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Views: 103 Author: 深圳市博森威电气有限公司 Publish Time: 2026-09-28 Origin: BSUMWELL
This article covers the following content
If you are an electrical wholesaler or a non-standard project manager undertaking custom enclosure requirements for your clients, this article will help you understand:
1️⃣ What are the differences in the cost structure between plastic injection molding and metal processing for customization?
2️⃣ At what volume is injection molding more cost-effective? At what volume is metal molding more flexible?
3️⃣ How much is the difference in delivery time? — 30-45 days vs 7-14 days
4️⃣ How can wholesalers choose the optimal customization solution based on order size?
This article is by BSUMWELL Written by our technical team, we are a manufacturer specializing in waterproof electrical enclosures. Our products cover three major material series: PC/ABS plastic, stainless steel, and aluminum enclosures, with protection levels ranging from IP55 to IP68. We support OEM/ODM customization.
When a customer requires a non-standard size, special openings, or custom silkscreen printing for a casing, wholesalers face two options:
Path 1: Plastic Injection Molding – Custom Mold Making
Injection mold development is required (NRE cost).
Once the mold is finalized, the unit price for mass production is extremely low.
Suitable for large-volume, long-term, stable standardized customization
Path Two: Metal Processing – Customization Without Mold Opening
Formed by laser cutting, CNC punching, and bending.
No mold opening fee is required; any size and opening can be achieved through CAD/CAM programming.
Suitable for projects with small batches, multiple varieties, and tight delivery times.
The cost structures of the two paths are completely different. Choosing the wrong path will either result in wasted initial investment or persistently high unit costs.
variable | Selection tendency |
Large batch（500+） | Plastic injection molding – extremely low unit price after mold opening cost is amortized |
Small batch（<200） | Metal processing – no mold required, controllable unit cost |
Tight delivery time(Within 2 weeks) | Metal processing – Samples available in 7-14 days |
Long delivery time(1-2 months) | Plastic injection molding – 30-45 days for mold opening and trial molding |
Sufficient budget | Both are acceptable. |
Limited budget, large batch | Plastic injection molding |
Limited budget, small batch | Metalworking |
Core logic: The larger the batch size, the more cost-effective the injection molding; the smaller the batch size, the more flexible the metal.
The cost of custom plastic injection molding consists of two parts:
Cost items | illustrate | estimation range |
NRE (Mold Fee) | One-time investment, non-refundable | Tens of thousands to over a hundred thousand yuan (based on the quotations of common molds in the industry) |
Unit cost | Materials + Injection Molding + Labor + Energy Consumption | Lower, decreasing with batch size |
The characteristic of NRE is "one-time investment, spread across each product".
For example:
Mold fee: ￥50,000.
If we make 500, each one costs ￥100 .
If we make 5000, each one costs ￥10 .
If we make 50,000, each one costs ￥1 .
The larger the batch size, the thinner the NRE (Net Residue Equivalent) spread, and the more obvious the unit price advantage.
Batch Threshold = NRE /(Metal Unit Price - Plastic Unit Price)
For example(Illustrative data, based on industry-standard cost models):
Injection mold fee: ￥50,000
Injection molding unit cost: ￥20
Metalworking unit cost: ￥50
Price difference per item: ￥30
Critical point = 50,000 /30 = 1667
in conclusion:
Batch size < 1,667 Metal processing is more cost-effective (saving on mold-making fees).
Batch size > 1,667 Plastic injection molding is more cost-effective (the unit price advantage covers the mold opening fee).
The actual critical point varies depending on product size, complexity, material, and processing method. The above calculation is for illustrative purposes only and is for reference only. For critical point calculations specific to a particular product, please contact our technical team. Get a customized cost estimate
stage | time | illustrate |
3D drawing confirmation | 3-5 days | Client confirms final design |
Mold processing | 20-30 days | Steel mold processing, heat treatment, assembly |
Trial mold | 3-5 days | First trial molding, checking size and appearance. |
Mold repair | 3-7 days | Adjust the mold based on the trial molding results. |
Mass production | 5-10 days | Mass injection molding |
total | 30-45 days | Based on the conventional injection mold processing cycle |
The flexibility of injection molding customization:
Once the mold is finalized, modifying its dimensions requires major alterations or even scrapping and starting over.
