In injection molding manufacturing, molding companies make custom parts by incorporating an injection molding process. In this process, the liquified material is injected into the custom-designed mold. Custom injection molding creates plastic parts by injecting molten plastic into a custom-made mold. This process allows for complex designs, tight tolerances, and consistent high-volume production.
Before moving ahead, let’s know what makes custom injection molding the go-to solution for creating high-quality products. Here are the process details, mold design, materials and applications.
Overview of the Injection Molding Process
Key Steps in the Injection Molding Process
1. Material Selection and Preparation
Material selection:
Material selection is the very first step involved in injection molding manufacturing. This is where the plastic resin is chosen. There is more to this; you must look for strength, flexibility, heat resistance, and chemical compatibility in the material.
Material preparation:
The material preparation is the process where certain resins are transformed into a consistent, moldable phase for injection into the mold cavity.
- Remove the moisture from the materials; for this, you can use drying ovens or desiccant dryers.
- Grinding is done when you need to reduce the size of resin pellets so that they consistently melt and flow into the injection mold.
- Adding color does increase aesthetic appeal.
- Where combining the various materials in the blending process will improve processes. For instance, reinforcements like fiberglass are most important to increase strength. And the UV stabilizer protects parts from degradation due to UV radiation caused by sunlight.
2. Mold Design and Production
The most important part of the injection molding process is all of the mold designs and production. That is the stage where we create and build a plastic mold. These molds are made to create the same shape as you need to produce the application parts.
- Use the best software available, like CAD. They are sufficient enough to design molds in particular shapes with desired wall thickness and undercuts.
- Draft angle is the way we prefer to slide out the finished part of the mold using reduced friction.
- You must set the thickness of the draft angle to about one degree per inch. However, the size and direction totally depend on the part shape and resin types.
- Choose the best material carefully, knowing the application requirements.
- The gating system is actually a pathway for melted material to flow into the mold cavity.
- And the cooling systems concern themselves with regulating the mold temperature to avoid warping.
- Venting is necessary to release the trapped air that might cause burn marks and voids.
- Testing molds is most commonly done to check whether mold creates an exact shape part or if there are any defects like incomplete fills, flashes, etc.
3. Injection, Cooling, and Ejection
注射をする：
We’ll get into a plasticizing phase when we do feed plastic granules into a heated barrel. That melted the material and homogenized it.
The injection phase is started when the molten material is injected through a nozzle into the mold under high pressure. For doing this, usually a screw or plunger is used. The pressure supply is to make sure the molds are equally filled.
冷却：
If talk about the cooling techniques that can be done by oil-based systems. It solidifies the plastic and also needs sufficient time; otherwise, there are chances for deformation or shrinking.
退場：
The ejector pins and plates help in sliding out the prepared part from the mold cavity. If needed, the mold agents can avoid sticking, coating the part to a clean release without damaging it. For quality assurance, you have to trim the excess material from gates and runners.
Injection Molding Manufacturing Advantages
The advantages of custom injection molding services we’re going to put here are:
- This is the unmatched versatility that is needed to create massive design ranges.
- You can select them to produce the most complex and detailed shapes for, of course, correlational applications.
- If you want to spend less, then this is the process that is highly cost-effective for large-volume production.
- Their created molds are reusable, and that cuts off the per-unit costs.
- The recyclability of scrap plastics and precise molding technique minimize material waste. Not only that, you will get consistency in quality and precision all the time, which is obviously necessary for the automotive, electronics, and healthcare industries.
- Besides these, injection molding services are suitable for those fast production cycles and reliability.
Challenges in Custom Injection Molding
Complex mold-making process:
The manufacturing process always involves some technical issues and challenging situations for workers along the way. Where the complex mold-making process is the most difficult part. It must require some expertise in design and engineering. That may be the cause of the delay in production timelines.
Initial costs for custom tooling:
High initial costs for custom tooling actually put barriers in front of small-scale companies. They might face difficulty maintaining consistent quality in high volume. Because faults in mold will result in rejection. More importantly, while combining additives with material, the material limitation may shrink or affect the part performance.
However, the mentioned challenges and all other major defects, like part sticking or cooling system failures, can be tackled by applying critical optimization rules.
Materials for Custom Injection Molding
Common Thermoplastics
These are the common plastic materials you can use.
- Polyethylene (PE): It can be used for packaging applications where you need flexible and low-cost material.
