness without surface oxidation or decarburization. This process prevents distortion that can compromise cavity accuracy.
Multiple Tempering Cycles – Eliminates internal stresses induced by quenching, enhancing the mould's ability to withstand the relentless pressures of continuous production.
Deep-Cryogenic Treatment (Optional) – Subjecting finished moulds to -196°C transforms retained austenite into martensite, extending service life by over 30%. This is particularly valuable for interlocking block moulds with thin sections prone to wear.
Plasma Nitriding – Adds a 0.03mm diffusion layer that provides up to 3 times the corrosion resistance of untreated steel, protecting moulds from the chemical effects of cement and moisture.
Industry standards for mould hardness vary by application. Standard block moulds typically achieve HRC45-50. High-quality concrete block moulds from professional manufacturers like UNIK achieve surface hardness of HRC60-63 on the Rockwell scale through carburizing and vacuum quenching processes. This significantly higher hardness translates directly into longer mould life and more consistent block quality.
China's national standards for tool and mould steels are governed by GB/T 1299 (latest version GB/T 1299-2025, effective May 2026), which specifies classification, ordering content, technical requirements, and test methods for tool and mould steels. Additionally, the industry standard JC/T 2293-2014 provides specific guidelines for the design, manufacturing, and acceptance of block making machine moulds, establishing authoritative benchmarks for the industry.
Precision Machining and Quality Control
Even the finest steel and most sophisticated heat treatment cannot compensate for poor machining precision. UNIK's mould manufacturing facility houses advanced CNC machining centers, wire EDM equipment, and precision grinding machinery capable of maintaining dimensional tolerances within ±0.01mm. Key precision parameters for UNIK concrete block moulds include:
Unilateral clearance between presser foot and mold cavity: 0.2 mm ≤ clearance ≤ 0.4 mm
Flatness of the whole board: ≤ 0.5 mm
Deviation in length and width dimensions of a single cavity model: -0.3 to +0.3 mm
Dimensional deviation of cavity height (filling depth): ± 0.5 mm
Surface finish: Ra ≤ 0.4 μm (mirror-polished)
Draft angle: 1.5° per side for smooth hydraulic ejection
Corner radii: 0.8 mm to prevent stress concentration
This meticulous attention to surface quality ensures smooth demoulding and flawless brick finishes that require no post-production treatment. The result is consistent block dimensions, clean edges, and reduced release-agent consumption-lowering operating costs while improving product quality.
Design Features That Enhance Output
Beyond material quality, mould design plays a critical role in production efficiency. UNIK's concrete block moulds incorporate several design features specifically aimed at maximizing output:
Automatic Demoulding Compatibility – Moulds are designed to work seamlessly with automatic demoulding systems, reducing cycle times and eliminating manual intervention.
Automatic Core Pulling – For hollow block production, UNIK moulds support automatic core pulling mechanisms, eliminating the need for manual core removal and increasing output by up to six times compared to traditional methods.
Quick-Change Design – Moulds can be changed directly on the brick machine without special tools, minimizing downtime during product changeovers. Interchangeable Inserts – For customers producing multiple block types, UNIK offers moulds with interchangeable cavity inserts, allowing rapid reconfiguration without purchasing complete new moulds.
Pre-Compensation Allowances – 0.3mm allowances compensate for steel rebound after ejection, ensuring finished blocks maintain specified dimensions throughout the mould's service life.
About Fujian Unik Machinery Technology Co., Ltd.
Founded in 2008 by a group of experienced engineers and technicians, Fujian Unik Machinery Technology Co., Ltd. specializes in the design, manufacture, and export of concrete block production lines, block making machines, and precision steel moulds. The company follows the business philosophy: "we won not succeed until our customer do" . UNIK has been manufacturing brick machines and moulds in Quanzhou, China since 2010, exporting to 28 countries worldwide.
Our comprehensive product range includes fully automatic concrete block production lines, batching stations, JS compulsory mixers, QT series block making machines, automatic stackers, automatic cubers, pallet return systems, concrete pipe making machines, and precision steel moulds for all block types. Our services include project analysis, engineering design, accessory quality control, on-site commissioning, operator training, and after-sales support.
For more information about UNIK's concrete block moulds-including steel grade options, heat treatment specifications, custom design capabilities, and pricing-please contact our sales team.
✉ sales@unikmachinery.com