Suitable for products whose designs are already finalized and do not change frequently.
Projects not suitable for "design and modification at the same time"
The cost structure for custom metal parts is completely different:
Cost items | illustrate | estimation range |
NRE | CNC programming + laser typesetting fee | Extremely low or zero |
Unit cost | Materials + Cutting + Bending + Welding + Surface Treatment | The higher the volume, the lower the volume. |
The core advantage of metal processing: no high mold-making fees.
No need to invest tens of thousands of dollars in mold fees; just CAD/CAM programming is sufficient to achieve any size and opening through laser cutting, CNC punching, and bending. Tolerance control is typically based on ISO 2768-m standard (medium precision), meeting the assembly requirements of most industrial enclosures.
Scene | Reasons for recommending metal customization |
Small batch(<200) | No mold opening fee, controllable unit cost |
Multiple varieties(Different sizes/openings) | Each product does not require a separate mold; programming is sufficient. |
Tight delivery time(Within 2 weeks) | Samples can be produced in 7-14 days. |
Frequent design changes | CAD/CAM can be adjusted at any time without modifying the mold. |
Extra Large Size | Injection molds are extremely expensive; metal processing is more economical. |
stage | time | illustrate |
3D drawing confirmation | 1-2 days | Client confirms design |
Laser cutting/stamping | 3-5 days | CNC machining |
Bending/Welding | 2-3 days | forming |
Surface treatment | 2-3 days | Spraying/Anodizing |
total | 7-14 days | Based on conventional metal processing cycles |
The flexibility of metal customization:
Adjust cutting drawings anytime via CAD/CAM without modifying the mold.
Projects suitable for "design and modification"
Suitable for non-standard projects with varying sizes and different opening positions.
How do I use this table?
Confirm your order size and delivery time requirements.
Find the corresponding customization plan in the table.
Check the special requirements section (such as heat dissipation and corrosion prevention).
For accurate calculations, please contact customer service for a customized solution.
Customization Dimensions | Plastic injection molding | Stainless steel sheet metal | Aluminum profiles/die casting |
Mold making/engineering costs (NRE) | Extremely high (tens of thousands to hundreds of thousands) | Very low or zero (programming + typesetting) | Medium to high quality (profiles require no mold, die casting requires molds). |
Mass production unit price | Extremely low (advantage of large-volume production) | Higher (manual welding + bending) | medium |
Development and delivery time | 30-45 days | 7-14 days | Profiles are the fastest, while die casting takes 25-35 days. |
Design modification flexibility | Poor quality (difficult to modify once the mold is finalized). | Excellent (CAD/CAM can be adjusted at any time) | Good (modular assembly of profiles) |
Suitable for batch processing | Large quantities (500+) | Small batch (<200) | Small to medium batch |
Suitable scenarios | Standard size bulk order distribution | Small-batch, multi-variety non-standard projects | Heat dissipation requirements + small to medium batch production |
Batch range | Recommended solution | reason |
1-100 | Metalworking | Mold opening costs cannot be shared; metal molds are exempt. |
100-500 | Mainly metal processing | The critical point varies from product to product; metals are generally more flexible. |
500-2000 | Critical points need to be calculated. | Determined based on NRE and unit price difference. |
More than 2000 | Plastic injection molding | The unit price advantage is obvious after the mold opening cost is shared. |
Simple judgment method: If the order volume is insufficient to cover the mold cost, choose metal; if it can be covered, choose injection molding.
Order type | Recommended solution | Our Services |
Sample/Small Batch Trial Order | Metalworking (no mold required) | Samples available in 7-14 days |
Small to medium batch (<500) | Aluminum profiles/sheet metal | No mold required, flexible customization |
Medium to large batches (500-2000) | Calculation of critical point determination | Provide cost comparison analysis |
Large batch (2000+) | Plastic injection molding | The unit price is extremely low after mold making. |
Long-term standardized products | Plastic injection molding/aluminum die casting | Investing in molds in exchange for long-term profit margins |
Our OEM/ODM services cover three materials:
Plastic injection molding: Suitable for large-scale standardized customization
Stainless steel sheet metal: Suitable for non-standard projects with small batches, multiple varieties, and tight delivery times.
