Introduction
In the manufacturing industry, molds represent a “major element of initial investment.” Especially in environments that demand high-mix, low-volume production and short delivery times, their cost significantly impacts product prices and profit margins. In recent years, “aluminum molds” have been gaining attention for their advantages over traditional steel molds, such as shorter manufacturing times, ease of processing, and lighter weight. This article will concretely explain the potential for cost reduction in aluminum molds by dividing it into three stages—”design,” “manufacturing,” and “operation”—while incorporating both success and failure stories.
Decomposing the Cost Structure of Aluminum Molds
Initial Cost vs. Lifecycle Cost
When evaluating mold costs, the “initial manufacturing cost” is often the first thing that comes to mind. Generally, mold costs include material costs, processing costs, design costs, and prototyping costs. In some cases, aluminum molds can be 20-40% cheaper in these aspects compared to steel. However, judging based on price alone is risky.
The manufacturing floor is rife with “hidden costs.” For example, repair expenses due to mold cracking or wear, losses from unexpected shutdowns, and maintenance frequency can accumulate, causing the total cost to fluctuate significantly.
This is where the perspective of “cost per shot” becomes crucial. This is calculated based on how many shots can be produced with a single mold—its lifetime production—and it visualizes the true cost performance. For instance, a ¥1,000,000 mold that can handle 10,000 shots has a cost of “¥10/shot.” If the same-priced mold only lasts for 5,000 shots, the cost doubles to “¥20/shot,” meaning the difference in lifespan directly impacts the unit cost.
Cost Structure Comparison: Steel Molds vs. Aluminum Molds
| Comparison Item | Steel Mold | Aluminum Mold |
|---|---|---|
| Material Cost | High | Medium to Low |
| Machinability | Low (High Hardness) | High (Easy to process) |
| Manufacturing Lead Time | Long (2-3 weeks or more) | Short (As fast as 5-7 business days) |
| Lifespan | Over 100,000-200,000 shots | Several thousand to 20,000 shots |
| Weight | Heavy (Handling restrictions) | Lightweight (Reduced workload) |
| Application Examples | Mass production, durable parts | Prototypes, small lots, short lead-time products |
Steel molds excel in durability but are expensive and have long lead times. On the other hand, aluminum molds are characterized by their ease of processing and light weight, making them suitable for prototyping, small-lot production, and situations requiring quick turnarounds. The benefits of cost optimization with aluminum molds are particularly prominent for product groups with short lifecycles, such as home appliances, automotive interior parts, and medical devices.
The optimal cost zone varies depending on the product’s lot size, usage period, and shape complexity. As a guideline, products requiring around 1,000 to 10,000 shots are considered to have high cost-effectiveness, and a thorough cost-benefit analysis before manufacturing is essential.
Cost Reduction Strategies in the Design Stage
1. Reducing Parts Through Integrated Design
The first step in cost reduction at the design stage is “simplifying the structure.” By integrating a structure that was traditionally assembled by welding or screwing multiple parts into a single piece using an aluminum die-cast mold, the assembly work itself can be eliminated.
For example, there are cases where changing a unit composed of three machined parts into a single integrated aluminum casting resulted in an 80% reduction in assembly man-hours, a zero welding defect rate, and an approximately 30% reduction in labor costs.
Of course, design changes come with costs, but an “ROI (Return on Investment)” perspective is crucial for quantitatively evaluating the initial investment of the design change against its long-term impact on manufacturing, quality, and man-hours. It is not uncommon for a single design change, even if it adds ¥200,000 to the mold cost, to result in annual savings of over ¥1,000,000 in man-hours and defect reduction.
2. Revisiting Product Specifications by Changing Manufacturing Methods
Next is to review the manufacturing method itself. By having the flexibility at the design stage to “not cling to conventional methods,” it’s possible to dramatically lower costs.
Specifically, the following changes are effective:
| Conventional Method | New Method | Effect |
|---|---|---|
| Machining | Die Casting | Improved material yield, 80% reduction in processing time |
| Casting (Sand Mold) | Die Casting | Improved precision and surface finish, no secondary processing needed |
| Lost Wax | Die Casting | Reduced mold cost, shortened lead time |
However, there are points to be cautious about. For example, die casting has a high initial mold cost and limitations in casting surface and dimensional accuracy, making it unsuitable for small lots or high-precision products. It is necessary to compare the cost-effectiveness of “lifetime production volume × unit price” for each product and make a decision by charting the optimal manufacturing method.
3. Mold Structure Optimization: Slide Mechanisms and Draft Angles
When molding complex shapes, adding a slide mechanism to the mold allows for a design that is “free of secondary processing.” For instance, by forming holes or concave shapes in a single shot with the mold, you can reduce additional processing costs and shorten processing time.
