Aluminum may not be the first material that comes to mind when you think about injection molding. But aluminum injection molding is growing in popularity due to the unique properties and advantages aluminum provides.
In this complete guide, as a plastic injection molding manufacturer, we’ll cover everything you need to know about aluminum injection molding, including:
- Can aluminum be injection molded?
- What is aluminum injection molding?
- The benefits of using aluminum molds
- Aluminum vs. steel molds
- Design considerations for aluminum molds
- Applications where aluminum molds make sense
- And more
So if you want to understand whether aluminum can be used for injection molding, how it compares to other mold materials like steel, and the unique capabilities it enables, read on.
Can Aluminum Be Injection Molded?
Yes, aluminum can be effectively used for injection molding, but it is best suited for applications involving lower production volumes and simpler designs. The choice between aluminum and steel molds ultimately depends on specific project requirements, including budget, production volume, and desired part quality.
For rapid prototyping and lower-cost production runs, aluminum molds present a viable option, but for high-volume production, steel molds may offer better long-term value despite their higher initial costs.
What is Aluminum Injection Molding?
Aluminum injection molding refers to the process of injection molding plastic using an aluminum mold. It involves injecting molten plastic into the mold cavity of a machined aluminum mold tool to produce plastic parts.
The molds used are typically made from high-strength aluminum alloys like 7075 and 6061 aluminum using CNC machining or EDM. The rapid heat transfer property of aluminum facilitates faster cooling cycles, allowing high-volume production.
Aluminum tooling is ideal for short run injection molding applications like bridge tooling and prototyping. But advances in aluminum alloys have expanded their capabilities, making them suitable even for volume production injection molding across industries.
4 Key Benefits of Using Aluminum Molds
Let’s examine some of the main advantages that aluminum injection molds provide over traditional steel molds:
1. Dramatically Lower Initial Tooling Costs
Aluminum molds can cost 20-50% less than steel tools initially. The softer aluminum material is easier to machine, keeping production costs low. For new ventures with small budgets, aluminum represents an affordable option to test product designs.
And even if you end up needing a higher capacity steel tool later, the initial aluminum mold allows you to stretch your capital further and get to market faster.
2. Faster Turnaround Time
You can get your first shots from an aluminum tool in just 25% of the time a steel tool would take. Easier machining coupled with modular designs makes aluminum molds faster to build.
Rapid iterations are possible too. So if you need to quickly test a new concept before finalizing a product design, aluminum tools enable agile development.
3. Excellent Heat Dissipation
With a heat conductivity nearly 4X that of steel, aluminum injection molds can dissipate heat rapidly from the molten plastic. This molten plastic cools and solidifies faster into the desired shapes.
Faster cooling cycles mean higher production throughput and lower part costs. For small plastic components with thin walls, an aluminum mold helps optimize the injection molding process.
4. Larger Mold Sizes At Lower Costs
Aluminum’s lightweight properties allow very large molds to be designed cost-effectively, unlike heavy steel tools. Larger mold sizes enable bigger plastic components to be manufactured efficiently.
Applications like automotive panels, appliance housings, and even kayaks benefit from oversized aluminum molds for injection molding their large plastic parts.
So if you need outsized molds on a budget, aluminum is worth considering.
Aluminum VS Steel Molds: Key Differences
Aluminum and steel molds have very different characteristics that make them suitable for different applications:
| Parameter | Aluminum Molds | Steel Molds |
|---|---|---|
| Initial tooling cost | Lower | Higher |
| Lead time | Faster build | Slower build |
| Durability | Lower | Extremely high |
| Part volumes | Ideal for short runs | Ideal for high-volume runs |
| Design complexity | Simpler parts | Complex parts possible |
| Lifespan | 10,000 to 30,000 cycles | Up to 1,000,000+ cycles |
| Heat dissipation | Extremely high | Lower |
| Surface finish | Simple textures | Highly polishable |
As we can see, aluminum makes sense for short run simpler molds, while steel works better for long production life and complex parts.
Key Takeaway: Aluminum molds offer faster and cheaper injection mold tooling, while steel molds provide exceptional longevity and versatility. Understanding these tradeoffs allows selecting the right material for your application.
