4 solutions for injection molding in China 2025

 

4 solutions for injection molding  China in 2025

1, Filling the defect

It always shows incomplete filling or edge collapse. It will decide on a product, waste material, labor, and time. There is much possible reason: Such as nozzle temperature is too low, not enough supply, flowability not good. The injection pressure is low. The gate is too small or not right position, the mold surface is injection mould companies not smooth enough. The nozzle is blocked, venting problem

2, Flash or burr

It always happens in the parting line. It will increase the difficulty of machining or shape, even defective. The possible reason such as nozzle temperature too high, injection too much material, flowability is very good. Injection pressure too high, clamping force too small

3, Sink mark

It always caused by material shrink after injection molding. The possible reason such as nozzle temperature too high, resin supply not enough, shrinkage is too big. Injection molding pressure too low, holding time too short, injection speed too slow, mold temperature to plastic molding company high, cooling time too short, the thickness of the product is uneven, gate too small

4, Welding line

It always happens in a product that has holes or another shape. The possible reason such as nozzle temperature too low, the material is not dry up enough, injection speed is too slow, gate too small, venting is not good. Injection pressure too low or other reason

4 solutions for injection molding：

As we can see the types and causes of injection molding defects, almost every kind of defect is formed by the combined effects of many factors. All these reasons are performance and molding machines, molding material character, mold design structure and material, filling control systems, and injection molding plastics different operating processes related. Although injection molding technology development in some areas is very quick, technology is relatively mature. But accompanied by increasing difficulty defect control, which requires us to reduce and Troubleshoot plastic injection molding defects with the help of advanced theory and advanced technology tools.

 

The Irreplaceable Advantages of China's Precision Injection Molding Industry Amid Global Tariff Changes

 The U.S. tariff hikes and rising global trade barriers have forced manufacturers to reconsider their supply chains. However, Chinese precision injection molding companies like CNMOULDING remain indispensable in global competition due to their complete supply chain, advanced technology, rapid response capability, and significant cost advantages.

1. Highly Efficient Integrated Supply Chain

China boasts the world's most comprehensive plastic processing ecosystem, covering everything from mold steel and precision CNC machining to injection molding and surface treatment. Companies like CNMOULDING leverage industrial clustering to deliver precision molds in just 3-4 weeks, compared to over 8 weeks for most Western manufacturers.

2. Technological Leadership in High-End Markets

China's injection molding industry has evolved from low-cost manufacturing to producing high-precision, complex plastic components. For example, CNMOULDING's expertise in microcellular foaming, multi-material molding, and optical-grade plastic molding serves high-value industries like automotive and medical devices, matching global leaders in technology.

3. U.S. Manufacturing Shortcomings: Long Lead Times & High Costs

• Development cycle: U.S. mold production takes 2-3 months, while Chinese suppliers like CNMOULDING can complete it in under a month.
• Production costs: China’s total costs (labor, energy, and supply chain) are just 30%-50% of U.S. costs.
• Flexible production: Companies like CNMOULDING support rapid small-batch, multi-variant production to meet dynamic market demands.

4. Strategic Response: High-End Innovation + Global Expansion

• Technology upgrade: Focus on medical-grade and automotive-grade precision molding for higher margins.
• Overseas production: Establish factories in Mexico and Southeast Asia to bypass tariffs while maintaining China’s core supply chain advantages.

Conclusion

While global tariffs increase trade costs, China’s precision injection molding industry—with its unbeatable combination of technology, speed, and cost—remains the optimal choice for international brands. Leading firms like CNMOULDING are reinforcing their irreplaceable position through innovation and strategic global expansion.

The factors affect the percentage of regrind materials

 The factors affect the percentage of regrind materials

The factors affect the percentage of regrind materials

The factors affect the percentage of regrind materials

1, The purpose: In order to control and improve the quality of plastic parts, reduce the cost of plastic parts and injection molding plant regrind materials management, to meet customer technical requirements.

2, The scope: for the injection of all of the Company ABS, PA66, PA6, PP plastic parts, and workshop back to powder, processing, storage, labeling, and other management regulations.

