Motor housing is a key shell‑type casting for motor equipment. It is densely‑distributed with internal cooling ribs, forming intricate and fragmented sand‑core structures. The thin‑walled ribs are prone to fracture, which imposes strict requirements on the sand core in terms of immediate tensile strength, dimensional stability and shake‑out performance. This motor housing is made of HT200 grey cast iron, weighs 11.5 kg, with wall thickness ranging from 3‑20 mm and large wall‑thickness variation.

In mass production, this type of casting frequently encounters process pain points: thin‑wall ribs break during core ejection; sand cores deform during transportation and core‑assembly; difficult core shake‑out after pouring; extra coating procedure increases working hours and production costs. Some resin products show poor adaptability to reclaimed sand, resulting in obvious strength loss of sand cores after sand reclamation and limiting cost‑reduction potential.

In this case, the combined system of ACR‑2211 / ACR‑2221 cold‑box resin is adopted. Reclaimed sand is directly used for production and the coating procedure is eliminated. Batch verification is carried out on existing automatic cold‑box production lines to simplify production procedures and stabilize casting quality while guaranteeing comprehensive sand‑core performance.

Ⅰ、Cold‑box Resin, Casting and Production Process Parameters

Cold‑box Resin Information:

Casting Information:

Production Information:

Ⅱ、Core Advantages of ACR‑2211 / ACR‑2221 Cold‑Box Resin

1. High immediate strength to match high‑speed automatic core‑making rhythm

   After blowing curing, the sand core rapidly gains immediate strength. Thin‑walled fragmented cooling ribs resist cracking and chipping during ejection. It perfectly adapts to high‑speed core‑making, quick ejection and material flow of automatic production lines and improves output of core‑making stations.

2. Excellent compatibility with reclaimed sand to reduce raw‑material costs

   This resin system tolerates performance fluctuation of reclaimed sand and delivers stable sand‑core strength with reclaimed sand. In this case, coating and drying processes are fully removed, cutting auxiliary‑material input and simplifying on‑site workflows.

3. Well‑matched viscosity of two components for uniform sand coating

   Differentiated viscosity design for ACR‑2211 and ACR‑2221 ensures even resin coating on sand grains during sand mixing. Uniform strength distribution across sand cores avoids core fracture and deformation caused by local insufficient strength.

4. Low free formaldehyde for improved workshop conditions

   ACR‑2211 features free formaldehyde below 0.3%, reducing irritating gas emission during core‑blowing operation. It effectively improves working environment of foundry workshops and meets environmental‑protection requirements.

5. Gradually‑increased later‑stage strength for reliable sand‑core storage stability

   Sand‑core strength keeps rising within 24 hours. Dimensions remain stable during storage, transportation and core assembly. Creep‑deformation risk is lowered to guarantee consistent dimensional accuracy of motor housing castings.

Ⅲ、On‑site Application and Result Analysis

On‑site working conditions: sand temperature 18℃, ambient temperature 22℃, humidity 63%, 100% reclaimed sand, total resin addition rate 1.45%, mixing ratio 55∶45, no coating applied.

The immediate tensile strength of finished sand cores reaches 0.56 MPa, and the 24‑hour tensile strength hits 1.55 MPa.

• Good core‑ejection performance: Sand cores eject intact. Thin‑walled complex cooling‑rib structures show no fracture or chipping. Sand‑core surface is sound without sand‑lifting defects.

• High stability during transportation and core‑assembly: No obvious deformation occurs during sand‑core storage, transportation and assembly. Smooth core‑assembly lowers risk of dimensional out‑of‑tolerance caused by deformed sand cores.

• Process simplification & cost saving: Coating and drying procedures are cancelled, saving materials and working hours and shortening overall production cycle.

• Qualified casting quality after pouring: After HT200 molten iron pouring, sand cores show favorable shake‑out performance for easy cavity cleaning. No burn‑on or porosity defects are observed on inner and outer surfaces. Dimensional and appearance requirements are fully satisfied for stable mass production.

Xinda Cold‑Box Resin fits automatic cold‑box core‑making lines, widely used for mass‑produced complex shell castings such as motor housings, pump‑valve parts and gearbox housings. It balances core‑making efficiency, mechanical properties of sand cores and workshop environmental‑protection requirements.

Besides cold‑box resins, Xinda provides a complete portfolio of foundry materials: Silicon Carbide Foam Ceramic Filter, Zirconia Foam Ceramic Filter, Alumina Foam Ceramic Filter, Alcohol‑based Coating, 3D Printing Resin and Supporting Materials, Furan Resin And Supporting Curing Agent, Alkaline Phenolic Resin And Supporting Curing Agent, Anti‑veining Additive. Covering molten‑metal filters, casting coatings, sand‑mold binders and foundry auxiliary materials, our product range suits resin‑bonded sand, cold‑box core‑making and sand‑mold 3D‑printing processes. Xinda delivers one‑stop material and technical solutions for wind‑power, heavy‑machinery, pump‑valve, automotive and aerospace sectors.