How to Address the Issue of Thin and Easily Broken Ejector Pins in Injection Molds

 1. Optimize the Ejection Process  

Adjust ejection parameters to minimize stress on delicate ejector pins.  

Reduce ejection speed: Excessively high ejection speeds generate significant impact forces, increasing the risk of breakage in thin ejector pins. A moderate reduction in speed can mitigate this risk.  

Implement multi-stage ejection: Utilize the multi-stage ejection capability of the injection molding machine. Initiate the first stage at a low speed and short stroke to release vacuum adhesion, followed by standard ejection in the second stage. This approach effectively reduces peak impact loads.  

Verify ejection stroke: Ensure the stroke is precisely calibrated to fully eject the part without over-extension, which may cause the ejector pin to lose guidance support and become unstable.  

Maintain proper lubrication: Regularly apply high-temperature mold release oil to the ejector pins to minimize friction between the pins and the mold core.

2. Revise Mold Design  

The most effective and long-term solution is to replace fragile, undersized thimbles with larger-diameter counterparts.  

This modification requires adjustments to the hole positions in both the mold core and the ejector plate. Although this involves higher initial costs, it provides a durable and reliable resolution.

3. Modify Ejection Methodology  

When spatial constraints prevent increasing the pin diameter, alternative ejection mechanisms should be considered.  

Use flat thimbles: In narrow regions such as rib areas, flat thimbles offer a greater cross-sectional area and superior resistance to bending compared to round thimbles.  

For boss columns with high shrinkage forces, employ stripper pins, which provide a broader and more uniform ejection surface.  

For deep cavities or thin-walled parts, consider air-assisted ejection systems. These introduce compressed air from within the cavity to disrupt vacuum formation, significantly reducing demolding resistance.  

Apply push plate ejection: For large, deep-container components, push plates offer full-surface contact, distributing ejection force evenly and minimizing localized stress compared to point-contact ejector pins.

4. Enhance Mold Structural Integrity  

Incorporate guide pillars: Install guide sleeves on the ejector plate to ensure precise alignment and smooth movement of the ejector system, thereby preventing lateral shear forces due to misalignment.  

Polish ejector pin bores: Inspect and refinish worn pin holes to reduce friction and improve operational smoothness.  

Inspect for and correct undercuts: Conduct a thorough mold inspection to identify any unintended undercuts that may contribute to excessive part retention force, and rectify them accordingly.

What Causes Corrosion in Metal Inserts within Plastic Products?

 Environmental Factors

Exposure to certain environments is the most common cause of corrosion.

Moisture/Humidity: The presence of water triggers the oxidation of iron (rust). In humid conditions, moisture condenses on the metal surface, initiating corrosion.

Chlorides: Exposure to salt (e.g., from coastal air, sweat, or deicing salts) drastically accelerates corrosion, causing severe "salt-induced rusting."

Acids/Alkalis: Contact with cleaning agents, sweat, or industrial chemicals can break down the metal's protective surface layer, increasing corrosion risk.

Insert-Specific Factors

The metal's inherent properties are critical.

Material: Carbon steel rusts easily unless protected. Some stainless steel grades (e.g., low-quality types) may still corrode in harsh environments.

Surface Coating: A lack of coating, or a poor-quality one (e.g., thin, porous plating like zinc or nickel), provides inadequate defense. Damage during handling also creates weak points for rust to start.

Design & Manufacturing Factors

The integration and assembly process plays a key role.

Residual Stress from Molding: The high heat of insert molding and subsequent cooling can create internal stress in the metal, making it more prone to "stress corrosion."

Over-Tightening during Assembly: Excessive force can strip protective coatings and create micro-cracks, offering a path for corrosion.

Galvanic Corrosion: If the insert contacts a different metal (e.g., an aluminum part) in a moist environment, an electrochemical reaction can rapidly corrode the less noble metal.

IV. Other Influences

Additional factors can contribute to the problem.

Plastic Properties: Some plastics (like PVC) can release acidic substances over time, which may slowly attack the metal.

Storage/Transport: Damp warehouses or inadequate packaging can expose products to moisture long before they reach the end user.

Summary of Mitigation Strategies

Material Selection: Choose appropriate corrosion-resistant alloys, such as 304 or 316 stainless steel, for the expected environment.

Surface Treatment: If using carbon steel, apply high-quality coatings like Dacromet or zinc phosphating, which are superior to standard electroplating.

Process Control: Optimize molding and assembly processes to minimize residual stress and avoid damaging the inserts.

Environmental Management: Control storage humidity and use protective packaging to limit exposure to moisture.

Overcoming Smart Bracelet Screw Corrosion: A Targeted Solution

 A smart bracelet we produced for a quality-focused Italian client recently faced a critical test: embedded metal screws began to rust during use. This issue, while seemingly small, compromised both the product's appearance and its long-term reliability.

Screw corrosion is a common challenge in wearables, typically resulting from a combination of factors:

Sweat Exposure: Frequent contact with skin exposes the screws to sweat, whose moisture and salts steadily corrode any weak points in the metal's protection.

