Taizhou PinGuan Mould CO., Ltd. SMC Sanitary Molds:

From Tooling Technology to Production Process, and Their Impact on Home Furnishing

1. What is SMC?

SMC (Sheet Molding Compound) is a high-strength composite material made from unsaturated polyester resin, glass fibers, fillers, curing agents, and other additives. It is supplied in sheet form and offers excellent mechanical properties, corrosion resistance, dimensional stability, and process ability.

In the bathroom industry, SMC is widely used for products such as bathtubs, shower trays, washbasins, and integrated bathroom units. Its ability to be molded in one shot, combined with a smooth surface, high strength, and excellent aging resistance, makes it an ideal choice for high-end sanitary ware.

2. SMC Mold Tooling Technology

The core of SMC products lies in the mold. The design and manufacturing of the mold directly determine the product’s quality, appearance, and consistency.

1). Mold Materials

SMC molding typically uses tool steels, such as P20, H13, and S136. These steels must offer:

High strength and wear resistance to withstand molding pressures (typically 10–20 MPa)

Good thermal conductivity for uniform mold temperature

Excellent corrosion resistance to prevent attack from acidic resin components

2). Mold Structure

SMC molds are typically compression molds, consisting of: Punch (upper mold); Cavity (lower mold); Heating system (cartridge heaters or oil channels); Ejection system; Shear edge (to control flash)

During the molding process, the mold is maintained at 140–160℃ to ensure complete curing of the resin.

3). Surface Treatment

Bathroom products demand high-quality surfaces. The mold cavity must be highly polished to a mirror finish (Ra ≤ 0.05 μm) to ensure a smooth product surface and easy demolding. For high-end products, chrome plating or PVD coatings are applied to enhance wear and corrosion resistance.

3. SMC Bathroom Product Manufacturing Process

SMC bathroom products are manufactured using compression molding, a highly automated process that ensures high efficiency and consistent quality.

Step 1: Material Preparation

SMC sheets are stored at low temperatures (<10℃) to maintain stability. Before production, the material is cut into a predetermined shape based on product weight and projected area, and the protective film is removed.

Step 2: Mold Heating and Cleaning

The mold is heated to 140–160℃ using electric heaters or thermal oil. The surface is cleaned to remove residues, and a release agent is sprayed to facilitate demolding.

Step 3: Material Placement and Mold Closing

The cut SMC sheets are placed into the lower mold cavity, and the upper mold closes rapidly. During closing, the material flows under high temperature and pressure, filling the entire cavity.

Step 4: Curing and Molding

After closing, the pressure is maintained (typically 10–20 MPa), and the curing time ranges from 2 to 5 minutes, depending on product thickness and size. During this stage, the resin undergoes cross-linking to form a stable three-dimensional network.

Step 5: Mold Opening and Ejection

After curing, the upper mold opens, and the ejection system gently pushes out the product. The product is still hot and must be cooled and shaped on a dedicated fixture.

Step 6: Post-Processing

The molded product undergoes deflashing, drilling, and surface finishing. Some products receive film lamination, painting, or hardware assembly before becoming finished goods.

4. The Impact of SMC Bathroom Products on Home Furnishing

The widespread adoption of SMC bathroom products is profoundly reshaping the modern home furnishing industry. Its impact is the following aspects:

1). Promoting the Popularization of Integrated Bathrooms

The one-piece molding characteristic of SMC makes it the core material for unit bathrooms (integrated bathrooms). These systems prefabricate the base, wall panels, and ceiling in factories, requiring only on-site assembly—transforming traditional “wet construction” into “dry installation.” This transformation:

Shortens construction time: from one to two weeks down to 1–2 days

Reduces pollution: no cement mortar, no noise or dust

Ensures quality control: factory production guarantees high consistency

2). Enhancing Durability and Ease of Maintenance

Traditional bathroom materials (such as ceramic tiles and artificial stone) are prone to dirt accumulation in grout lines and water leakage or cracking over time. SMC bathroom products offer:

Seamless integration: completely eliminates leakage risks

Dense surface: resists mold growth and is easy to clean

Strong durability: service life can exceed 20 years

3). Aligning with the Prefabricated Construction Trend

As governments and industries actively promote prefabricated construction, the standardization and modularization of building components have become essential. SMC bathroom products, with their high precision, lightweight nature, easy transport, and fast installation, perfectly align with the logic of prefabricated construction. Developers can significantly reduce on-site management costs and improve delivery efficiency.

4). Empowering Personalization and Design Freedom

SMC molds can flexibly accommodate various shapes, textures, and colors. By etching textures onto the mold surface or using in-mold decoration (IMD) technology, SMC products can mimic the look of stone, wood grain, metal, and other finishes—meeting diverse home furnishing styles while retaining the material’s core performance advantages.

5). Promoting Environmental Sustainability

SMC materials have lower energy consumption during production, and their long service life reduces the need for frequent renovations. The dry construction method of integrated bathrooms significantly reduces construction waste. With ongoing development of recyclable SMC materials, their environmental advantages will become even more pronounced.