Introducing a slide costs several tens of thousands to hundreds of thousands of yen initially, but in cases where mass production effects can be expected, it can lead to a total cost reduction of 10% or more. Additionally, by optimizing the draft angle (e.g., from 1° to 2°), you can improve castability, suppress mold wear, and extend the mold’s lifespan.
By considering both “ease of processing” and “impact on lifespan” simultaneously at the design stage, the overall cost performance can be significantly improved.
The Difference is in the Manufacturing Process! Creating Cost-Efficient Molds
1. Cost-Effectiveness of Overseas Procurement vs. Domestic Manufacturing
“Overseas manufacturing” has also been gaining attention in recent years as a means to suppress mold costs. Among them, mold manufacturing at a base in Vietnam offers the following advantages:
- Labor costs are less than 1/3 of Japan’s: The total cost can be reduced by about 30-50% for the same processing content.
- Local material procurement: Further compression of material costs by procuring aluminum alloys and standard parts locally.
- Developed ports and logistics network: Delivery times of about 10-14 days are achievable even by sea freight (air freight is available for emergencies).
On the other hand, a concern is the risk within the supply chain. This includes differences in language, culture, and quality standards, sudden political changes, and customs delays. However, by collaborating with a reliable local partner and establishing a multi-stage check system (local inspection → domestic re-inspection → final approval), these risks can be considerably mitigated in practice.
In particular, a system like Daiwa Aluminum Vietnam, where Japanese management collaborates with skilled local workers, makes it possible to achieve both quality and cost.
2. Reducing Post-Processing Costs with High-Precision Machining
The manufacturing precision of a mold directly impacts the “processing costs,” “defect rate,” and “yield” of the products it produces. Especially when the dimensional accuracy of the product is strict, the mold’s precision can be critical.
At Daiwa, we utilize 5-axis machining centers and CNC electrical discharge machines to achieve a “shape that is true to the drawing” with a processing accuracy of ±0.01mm. This eliminates the need for secondary processing, resulting in:
- 50% reduction in cutting time
- Significant reduction in defect rates due to out-of-tolerance dimensions
- Simplification of finishing processes (reduced man-hours for buffing and chamfering)
In fact, for a certain medical device part, the dimensional variation of a conventional Chinese-made mold was ±0.2mm. By switching to our Vietnamese-made mold, the variation was kept within ±0.03mm, and the defect rate improved from 12% to less than 1%.
3. Extending Lifespan with a Combination of Surface and Heat Treatments
Since molds are used for tens of thousands to hundreds of thousands of shots, measures against “wear,” “thermal cracking,” and “corrosion” are extremely important. The optimal combination of surface treatment and heat treatment addresses this.
The main treatments and their effects are as follows:
| Treatment Method | Main Effect | Application Example |
|---|---|---|
| Nitriding (Gas/Ion) | Surface hardness UP, wear resistance | High-lot molds, high-pressure casting |
| TiN/CrN Coating | Mold release properties, heat resistance | Complex shapes, high-temperature materials |
| Vacuum Hardening | Stress relief, crack prevention | Precision part molds, high-durability molds |
Furthermore, in recent years, “lifespan simulations” that combine wear prediction AI with practical tests have emerged, contributing to the optimization of mold replacement timing. This allows for planned maintenance before failure while avoiding wasteful early replacements.
Achieving both “high precision + long life” in the manufacturing process is the key that directly leads to the reduction of running costs.
The Impact of Operation and Maintenance on Mold Profitability
1. The Relationship Between Maintenance Frequency and Cost
The presence or absence of regular maintenance is something that cannot be overlooked in the operational phase of a mold. At first glance, it may seem cheaper to operate a mold without maintenance as long as it’s usable, but when production stops due to sudden trouble, mold repairs, and alternative costs pile up, it leads to unexpected losses.
According to one survey, the loss per sudden repair is, on average, 5 to 8 times that of regular maintenance (from JIS B 0405 survey). Aluminum molds, in particular, are weak against thermal expansion, stress concentration, and repeated wear, so periodic inspection, greasing, and dimensional re-measurement are important.
In recent years, more companies are digitally recording and managing the usage history of their molds. By creating a database of shot counts, replaced parts, wear locations, and abnormality histories, it becomes possible to:
- Predict optimal maintenance timing
- Visualize and standardize lifespan trends
- Evaluate the profitability of each mold
This enables operational improvements and increased maintenance efficiency.
2. Repair and Recycling: Innovations to Avoid a Throwaway Culture
Molds are “consumables,” but they don’t necessarily have to be thrown away. When wear or local damage occurs, it is possible to extend their lifespan while suppressing costs by performing partial repairs, part replacements, and re-coating.
