Brief Intro
In the injection molding industry, molds are core production equipment, and the choice of materials directly determines production efficiency, product quality, and overall cost. Many companies fall into the misconception that “ordinary materials save money” during the mold-making stage, neglecting the hidden costs in long-term production.
In fact, the overall cost difference between molds made of ordinary materials and those made of high-quality materials extends throughout the entire lifecycle of mold purchase, production operation, maintenance, repair, and replacement.
This article will break down the cost composition of both from multiple dimensions to provide a rational reference for enterprises in material selection.
Comparison of the overall costs of the two materials
1, Initial purchase cost
From the perspective of initial investment, injection molds made of ordinary materials do indeed have a significant price advantage.
Common mold materials mostly use basic steels such as 45 # steel and P20. These materials have simple smelting processes, ample market supply, and a unit price of $7,500-$12,000 per ton.
High-quality mold materials such as H13, S136, and NAK80 are refined using advanced processes, resulting in higher purity, hardness, and wear resistance. Their price can reach $30,000-$60,000 per ton, and some imported high-quality materials are even more expensive.
Reflected in the price of finished molds, the cost of an injection mold with the same structure using ordinary materials may be only 30%-50% of that using high-quality materials.
For projects with limited funds, small-batch trial production, or short-term projects, the low initial investment of ordinary materials is indeed attractive. However, it should be noted that this advantage only exists in the initial mold-making stage and cannot cover the costs of the entire subsequent production process.
2, Production and operating costs
The production and operation phase is where the core difference in overall cost between the two is reflected, mainly in three aspects: production efficiency, scrap rate, and energy consumption.
In terms of production efficiency, high-quality mold materials offer significant advantages in terms of high wear resistance and stability. Molds made from high-quality materials have higher surface hardness, are less prone to wear and deformation, and can maintain precise cavity dimensions over a long period, eliminating the need for frequent machine downtime for parameter adjustments.
Taking conventional injection molding production as an example, the single continuous production cycle of high-quality material molds can reach more than 100,000 mold cycles, while ordinary material molds wear out quickly and usually need to be stopped for maintenance and polishing after 30,000 to 50,000 mold cycles. Each shutdown adjustment takes at least a few hours and sometimes 1 to 2 days, which directly affects the production schedule.
Based on a daily production capacity of 10,000 modules and a profit of $0.21 per module , a two-day downtime can result in a loss of approximately $4,140 . The accumulated efficiency loss over the long term far exceeds the difference in initial purchase cost.
Scrap rate is another key hidden cost. In long-term production, wear and tear on the mold cavity of ordinary material molds can lead to defects such as product dimensional deviations, surface roughness, and flash. As the number of mold runs increases, the scrap rate will gradually rise from 1%-2% in the early stage to 5%-10% or even higher.
High-quality material molds, with their stable cavity precision, can maintain a scrap rate of less than 1% for a long time.
Based on an annual production of 1 million products and a production cost of $4.14 per product , if ordinary material molds produce 4% more scrap than high-quality material molds, the annual scrap loss would reach approximately $165,600 .
In terms of energy consumption, ordinary material molds have poor thermal conductivity, requiring higher temperatures and pressures during injection molding to ensure product molding. The energy consumption per unit product is 10%-15% higher than that of high-quality material molds.
At the same time, frequent shutdowns for maintenance will increase energy consumption during equipment startup, and in the long run, the difference in energy costs cannot be ignored.
3, Maintenance and repair costs
The maintenance and repair costs of molds are directly related to the material properties.
Ordinary material molds are prone to problems such as cavity scratches, wear, ejector pin bending, and guide post jamming during use due to their low hardness and poor wear resistance. They require regular maintenance such as polishing, welding repair, and replacement of parts.
The annual maintenance cost of a set of ordinary material molds usually accounts for 20%-30% of its initial purchase cost, and for some high-wear molds, it can even reach more than 50%.
For example, the cavity polishing of a regular mold needs to be done once every 30,000 to 50,000 mold cycles, and the cost of each polishing is about $415-$1,035.
If severe wear occurs and welding is required, the cost of a single repair can reach $2,070-$4,140 . Moreover, the precision of the mold after welding is difficult to fully restore, which will further affect the product quality.
High-quality material molds, with their excellent wear resistance and corrosion resistance, significantly reduce the frequency of maintenance and repair.
High-quality materials such as S136 have excellent polishing properties and corrosion resistance, eliminating the need for frequent polishing and rust prevention when producing high-requirement transparent products or corrosive plastics.
H13 material has strong high-temperature stability and is suitable for high-temperature injection molding applications such as engineering plastics. It is not prone to thermal fatigue cracks and the maintenance frequency is only 1/3 to 1/5 of that of ordinary material molds. The annual maintenance cost is usually no more than 5% of the initial purchase cost, which can save a lot of maintenance expenses in the long run.
4, Costs of scrapping and replacement
The lifespan of a mold directly determines its total cost over its entire lifecycle.
The service life of ordinary material molds is usually 100,000 to 200,000 cycles, while the service life of high-quality material molds can reach 500,000 to 1,000,000 cycles, and some high-end high-quality material molds can even exceed 1,000,000 cycles.
Taking the production of the same total quantity of products (assuming 500,000 mold cycles) as an example, ordinary material molds need to be replaced 2-5 times, while high-quality material molds only need 1 set.
In addition to the cost of replacing the mold itself, frequent mold replacements also incur additional downtime and debugging costs, trial molding costs for new molds, and disposal costs for old molds.
The trial molding process not only consumes a large amount of plastic raw materials, but may also generate multiple batches of waste products, further increasing costs.
In addition, high-quality material molds have a higher material recycling value than ordinary materials after they are scrapped, which can offset part of the initial investment to a certain extent.
Final Words
In summary, the cost difference between injection molds made of ordinary materials and those made of high-quality materials is not simply a matter of “higher or lower initial price,” but rather a comprehensive balance of various costs throughout the entire life cycle.
The advantage of ordinary material molds lies only in the short-term initial investment, but there are a lot of hidden costs in terms of production efficiency, scrap rate, maintenance and repair. They are suitable for small batches, short-term projects or low-precision products.
Although high-quality material molds have a higher initial investment, their advantages such as long life, high stability, and low maintenance can significantly reduce the overall cost of long-term production, making them more suitable for mass production of high-precision and high-requirement products.
For businesses, when choosing mold materials, they should not only focus on the one-time investment when opening the mold, but should also consider factors such as product output, quality requirements, and production cycle to conduct a cost calculation for the entire life cycle.
