Prototype Plastic Injection Molding​

Characteristics of Aluminum Molds：
Lightweight
 The lower density of aluminum alloy makes the mold lightweight and easy to process, transport, and assemble.
 It reduces the need for injection molding machine tonnage and lowers the cost of using processing equipment.
High thermal conductivity
 Aluminum alloys have excellent thermal conductivity, which significantly reduces cooling time and improves injection molding productivity.
 This is particularly advantageous for rapid molding and short-cycle production.
Easy Machinability
 Aluminum is a softer material, making it easier for CNC machining, cutting, drilling, and other operations.
 The production cycle is short, usually only 3-10 days to complete the mold.
Cost Advantage
 Production costs are lower than steel molds, making it suitable for small-batch production projects with limited budgets.
 Complex heat treatment and hardening processes are not required, further reducing production costs.
Good surface finish
 The surface of aluminum is easy to be polished, sandblasted, anodized, etc., which can meet certain appearance requirements.

Advantages of Aluminum Molds:
Short production cycle
 From design to delivery, aluminum molds typically take only 3 days to 2 weeks, which is faster than traditional steel molds.
Affordable
 Suitable for small batch or ad-hoc production needs, it can significantly reduce initial development costs.
Flexible
 The mold structure can be easily adjusted, which is suitable for a rapid iterative product development process.
Suitable for a wide range of products
 Complex shapes or thin-walled parts can be produced to meet diversified product design requirements.
Easy maintenance
 Aluminum mold surface treatment is simple, with a low maintenance cost.

Disadvantages of Aluminum Molds:
Short service life
 Aluminum alloy has low hardness and abrasion resistance. Usually can only withstand 500-10,000 injections, which cannot meet the demand of mass production.
Poor heat resistance
 Aluminum has limited ability to withstand high temperatures, and prolonged high-temperature injection may lead to mold deformation.
Insufficient strength
 For products that require high strength or ultra-high pressure injection (e.g. glass fiber reinforced plastics), aluminum molds may not be suitable.
Limited precision
 Although aluminum molds can achieve higher precision, the tolerance control ability is still slightly inferior compared to high-end steel molds.

Scenarios for Aluminum Molds:
Prototype development
 Verify the feasibility of the design and quickly generate samples for testing.
Small batch production
 Meet the production demand of tens to thousands of pieces, suitable for trial production and market testing stage.
Product Verification
 Produce samples close to mass production for functional verification or appearance demonstration.
Short lead time projects
 Apply to production tasks with tight delivery times to support quick turnaround.

flexible steel mold

Characteristics of Soft Steel Molds:
Moderate strength
 The material hardness is usually between 28-32 HRC, which can meet the needs of medium-volume injection molding (5,000 to 50,000 cycles).
 Easier to work with than hard steel molds, able to withstand a certain level of strength and pressure.
Better abrasion resistance
 Soft steel has better wear resistance than aluminum molds, making it suitable for longer cycle times.
Moderate cost
 Lower cost compared to hard steel molds, but significantly higher strength and service life than aluminum molds, suitable for medium production projects with limited budgets.
Easy to modify
 The high toughness of the material allows the mold to be easily processed and adjusted after the mold trial, supporting design optimization.
Versatility
 Can be used to make complex structures or multi-cavity molds to meet a wide range of product needs.

Advantages of Flexible Steel Molds:
Longer life
 Typically supports tens of thousands of injection cycles, making it suitable for medium-volume production needs.
Moderate cycle time
 The processing speed is faster than that of hard steel molds. But slightly slower than that of aluminum molds, with a general production cycle of about 2-4 weeks.
Cost-effective
 The balance between strength, life, and cost. It is especially suitable for function testing, trial production, and some mass production projects.
Suitable for a wide range of plastics
 Adaptable to injection molding of most engineering plastics, including ABS, PC, PP, etc.
Higher precision
 Compared with aluminum molds, flexible steel molds can achieve higher dimensional accuracy and surface finish.

Disadvantages of Soft Steel Molds:
Limited hardness
 Weak for ultra-high-pressure force injection molding or processing of glass-fiber-reinforced materials
Poor corrosion resistance
 Prone to rust in high humidity or acidic environments, requiring regular maintenance and the application of rust inhibitors.
Heavyweight
 Heavier than aluminum molds, resulting in higher transportation and assembly costs.
Longevity is not as good as hard steel molds
 Cannot support long-term mass production needs. Not suitable for projects with more than one million cycles.

