Thermoforming vs injection molding: what is the difference?

The main differences between thermoforming and injection molding are as follows:

Thermal pressure molding: Thermoplastic sheets are heated to a a softened state and then the surface of the die is compressed by vacuum suction, air pressure or mechanical pressure. After cooling, the product is removed.
Injection Molding: Thermoplastic granules are heated to a molten state and injected into a metal mold cavity under high pressure. After cooling and curing, the product is removed.

Mold Cost: Thermoforming molds are usually single-sided (stamping or molding) and are usually made of aluminum or low-cost materials, making them less costly.
Injection molds are double-sided (punch + die), require high pressure resistance and are usually made of steel or high-strength alloys, resulting in higher costs.
Equipment complexity: Thermoforming equipment structure is simple, mainly composed of heating system, molding mould and cooling device.
Injection molding equipment is more complex, including heating drum, screw, high pressure injection molding system, precision mold, etc.

Heat forming:
Small-batch production: Low mold cost cost, suitable for rapid prototyping or small-scale scale production. Large thin-walled products: such as blister packaging, disposable tableware, car upholstery, etc.
Surface decoration: can be combined with printing, painting and other processes to achieve colorful results.

Injection molding:
Mass production: Mould durable, suitable for mass production.
Complex components: moldable into precision gears, connectors, medical devices, etc.
High strength requirements: high density and excellent mechanical properties after high pressure molding.

Thermal molding: Low material utilization rate, as plates require to be allowed and edges trimmed.
High production efficiency, long heating and cooling cycle.
Injection molding: high material utilization rate, molten plastic can accurately fill mold, reduce waste.
High production efficiency, short molding cycle, suitable for automatic production.

Thermoformed products: due to plate stretching resulting in localized thinning, wall thickness uniformity.
In general, the finish of the surface is high, and later treatment is needed to improve texture.
Injection molding product: Accurate control of wall thickness to achieve complex geometry. High surface quality, suitable for direct use of end products.

Thermal molding: Low initial investment and short mold development cycle (from a few days to a few weeks).
Unit cost increases with production and is suitable for small batches.
Injection Molding: High initial investment, long mold development cycle (weeks to months).
Unit cost decreases with production and is suitable for mass production.

How to choose?

Opting for thermal molding: The cost of rapid prototyping, producing large thin-walled products, or placing small orders and being there is an concern.
Choose Choose Injection Molding: for products with high precision, strength, high yield and high initial investment.