Aluminum profiles/die casting: Suitable for small to medium batch production scenarios with heat dissipation requirements.
Regardless of order size, we can provide customized solutions. Click to submit your customization request
Real-world case studies for reference:
A European electrical wholesaler received an order for 150 non-standard outdoor control cabinets, requiring samples to be delivered within two weeks. If they chose plastic injection molding, the mold fee would be ￥80,000, with a delivery time of 35 days; if they chose stainless steel sheet metal customization, the mold fee would be waived, and the delivery time would be 10 days. Ultimately, the customer chose the sheet metal solution, with samples delivered within 12 days. Subsequent bulk orders for 500 units remained within an acceptable price range. The wholesaler commented, "For small-batch non-standard projects, metal processing is far more flexible than injection molding."
Q: For small-batch customization, should I choose plastic or metal?
A：For small batches (<200 pieces), metal processing is recommended. Plastic injection molding requires mold making, which costs tens of thousands, resulting in an extremely high unit price when spread across small batch orders. Metal processing eliminates the need for mold making and can be customized through CAD/CAM programming, making it more suitable for small batches and multiple product varieties.
Q: Why does the delivery time for custom injection molding take so long?
A：Custom injection molding requires mold making, and the process includes: 3D drawing confirmation (3-5 days), mold processing (20-30 days), trial molding (3-5 days), mold repair (3-7 days), and mass production (5-10 days), totaling 30-45 days. Metal processing eliminates the need for mold making, and samples can be produced in 7-14 days.
Q: Why is the unit cost of custom metal parts higher than that of injection molded parts?
A：Metal processing requires manual bending, welding, and polishing, which takes a lot of time. Injection molding, once the mold is finalized, has extremely low unit cost (material + injection molding + energy consumption), but this is contingent on a large enough batch size to spread the mold cost. The two represent a trade-off between "initial investment vs. unit cost".
Q: What if there are design changes?
A：Metal working allows for easy adjustment of cutting drawings via CAD/CAM without requiring mold modifications, offering exceptional flexibility. In contrast, with plastic injection molding, once the mold is finalized, any dimensional changes require significant alterations or even complete rework. If a project's design is likely to undergo frequent changes, metalworking is the recommended choice.
Q: What is the maximum batch size you support for custom orders?
A：We support a full range of customization, from sample production to mass production:
Samples/Small Batch: Metalworking, samples available in 7-14 days.
Small to medium batch production: Aluminum profiles/sheet metal, mold-free
Large-volume production: Plastic injection molding, extremely low unit price after mold opening.
The specific solution needs to be comprehensively evaluated based on the product size, complexity, and order volume.
Summary of the key points of this article
1️⃣ Plastic injection molding vs. metal processing: completely different cost structures Injection molding is characterized by "high NRE (Non-Recurring Equipment) + low unit price," while metal molding is characterized by "zero NRE + relatively high unit price."
2️⃣ Batch decision mode: For small batches, choose metal (no mold required); for large batches, choose injection molding (split mold costs).
3️⃣ Delivery time difference 3-5 times — Metal samples take 7-14 days to produce, injection molded samples take 30-45 days.
4️⃣ Design flexibility varies greatly — Metal can be modified at any time, but injection molding cannot.
5️⃣ We can cover the entire range of customization — From samples to mass production, all three materials can be customized.
(Previous article: Is the account settled? Please read the third article in this series, "[ ...Lifecycle cost analysis: 10-year total cost of plastic, stainless steel, and aluminum casings》。
This is the final article in the series "Plastic Casing vs. Metal Casing - A Complete Comparative Analysis of B2B Procurement." For a basic comparison of materials, scenario-based selection, or TCO analysis, please read the first three articles in this series.
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