Material Vulnerability: Previously used carbon steel screws with electroplated zinc were cost-effective, but the coating could be thin or easily damaged, allowing sweat to penetrate and cause rust.

Manufacturing Stress: The high heat of the molding process creates residual stress in the screws as the plastic cools, making the metal more prone to corrosion.

Implemented Solutions:

Improved Mold Design: We redesigned the mold to ensure the plastic encapsulates the screw more completely, minimizing its exposure to air and moisture.

Superior Screw Material: We replaced the carbon steel with AISI 304 stainless steel, which has a self-repairing protective oxide layer that resists sweat and corrosion.

Better Plastics: We switched to more stable, less moisture-absorbent engineering plastics to reduce the corrosive elements in the immediate environment.

We thank our client for their valuable feedback. This solution underscores our commitment to continuous improvement and delivering durable, high-quality products.

plastic bar handle

 

• Plastic Handle and Plastic Bar
• Price:2USD/SET
• Delivery Time within 30 days, 100K
• Product description: Cn-moulding has 10 years of experience produce plastics handle and plastic bar mold and parts in china. It through injection molding and ultrasonic welding technic

The development of the Chinese fitness equipment industry began in the 20th century in the late 1980s. With China’s accession to WTO and the success of Beijing’s bid for the development of the fitness equipment industry. Providing favorable conditions and opportunities for development, customer demand for plastic products, rapid growth.
Such as various types of plastic handle plastic bar.

China’s fitness equipment industry in the rapid development of a number of issues is increasingly apparent. Especially the lack of well-known brands in the international market, low value-added products. While compared with the international advanced level, many Chinese injection molds and plastic products manufacturing enterprises are still in the generic production stage. A lack of product development and technological innovation. In the consumer area, compared with Europe and other developed countries, fitness equipment products in household penetration and per capita consumption is still very low for fitness. Fitness equipment, plastic products in the Chinese market is still small.

Therefore, Chinese enterprises must seize the new injection mold development situation, increase scientific and technological innovation, and strive to improve the quality of plastic products, strengthening R & D capabilities and strengthen after-sales service. The only way to be invincible in the new situation.

CNMOULDING focus on all kinds of fitness equipment, plastic molds, and plastic products, we as supporting long-term supplier for many famous foreign companies supporting the production of sports equipment, all kinds of plastic molds and related plastic products If you need our help, please immediately contact our sales manager.

What is injection Moulding used for?

 

Plastic Injection Molding service

The process can produce precise complex plastic products action of a gram to more than a hundred
kilograms, in virtually any plastic material. The process starts with feeding small plastic beads into a
heated screw and barrel system that melts the plastic into a high–viscosity liquid. The screw then
forces the molten plastic into a closed mold that provides the shape, cooling, and solidification, and
finally ejects the part. China Injection molding is fast and can be economical. But because every part
needs its own costly injection molding tool, the process is economically viable only for mass production,
usually more than 10,000 parts.

China Injection molding tools take weeks to build. Often, design mistakes become apparent, requiring
time–consuming mold corrections. Multiple iterations may go from the producer to the tool builder until the final
part design and quality are achieved, increasing costs and product time to market.

What is injection Moulding used

Plastic Injection molding is a method of producing parts with a heat-melt able plastics material.

 This is done by the use of a plastic injection molding machine. The shape which is produced is controlled by
what is called a “mold china” The plastic injection molding machine has two basic parts; the injection unit,
which melts the plastic and then injects or moves it into the mold, and the clamping unit, which holds the
mold. The unit clamps the mold in a closed position during injection, opens the mold after cooling, and ejects the finished part.

 Materials  can be used in a process called china injection molding

 These are thermoplastics such as polystyrene, nylon, polypropylene, and polythene – this means when
they are heated and then pressured in a mould they can be formed into different shapes. China injection
molding unit seen opposite has been made in one piece using this process An animation of an injection
moulding process is shown below. Injection moldings count for a significant proportion of all plastics
products from micro parts to large components such as bumpers and wheelie bins.  Virtually all sectors
of manufacturing use injection molded parts – the flexibility in size and shape possible through the use
of this process have consistently extended the boundaries of design in plastics and enabled the significant
replacement of traditional materials thanks to light-weighting and design freedom.  The table below shows
the type of products that can be injection moulded but is by no means comprehensive.

Plastic Injection Molding service industry include following

 1,Assemblies

2,Consumer Products
 3,Containers
 4,Medical / Dental Disposable
 5,Electrical / Computer Parts
 6,Food & Beverage
 7,Insertion Molding
 8,Living Hinge

List products that have been manufactured through injection moulding. Reference article for china injection molding companies 

china plastic injection molding

 

 China plastic injection molding-tooling for injection molds

CNMOULDING is one of the few plastic injection mold makers in China that specialize in manufacturing cost-effective custom injection molding and custom design tooling in China for injection molded plastic parts, compression molds, overmolding, and molds for investment casting. Innovative custom design tooling solutions such as our CAD plastic injection mold design services in China. Our custom design tooling manufacturing in China. Tooling for export program ensures a low upfront cost, high-quality solution for our client’s custom design tooling projects.