3, Regrind material recovery and grade classification

1, Recyclable materials:

A.Defective products produced during injection molding (such as scratches, incomplete, burr) and other defective products.

B, injection molding process generated in the runner compound (nozzle material).

C, other (such as: engineering testing and other models can not be shipped demolition of plastic pieces or scrap pieces).

2, Regrind materials level:

A, The first regrind materials: the new material produced by the first injection of plastic.

B, The second regrind materials: after the second injection of plastic produced.

C, The third regrind materials: the second or more (including three) after injection of plastic and scrap.

The bulk density of the regrind is probably the single biggest factor affecting how much regrind one can use.

If you are using a recycled film scrap that hasn’t been densified then you pay a tremendous penalty in your rate. There are densifiers like a Munchy that will compact the film scrap to something close to a virgin pellet. In this case, then you can use quite a bit of scrap – 20 – 30%.

Another thing affecting your percentage of regrind is the use of grooved feed sections for extruders. They really are not designed for anything but pelletized material. It is best not to use more than 5% regrind if you have a grooved feed otherwise the grooves will clog and production rate will drop significantly and product quality will also suffer.

In blow molding, for instance, it is not uncommon for bottlers to use 35% regrind as the moels and tails comprise a considerable amount of material in relationship to the end product. That stuff is usually compressed and put back in the hopper.

Pre-hot runner systems had a lot of regrind as dense material sitting in the runners and gates was recycled. Those rates were quite high. I have seen that as high as 50%.

The other points are quite well such as contamination from streams and other things that need to be considered. In the end, I would say there is NO rule of thumb it greatly depends on so many factors.

There is no 1 rule of thumb. It will depend on several elements;

What type of Polymer and how they degrade (heat stability and moisture content)

whether filled and type of filler. Glass length will degrade making more brittle, lower modulus

whether it is a blend, PC: PBT interact with each other (transesterification)

can you add heat stabilizers, can increase the level of regrind

what kind of shear are you putting into the mix

you won’t try to color match or all bets are off on color stability

Ultem PEI is great, but high heat, I’ve seen >50% regrind work fine, unfilled PP of PE can go a long way with the addition of phosphate/phenol stabilizers.

The importance of packaging for plastic products

 In today's world, plastic products have become an integral part of our lives. From household items to industrial tools, plastics are used in almost every sector. However, with the increasing use of plastic products, the importance of packaging has also increased significantly. Packaging plays a crucial role in protecting and preserving plastic products throughout the supply chain. In this blog post, we will discuss the importance of packaging for plastic products.

 

Firstly, packaging helps to protect plastic products from damage during transportation and storage. Plastic products are often fragile and can easily get damaged if not handled carefully. Proper packaging ensures that the products are protected from moisture, dust, and other external factors that can cause damage. Moreover, packaging also helps in reducing the risk of theft and tampering during transportation.

 

Secondly, packaging helps to preserve the quality of plastic products. Plastic products are susceptible to degradation over time due to exposure to light, heat, and moisture. Proper packaging helps to prevent these factors from affecting the products and ensures that they remain in good condition for a longer period. This is particularly important for plastic products that have a longer shelf life, such as medical devices and electronic components.

 

Thirdly, packaging plays a vital role in branding and marketing plastic products. The packaging design and quality can significantly impact the consumer's perception of the product. A well-designed and high-quality packaging can create a positive impression on the consumer and increase brand loyalty. Moreover, packaging can also be used as a tool for differentiation in a highly competitive market.

 

Fourthly, packaging helps to reduce the environmental impact of plastic products. Plastic waste is a significant environmental concern, and proper packaging can help to reduce the amount of plastic waste generated. Packaging that is reusable or recyclable can significantly reduce the environmental impact of plastic products. Moreover, packaging can also be designed to use fewer materials, thereby reducing the overall carbon footprint of the product.

In conclusion, packaging is an essential aspect of plastic products that should not be overlooked. Proper packaging helps to protect and preserve the quality of plastic products, enhances branding and marketing efforts, and reduces the environmental impact of plastic waste. As such, businesses that deal with plastic products should give due consideration to packaging design and quality to ensure that their products are well-protected and marketed effectively.