- Polypropylene (PP): It is a tough and strong material and is a good option for chemical resistance and high heat deflection temperature.
- Acrylonitrile Butadiene Styrene (ABS): It can provide impact resistance. So, if you use this material, you can already make paintable surfaces.
- Polycarbonate (PC): It is the proof of concept for strength and good dimensional stability.
- Nylon (PA): This combines the advantages of both tensile strength and wear resistance.
- Polyvinyl chloride (PVC): This is a very widely used material, most commonly for flexible parts.
How to choose injection molding materials?
Before you get into custom injection molding services, the materials are chosen to meet demanding applications. Such as the high-performance polymers. The Peek (Polyether Ether Ketone) is the solution that you can use for its high heat resistance, chemical stability, and strength. Especially in the industries of aerospace, automotive and medical equipment.
Meanwhile, TPU (thermoplastic polyurethane) is the go-to option to get flexible, abrasion resistance and elastic for footwear, seals, and electronics.
Common Materials Used in Custom Injection Molding
| 素材 | グレード | 引張強さ (MPa) | Impact Strength (kJ/m) | 曲げ弾性率 (GPa) | Heat Deflection Temperature (°C) |
|---|---|---|---|---|---|
| ABS（アクリロニトリル・ブタジエン・スチレン） | General Purpose | 40-50 | 10-15 | 2.5-3.5 | 90-100 |
| 耐衝撃性 | 30-40 | 20-30 | 2.0-3.0 | 80-90 | |
| PC (Polycarbonate) | General Purpose | 60-70 | 10-15 | 2.5-3.5 | 130-140 |
| 耐衝撃性 | 50-60 | 20-30 | 2.0-3.0 | 120-130 | |
| PA (Polyamide, Nylon) | General Purpose | 80-100 | 10-15 | 3.0-4.0 | 150-160 |
| High Impact | 60-80 | 20-30 | 2.5-3.5 | 140-150 | |
| POM (Polyoxymethylene, Acetal) | General Purpose | 60-70 | 10-15 | 3.0-4.0 | 120-130 |
| High Impact | 50-60 | 20-30 | 2.5-3.5 | 110-120 | |
| HDPE (High-Density Polyethylene) | General Purpose | 20-30 | 5-10 | 1.0-2.0 | 80-90 |
| High Molecular Weight | 30-40 | 10-15 | 1.5-2.5 | 90-100 | |
| PP (Polypropylene) | General Purpose | 20-30 | 5-10 | 1.0-2.0 | 80-90 |
| 耐衝撃性 | 15-25 | 10-15 | 0.8-1.8 | 70-80 | |
| TPU（熱可塑性ポリウレタン） | General Purpose | 30-50 | 10-20 | 0.5-1.5 | 60-80 |
| High Abrasion Resistance | 50-70 | 20-30 | 1.0-2.0 | 80-100 | |
| PET (Polyethylene Terephthalate) | General Purpose | 50-70 | 10-15 | 2.5-3.5 | 120-130 |
| High Impact | 40-60 | 20-30 | 2.0-3.0 | 110-120 |
Note:
1: Tensile strength, impact strength, and flexural modulus are measured according to ISO 527, ISO 179, and ISO 178, respectively.
2: Heat deflection temperature is measured according to ISO 75.
Sustainability in Material Selection
Sustainability is the topic that is sought by manufacturers to meet the green environment demands.
Recyclable plastics like polyethylene (PE) and polypropylene (PP) are the most common options among other materials. Bioplastics and eco-friendly alternatives like polylactic acid (PLA) are usually created from corn starch-like materials.
Incorporating recycled materials in production promotes a green future. And the underprocess techniques for improving reprocesses are also helping the manufacturers to make quality parts for reuse.
Applications of Custom Injection Molding
自動車産業
Automotive injection molding manufacturer builds such parts in custom injection molding. That needs to be safe and durable. The reason behind using plastic is to replace those heavy metal parts so as to improve fuel efficiency. Usually, automotive parts are dashboards and gear housings.
医療・ヘルスケア
Surgical instruments, diagnostic parts, or biocompatible implant types can be made with medical-grade polycarbonate. So that the safety assurances and sterility remain present. This process is especially beneficial for processing with prosthetics and drug delivery systems.