The following are typical repair options and a cost comparison:
| Method | Feature | Reference Cost | Effect |
|---|---|---|---|
| Partial Repair (Pins, Cores, Slides) | Renew only a small area | 20-40% of new | Extend life by 10,000-20,000 shots |
| Surface Re-treatment (Nitriding/PVD) | Reduce wear | 10-30% of new | Maintain 80% of initial performance |
| Complete Remanufacturing | Full renewal | 100% | Long-term operation possible (expensive) |
For example, one industrial equipment manufacturer reported a case where they extended the replacement cycle per mold by about 1.5 times through repair measures, reducing their annual mold replacement costs by 35%.
Furthermore, from an environmental perspective, “sustainable mold operation” is gaining attention. Initiatives have begun in some areas to reprocess worn mold materials as recycled materials, which can reduce CO₂ emissions during the manufacturing process by up to 40%.
Thus, the profitability of a mold varies greatly not only by its manufacturing but also by its operational strategy and maintenance philosophy. Depending on how it is used, its investment value can be multiplied many times over.
Success Story: A Hollow Mold That Achieved a 20% Cost Reduction
A prime example of how the combination of product structure ingenuity and high-performance molds produced significant results in aluminum part mold cost reduction is the hollowing case of a certain machine manufacturer, Company B.
Company B was facing challenges with rising material and machining costs for a newly developed large aluminum part. To move away from the conventional solid structure, they collaborated with Hakko Metal Industry to consider the introduction of a “large-diameter hollow structure + hollow forging die set.” By implementing hollow forging using a 1000-ton class large press and a die set capable of inserting forming pins from four directions (front, back, left, and right), they executed a total improvement that included design changes.
The results achieved were as follows:
- Material Cost: 22% reduction
- Machining Cost: 10% reduction
- Total: Achieved a 20% cost reduction
- Mold replacement costs could be amortized within six months
- A secondary effect of improved strength (increased toughness due to complex grain flow) also occurred
Thus, by optimizing the mold structure in collaboration with a specialized vendor from the concept stage, it is possible to achieve overall optimization—true cost reduction—that goes beyond simple mold cost savings.
Failure Story: The Consequence of Overemphasizing Initial Costs…
On the other hand, there are failure stories where rushing to reduce costs led to an increase in total costs.
An electronics manufacturer, focusing only on initial costs during a mold replacement, commissioned a cheap overseas supplier. The price was attractive at about 60% of the domestic cost, but the following problems occurred one after another:
- Variation in dimensional accuracy (out of tolerance)
- Frequent shrinkage and chipping after casting
- The slide part wore out quickly, breaking after 1,000 shots
- A two-month delay in delivery due to discrepancies with the design drawings requiring re-correction
In the end, the additional costs for remanufacturing and adjustments, along with the delivery loss, resulted in a loss of over ¥1.5 million more than anticipated. As a result, the initial “cheapness” was completely nullified.
Such cases illustrate the importance of viewing a mold not as a “lump-sum expense” but by assessing “how it affects the cost of the entire product life.” In particular, selecting a partner with an integrated technical foundation covering design, processing, and casting is the key that separates success from failure.
Conclusion
Cost reduction with aluminum molds is not about “choosing a cheap mold,” but about accumulating optimal solutions in each phase of design, manufacturing, and operation. At the design stage, waste is eliminated from the initial structure through part integration, changes in manufacturing methods, and the introduction of slide structures. In the manufacturing stage, mold lifespan and yield are improved through high-precision processing and appropriate surface treatments. And in the operational stage, continuous performance maintenance and the leveling of replacement costs can be achieved through preventive maintenance, repairs, and digital management.
What is important is to judge these not as partial optimizations but with a perspective of “total optimization.” The option that results in a lower total cost when viewed over the entire lifecycle, even if the initial cost is slightly higher, is the true cost reduction measure.
In particular, utilizing manufacturing bases in Vietnam is an excellent choice that balances manufacturing costs, delivery times, and human resources, and it is a field that will attract even more attention in the future. Now that local processing know-how and international quality control systems are being established, the overseas expansion of aluminum molds holds great potential as a rational procurement strategy that covers everything from “prototyping to mass production.”
The era where a forward-looking choice of molds determines the competitiveness of the entire manufacturing site has already begun.
Sources:
- Taiyo Parts, “The Importance of Molds in Cost Reduction for Aluminum Die Casting”
- Hakko Metal, “Forging Cost Reduction through Hollowing”
- Ministry of Economy, Trade and Industry, “Annual Report of Casting Statistics”
- Ministry of Economy, Trade and Industry, “Issues and Future of the Casting Industry” (2023-2024)
- Die Casting Mold Association, “Mold Durability Standards”