Tooling and mold making in China is our preferred manufacturing method for our customers when the time will allow. We feel by offering custom design tooling in China. We are able to give our customers quality steel tools for the price they would pay for aluminum tools in the US or Europe. We can make molds and tools in China to run at our plastics facilities, or to ship to your location.

 

We offer custom design tooling for OEMs, end-users, injection-molded plastics shops. And injection mold makers at our engineering facilities in China. Our experienced engineers allow us to maintain the high quality of our injection mold makers’ design services while keeping costs low. We also work with many U.S. And European design firms producing tools for them and will not sell our design services to their customers.

CNMOULDING designs and manufactures its clients’ custom tools. Die’s and molds to their specifications, produce new molds from its customers’ CAD files, or reverse engineer existing parts. As one of the premier injection mold makers, we are very proficient at reverse engineering many types of parts. We have many different 3D design software platforms to adapt to our customers’ systems. Digital data files and computerized machining are used almost exclusively for the tooling of custom molds.

For small and extremely large parts, which can be manufactured specifically for small or dedicated long-run production molds, provide high-quality custom design tooling. CNMOULDING is one of the best custom design tooling manufacturers in China, specializing in die and tooling design and tooling for export. We can manufacture tools that are multi-cavity molds, unscrewing molds, closure molds, hot-runner molds, and stack molds.

Custom Tooling for Export

Custom tooling for export to the U.S. and other countries is becoming more popular. CNMOULDING builds a large portion of its custom design tools for export. Our clients have found that they can save 50-70% on tooling by having us manufacture the tools for them in China and export them to their facility, a local plastic shop, or our plastic injection molding facility. By making the molds in China customers can reduce their initial investment substantially, and allocate that revenue towards extra inventory if they choose.

CNMOULDING ensures 100% satisfaction with our tools. Detailed drawings are provided for customer approvals, and we always provide prototypes for first article approval prior to packaging and shipping the tools. Custom tools are also designed to fit in whatever injection molding equipment our customers or their suppliers might have. Those dimensions are obtained from our customers prior to finalizing pricing and drawings.
Send us your next custom tooling project for a free reference quote from our factory. We guarantee you will be impressed with the quality and savings!

CNMOULDING: Professional Soft Rubber Product Solutions Provider

 As a company specializing in soft rubber product design, mold development, and manufacturing, CNMOULDING leverages extensive industry experience and technical expertise to provide one-stop soft rubber product solutions, including customized production using various materials such as silicone, TPU, and TPE.  

CNMOULDING’s Core Advantages  

one. Diverse Material Options to Meet Various Needs

We offer a wide range of soft rubber materials, including:  

Food-grade silicone (FDA/LFGB compliant, suitable for baby products and kitchenware)  

High-elasticity TPU (wear-resistant, tear-resistant, ideal for sports gear and industrial components)  

Eco-friendly TPE (recyclable, low hardness, perfect for medical devices and electronic accessories)  

Special-performance soft rubber (custom options for high-temperature resistance, flame retardancy, conductivity, etc.)  

two. Precision Mold Development Ensures Product Quality  

High-precision CNC machining and 3D printing mold flow analysis optimize mold structure  

Support for multi-cavity and stack mold designs to improve production efficiency  

Capable of producing ultra-thin soft rubber parts (as thin as 0.2mm)** to meet high-precision requirements  

three. Advanced Manufacturing Processes Guarantee Performance  

Liquid Silicone Rubber (LSR) Injection Molding—Ideal for high-precision medical and electronic components  

Solid Silicone Compression Molding—Suitable for high-temperature kitchenware and seals  

TPU/TPE Injection Molding—Used for anti-slip grips, sports protectors, etc.  

Overmolding (Two-Shot Molding)—Combines hard and soft rubber for enhanced functionality  

four. Strict Quality Control Complies with International Standards  

ISO 9001 certification ensures standardized production processes  

RoHS/REACH compliance testing meets export requirements  

Physical performance testing (tensile strength, tear resistance, temperature resistance, etc.)  

Why Choose CNMOULDING?

End-to-end support from design to mass production—DFM (Design for Manufacturability) analysis optimizes product structure  

Rapid prototyping and small-batch production—Shortens product development cycles  

Cost-optimized solutions—Material selection and process improvements reduce overall costs  

Global logistics support—Stable supply chain for markets in Europe, America, Asia, and beyond  

Contact Us for Professional Soft Rubber Solutions!  

TEL: 86-21-52913487

FAX: 86-21-59907980

WhatsApp/Wechat: +8613061707408

Email: webmaster@cnmoulding.com  

CNMOULDING—Your Trusted Soft Rubber Manufacturing Partner!