Aluminum casting & mold design services

Introduction: Key Points of the Aluminum Mold FAQ

Aluminum molds leverage “lightweight,” “high thermal conductivity,” and “design freedom” to enable short lead times and small-lot production in diverse fields such as automotive parts, home appliances, and medical devices. A major appeal is the ability to switch speedily from prototyping to mass production while keeping initial investment lower than with steel molds. For this reason, the adoption of aluminum molds has been rapidly increasing in recent years.

This article, presented as an “Aluminum Mold FAQ,” introduces readers’ questions in a Q&A format, covering topics like design, cost, and troubleshooting. Starting with the “Basics of Aluminum Molds,” you can quickly grasp their applications and benefits.

What is an Aluminum Mold? | Aluminum Mold FAQ

Q1. What is the difference between aluminum molds and steel molds?

• Weight & Rigidity

  Aluminum molds are about 30-50% lighter than steel molds, significantly reducing the workload during mold transport and setup. Their rigidity is slightly lower, making them more suitable for small- to medium-lot production or prototyping rather than mass-produced items requiring high pressure and high shot counts.

• Thermal Conductivity

  Aluminum alloys have high thermal conductivity, which can shorten the cooling cycle. Compared to steel molds, the cycle time can be reduced by 10-20%, leading to improved production efficiency.

• Cost & Lead Time

  Their excellent machinability reduces the man-hours for CNC cutting and electrical discharge machining, allowing manufacturing costs to be suppressed by 20-40% compared to steel molds. The lead time can also typically be shortened to 2-6 weeks.

• Durability

  The durable shot count is typically around 50,000 to 200,000 shots. While this does not match steel molds (several million shots or more), the lifespan can be extended by combining it with the right application, resin type, and re-polishing.

Q2. What is the structure and basic process of an aluminum mold?

1. Design (3D-CAD + CAE)

   The mold base, core/cavity, runner/gate, and cooling channels are designed in CAD. CAE analysis can predict and correct areas prone to wall thickness variations or burrs.

2. Machining (CNC / Electrical Discharge Machining)

   An aluminum block can be machined from roughing to finishing using a CNC milling machine or wire-cut EDM. Tool wear is minimal, allowing for high-precision shaping.

3. Assembly & Prototyping

   The machined parts are assembled, and bushings, guides, and ejector parts are set. In the first prototype, molding conditions can be monitored to check for burrs, shot marks, and dimensional accuracy.

4. Finishing & Maintenance

   Based on the prototype results, fine adjustments can be made with an end mill or a rotary tool, and the surface quality can be improved by polishing with a compound equivalent to #2000 grit.

Advantages & Disadvantages of Aluminum Molds | Aluminum Mold FAQ

Q3. What are the advantages of choosing an aluminum mold?

• Short Lead Time & Cost Reduction

  Man-hours for CNC cutting and electrical discharge machining can be significantly reduced, shortening the manufacturing lead time to 2-6 weeks and achieving a 20-40% cost reduction compared to steel molds.

• Improved Handling Due to Lightweight

  Being about 30-50% lighter, it reduces the workload and installation time during mold changes, thereby suppressing downtime.

• High Thermal Conductivity

  The cooling cycle can be shortened by 10-20%, contributing to improved production efficiency, especially in small-lot and prototyping processes.

Q4. What are the limits of durability and wear resistance?

• Durable Shot Count

  A general guideline is around 50,000 to 200,000 shots. Exceeding this increases the risk of dimensional deviation and burr formation.

• Wear Countermeasures

  When frequently using glass-fiber-filled resins or high-temperature molding, surface hardening treatments or wear-resistant coatings can be considered. Ensuring an appropriate draft angle at the design stage is also important.

Durability Lifecycle Management | Aluminum Mold FAQ

■ Case Examples (Variations in Lifespan)

• Around 1,000 shots: Cases where problems become apparent under high-temperature, high-stress conditions or with complex shapes.
• Over 100,000 shots: Long life can be achieved when molding general-purpose resins at low temperatures with a simple mechanism.

■ Recommended Maintenance Cycle

1. After Initial Prototyping (up to 10,000 shots)

   Check for burrs and shot marks, and make local corrections with an end mill or a rotary tool.

2. Intermediate Inspection (around 50,000 shots)

   Measure dimensional accuracy and surface roughness, and perform polishing with a compound equivalent to #2000 grit.