Electronics and Consumer Goods
The injection process for electronic devices like smartphone cases and household appliances brings precision. And as far as electronics housings, connectors, and other durable, heat-resistant parts concerns, it can offer aesthetic, functional, and durable solutions.
Emerging Industries
Aerospace, robotics, and renewable energy sectors leverage this process as they need to build complex parts with lightweight features. And more often, drones, wind turbine components, and robotic joints are created in some kind of special mold to give them better-optimized performances.
Importance of Design for Manufacturability (DFM)
Design for Manufacturability (DFM) for custom injection molds: this is to set the product efficiency and cost. So the quality of the product may be enhanced and there is a faster time to market.
It allows manufacturers to simply create complicated mold designs and increase production time. As the example of this is avoiding undercuts to reduce toling issues.
The other feature is to swiftly eject the parts by protecting them from damage as they incorporate draft angles.
Reduce some material waste as it maintains uniformity in wall thickness at a minimum of 1.5mm, truly based on the material. But somehow, these 薄肉射出成形 materials still need strength.
Tooling and Mold Customization
Instead of using affordable standard tools, you must choose high-quality tools in custom injection molding services. That comes with precision and durability. But you can’t go straight to the same tooling material.
As the steel molds are particularly suited for high-volume production. And the aluminum option is good for prototypes or small batch units. Because these are easy to work with and faster to machine.
Speaking of mould design, here come several factors to weigh, like shrinkage rates and wall thickness. Meanwhile, the gating systems will control the flow of liquefied resins into the mold. Cooling systems this in mold increase thermal efficacy, take less time to produce large volumes and reduce defects issues in created parts.
Prototyping for Custom Parts
Prototyping is necessary to improve the part’s design and functionality. This can be done by 3D printing and the soft tooling method. It generally helps in verifying the part’s functionality, fit, and aesthetics. You can easily get into the areas where the issue lies, whether in material flow cooling or ejection, before large-scale production.
Checklist for Designers To Avoid Defects in Injection Molding
1. Part Design Considerations
- Ensure Uniform Wall Thickness:
- Design parts with consistent wall thickness. It will help you to avoid warping and uneven cooling.
- Add Draft Angles:
- Include at least 1° to 2° of draft per side. It will give smooth part ejection from the mold.
2. Flow and Fill Optimization
- Design for Balanced Flow Paths:
- Ensure gate locations allow for even material distribution.
- Avoid Thin Sections:
- Ensure walls are thick enough to allow proper material flow.
3. Assembly Features
- Use Snap-Fit Designs Where Possible
- Ensure Tolerances for Press Fits
4. Avoid Common Defects
- Minimize Weld Lines:
- Adjust gate location to avoid weak points .
- Prevent Sink Marks:
- Avoid excessive wall thickness; maintain a ratio of ribs and bosses to wall thickness at 0.5:1 or less.
Cost Factors in Custom Injection Molding
Tooling and Setup Costs
The initial investment in molds, including setups, is most likely to range between $3000 and $100000. And also depends on the material you choose and complexity levels.
Cost Optimization Strategies
Integrating an impactful strategy may save you the most, as you can plan to generate in bulk quantities. That results in reduced per-unit cost, and of course, design efficiency and material usage may also minimize waste.
Balancing Cost and Quality
The most specific tools with those top-quality features cost more, so choose Wisley by balancing the moderate but durable setups.
How to choose right custom injection molding service?
Criteria for Selection
If there’re options to select your best injection molding service provider, then choose the best platforms, like PCBasic. Look for criteria and expertise in specific industries. As you’re going to receive customization capabilities, also consider the range of materials and high-performance options.
Quality Assurance in Services
Service providers should provide certifications like ISO standards. That is there to ensure precision and repeatability in their manufacturing processes.
Added Services and Support
We, as the most skilled manufacturers, offer comprehensive support. Whether you need us in the design phase to refine the concepts, post-production services, or logistic support.
We effectively streamline the delivery and inventory management. That is why collaborating with us will give you a chance to have high-performance injection molding processing with included added services.
結論
At this conclusion point, custom injection molding service providers have a pivotal role in advancing modern manufacturing. So, the key takeaways are that they are tailored solutions that provide high precision and cost efficiency. And this technique drives innovation across industries.
Plastic Mold is a leading custom injection mold manufacturer in China. Our company provides a free quotation engine system for unlimited quotes for ダイカスト金型, silicone rubber, machining, and electronic components.
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