Advanced Plastics: Driving Innovation and Sustainability in New Energy Vehicles

 The global shift towards sustainable energy sources has propelled the popularity of new energy vehicles (NEVs), which rely on electricity or alternative fuels. This transition has introduced new demands for materials used in their manufacturing, with plastics emerging as a critical component due to their lightweight and durable properties. However, traditional automotive plastics fall short of meeting the unique requirements of NEVs, which necessitate materials that are not only lightweight and durable but also resistant to high temperatures and possess superior electrical insulation properties. Such advanced plastics are vital for ensuring the functionality, safety, and efficiency of NEVs.

Advantages of Plastics in New Energy Vehicles

1. Weight Reduction: Plastics significantly reduce the overall weight of vehicles, enhancing energy efficiency and extending the driving range.
2. Cost Efficiency: The use of plastics lowers production costs, making NEVs more affordable for consumers.
3. Design Flexibility: Plastics enable the creation of complex shapes and structures that are unachievable with traditional materials, fostering innovation in vehicle design.

Key Requirements for Plastics in NEVs

To meet the stringent demands of NEVs, manufacturers are developing specialized plastics with the following properties:

• High Strength: Ensures durability and longevity.
• Thermal Stability: Withstands high temperatures, particularly in battery systems.
• Electrical Insulation: Prevents electrical interference and enhances safety.
• Recyclability: Supports sustainability by reducing environmental impact.

Prominent Plastics for NEVs

1. Polyamide 6 (PA6):

• Properties: High mechanical strength, excellent thermal stability, and superior electrical insulation.
• Applications: Ideal for battery packs and other high-temperature components due to its lightweight and heat-resistant nature.

1. Polyphenylene Oxide (PPO):

• Properties: Exceptional electrical insulation, thermal stability, chemical resistance, and UV radiation resistance.
• Applications: Suitable for various NEV components, ensuring durability and safety under harsh conditions.

Conclusion

The rise of new energy vehicles has redefined the role of plastics in the automotive industry. Advanced plastics that combine lightweight properties, durability, thermal stability, and electrical insulation are indispensable for the performance and safety of NEVs. By developing sustainable and environmentally friendly plastics, manufacturers are not only meeting the evolving demands of the industry but also contributing to the broader goals of energy efficiency and affordability. The integration of these innovative materials will continue to drive the growth and adoption of new energy vehicles worldwide.

automotive part

 

Plastic Injection Molding in China

CNMOULDING is a leading supplier and manufacturer of plastic injection molded products, specializing in the automotive and general industry areas. Manufacture. We are certified ISO9001-2015 certificate. We have a professional engineer team to assist our customers to develop their products and tools, with over 100 engineers with more than 10 years of experience. Now we are the leading supplier of plastic injection mold in Shanghai China.

China is one of the largest and most dynamic markets for automotive parts manufacturing, supplying both domestic and international automotive industries.   The country has a well-established supply chain, advanced manufacturing capabilities, and a growing focus on innovation, particularly in the electric vehicle (EV) sector.   Below is an overview of automotive parts production in China, key players, and trends shaping the industry.

 

Key Automotive Parts Produced in China

China manufactures a wide range of automotive components, including:

 

1.   Engine Components

Cylinder heads, pistons, crankshafts, and camshafts.

Turbochargers and fuel injection systems.

 

2.   Transmission and Drivetrain Parts

Gearboxes, clutches, and drive shafts.

Differential systems and axles.

 

3.   Electrical and Electronic Components

Sensors, control units, and wiring harnesses.

Infotainment systems and displays.

 

4.   Chassis and Suspension Parts

Shock absorbers, springs, and steering systems.

 Brake systems (discs, pads, and calipers).

 

5.   Body and Interior Parts

Sheet metal components, bumpers, and doors.

 Seats, dashboards, and trim panels.

 

6.   Lighting Systems

LED headlights, taillights, and interior lighting.

 

7.   EV-Specific Components

Battery packs, battery management systems (BMS), and electric motors.

 Charging ports, inverters, and power electronics.

