The wind power industry is undergoing rapid market expansion. Orders for high‑megawatt onshore and offshore wind turbines keep coming in, and large‑scale wind power casting manufacturers are undertaking production tasks for individual components weighing up to 100 tons. Key parts such as hubs, bases and main shaft housings feature complex structures and heavy wall thicknesses, which impose stringent practical requirements on the overall hardening performance of no‑bake moulding materials. Uneven curing between the surface and the inner part of sand moulds has become a critical process bottleneck restricting the yield rate of large castings.

I. Core Pain Points of Cracking from Uneven Curing for Large Wind‑Power Sand Moulds: More Than Surface Defects, But Underlying Process Shortcomings

Unlike small‑and‑medium‑sized castings produced with thin sand layers that achieve rapid and uniform curing, sand moulds for 100‑ton‑class wind power castings are characterised by ultra‑thick sand layers, numerous structural dead zones, dense chills and uneven heat dissipation. Conventional ordinary furan resins feature slow curing reaction rates, insufficient active groups and high water generation during polymerisation. The curing reaction only occurs on the surface layer of the sand mould, while the reaction in the deep sand body lags behind with incomplete hardening, giving rise to a series of stubborn production problems reflected in three key issues:

1. Unbalanced curing between surface and interior, insufficient deep‑layer strength, prone to cracking and sand dropping during stripping

   The resin on the surface of large sand moulds reacts sufficiently and hardens rapidly to meet the visual requirements for pattern stripping. Nevertheless, curing reactions are restricted in deep mould sections, core dead zones and areas covered by chills, resulting in loose sand mass and low internal strength. Hidden defects such as cracking and sand dropping tend to occur under stress during stripping, handling and mould closing. These defects are difficult to detect at an early stage and ultimately lead to casting scrap, higher production costs and longer working hours.

2. Strength sharp drop after torch drying of coatings, drastically increased risk of hot cracking

   Sand moulds for wind power castings need to be coated with refractory coatings and torch‑dried for dehydration to avoid porosity during pouring. Ordinary furan resins lack thermal resistance; their resin structures on the surface are damaged and strength declines rapidly after high‑temperature heating. Temperature difference stress forms between the inner and outer layers of sand moulds, and cracks easily emerge at positions including chills, wall‑thickness transition zones and corners, triggering hot cracking defects on castings.

3. Sluggish curing under low‑temperature conditions, persistently high defect rates in winter production

   Low temperatures reduce the polymerisation activity of resins and further aggravate the difficulty of deep‑layer curing for thick sand moulds. Winter production commonly faces longer stripping cycles and frequent cracks around chills. Actual workshop data shows that the crack defect rate of large wind‑power castings after torch drying can reach three times that in summer, seriously affecting yield stability and production capacity.

In addition, uneven curing of traditional resins causes mismatched rigidity and collapsibility of the whole sand mould. The sand mould cannot adapt to the solidification shrinkage rhythm of castings during pouring, which further aggravates defects such as hot cracking and deformation of castings. It has become a core obstacle for the high‑end production of large wind‑power castings.

II. Technical Mechanism of XINDA New‑Generation Furan Resin: Dual‑dimensional Optimisation to Tackle Curing Problems at the Source

Mechanism 1: Improve reaction activity and cross‑linking strength

Increase the proportion of active groups in furan resin to enhance its chemical reactivity and boost the cross‑linking structural strength of sand moulds.

Mechanism 2: Reduce water generation during polymerisation and optimise deep‑layer curing performance

Formula and process optimisation cuts down water generated in the polymerisation reaction of resin, effectively improving the deep‑curing performance of thick sand moulds.

III. Comprehensive Upgrades in Efficiency, Strength and Stability for XINDA Furan Resin

1. Greatly improved final strength

   The 24‑hour final strength of the product is over 10 % higher than that of ordinary furan resins. Sand moulds possess stronger overall rigidity with excellent impact and deformation resistance, perfectly withstanding the pouring pressure of 100‑ton‑class large castings.

2. Extremely optimised through‑curing performance

   While guaranteeing the same working time without changing conventional moulding operations for workers, FDF280 cures more uniformly with superior sand penetration, completely eliminating the incomplete curing problem of thick sand layers.

3. Markedly improved production efficiency

   The stripping time for large wind‑power sand moulds can be shortened by approximately one hour, greatly cutting the waiting cycle for large‑component moulding and improving line turnover efficiency. It effectively solves the pain points of long production cycles and limited capacity for heavy castings.

4. Leap‑forward upgraded low‑temperature performance

   It maintains high reaction activity under low‑temperature conditions in autumn and winter, featuring stable curing rates and excellent deep‑curing effects. It effectively reduces frequent sand mould cracks and yield decline in winter. Meanwhile, the strength loss of sand moulds after coating and torch drying is minimal, with greatly improved thermal cracking resistance to efficiently avoid hot crack defects.

Breaking the inherent technical bottlenecks of traditional furan resins, XINDA integrates multiple advantages: high activity, fast curing, excellent through‑curing, high final strength, low‑temperature tolerance and hot‑crack resistance. It comprehensively addresses core challenges including sand mould cracking, insufficient curing, low production efficiency and unstable yield for large wind‑power castings, helping foundries reduce costs, improve quality and raise efficiency.