3. Regular Maintenance (from 100,000 shots onwards)

   Check for wear and cracks using infrared or non-destructive testing, and perform re-polishing or re-coating.

Key Points in Design & Machining | Aluminum Mold FAQ

Q7. What are the precautions for CAD design and CNC machining?

• Avoiding Wall Thickness Variations: Uniform wall thickness can be achieved on CAD, and ribs can be inserted as needed.
• Optimizing Gate Position: The number and position of gates can be determined with CAE, and multiple gates can reduce filling inconsistencies.
• Undercut Countermeasures: A structure incorporating movable pins or slide cores can be designed.
• Setting Machining Tolerances: Tolerances can be suppressed to ±0.02 to 0.05 mm, and process division can be clearly reflected.

Q8. How to optimize cooling channels and draft angles?

1. Channel Placement: Place straight channels on the backside of thick-walled sections to achieve uniform cooling.
2. Setting Draft Angles: Ensure a draft of 1° or more for flat surfaces and 1.5-2° or more for rib sections.
3. Utilizing Simulation: Derive the optimal path and venting through cooling and flow analysis.
4. Maintainability: Design access holes to accommodate flushing for cleaning.

Questions About Cost & Lead Time | Aluminum Mold FAQ

Q9. What is the approximate cost of an aluminum mold?

• Small (up to 200×200 mm): Approx. 200,000 – 400,000 JPY
• Medium (200×200 to 400×400 mm): Approx. 400,000 – 700,000 JPY
• Large / Complex Shape: Approx. 700,000 – 1,500,000 JPY or more

Adding multi-cavities or wear-resistant treatments will increase the cost by 10-20%.

Q10. How can lead time be shortened?

1. Modular Design: Standardize the base part and shorten the time by only replacing the cavity.
2. Concurrent Processes: Run design and machining arrangements in parallel to shorten the period by 10-20%.
3. 3D Printed Prototypes: Reduce rework through mock-up verification, suppressing the number of corrections in the main machining process.
4. Online Reviews: Fix the approval response time to within 24 hours to shorten the lead time by about a week.

Common Troubleshooting Q&A | Aluminum Mold FAQ

Q11. How to deal with molding defects (burrs, shot marks)?

1. Confirm the Location of Occurrence: Visually inspect and feel the surface of the molded part, the runner/gate area, and around the ejector pins.
2. Analyze the Cause: For poor gate sealing, adjust the gap to within 0.02 mm. For cavity wear, re-finish by polishing with #2000 grit.
3. Review Molding Conditions: Control injection pressure within ±10% and mold temperature within ±5°C.
4. Re-prototyping Cycle: Conduct visual inspection and dimensional measurement simultaneously to drive the defect rate down to 5% or less.

Q12. How to handle undercuts and complex shapes?

1. Introduce Movable Cores: Ensure demoldability with movable pin/slide core mechanisms.
2. Multi-split Molds: Split the mold vertically and horizontally for post-molding assembly.
3. Optimize Draft Angles: Ensure a draft of 1° or more for flat surfaces and 1.5-2° or more for undercut sections.
4. Select Resin: Improve release properties with highly self-lubricating resins like POM or PA6.

Case Studies: Success & Failure Stories | Aluminum Mold FAQ

Success Story

• Company: Automotive parts manufacturer A
• Results: Lead time 8 weeks → 3 weeks, Mold cost 10M JPY → 7M JPY (30% reduction), Lead time shortened by 5 weeks (63% reduction)

Failure Story

• Company: Home appliance parts manufacturer B
• Problem: Defect rate of 10% around 60,000 shots due to lack of maintenance, resulting in an additional 2M JPY in correction costs.
• Lesson: An intermediate inspection and re-polishing plan at 50,000 shots is essential.

Conclusion: Next Actions | Aluminum Mold FAQ

This article has covered everything from the characteristics of aluminum molds to design, machining, cost, lead time, troubleshooting, and sustainability in an “Aluminum Mold FAQ” format. For specific consultations or sample requests, please feel free to contact us.

Sources:

• Miyoshi Co., Ltd. Frequently Asked Questions (Aluminum Molds, Simple Molds, Prototype Molds)

  https://www.miyoshi-mf.co.jp/qa/

• Essengold Parts Complete Guide to Aluminum Molds

  https://essengoldparts.com/ja/blog/what-is-an-aluminum-mold/

• Nihon Shinkan Co., Ltd. FAQ & Metal Handling

  https://www.nihonshinkan.co.jp/faq.html