What Factors Affect the Cost of Injection Molding Products?

Based on Kingsjeng’s over 16 years of experience in plastic injection molding.

The cost of injection molding products is affected by multiple factors such as raw materials, molds, production processes, labor management, and logistics packaging. The weight of each factor varies with product structure, order quantity, and material type. Please refer to the detailed explanation below:

1.Raw Material Cost (Core Proportion: 30% - 60%)

This is the largest cost component of injection molding products, directly determining the base cost.

    1.1 Material Type and Price: General-purpose plastics (PP, PE, ABS) are low in unit price, while engineering plastics (PC, PBT, PA) and special plastics (heat-resistant, weather-resistant, flame-retardant modified plastics) are high-priced. Moreover, the price of modified plastics is 20% - 100% higher than that of virgin materials.

    1.2 Material Utilization Rate: The more complex the product structure, the more waste is generated from gates and runners. If the waste cannot be crushed and recycled (e.g., transparent parts, high-precision engineering parts), it will increase material loss costs. The proportion of recyclable materials also affects the cost (recycled materials need to be pelletized again, resulting in additional processing fees).

    1.3 Loss Rate: Edge trim, defective products, and waste from mold trial and machine adjustment during production will all increase the material consumption per unit product.

2. Mold Cost (Long-term Amortization, Order Quantity is the Key)

Molds represent a one-time investment cost that must be amortized across each unit of product. **The larger the order quantity, the lower the amortized mold cost per unit product.

    2.1 Mold Structure and Complexity: Single-cavity molds have low costs but low production efficiency. Multi-cavity molds (2-cavity, 4-cavity, 8-cavity, etc.) have higher costs but can significantly improve output and reduce the amortized cost per unit. Molds for complex structural parts (e.g., products with threads, side cores, or inserts) involve higher design and processing difficulty, and their costs are 50% - 200% higher than those of ordinary molds.

    2.2 Mold Material and Service Life: Ordinary carbon steel molds are low-cost with a service life of about 100,000 - 500,000 shots. High-quality mold steels such as P20 and H13 have higher costs but a service life of 500,000 - 3,000,000 shots, making them suitable for mass production.

    2.3 Mold Maintenance and Repair: Mold wear and troubleshooting during production will incur additional costs, especially for precision molds, which have higher maintenance expenses.

3.Production and Processing Cost (Energy Consumption + Equipment + Efficiency)

This cost component is directly linked to production efficiency—the higher the efficiency, the lower the processing cost per unit product.

    3.1 Injection Molding Machine Selection and Energy Consumption: Large-tonnage injection molding machines have much higher energy consumption and hourly rates than small-tonnage models. Using a large machine to produce small products leads to "overcapacity" waste and drives up unit costs. In addition, servo motor injection molding machines save 30% - 50% more energy than ordinary asynchronous motor injection molding machines, which can reduce energy costs in long-term production.

    3.2 Production Efficiency (Cycle Time): The shorter the injection molding cycle (clamping → injection → holding pressure → cooling → mold opening → ejection), the higher the output per unit time, and the lower the processing cost per unit product. Cooling time is the key factor affecting the cycle; the thicker the product wall thickness, the longer the cooling time and the higher the cost.

    3.3 Defective Product Rate: Improper machine adjustment, mold defects, unstable materials, and other factors will increase defective products. For every 1% increase in the defective rate, the cost will rise by 1% - 2% accordingly.

    3.4 Auxiliary Process Cost: If the product requires secondary processing (e.g., spraying, silk screening, electroplating, assembly), additional process costs will be incurred. Products with inserts require manual or robotic placement of inserts, which also increases processing fees.

4.Labor and Management Costs

This cost component is related to the factory's management level and degree of automation.

    4.1 Labor Cost: Expenses for manual loading/unloading, gate trimming, and quality inspection. Automated production lines (robotic arms, conveyors, automatic testing equipment) require high upfront investment but can reduce labor costs and lower expenses in the long run.

    4.2 Management Cost: Factory rent, water and electricity fees, equipment depreciation, quality inspection costs, administrative expenses, etc., which need to be allocated to each unit product based on output value.

5.Logistics and Packaging Costs

This factor is easily overlooked but has a significant impact on products for export or long-distance transportation.

    5.1 Packaging Materials: Ordinary cartons and bubble bags are low-cost, while anti-static packaging, blister trays, and export-standard wooden cases are more expensive. Especially for precision or fragile parts, packaging costs can account for 5% - 15% of the total cost.

    5.2 Transportation Costs: The smaller the order quantity, the higher the unit transportation cost. LCL (Less than Container Load) shipping has a higher unit price than FCL (Full Container Load) shipping, and long-distance transportation also leads to a significant increase in logistics costs.

6.Other Hidden Costs

    6.1 R&D and Prototyping Costs: Multiple prototyping and mold modification costs during new product development will squeeze profit margins if not included in the quotation.

    6.2 Order Scale: Small-batch, multi-batch orders have a high proportion of mold change and machine adjustment time, with unit costs 20% - 50% higher than those of large-batch orders. Large-batch orders can reduce costs through optimized production processes and raw material price negotiation.

    6.3 Quality Control Cost: The higher the customer's requirements for product dimensional accuracy and appearance, the stricter the quality inspection process, which will increase the corresponding costs of testing equipment and labor.