Advantages of China’s Automotive Parts Industry

1.   Cost Efficiency: Lower labor and production costs compared to many other countries.

2.   Scale and Capacity: Massive production capacity to meet both domestic and global demand.

3.   Supply Chain Integration: A well-developed supply chain with access to raw materials and components.

4.   Government Support: Strong government backing for the automotive industry, particularly for EVs and new energy vehicles (NEVs).

5.   Technological Advancements: Increasing investment in R&D, particularly in EV and autonomous driving technologies.

Trends Shaping the Industry

1.   Electric Vehicle (EV) Boom

China is the world’s largest EV market, driving demand for EV-specific components like batteries, motors, and power electronics.

The government’s push for NEVs (New Energy Vehicles) has accelerated innovation and production.

 

2.   Localization of Supply Chains

International automakers are increasingly sourcing parts locally to reduce costs and comply with Chinese regulations.

Domestic suppliers are expanding their capabilities to meet global standards.

 

3.   Smart and Connected Vehicles

Growing demand for advanced driver-assistance systems (ADAS), sensors, and connectivity solutions.

Chinese companies are investing heavily in autonomous driving technologies.

 

4.   Sustainability and Green Manufacturing

Emphasis on reducing emissions and adopting eco-friendly production methods.

Increasing use of lightweight materials like aluminum and advanced plastics to improve fuel efficiency.

 

5.   Digitalization and Industry 4.0

Adoption of smart manufacturing technologies, such as AI, IoT, and robotics, to improve efficiency and quality.

Digital platforms for supply chain management and production optimization.

 

6.   Export Growth

Chinese auto parts suppliers are expanding their presence in international markets, particularly in Southeast Asia, Europe, and North Americ

injection moulding sink mark

 In plastic injection molding, a sink mark is a surface defect that appears as a depression, dimple, or dent on the surface of a molded part. It typically occurs in thicker sections of the part or near features like ribs, bosses, or other areas where there is a significant variation in wall thickness. Sink marks are caused by uneven cooling and shrinkage of the plastic material during the molding process.

 

Causes of Sink Marks

1. Material Shrinkage:
As the molten plastic cools and solidifies, it shrinks. If the outer surface cools and hardens faster than the inner material, the inner material continues to shrink, pulling the surface inward and creating a sink mark.

2. Insufficient Packing Pressure or Time:
During the holding/packing phase, additional material is pushed into the mold to compensate for shrinkage. If the packing pressure or time is too low, the material shrinks excessively, leading to sink marks.

3. Thick Sections:
hicker areas of the part cool more slowly, increasing the likelihood of shrinkage and sink marks.

4. High Melt Temperature:
Higher melt temperatures can increase the material's shrinkage as it cools, contributing to sink marks.

5. Improper Gate Location or Size:
If the gate (the entry point of molten plastic into the mold) is too small or poorly located, it may restrict material flow, preventing adequate packing and causing sink marks.

6. Material Properties:
Some materials, especially semi-crystalline plastics (e.g., polypropylene, nylon), have higher shrinkage rates and are more prone to sink marks.

 

How to Identify Sink Marks

Sink marks are visible as shallow depressions on the surface of the part.

They are most common in areas with thicker walls or near structural features like ribs, bosses, or mounting points.

 

How to Prevent Sink Marks

1. Optimize Part Design:
Maintain uniform wall thickness throughout the part.
Use ribs or coring to reduce material volume in thick sections.

2. Adjust Process Parameters:
Increase holding/packing pressure and time to ensure adequate material packing.
Optimize cooling time to allow uniform cooling of the part.
Reduce melt temperature to minimize shrinkage.

3. Improve Mold Design:
Position gates near thick sections to ensure proper material flow and packing.
Optimize cooling channels to ensure even cooling, especially in thick areas.

4. Select Appropriate Materials:
Use materials with lower shrinkage rates, such as amorphous plastics (e.g., ABS, PC).
For crystalline plastics, consider using filled or reinforced materials to reduce shrinkage.

 

Corrective Actions for Existing Sink Marks
Increase holding pressure and time.
Reduce melt temperature.
Extend cooling time.
Modify part design to reduce wall thickness or add coring.
Adjust gate size or location.

 

By addressing these factors, sink marks can be minimized or eliminated, resulting in higher-quality injection-molded parts.