Design Considerations For Aluminum Injection Molds
To leverage aluminum’s benefits successfully, the mold has to be designed appropriately considering its unique thermal and mechanical characteristics.
Here are some key design guidelines to follow:
1. Use The Right Aluminum Alloy
While several aluminum alloys work, 6061 and 7075 aluminum offer the best combination of machinability, mechanical strength, hardness and corrosion resistance. These are cost-effective choices for injection molds needing up to 30,000 shots.
2. Include Cooling Channels
Take advantage of aluminum’s thermal conductivity by incorporating conformal cooling channels into the mold design. Strategically placed cooling lines speed up heat removal and plastic solidification. This approach enhances quality and throughput.
3. Use Secondary Steel Backing
For added strength and rigidity, use a steel mold base along with aluminum mold inserts for the core and cavity. The steel base offers durable framework support despite aluminum’s lower mechanical strength.
4. Add Wear Resistant Coatings
Apply DLC (diamond-like) coatings in areas needing enhanced abrasion resistance like the ejection system, runner and gate ends. This minimizes wear, extends mold lifespan and improves surface finishes.
5. Include Draft Angles
Add small draft angles (~1-2°) along part edges that contact the mold walls. The slight tapers ease part ejection, preventing damage during demolding.
Overall, incorporate these design considerations right from the start to overcome aluminum limitations while enhancing its natural strengths for injection molding applications.
Industries Using Aluminum Injection Molds
Here are some of the key application areas where aluminum injection molds are gaining traction:
Automotive
Aluminum molds help efficiently produce automotive parts like interior trims, ducts, and decorative panels using cheaper tooling. The faster process enables parts to be tested sooner.
Aerospace
Aerospace companies leverage large aluminum molds for iteratively developing intricate aircraft interior components and housings using injection molding.
Medical Devices
Medical device makers use aluminum molds to rapidly prototype surgical instrument housings, drug delivery devices, single-use consumables, and medical equipment parts needing frequent design updates.
Electronics
Aluminum molds assist consumer electronics manufacturers in swiftly evaluating aesthetic plastic enclosures and housings for tablets, IoT devices, wearables and gaming accessories using injection molding.
Consumer Goods
Several consumer goods categories including sporting equipment, household items, and lifestyle products rely on aluminum injection molds for quickly assessing new designs and variants during new product introduction.
In essence, aluminum tooling is making inroads into various industries to facilitate faster injection molding iteration, more flexible production systems, and economical short run parts manufacturing.
Can Aluminum Injection Molding Work For Your Application?
As we’ve explored in detail, aluminum injection molds can enable rapid, affordable plastic parts production through injection molding across a wide range of applications, despite a shorter lifespan.
The optimal balance of cost savings and mold longevity depends greatly on your specific product requirements and business priorities. Evaluating all technical and commercial considerations is key before deciding on aluminum versus steel for an injection molding project.
Here are a few quick questions to assess if aluminum tooling suits your needs:
1. What production quantities do you expect over the mold’s lifetime?
For fewer than 30,000 shots, aluminum makes sense. Above 100,000 shots, steel is preferable. In between, either may work depending on part size, complexity and your budget.
2. How important is it to get test parts quickly?
If accelerating iterative prototyping is vital, then aluminum allows parts in just 25% of the time. Faster mold fabrication coupled with rapid cycling produces test pieces sooner.
3. Does the part design include fine details and ultra-smooth surfaces?
Aluminum can only achieve simpler geometries and basic textures. For intricate features and mirror polish finishes, steel is better.
4. What plastic material will you use?
With its lower operating temperatures, aluminum works for common plastics like ABS, PP, PE and PU. For engineering resins needing higher heat or abrasion resistance, steel is essential.
Analyzing these criteria helps determine if aluminum meets your cost, lead time and part quality goals. Aligning the mold material with product requirements saves rework costs.
In closing, aluminum injection molding provides transformative advantages like rapid production and economical short runs. Hope this guide offered valuable insights into successfully leveraging aluminum molds!
Feel free to share any questions in the comments section below.