Common Materials for Soft Steel Molds
P20 steel
 Commonly used low hardness mold steel, hardness in 28-32 HRC, suitable for medium volume production.
 Good workability, moderate wear resistance, cost-effective.
718 steel
 Chromium-containing mold steel has good wear resistance and corrosion resistance.
 Commonly used in demanding injection molds, such as transparent parts, and precision parts.
S50C steel
 A carbon tool steel that is inexpensive but less durable.
 Suitable for short-term use or low-budget projects.
NAK80 Steel
 Highly polished steel is suitable for products requiring a high surface finish, such as cosmetic housings.

Comparison of Soft Steel Molds with Other Molds

3D Printing Molds

Features of 3D Printed Molds:
High flexibility
 Complex geometric shapes can be printed with a high degree of design freedom, enabling the realization of structures that are difficult to manufacture by traditional processing methods, such as internal cooling channels and lightweight design.
Short production cycle
 Usually, 1-3 days to complete the mold manufacturing, compared with the traditional mold to save a lot of time.
Low cost
 Especially suitable for small batches or one-time production, avoiding the high upfront investment of traditional molds.
Material Diversity
 Plastic, photosensitive resin, metal powder, and other materials can be used to adjust the performance of the mold according to the demand.
Suitable for verification design
 Prototype molds can be made quickly for product design verification or small-lot trial production.

Advantages of 3D Printed Molds:
Rapid Manufacturing
 From design to molding in hours to days, suitable for rapid iteration and validation.
Low Cost
 Eliminates the need for expensive traditional mold steel and machining equipment, making it particularly suitable for low-volume production and experimental projects.
Complex Structure Manufacturing
 Easy implementation of internal structures, shaped surfaces, and functional optimization such as hydrodynamic cooling channels.
Reduced material waste
 Additive manufacturing uses only the materials needed and is more environmentally friendly than traditional cutting processes.
Design optimization support
 Flexibility to modify mold designs as needed during production to quickly adapt to changes in demand.

Disadvantages of 3D Printed Molds:
Shorter lifespan
 Compared with traditional steel molds, 3D-printed molds are less durable and are not suitable for prolonged use under high pressure and high temperatures.
Limited load-bearing capacity
 Especially molds made of plastic or resin are easy to be deformed or damaged in the process of injection or die-casting.
Limited precision and surface quality
 The texture of the printed layer may require additional processing, and the surface finish is not as good as traditional molds.
Material limitations
 Although metal 3D printing technology is available, the cost is high, and common resin or plastic molds are limited in their applicability.
Insufficient batch capacity
 Suitable for small batch trial production or validation, but not suitable for long-term mass production.

Material Selection for 3D Printing Molds:
Photosensitive resin
 Suitable for small batch injection molding test or verification, with better molding accuracy and detail performance.
Plastic (e.g. PLA, ABS)
 Molds printed using FDM technology, low cost, but lower heat resistance and strength.
Metals
 Molds printed using metal powder (e.g. stainless steel, aluminum alloy) are suitable for high strength and high precision needs, with higher cost.
Composite Materials
 Printing molds through reinforced plastic or composite materials for enhanced durability and functionality.

Comparison of 3D Printed Molds and Traditional Molds:

Silicone Mold

Features of Silicone Molds:
High flexibility and malleability
 Silicone material has good flexibility and ductility. And can accurately replicate the details of the surface of the mother mold, suitable for complex geometric shapes.
High temperature resistance and chemical stability
 High-quality silicone molds are typically resistant to high temperatures (-60°C to 250°C) and are resistant to most chemicals.
Low cost
 Low production costs make them particularly suitable for small-lot production and rapid prototyping.
Short production cycle
 The production process is simple, usually 1-3 days to complete the mold production and put it into use.
Wide range of applications
 Can be used for molding a wide range of materials, including resins, polyurethane, wax, low melting point metals, etc.

Advantages of Silicone Molds
Simple manufacturing
 Simple manufacturing process, no need for complex equipment or processes.
Low-cost adaptability
 Ideal for small batch production or rapid prototyping, with significant savings in development costs.
High Reproduction Accuracy
 Can accurately reproduce the details of the master mold, including minute textures and complex structures.
Flexible
 Easy to release the mold, avoiding damage to the finished product.
Wide choice of materials
 Can be used for molding a wide range of materials such as resin, polyurethane, gypsum, and low melting point metals.

Disadvantages of Silicone Molds:
Short service life
 Compared with metal molds, silicone molds have a shorter wear resistance and life span. And generally can only produce dozens to hundreds of products.
Limited mechanical properties
 Silicone molds have low hardness and strength, making it difficult to withstand high-pressure or high-temperature injection molding.
Insufficient dimensional stability
 Silicone molds are prone to deformation due to repeated use, affecting the dimensional accuracy of products.
Sensitive to the environment
 Silicone materials are susceptible to humidity and temperature and need to be stored under suitable conditions.

Silicone Mold Material Selection:
Transparent Silicone
 For high precision molds and visual mold applications.
High Hardness Silicone
 Provides better abrasion resistance and dimensional stability, and is suitable for small-batch production.
Food Grade Silicone
 Used for food mold making, such as chocolate and cake molds.
Industrial Silicone
 Suitable for industrial parts production, such as automobile parts, seals, etc.

Epoxy resin mold

Characteristics of Epoxy Resin Molds:
High strength and wear resistance
 The epoxy resin hardens to form a hard surface that can withstand high mechanical stress, suitable for complex processes and long-time use.
Good chemical resistance
 Resistant to acid, alkali, and most chemical solvents, especially suitable for resin impregnation molding of composite materials.
Excellent thermal stability
 Epoxy resin molds can withstand high temperatures (usually 120°C-180°C, special epoxy can withstand up to 250°C), suitable for the hot press molding process.
High dimensional accuracy
 Low curing shrinkage (usually less than 1%) maintains the detail and shape accuracy of the master mold.
High surface smoothness
 The surface of the mold can be polished to a mirror effect, which helps to improve the quality of the finished product and the release effect.

Advantages of Epoxy Resin Molds:
Relatively low manufacturing cost
 Lower cost than metal molds, suitable for small lot production and prototyping.
Lightweight
 Compared to metal molds, epoxy resin molds are lighter in weight, making them easier to handle and manipulate.
High corrosion resistance
 Resistant to a wide range of chemical solvents and materials, extending the life of the mold.
High processing flexibility
 Mold properties can be adjusted with fillers or other reinforcing materials to meet a wide range of process needs.
Rapid molding capability
 Short production cycle, suitable for rapid response to market demand.

Disadvantages of Epoxy Resin Molds:
Limited durability
 Compared with metal molds, epoxy resin molds are less resistant to impact and abrasion. And are suitable for small and medium-sized mass production.
Lower thermal conductivity
 Thermal conductivity is lower than metal molds, which may reduce productivity in certain heating processes.
High demolding requirements
 It is easy to damage the surface of the mold when demolding, so it is necessary to use a high-quality mold release agent.
Easy to deform in large size
 Large-size molds may be deformed under stress or a high-temperature environment.

Care and Maintenance of Epoxy Resin Molds:
Clean the surface
 Clean the surface of the mold after each use to avoid residue damage to the mold.
Regular Inspection
 Inspect the mold regularly for cracks, deformation, or wear.
Use of mold release agent
 Apply the release agent evenly before each use to reduce damage to the mold surface.
Storage environment
 Store the mold in a dry and cool place, avoid direct sunlight or a high-temperature environment.
Repair and Renovation
 If the mold is damaged, it can be repaired with epoxy resin material to prolong the service life of the mold.

Comparison table of the number of times the mold is used

Mould Type	Manufacturing Cycle	Number of Times Used	Applicable Scenarios
Aluminum Mold	5-15 days	About 500-1000 times	Suitable for small batch production or prototype development, less frequent use, suitable for rapid prototyping.
Flexible Steel Mold	10-30 days	About 5000-10000 times	Suitable for small and medium-sized batch production, longer service life, suitable for mass production with medium precision requirements.
Silicone Mold	2-7 days	About 10-50 times	Suitable for rapid prototyping, small batch production or artwork, etc. Limited use, easily damaged, suitable for parts with complex shapes.
3D Printing Molds	1-7days	About 10-100 times	Suitable for low volume production, prototyping or complex shaped parts, but poor durability and not suitable for long term use.
Epoxy resin mold	5-10days	About 100-500 times	Applicable to small and medium-sized mass production, higher precision, relatively more frequent use, but still less durable than metal molds.

 

How to Choose the Best Suitable Injection Mold?

Sample Quantity

choose 3D printing mold or silicone mold for small quantity; choose aluminum mold or soft steel mold for medium quantity.

Product Requirements

Aluminum or soft steel molds for high precision and surface finish.

Time cost

when time is tight, choose 3D printing mold or silicone mold.

Budget constraints

when low budget, choose epoxy resin or silicone mold.

It should be noted that the selection of all injection molding prototypes should first refer to the product's own requirements and price, the combination of the two in order to select the most suitable prototype molds